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Context. The decline and extinction of native burrowing mammals across much of Australia has resulted in a loss of underground refugia constructed by native fauna in the environment. The introduced European rabbit (Oryctolagus cuniculus) is now the most widespread mammalian burrower across Australia. Rabbits are an invasive species in Australia, and the destruction of rabbit warrens for pest management is common practice. This destruction of warrens removes a potential refuge for both rabbits and other species in the environment. In landscapes where critical weight range burrowing mammals have declined, the widespread destruction of rabbit warrens removes many underground refuges for several commensal animal species. Aims. To identify the use of rabbit warrens by fauna in the seasonally hot, semi-arid Ikara-Flinders Ranges National Park (IFRNP) in South Australia. Methods. We used camera traps placed at burrow entrances of warrens and nearby structure to identify the vertebrate species that interact with rabbit warrens in the IFRNP. Key results. We recorded 11 bird, nine mammal and eight reptile species present at the entrances of rabbit warrens. Only four of the taxa recorded on cameras in our study showed a preference for warrens over adjacent above-ground structure, three of them introduced species. The alien commensal species recorded using the burrows were rabbits, house mice (Mus musculus) and feral cats (Felis catus). Conclusions. Rabbit warrens in the IFRNP are an important resource for a range of native and alien commensal species. In our study, they seem to be of special importance for introduced species. Implications. Warren removal in the IFRNP may negatively impact native commensal species in treated areas but is likely to be of long-term net benefit for a wider range of native animals. [ABSTRACT FROM AUTHOR]

Abstract The objective of this work was to evaluate the effect of the dietary addition of calcium anacardate as a source of phenolic compounds on the reproductive performance and blood antioxidant parameters of New Zealand White female rabbits. Twenty-seven New Zealand White female rabbits were distributed in a randomized complete block design with three treatments and nine replicates, considering one animal as the experimental unit. The treatments consisted of pelleted diets with different inclusion levels of calcium anacardate (0, 0.5, and 1.0%). The inclusion of calcium anacardate in the diets increased the concentration of phenolic compounds and the antioxidant capacity in the blood of lactating female rabbits. Calcium anacardate at the level of 1.0% improves the feed conversion ratio during gestation and increases the phenolic compounds and antioxidant capacity in the blood serum of female rabbits at 21 days of lactation.

Global meat production and consumption are increasingly unsustainable. One way to counteract this development is to change the type of meat consumed. Rabbit meat has relatively lower climate impact than many other types of meat, but consumer acceptance is crucial for a socially sustainable production. In this study we examine the acceptance of industrial, extensive and urban rabbit production among Swedish senior high school youth, 17 to 19 yr old. An electronic survey was sent to ten randomly selected senior high school classes with 17 to 19 year-old students. The survey included inquiries about background, scaled responses and open-end questions with the opportunity to comment. A total of 111 students completed the survey, of which 62 were women, 74 from rural areas and 91 with previous animal experience. Extensive production was more accepted than industrial and urban production, while no difference was observed between industrial and urban production. Thus, the results advocate a farming system with more animal movement, less productivity and higher space requirements. In general, male respondents were more accepting of all production systems than women, while no difference could be detected between rural and urban citizens. The scaling shows that animal welfare, local production and meat quality was given priority over climate impact, biodiversity and price. Our study suggests useful prerequisites to consider for the meat industry in general, and for the development of Swedish rabbit production.

Abstract Background Indonesian local rabbit (Oryctolagus cuniculus) is a local breed in Indonesia. We reveal the mitochondrial genome sequence of the Indonesian local Rabbit for the first time. A better understanding of the mechanisms underlying these beneficial aspects of local breeds over imported ones requires detailed genetic investigations, of which mtDNA genome sequencing is of particular importance. Such an investigation will solve the major issues of misidentification with Javanese hares (Lepus nigricollis) and maternal lineage. In addition, this information will guide better statistics on the Indonesian local rabbit breed population and strategies for its conservation and breeding plans. This study aimed to identify and explore the characteristics of the mtDNA genomes of Indonesian local rabbits. Result This study observed that the length of the mtDNA genome is 17,469 bp, consisting of two ribosomal RNA (12S rRNA, 16S rRNA), 22 transfer RNA genes (trnR, trnG, trnK, trnD, trnS, trnY, trnC, trnN, trnA, trnW, trnM, trnQ, trnl, trnL, trnV, trnF, trnP, trnT, trnE, trnL, trnS, trnH), 13 protein-coding genes (PCGs) (ND4l, ND3, COX3, ATP6, ATP8, COX2, COX1, ND2, ND1, CYTB, ND6, ND5, ND4), a replication origin, and a noncoding control region (D-loop). Conclusions mtDNA genome of Indonesian local rabbit was the longest and had the most extended D-loop sequence among the other references of Oryctolagus cuniculus. Other specific differences were also found in the percentage of nucleotides and variation in most of the PCGs when they were aligned with Oryctolagus cuniculus references from GenBank. Indonesian local Rabbits strongly suspected brought from Europe during the colonial period in Indonesia.

The introduction of a domestically produced Rabbit Hemorrhagic Disease type 2 (RHDV2) Vaccine (Medgene Labs) has been a welcome relief to veterinarians, rabbitries, and pet rabbit caretakers. Currently, the vaccine is only available in a 10-dose vial that must be used immediately. The purpose of this study was to determine if the vaccine can maintain sterility as a multidose vial across 16 days. Over a period of 16 days, a total of ten 0.5 mL samples were aseptically collected from 2 experimental vaccine bottles, and 1 control bottle was sampled on day 10. A total of 21 aerobic bacterial cultures and 5 fungal cultures were collected. The samples were collected daily, that all vials were opened on the first day of the experiment and the control vial was pierced for the first time on day 10. Of the 21 aerobic bacterial cultures collected and 5 fungal cultures collected over 16 days, there was no growth detected by the microbiology lab. In summary, this study provided evidence that when collected with appropriate aseptic precautions, the recombinant subunit RHDV2 vaccine could potentially be used extra-label, once fully approved by the USDA, as a multidose vial for at least 16 calendar days without compromising sterility, pending pyrogen and endotoxin testing as well as anaerobic cultures and potentially next generation DNA sequencing. [ABSTRACT FROM AUTHOR]

Surveillance of wildlife virus impacts can be passive or active. Both approaches have their strengths and weaknesses, especially regarding cost and knowledge that can be gained. Monitoring of rabbit haemorrhagic disease virus (GI.1 and GI.2) in South Australia has utilised both strategies and their methods and gained insights are discussed. Active strategies to monitor the continuing impact of rabbit haemorrhagic disease virus 2 (GI.2) on susceptible lagomorphs in countries such as the USA, Mexico, South Africa, Spain, France and Portugal are encouraged to gain critical insights into the evolution, spread and impact of this virus. Furthermore, there are lessons here for the international monitoring of diseases in wildlife, particularly where there is a risk of them becoming zoonotic.

Ovarian torsion (OT) is a condition that can affect both humans and animals, although it is less common in the latter, with very few cases documented in the literature. To our knowledge, no previous reports have documented the occurrence of this condition in rabbits. In this study, we present the first documented case of spontaneous OT in a 2-year-old female intact rabbit. The patient was brought to the clinic for a routine check-up, during which a firm, large abdominal mass was palpated. Subsequent ultrasound examination of the abdomen revealed the presence of a large, hypoechoic, non-vascularized mass occupying the majority of the caudal abdomen. A computed tomography (CT) scan further confirmed the presence of a heterogeneous mass exhibiting the Whirlpool sign, which is characteristic of organ torsion. Upon laparotomy, an enlargement of the right ovary was observed, characterized by twisting of the ovarian pedicle, consistent with the mass detected via ultrasound and CT scan. Ovariohysterovaginectomy was performed, and the mass was subsequently analyzed. Microscopic analysis of the mass revealed predominantly necrotic tissue, with only a few ovarian epithelial cells present. The underlying cause of the OT described in this study remains unclear. However, it is plausible that a previous neoplastic condition or ovarian necrosis led to an increase in the size and weight of the mass, ultimately resulting in the twisting of the supporting structures.

The aim of the present study was to evaluate the characteristics of carcasses, monitor their pH evolution during the first 24 h post-mortem, and determine the time required for the establishment and resolution of rigor mortis in different categories of Botucatu rabbits. Live weight at slaughter, carcass weight, and yield were higher in 12-month-old animals compared to 3-month-old rabbits, regardless of sex. There was an effect of muscle type, age, and sex on the kinetics of muscle acidification, with the Biceps femoris showing a significantly higher pH than the Longissimus lumborum from 4 h post-mortem onward. The establishment of rigor mortis occurred at 5 h post-mortem in young rabbits and bucks and at 6 h post-mortem in does, along with pH stabilization, while the resolution of rigor occurred at 18 h post-mortem for all types of carcasses evaluated. In conclusion, Botucatu rabbit carcasses should be chilled continuously at 4 °C for a minimum of 18 h to ensure efficient rigor mortis progression and muscle-to-meat transformation throughout the carcass.

The aim was to assess the impact of long-term storage on the quality of Botucatu rabbit meat frozen in pre- and post-rigor stages. The stability of the technological and nutritional parameters of Longissimus lumborum (LL) muscle was analyzed over 12 months. In the post-rigor phase, the dorsal LL surface showed a higher level (p < 0.05) of redness and saturation, while the ventral surface showed a higher level (p < 0.05) of yellowness compared to the pre-rigor LL muscle. During storage, the redness and saturation in the LL muscle decreased (p < 0.05), while the yellowness increased (p < 0.05) on both dorsal and ventral surfaces. In the first six months, the pre-rigor meat had a higher pH (p < 0.05) compared to the post-rigor meat. The fresh meat showed higher (p < 0.05) shear force values in the post-rigor stage. Over the 12-month study period, the lipid oxidation, myofibrillar fragmentation index, gross energy, and levels of protein, fat, and carbohydrates increased (p < 0.05), while the shear force, mineral content, and moisture decreased (p < 0.05). Thus, rigor mortis affects meat color in Botucatu rabbits. Fresh meat in the pre-rigor stage is softer, moister, and less acidic than post-rigor meat after 24 h of chilling. Long-term freezing enhances tenderness, regardless of the rigor phase at freezing, preserving its physical, chemical, and nutritional quality, with minor changes in color, lipid oxidation, and chemical composition.

Abstract Several conventional and recently available tools are available for an integrated control of European rabbits in Australia. We quantified the impact of the release of rabbit haemorrhagic disease virus K5 (RHDV K5, hereafter K5) and pindone (2‐pivalyl‐1,3‐indandione) baiting at 13 sites within Cudlee Creek fire scar in the Adelaide Hills, South Australia. K5 release was followed by pindone baiting between December 2021 and March 2022; the application of both control methods followed industry best practice. We counted rabbits using spotlights before and after the application of both control methods. Fly samples and livers from dead rabbits were collected to track K5 transmission within and between sites, and to detect the natural circulation of rabbit haemorrhagic disease virus 2 (RHDV2). K5 release had minimal impact on rabbit populations, with treated populations increasing by a mean of 65.5% at 14 days post‐release and 27.9% at 77 days post‐K5 release across all sites, comparable to the changes at control sites. K5 detection in flies up to 77 days post its release, and its detection in rabbit livers, demonstrates that it can survive and transmit in the environment for prolonged periods and that it can lethally infect some rabbits. This limited impact of K5 is consistent with previous studies and may be explained by pre‐existing RHDV/RHDV2 immunity in the target populations or the presence of young rabbits with natural innate RHDV immunity. The detection of K5 in flies from control sites demonstrates that it was vectored beyond its release location. A reduction in rabbit counts post‐pindone baiting was observed at most treatment sites, with a mean population reduction of 36.6% across all sites. Landholders need to carefully and strategically plan their integrated rabbit control programmes. Not all combinations of controls, even if theoretically logical, achieve meaningful outcomes for rabbit management.

Digestive problems, both those with a clear pathogenic origin (e.g., Escherichia coli) and those without obvious pathogen involvement [e.g., syndromes like epizootic rabbit enteropathy (ERE)], are common in production rabbits and account for the majority of losses in meat rabbit production. A multitude of nutritional, genetic and housing factors have been found to play a role in the occurrence of digestive problems. However, the exact early pathophysiological mechanism, including the links between aforementioned risk factors and subsequent development and expression of gastrointestinal disease, is less clear, especially in non-specific enteropathies without obvious pathogen involvement. In this review, we aim to shed more light on the derailment of the normal gastrointestinal functioning in rabbits. We discuss a conceptual integrated view of this derailment, based on an “overload” pathway and a “chymus jam” pathway, which may occur simultaneously and interact. The “overload” pathway centers around exposure to excess amounts of easily fermentable substrate (e.g., starch and protein) that might be incompletely digested prior to entering the caecum. Once there, hyperfermentation may result in changes in caecal pH and inhibition of the normal microflora. The second pathway centers around a chymus jam resulting from a compromised passage rate. Here, reduced hindgut motility (e.g., resulting from stress or limited fiber supply) leads to reduced flow of digesta and increased caecal retention times, which might lead to the production of abnormal caecal fermentation products and subsequent inhibition of the normal microflora. A central role in the presumed mechanism is attributed to the fusus coli. We discuss the suggested mechanisms behind both pathways, as well as the empirical substantiation and alignment between theoretical concepts and observations in practice. The proposed hypotheses may explain the effect of time-based restriction to prevent ERE, which is widely applied in practice but to date not really understood, and suggest that the particle size of fiber may be a key point in the normal functioning of the colon and fusus coli. Further insight into the circumstances leading to the derailment of physiological processes in the rabbit hindgut could provide a meaningful starting point to help improve their gastrointestinal resilience.

Both the nature of the human-animal relationship (HAR) and housing conditions significantly impact the welfare of farmed animals. To evaluate the influence of HAR on the behaviour, emotions and stress of rabbits (Oryctolagus cuniculus) in two distinct outdoor living environments, we allocated 144 young rabbits to four groups (CPX-H, CPX-N, SPL-H, SPL-N) differing in the living environments (CPX for complex, and SPL for simple). The treatment by human (H) involved daily provision of additional food resources and stroking (thoughtful farmer). It commenced at 49 days of age and lasted for 16 days. N groups did not receive the treatment (distant farmer). The rabbits were observed between 48 and 73 days of age. Their behavioural responses to human presence were evaluated at 48 and 68 days using Qualitative Behaviour Assessment (QBA) and scan sampling. A set of tests was conducted at 68 days of age to assess their reactions to a novel object and human presence. Stress levels were measured by analysing corticosterone concentrations in their hair. Rabbits in the SPL environment spent significantly more time near the novel object than those in the CPX environment (24.7 vs 17.2%). Additionally, rabbits in the H treatment group spent more time near the human than those in the N treatment group (28.2 vs 17.1%) and accepted more strokes (90.2 vs 45.9%). Following the HAR treatment, rabbits in the H group were significantly more likely to be described as ‘Affectionate/Interested’ than those in the N treatment. Rabbits in the N treatment were described as ‘Indifferent’ significantly more in the SPL environment. However, there were no significant differences in hair corticosterone concentrations between the groups. These findings indicate that rabbits’ responses are influenced by both their living environment and the quality of their relationship with humans. Encouraging positive interactions with animals may enhance their welfare and facilitate daily care from farmers.

The impacts of different dietary levels of rice gluten meal (RGM) on growth performance, digestibility, carcass characteristics, and blood traits of growing New Zealand White (NZW) rabbits were studied. One hundred and twenty, 6 weeks old weaned male rabbits (body weight; 682 [g] ± 23) were randomly allotted into four groups. The control diet contained 160 [g/kg] soybean meal (SBM), while the other three diets were obtained by replacing 40, 80, and 120 [g/kg] SBM with RGM (RGM40, RGM80, and RGM120, respectively). The results showed that RGM contained higher levels of dry matter (DM), crude protein (CP), ether extract (EE), ash, and gross energy than SBM. RGM contained a high level of arginine followed by leucine and valine as essential amino acids and high levels of glutamic, aspartic acid, and alanine as non-essential amino acids. The obtained results showed that the final body weight of rabbits fed diets containing 40, 80, and 120 [g/kg] RGM was higher than those fed the control diet. The daily weight gain of rabbits fed RGM diets increased (p < 0.05) by 10.50%, 6.50%, and 10.00%, respectively, compared to the control group. Rabbits fed RGM80 showed the highest (p < 0.05) digestibility of DM, organic matter (OM), EE, neutral detergent fibre (NDF), and acid detergent fibre (ADF) compared to the other tested levels. Rabbits fed RGM120 had the highest (p < 0.05) digestible energy (DE) and digestible crude protein (DCP) values. RGM inclusion levels of 40 and 80 [g/kg] increased (p < 0.05) plasma total protein and albumin compared to the control group. Rabbits fed a diet containing RGM40 had the highest (p < 0.05) globulin level. The highest (p < 0.05) plasma urea concentration level was measured in the rabbit group fed the RGM120 diet. Conclusively, RGM could be a valuable ingredient for growing rabbits, as at all the tested levels improved growth performance, digestibility, and nutritional values. [ABSTRACT FROM AUTHOR]

Background. Antipredator behaviors are theoretically subjected to a balance by which their display should be minimized when their benefits do not outweigh their costs. Such costs may be not only energetic, but also entail a reduction in the time available for other fitness-enhancing behaviors. However, these behaviors are only beneficial under predation risk. Therefore, antipredator behaviors are predicted to be maximized under strong predation risk. Moreover, predation pressure can differ among individuals according to traits such as sex or body size, if these traits increase vulnerability. Antipredator behaviors are expected to be maximized in individuals whose traits make them more conspicuous to predators. However, how sex, body size and antipredator behaviors interact is not always understood. Methods. In this work, I tested the interaction between sex, body size and antipredator behavior in the common pill woodlouse (Armadillidium vulgare), which conglobate (i.e., they roll up their bodies almost conforming a sphere that conceals their appendages) in response to predator attacks. Specifically, I tested whether latency to unroll after a standardized mechanical induction was greater in animals exposed to predator chemical cues (toad feces) than in conspecifics exposed to cues of non-predatory animals (rabbits) or no chemical cues whatsoever (distilled water), incorporating sex and body mass in the analyses. Results. In agreement with my prediction, latency to unroll was greater in individuals exposed to predator chemical cues. In other words, these animals engage in conglobation for longer under perceived predator vicinity. However, this result was only true for males. This sexual dimorphism in antipredator behavior could result from males being under greater predation risk than females, thus having evolved more refined antipredator strategies. Indeed, males of this species are known to actively search for females, which makes them more prone to superficial ground mobility, and likely to being detected by predators. Body size was unrelated to latency to unroll. As a whole, these results support the hypothesis that antipredator behavior is tuned to predator cues in a way consistent with a balance between costs and benefits, which might differ between the sexes. [ABSTRACT FROM AUTHOR]

Following the recent domestication process of the European rabbit (Oryctolagus cuniculus), many different breeds and lines, distinguished primarily by exterior traits such as coat colour, fur structure and body size and shape, have been constituted. In this study, we genotyped, with a high‐density single‐nucleotide polymorphism panel, a total of 645 rabbits from 10 fancy breeds (Belgian Hare, Champagne d'Argent, Checkered Giant, Coloured Dwarf, Dwarf Lop, Ermine, Giant Grey, Giant White, Rex and Rhinelander) and three meat breeds (Italian White, Italian Spotted and Italian Silver). ADMIXTURE analysis indicated that breeds with similar phenotypic traits (e.g. coat colour and body size) shared common ancestries. Signatures of selection using two haplotype‐based approaches (iHS and XP‐EHH), combined with the results obtained with other methods previously reported that we applied to the same breeds, we identified a total of 5079 independent genomic regions with some signatures of selection, covering about 1777 Mb of the rabbit genome. These regions consistently encompassed many genes involved in pigmentation processes (ASIP, EDNRA, EDNRB, KIT, KITLG, MITF, OCA2, TYR and TYRP1), coat structure (LIPH) and body size, including two major genes (LCORL and HMGA2) among many others. This study revealed novel genomic regions under signatures of selection and further demonstrated that population structures and signatures of selection, left into the genome of these rabbit breeds, may contribute to understanding the genetic events that led to their constitution and the complex genetic mechanisms determining the broad phenotypic variability present in these untapped rabbit genetic resources. [ABSTRACT FROM AUTHOR]

To improve the global optimization ability and convergence speed of the swarm intelligence algorithm, we proposed a new swarm intelligence optimization algorithm, namely the Oryctolagus cuniculus algorithm. This includes five mechanisms: the determination of safety zones, the cave escape, the agglomeration of Oryctolagus cuniculi, the maintenance of the Oryctolagus cuniculus king, and the zone competition. Each solution is represented by each Oryctolagus cuniculus's position (including zone number and specific location number). The grass density and safety index at the location of the Oryctolagus cuniculus represents its fitness value. The determination of safety zones implies that predators such as eagles hunt Oryctolagus cuniculi in dangerous zones, and the zone without predators is considered a safety zone. The cave escape refers to the act of Oryctolagus cuniculi using a connected cave system to flee from a dangerous zone and reach a secure zone, thereby evading potential predators. We select the Oryctolagus cuniculus with higher fitness values as the king of each zone, and the Oryctolagus cuniculi gather towards the Oryctolagus cuniculus king. This mechanism ensures that Oryctolagus cuniculus mainly searches in zones with abundant grass and quickly finds the optimal solution. In the maintenance of the Oryctolagus cuniculus king, we choose the one with higher fitness values as the Oryctolagus cuniculus king. Zone competition is induced by an increase in the number of Oryctolagus cuniculi in zones with abundant grass by ordering the fitness values of each zone, and vice versa. We apply the Oryctolagus cuniculus algorithm to the inversion method of the asteroid spectra reflectance template. The experimental results show that compared with artificial rabbit optimization, this algorithm has a faster rate of convergence and better solution, effectively screens the reflectance template, and improves the Doppler difference velocimetry accuracy. In addition, the application of the Oryctolagus cuniculus algorithm to the knapsack problem also performs effectively. [ABSTRACT FROM AUTHOR]

Background Indonesian local rabbit (Oryctolagus cuniculus) is a local breed in Indonesia. We reveal the mitochondrial genome sequence of the Indonesian local Rabbit for the first time. A better understanding of the mechanisms underlying these beneficial aspects of local breeds over imported ones requires detailed genetic investigations, of which mtDNA genome sequencing is of particular importance. Such an investigation will solve the major issues of misidentification with Javanese hares (Lepus nigricollis) and maternal lineage. In addition, this information will guide better statistics on the Indonesian local rabbit breed population and strategies for its conservation and breeding plans. This study aimed to identify and explore the characteristics of the mtDNA genomes of Indonesian local rabbits. Result This study observed that the length of the mtDNA genome is 17,469 bp, consisting of two ribosomal RNA (12S rRNA, 16S rRNA), 22 transfer RNA genes (trnR, trnG, trnK, trnD, trnS, trnY, trnC, trnN, trnA, trnW, trnM, trnQ, trnl, trnL, trnV, trnF, trnP, trnT, trnE, trnL, trnS, trnH), 13 protein-coding genes (PCGs) (ND4l, ND3, COX3, ATP6, ATP8, COX2, COX1, ND2, ND1, CYTB, ND6, ND5, ND4), a replication origin, and a noncoding control region (D-loop). Conclusions mtDNA genome of Indonesian local rabbit was the longest and had the most extended D-loop sequence among the other references of Oryctolagus cuniculus. Other specific differences were also found in the percentage of nucleotides and variation in most of the PCGs when they were aligned with Oryctolagus cuniculus references from GenBank. Indonesian local Rabbits strongly suspected brought from Europe during the colonial period in Indonesia. [ABSTRACT FROM AUTHOR]

This study describes the pharmacokinetics and adverse effects of methadone in six healthy female New Zealand white rabbits (Oryctolagus cuniculus). In a randomized crossover study, methadone was administered at 0.3 mg/kg intravenously (IV), 0.6 mg/kg intramuscularly (IM), and 1 mg/kg subcutaneously (SC), with 10-day washout periods. The same catheter was used for IV methadone administration and blood sampling. Plasma methadone concentrations were determined by high-performance liquid chromatography-mass spectrometry immediately before and up to 24 hours after drug administration. Respiratory rates and sedation scores were assessed at each timepoint. Food and water intake, stool, and urine outputs were quantified. For IV, IM, and SC routes, the median elimination half-life was 2.3, 3.4, and 5.8, hours, respectively. Median clearance was 1.5 L/h/kg and the volume of distribution was 4.1 L/kg for the IV route. Median bioavailability for IM and SC was 21.5% and 18.0% respectively. Median maximum plasma concentrations were 41.8 and 26.4 ng/mL at 0.2 and 0.4 hours after IM and SC administration, respectively. High interindividual variability was noted. At the doses tested, methadone did not cause sedation. Water intake was decreased immediately after, and food intake was decreased two days after methadone administration. No effects were noted on urine, fecal production, and respiratory rate. At the doses administered, IV reached higher methadone plasmatic concentrations, followed by IM and SC. However, results obtained for the IV should be confirmed in future studies using different catheters for drug administration and blood collection. The minimum effective plasma concentration of methadone is unknown in rabbits; caution should therefore be used when extrapolating from other species. Further studies are warranted to evaluate the pharmacodynamics of methadone in rabbits. [ABSTRACT FROM AUTHOR]

Pain control is a challenge in domestic rabbits (Oryctolagus cuniculus). The objective of this study was to describe the effect of maropitant on pain scores, food intake, and fecal output in domestic rabbits following elective orchiectomy or ovariohysterectomy. Rabbits that underwent orchiectomy or ovariohysterectomy at three institutions were randomly assigned to one of three treatment groups: low-dose maropitant (2 mg/kg SC once), high-dose maropitant (10 mg/kg SC once), and control (1 mL/kg saline SC once). Rabbits were monitored using video surveillance postoperatively. Pain scores were assessed by three blinded observers, and results were grouped into time frames after surgery. Food intake and fecal output were measured until discharge. There were no local side effects with maropitant administration. There were no statistically significant differences between groups with regard to pain behaviors. An inverse trend was noted between increasing maropitant dosage versus food intake and fecal output, which was not statistically significant. Maropitant at 2 mg/kg SC and at 10 mg/kg SC failed to significantly reduce pain when compared to control group. [ABSTRACT FROM AUTHOR]

Bullous keratopathy (BK) is an excessive accumulation of fluid in the cornea resulting in severe edema and protrusion. Based on the literature search, naturally occurring BK has not been reported in a rabbit. A two-year-old female neutered dwarf rabbit (Oryctolagus cuniculus domesticus) presented for worsening corneal edema of the left eye. The left eye was diagnosed with BK that was fluorescein negative. Optical coherence tomography revealed profound corneal lamellar separation typical of BK. The patient was anaesthetized and a temporary tarsorrhaphy (TT) was placed using 5/0 silk with fluid line stents in the upper and lower eyelids. The patient was treated with ofloxacin ophthalmic solution, atropine ophthalmic solution, and oral meloxicam. Following 10 days of TT the corneal thickness improved but edema progressed to occupy most of the cornea. An area of corneal infiltrate could then be seen. A fungal infection was suspected and topical voriconazole 1% was added to the treatment regimen. Following two months of topical therapy the patient healed with mild fibrosis associated with the infiltrated area. Rabbits can be affected by naturally occurring bullous keratopathy and in this case healing was achieved following a temporary tarsorrhaphy and extended medical therapy. [ABSTRACT FROM AUTHOR]

Ureteral cystic lesions are rarely described in pet rabbits. A two-year-old spayed female rabbit was presented for lethargy, anorexia and decreased fecal output of one-day duration. Upon physical examination, a 5−6 cm, mobile, firm abdominal mass was palpated cranially to the urinary bladder. Bloodwork was within normal limits. A contrast-enhanced abdominal computed tomography examination revealed a severe right-sided hydronephrosis, an ipsilateral hydroureter and a voluminous fluid dense nonenhancing mass abutting the right ureter. Medical management was initiated, and a laparotomy was scheduled. In surgery, the mass was diagnosed as ureteral in origin. The right kidney and ureter, along with the mass, were successfully excised and sent for histopathology and bacterial culture. A para-ureteral cyst associated with a severe unilateral hydronephrosis and moderate hydroureter were diagnosed. No associated infection was confirmed. The rabbit recovered uneventfully and bloodwork was unremarkable 2-months postsurgery. This case reports an unusual and likely acquired ureteral lesion. Although rare, a para-ureteral cyst should be considered in the differential diagnosis for an abdominal mass with concurrent anorexia and decreased defecation in the female neutered rabbit. [ABSTRACT FROM AUTHOR]

Primary lung neoplasms have rarely been reported in rabbits. The present case describes the diagnosis and successful surgical management of acinar adenocarcinoma in a pet rabbit. An 8-year-old neutered male rabbit presented with signs of dyspnea that had worsened over several days. Thoracic radiography revealed a soft-tissue opacity in the right medial pulmonary lobe, which was subsequently confirmed on thoracic ultrasound. Computed tomography was performed, revealing a heterogeneous ovoid parenchymal mass. This mass was in contact with the caudal vena cava and the right diaphragmatic pilar. Fine-needle aspiration was performed, and the cytology results were consistent with an epithelial neoplasm in the right medial lobe. Right lateral thoracotomy and lobectomy of the right medial pulmonary lobe were performed. The patient recovered uneventfully, with improved appetite and fecal output. Histological analysis of the mass was consistent with acinar adenocarcinoma. Regular follow-up radiographs did not reveal any significant abnormalities. This case report describes the successful clinical management of an acinar adenocarcinoma of the lung treated by thoracic surgery in a pet rabbit. Primary pulmonary neoplasm should be a differential in rabbits presenting with respiratory signs. [ABSTRACT FROM AUTHOR]

Global meat production and consumption are increasingly unsustainable. One way to counteract this development is to change the type of meat consumed. Rabbit meat has relatively lower climate impact than many other types of meat, but consumer acceptance is crucial for a socially sustainable production. In this study we examine the acceptance of industrial, extensive and urban rabbit production among Swedish senior high school youth, 17 to 19 yr old. An electronic survey was sent to ten randomly selected senior high school classes with 17 to 19 year-old students. The survey included inquiries about background, scaled responses and open-end questions with the opportunity to comment. A total of 111 students completed the survey, of which 62 were women, 74 from rural areas and 91 with previous animal experience. Extensive production was more accepted than industrial and urban production, while no difference was observed between industrial and urban production. Thus, the results advocate a farming system with more animal movement, less productivity and higher space requirements. In general, male respondents were more accepting of all production systems than women, while no difference could be detected between rural and urban citizens. The scaling shows that animal welfare, local production and meat quality was given priority over climate impact, biodiversity and price. Our study suggests useful prerequisites to consider for the meat industry in general, and for the development of Swedish rabbit production. [ABSTRACT FROM AUTHOR]

Simple Summary: Rabbit farming plays a significant role in the global production of animal-derived protein, with hundreds of millions of rabbits being produced every year. However, research on feto-maternal monitoring in rabbits remains limited. This review aims to explore intricate factors affecting maternal and fetal health, providing valuable insights for farmers and researchers alike. Standardizing monitoring approaches, such as ultrasonography and other screening methods, and establishing reference parameters would enable more effective tracking of fetal well-being. This, in turn, would facilitate differentiation between healthy and unhealthy rabbits, offer guidance for treatments, and enhance rabbit welfare and reproductive efficiency, thereby holding substantial promise for the rabbit farming industry. Rabbit production holds significant relevance in modern agriculture due to its potential as a sustainable source of high-quality protein and efficient feed conversion, contributing to food security and economic diversification. Nevertheless, studies incorporating feto-maternal monitoring in this species are uncommon. This review gathers research on the monitoring and evaluation of factors affecting rabbit gestation, providing a better understanding of the causes of prenatal development abnormalities. These include studies regarding how chronic maternal hypertension, gestational diabetes, maternal stress, ectopic gestation, maternal uterine ischemia and fetal hypoxia, intrauterine growth restriction, superfetation, maternal age, maternal nutritional status, maternal physical condition, maternal and embryonic genotype, and the intrauterine location of rabbit fetuses can potentially impact rabbits' reproduction and maternal and fetal health. Among other monitoring techniques, ultrasonography, considered one of the best tools for diagnosing pregnancy and conducting follow-up, is also reviewed. Details on measurable fetal-development parameters in rabbits and precautions to be considered before and during the examination are also provided. Additional studies are required to understand why some events occur and their consequences throughout gestation, allowing the determination of new biomarkers or cut-offs that can be helpful for early diagnosis and improve reproductive efficiency. [ABSTRACT FROM AUTHOR]

Pasteurellosis, a disease caused by Pasteurella multocida, is responsible for economic losses in rabbit industrial farms due to rhinitis, conjunctivitis, pneumonia, metritis, mastitis, orchitis, subcutaneous abscesses, otitis, encephalitis, and septicaemic forms. Although the occurrence of the disease is conditioned by predisposing factors that affect the rabbit immune response, the strains of P. multocida involved in the infection may have a different pathogenic ability. Therefore, typing of strains spread among the rabbits is important to assess their pathogenic potential. The aim of this study is to investigate the P. multocida strains responsible for disease in rabbit industrial farms. A total of 114 strains identified from different lesions were serotyped. Additionally, the presence of virulence-associated genes was investigated using three PCR (polymerase chain reaction) protocols. Capsular type A was prevalently found in strains from respiratory lesions while types D and F in those from metritis, mastitis, and other lesions. Different associations between some virulence-associated genes and both capsular type and lesions found in rabbits were detected. The presence of 8 virulence-associated genes seems to increase the occurrence of metritis. In addition, strains belonging to capsular type A and responsible for respiratory disorders especially, were found equipped with 10 and 11 virulence-associated genes. Nevertheless, the presence of strains responsible only for rhinitis was also detected among the latter, suggesting that the pathogenic ability of the bacteria depends on the expression rather than the presence of a gene.

The concentration of ammonia (NH3) and the temperature of the air surrounding the rabbit habitat in the farm condition basic health processes such as breathing and feeding. The indoor climate in a rabbit farm is largely conditioned by the ventilation system (air conditioning). The objective of this study was to build a numerical model based on computational fluid dynamics (CFD) in order to evaluate, by numerical simulations, the air dynamics of a rustic farm. After the validation of the computational model, the thermal gradient and ammonia concentration were analyzed under three wind incidence angles (0°, 45°, and 90° with respect to the horizontal Z axis of the facility). The results of the simulations showed that, in the area occupied by the rabbits (AOR), the concentration of ammonia with respect to the source was reduced by 37.3% in the most favorable case (wind direction at 45°), and 21.2% in the least favorable case (wind direction at 0°), and the indoor temperature presented a maximum difference of 2 °C with respect to the outside temperature. Climate control is a more expensive cost in rabbit farm exploitation; dynamics modulation can serve as an auxiliary tool for reducing health risks in rabbits. The use of models based on fluid dynamics allowed us to understand the efficiency of the ventilation system, which must be increased to reduce the found temperature gradient. Through numerical simulation it will be possible to find alternatives to increase the ventilation rate.

Leishmania infantum is a zoonotic protozoan parasite distributed worldwide that is transmitted by phlebotomine sandflies. Dogs are the main reservoir for human infections. However, in recent years, the capacity of lagomorphs to contribute to Leishmania transmission has been confirmed. The present study aimed to assess Leishmania spp. exposure and infection in lagomorphs and sympatric domestic dogs in NE Spain. Sera from European hares, European rabbits, and rural dogs were tested for antibodies against L. infantum using an in-house indirect ELISA. PCR analysis targeting Leishmania spp. was performed in spleens from L. europaeus. Antibodies against Leishmania spp. were detected in all the species analyzed. Total sample prevalence was significantly higher in O. cuniculus (27.9%) than in L. europaeus (2.0%). Results of the PCR were all negative. The present study expands knowledge about Leishmania infections in free-ranging lagomorphs in the Iberian Peninsula, suggesting a more important role of O. cuniculus in the study area. Given the strong correlation between lagomorph densities and human leishmaniasis outbreaks in Spain, the high rabbit and human densities in NE Spain, and the high Leishmania spp. seroprevalence in rabbits, it becomes imperative to establish surveillance programs for lagomorphs in this region.

Background Antipredator behaviors are theoretically subjected to a balance by which their display should be minimized when their benefits do not outweigh their costs. Such costs may be not only energetic, but also entail a reduction in the time available for other fitness-enhancing behaviors. However, these behaviors are only beneficial under predation risk. Therefore, antipredator behaviors are predicted to be maximized under strong predation risk. Moreover, predation pressure can differ among individuals according to traits such as sex or body size, if these traits increase vulnerability. Antipredator behaviors are expected to be maximized in individuals whose traits make them more conspicuous to predators. However, how sex, body size and antipredator behaviors interact is not always understood. Methods In this work, I tested the interaction between sex, body size and antipredator behavior in the common pill woodlouse (Armadillidium vulgare), which conglobate (i.e., they roll up their bodies almost conforming a sphere that conceals their appendages) in response to predator attacks. Specifically, I tested whether latency to unroll after a standardized mechanical induction was greater in animals exposed to predator chemical cues (toad feces) than in conspecifics exposed to cues of non-predatory animals (rabbits) or no chemical cues whatsoever (distilled water), incorporating sex and body mass in the analyses. Results In agreement with my prediction, latency to unroll was greater in individuals exposed to predator chemical cues. In other words, these animals engage in conglobation for longer under perceived predator vicinity. However, this result was only true for males. This sexual dimorphism in antipredator behavior could result from males being under greater predation risk than females, thus having evolved more refined antipredator strategies. Indeed, males of this species are known to actively search for females, which makes them more prone to superficial ground mobility, and likely to being detected by predators. Body size was unrelated to latency to unroll. As a whole, these results support the hypothesis that antipredator behavior is tuned to predator cues in a way consistent with a balance between costs and benefits, which might differ between the sexes.

Rabbit haemorrhagic disease virus (RHDV) is established as a landscape-scale biocontrol that assists the management of invasive European rabbits and their impacts in both Australia and New Zealand. In addition to this, it is also available to land managers to augment rabbit control efforts at a local scale. However, current methods of deploying RHDV to rabbits that rely on the consumption of virus-treated baits can be problematic as rabbits are reluctant to consume bait when there is abundant, green, protein-rich feed available. We ran a suite of interrupted time-series experiments to compare the duration of infectivity of two conventional (carrot and oat baits) and two novel (meat bait and soil burrow spray) methods of deploying RHDV to rabbits. All methods effectively killed exposed rabbits. Soil burrow spray and carrot baits resulted in infection and mortality out to 5 days post their deployment in the field, and meat baits caused infection out to 10 days post their deployment. In contrast, oat baits continued to infect and kill exposed rabbits out to 20 days post deployment. Molecular assays demonstrated high viral loads in deployed baits beyond the duration for which they were infectious or lethal to rabbits. Based on our results, we suggest that the drying of meat baits may create a barrier to effective transmission of RHDV by adult flies within 10 days. We therefore hypothesise that fly larvae production and development on infected tissues is critical to prolonged viral transmission from meat baits, and similarly from carcasses of RHDV mortalities, via mechanical fly vectors. Our study demonstrates that meat baits and soil spray could provide additional virus deployment options that remove the need for rabbits to consume baits at times when they are reluctant to do so. [ABSTRACT FROM AUTHOR]

The European rabbit (Oryctolagus cuniculus) is among the 100 most harmful invasive alien organisms worldwide designated by the International Union for Conservation of Nature. Therefore, the Argentine government officially declared this species as being detrimental to biodiversity conservation. Rabbits represent a potential threat to the regeneration of Patagonian forests, which host unique biodiversity and functional relationships. However, two local studies that evaluated diet composition using microhistological analysis of feces in the north and south of Patagonian forests found that trees represent a small proportion of the annual diet of rabbits. The objective of this study was to evaluate the impact of rabbits on saplings in an area of Patagonian forest with high rabbit densities. We sampled 294 saplings for rabbit herbivory in 20 1-ha forest plots adjacent to grasslands and shrublands in Lanin National Park, Argentina. No evidence of tree regeneration limitations was found in the affected stands, which concurs with the results of previous local studies on diet composition. Other anthropogenic impacts, such as domestic ungulate breeding, intentional fires, urban growth, and forestry, appear to represent more serious threats to Patagonian forests than rabbit herbivory. [ABSTRACT FROM AUTHOR]

Rabbits have travelled with humans to the most remote archipelagos, having been introduced on at least 800 islands worldwide. This herbivore has caused a devastating effect on endemic insular plants, causing changes in species composition, cascading extinctions and disruption of native seed dispersal systems worldwide. However, its ecological impacts as disrupting native seed dispersal systems have not been studied from a holistic perspective in any of the archipelagos where rabbits were introduced. Here, we assess the role of rabbits as frugivores and seed-dispersers on the most extensive and diverse island of the Canary Archipelago, Tenerife, across its five main vegetation zones represented in an altitudinal gradient 0–3715 m a.s.l. To this end, 120 transects per vegetation zone were conducted (August 2020–November 2021) to collect fresh faecal samples from a total of 244 latrines. They consisted of 29,538 droppings in which we found seeds from 73 plant species, 29 of which were identified to species level (13 endemic, eight natives and eight introduced by humans). About 70% of the seeds were identified as fleshy-fruited plant species while the remaining nine were dry fruits. Of the former, only nine showed a percentage of intact seeds greater than 75%, another nine species between 50 and 75%, and three lower than 50%. The digestive effect of rabbits on seedling emergence was generally low, compared to that produced by native seed dispersers. Since fleshy-fruited plants and rabbits have not been linked in their evolutionary history in the Canaries, the former seems to have their own legitimate seed dispersers. [ABSTRACT FROM AUTHOR]

Simple Summary: Oncology in pet rabbits (Oryctolagus cuniculus) has emerged in recent years as medical treatments are required with increasing frequency. In this report, we describe a case of cutaneous malignant melanoma occurring in the scrotum in a wild rabbit, with testicular metastases, as an unusual metastatic site only described in human patients to date. Case presentation and gross, histopathological, and immunohistochemical findings are detailed. Descriptions of the biological behaviour of spontaneous tumours may serve to improve current knowledge in animal species and humans in which the same neoplasm occurs. Furthermore, the increasing popularity of rabbits as pets allows for more data on the spontaneous occurrence of cancer. Melanocytic skin tumours have been rarely described in pet rabbits, and exposure to UV light in sparsely haired areas has been hypothesised to play a cancerogenic role. Here, we describe a case of cutaneous malignant melanoma arising from the skin of the scrotum in an 8-year-old male wild rabbit, with testicular metastases as an unusual metastatic site for melanoma reported in humans to date. The tumour was nearly 5 cm in size, firm, and highly pigmented, with multifocal superficial ulcerations and large areas of intratumoural necrosis. The adjacent testis was 1.5 cm, multinodular, and black, obscuring tissue morphology. Histologically, the dermis was expanded by an infiltrative, densely cellular neoplasm composed of nests and sheets of polygonal to spindle neoplastic melanocytes, supported by scant fibrovascular stroma. Neoplastic cells showed intermediate N/C ratio, moderate basophilic cytoplasm, often obscured by abundant brownish granular pigment, and eccentric nuclei with prominent nucleoli. Cellular pleomorphism and nuclear atypia were severe, and high mitotic activity was observed. Diffuse dermal lymphovascular invasion was also observed. The testis was delimited by a thin tunica albuginea, and the parenchyma was largely obscured in its morphology by densely packed neoplastic cells. Seminiferous tubules, lined with a thin basement membrane and containing neoplastic and scattered spermatogenic cells, were occasionally observed. Neoplastic cells within the skin and the testis were positive for HMB-45, Melan-A, and S-100. The growing popularity of rabbits as pets allows for a greater ability to accumulate data on the spontaneous occurrence of tumours in these animals. Furthermore, descriptions of the biological aspects of spontaneously occurring tumours may serve to improve current knowledge in animal species and humans in which the same neoplasm may occur. [ABSTRACT FROM AUTHOR]

Heat stress has become a widespread concern worldwide, which is a major environmental stress that causes substantial economic loss in the rabbit industry. Compared to other agricultural animals, rabbits are more sensitive to heat stress as they have fewer sweat glands and a thicker coat of fur, increasing the heat dissipation complexity. Thus, heat stress hurts rabbits' productivity, meat quality, reproductive performance, antioxidative properties, immune responsiveness, intestinal histomorphology, and microbiome. Nutraceuticals include vitamins, minerals, antioxidants, organic acids, fatty acids, probiotics, prebiotics, synbiotics, enzymes, and medicinal plants due to the possible impacts on maintaining common biological situations, strengthening immune response, and preventing illness, which ultimately led to an increase in productivity. Nutraceuticals have recently attracted a lot of attention to alleviate the adverse impacts of heat stress in rabbit farms. The objective of the current review is to provide acquaintance with the recent findings about the impact of heat stress on rabbit productivity and the advantages of dietary supplementation of nutraceuticals in mitigating it. [ABSTRACT FROM AUTHOR]

Biomass allowance is a key feature in pasture-based rabbit production systems. It conditions not only the stock density (rabbits/m²) and/or the number of grazing days, it also influences the grazing behaviour of animals. When herbage restriction occurs, pelleted feed and/or cereal intake goes up. Inadequate pasture management may also impair the biomass quantity and quality if overgrazing occurs. To avoid the undesirable effects of overgrazing and better manage pellet and cereal intake, information on both biomass availability and rabbits’ grazing capacity are needed. Here, we present an adaptation of the rising plate meter method (developed for biomass intake measures for ruminants) for use in rabbit. To this end, we designed an experiment where two groups of 12 rabbits each were kept in two different fields: under an apple orchard (AO) or on fallow land (FL). We followed the animals for 5 consecutive weeks (from 45 to 80 d old). Rabbits lived in 25 m² movable paddocks, and every week a new paddock location (called paddock-spot) was made available for them. At each new paddock-spot, we measured the herbage height inside the paddocks and performed samplings of the available biomass (i.e. herbage cut after herbage height measurement) outside the paddocks. From this data we estimated the available biomass inside each paddock-spot by fitting linear regression equations of biomass to herbage height. Overall, rabbits in the AO and FL had access to 1328±65.7 and 1386±58.6 kg of dry matter (DM) per ha, respectively. In every field and paddock-spot, the biomass available was lower than the rabbits’ grazing capacity; overgrazing was the rule. Roughly, and under a restricted herbage allowance, rabbits in the AO ingested 45.2 g DM/d and rabbits in the FL 43.4 g DM/d. In the last week (64 to 80 d old), the biomass intake of rabbits in the AO and AL represented 26.4 and 23.5% of the total DM intake, respectively. These values, however, does not represent the real grazing capacity of growing rabbits. In this study, we provide some advice on the sampling method to obtain reliable biomass estimations and we mention two methods for handling influential observations in linear regression.

Studies on pathogen-associated muscle degeneration (PAMD) seem not to progress despite the recent advancements in omics. The limited and outdated literature about pathogen-associated muscle degeneration in different animal models contradicts the thorough understanding of their genome. In this paper, we review the pathophysiology of pathogen infection through association with the physiologic, biochemical, and molecular changes happening in the skeletal, cardiac, and smooth muscles of different well-established mammalian models, namely rats (Rattus sp.), mice (Mus musculus), and rabbit (Oryctolagus cuniculus). The use of model organisms is beneficial to the advances in muscle degeneration research since they are inexpensive, low maintenance, and can be used for genetic screenings. This review illuminated an understanding of the potential application of well-established model organisms in advancing the current knowledge about pathogen-associated muscle degeneration.

Household waste landfills represent a huge source of trophic resources for opportunistic and versatile wildlife species. Among them, the red kite (Milvus milvus) is one of the most endangered in Europe. Several studies have pointed out the importance of landfills as a source of food for this species during the wintering season, but the information on the frequency, seasonal and daily patterns of use, and age of red kites that exploit this food source is still insufficient to understand their actual role in conservation. In this study, we evaluated the patterns of use of household waste by overwintering red kites in southeastern Madrid, central Spain. The results showed the constant presence of relatively low numbers (<30 on average) and a reduced hourly inflow and outflow of red kites throughout the day and during the whole winter period in the studied landfill. A higher proportion of juveniles was found in the landfill than in the overall wintering population. Pellet analysis clearly shows that the diet of red kites is dominated by the wild rabbit (Oryctolagus cuniculus), which is quantitatively very relevant compared to household waste obtained from the landfill. This suggests a relatively low quantitative importance of landfills as foraging grounds for the increasing population of wintering red kites in the study area. Instead, the high regional density of wild rabbits attracts large numbers of red kites that can eventually use landfills as a non-optimal last-resort foraging option, owing to the predictability of household waste, especially for juveniles. The continuous presence of red kites in landfills likely influences an uninformed positive perception about their relevance to the conservation of the wintering population, despite risks there faced, such as collision, electrocution, and intoxication. Future research is needed to assess in depth the influence of wild rabbits in Spain on the habitat use and global population dynamics of red kites. [ABSTRACT FROM AUTHOR]

Pseudopterygium has been previously documented in rabbits. In this condition, there is a circumferential overgrowth of the conjunctiva over the cornea without adherence to the corneal surface. In contrast, focal conjunctival overgrowth with adherence to the corneal surface, pterygium, occurs in humans. Pterygium has not been reported in rabbits. Case 1, a 5-year-old, spayed female, rex rabbit, presented for an evaluation of a suspected pseudopterygium of both eyes (OU). Medical treatment was unsuccessful. Surgery was performed and partial corneal adherence was detected. The portion of conjunctiva adhered to the cornea was left in place, and the nonadhered conjunctiva was transected adjacent to this attachment and sutured into the fornix. Over the next 8 months, the left eye (OS) had mild recurrence of aberrant conjunctival overgrowth noted temporally, with adhesion to the corneal surface at its previous attachment. The axial cornea remained clear OU. Case 2, a 6.5-year-old, intact male, mixed breed rabbit, was presented for cutaneous wounds and myiasis. During the initial examination, an incidental pseudopterygium was identified OU. Upon further evaluation, corneal adhesion was identified. As the conjunctival overgrowth was not affecting the rabbit's vision, no additional treatments were pursued. The animal was lost to recheck. This case series describes 2 cases of aberrant conjunctival overgrowth with corneal adhesions in rabbits. Although pseudopterygium without adhesions is the most common presentation in rabbits, veterinarians should be aware that corneal adhesions can occur in rabbits and it may require modifications to the surgical procedure. [ABSTRACT FROM AUTHOR]

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Simple Summary: The emergence of two strains of rabbit haemorrhagic disease (i.e., GI.1 and GI.2) in the1990s and 2010s, respectively, has been the primary determinant for the decline of wild European rabbits within their native range. We compared the impact of both strains on the wild rabbit populations in Spain using national hunting bags. Our findings showed that GI.1 had a greater impact on wild rabbit populations than GI.2. This disparity is likely to be explained by several factors, such as climatic conditions, host resistance improvement, virulence attenuation, and population density, among others. The outbreaks of two strains of rabbit haemorrhagic disease (RHD) (GI.1 and GI.2) in the Iberian Peninsula have caused substantial economic losses in commercial rabbitries and have affected the conservation of rabbit-sensitive predators due to the dramatic decline of their natural populations. However, the assessment of the impact of both RHD strains on wild rabbit populations has been limited to a few small-scale studies. Little is known about the overall impact within its native range. In this study, we described and compared the effects of GI.1 and GI.2 countrywide by using time series of hunting bag data widely available across the country and compared their trend during the first eight years after the first outbreak of GI.1 (i.e., 1998) and GI.2 (i.e., 2011), respectively. We used Gaussian generalised additive models (GAM) with the number of hunted rabbits as the response variable and year as the predictor to evaluate the non-linear temporal dynamics of the population at the national and regional community levels. The first GI.1 caused a population decline of around 53%, affecting most Spanish regional communities where the disease occurred. The positive trend observed after GI.1 in Spain ended with the initial outbreak of GI.2, which did not appear to cause a national population decline. In contrast, we found significant variability in the rabbit population trend among regional communities, where some increased, and others decreased. Such a disparity is unlikely to be explained by a single factor; rather, it appears to result from several factors, such as climatic conditions, host resistance improvement, virulence attenuation, or population density. Our study suggests that a national comprehensive hunting bag series could aid in elucidating the differences in the impact of emerging diseases on a large scale. Future research should focus on national longitudinal serological studies to shed light on the immunological status of rabbit populations in different regions to better understand the evolution of RHD strains and the resistance gained by the wild populations. [ABSTRACT FROM AUTHOR]

Simple Summary: Vitamin D is an important hormone that can be acquired through diet or exposure to ultraviolet B (UVB) radiation. Few studies have evaluated the effects of UVB radiation on vitamin D concentrations in the domestic rabbit (Oryctolagus cuniculus); however, initial findings have found they can increase their serum 25-hydroxyvitamin D3 (25-OHD3) following 12 h of artificial UVB exposure. Current husbandry recommendations for rabbits do not include specific UVB lighting requirements. Rabbits are a common pet and research model and are frequently housed indoors without access to natural UVB lighting. Rabbits that are chronically vitamin D deficient may develop mineral deficiencies that can lead to poor calcification of the teeth and skull, predisposing these animals to dental abnormalities, bone infections, and other debilitating diseases. While initial results suggest artificial UVB is positive for rabbits, UVB can also be detrimental to the health of vertebrates. The aim of this study was to determine if shorter-duration UVB exposure could also increase 25-OHD3 concentrations. Rabbits were provided 6 h of artificial UVB daily for 14 days, and there was a significant increase in 25-OHD3 concentrations over time. These findings affirm that rabbits can use short-duration artificial UVB to increase 25-OHD3 concentrations. Vitamin D is an important hormone that can be acquired through diet, exposure to ultraviolet B (UVB) radiation, or a combination of these methods. In domestic rabbits (Oryctolagus cuniculus), both methods appear viable, but there is limited research evaluating the effects of UVB on this species. Previous studies found that 12 h of artificial UVB radiation significantly increased 25-hydroxyvitamin D3 (25-OHD3) concentrations over time. While these findings suggest UVB can be beneficial in rabbits, this form of radiation can also be detrimental to vertebrates. The purpose of this study was to determine if shorter-duration UVB could elicit a similar physiological response in rabbits while minimizing potential negative effects. Six rabbits were used for this pilot study. The baseline serum 25-OHD3 was measured for each rabbit and following 14 days of 6 h/day exposure to artificial UVB, a second 25-OHD3 sample was collected. There was a significant increase (p = 0.001) in serum 25-OHD3 over time (Baseline: 27.7 ± 8.1 nmol/L; Day 14: 79.8 ± 9 nmol/L). This study affirmed that 6 h of UVB produced 25-OHD3 concentrations similar to those found in rabbits exposed to 12 h of UVB. Future studies should continue to determine how the duration of UVB exposure affects 25-OHD3 concentrations. [ABSTRACT FROM AUTHOR]

The European rabbit (Oryctolagus cuniculus) is one of the main invasive species in Chile, where it became naturalized ca. 150 years ago. Their high reproductive capacity, lack of specialist predators, and great adaptability favored the settlement of rabbits in diverse mainland and island ecosystems of the country. Recently, rabbits have become central players in semi-arid ecosystems, such as those represented in Las Chinchillas National Reserve in north-central Chile. We undertook to analyze the place and role of rabbits in the food web of that Reserve, based on a bibliographic review and long-term annual data gathered from 1987 until 2022 (36 years). Results showed that the network comprised 77 species, where 69% were primary producers (plants), 18% were mid-level consumers (herbivores), and 13% were top-level consumers (predators). The most connected species in the food web was the rabbit, which positively or negatively affected the species interacting with it. Predators such as Galictis cuja, Geranoaetus polyosoma, Leopardus colocolo, and Puma concolor, and the scavenger Vultur gryphus, could be negatively affected by an eventual decrease (natural or human-caused) in the rabbit population of the Reserve. To the contrary, primary producers such as Oxalis perdicaria, Plantago hispidula, Schizanthus parvulus, Senna cumminggi, and Tropaeolum azureum could be positively affected by an increase in their biomass in response to a decrease in rabbits, favoring native rodents. We consider that analyzing the rabbit-centered food web and its impacts on native interacting species allows a better understanding of the relevance of invasive species in the local community, providing conceptual tools for rabbit management. [ABSTRACT FROM AUTHOR]

Assessing the underlying mechanisms of species co-occurrence patterns can be challenging as biotic and abiotic factors are hard to disentangle. To date, few studies have investigated co-occurrence patterns of mammals within urban areas. As urban areas are increasingly used as habitat by wildlife, there is a need for a better understanding of urban ecology to facilitate human-wildlife co-existence. Here, we investigated co-occurrence patterns and habitat selection of the European hare (Lepus europaeus), mountain hare (L. timidus), and European rabbit (Oryctolagus cuniculus) inside urban areas of Sweden, using joint species distribution models and generalized linear mixed models based on citizen science observations. All three species were observed within urban areas, but European hares and rabbits appear to be more successful urban colonizers compared to mountain hares. Overall, our findings suggested that urban occurrence by all three lagomorphs was related to suitable conditions within the distribution of each species (e.g., climate and elevation), rather than by the presence of other lagomorph species or specific land cover types within urban areas. On a finer spatial scale, European hares and rabbits generally selected for green urban areas and mountain hares for residential gardens, which likely constitute suitable foraging sites. Moreover, overlap in activity times between European hares and rabbits was mediated by land cover type and sympatry. Our findings contribute to the understanding of urban ecology and provide insights for management measures of the three lagomorphs in urban areas of Sweden. [ABSTRACT FROM AUTHOR]

In rabbits and guinea pigs, total thyroxine (TT4) and free thyroxine (fT4) reference values have been previously published. However, most studies have been performed on laboratory animals with small sample sizes. A reference value for thyroid-stimulating hormone (TSH) measurement has not yet been established for either species. With the increasing popularity of pet guinea pigs and rabbits in veterinary practice, established reference values are needed to make a diagnosis and promptly initiate appropriate treatment. Plasma samples from a healthy and defined animal population of 41 pet rabbits (n = 41 TT4, fT4, TSH) and 73 pet guinea pigs (n = 73 TT4 and fT4; n = 51 TSH) were evaluated using chemiluminescence assay (CLIA; for TT4, fT4) and enzyme-linked immunosorbent assay (ELISA; for TSH) to establish reference values. A thyrotropin teleasing hormone (TRH)-stimulation test (n = 4; for each species) was conducted to validate the TSH ELISA test kits. Range, mean, median, standard deviation, interquartile range, 95% reference interval, and 90% confidence intervals for lower and upper reference limits of TT4, fT4, and TSH in healthy pet guinea pigs and healthy pet rabbits were assessed. In addition, the influence of age, sex, and housing on TT4, fT4, and TSH levels was investigated. In this study, TSH reference values were established in pet rabbits and guinea pigs for the first time. Reference values for both TT4 and fT4 were also established de novo for both species. Only with evidence- and population-based reference values can thyroid diseases be precisely and correctly diagnosed to prevent inadequate treatment. [ABSTRACT FROM AUTHOR]

Spontaneous pneumothorax is uncommon in rabbits and could severely affect the respiratory status of the animals. This retrospective case series aimed to provide clinical and diagnostic imaging data associated with this pathological finding in pet rabbits. Medical records over the past five years (2017–2022) were reviewed. Four cases were identified: three female and one male rabbit between 5 and 7 years of age. Three rabbits had no history of respiratory signs, and two rabbits presented with respiratory distress. Radiographs revealed severe pneumothorax in two patients. Computed tomography (CT) findings revealed moderate unilateral pneumothorax (3/4) and bilateral pneumothorax (1/4). Other concurrent pulmonary findings included emphysematous bullae (2/4), cavitary lesions (1/4), and neoplasia (1/4). An infectious component was suspected in all cases and all rabbits were treated with a combination of antibiotics. Several thoracocenteses were performed and chest tubes were inserted in two rabbits. Three rabbits died shortly after the CT scan, whereas the last rabbit recovered temporarily. Histopathology was performed in two cases. The first rabbit had mild-to-severe chronic multifocal granulomatous pneumonia, nephritis, and hepatitis. The second case showed a large epithelioid cell tumor consistent with histiocytic sarcoma. Spontaneous pneumothorax is a severe condition that may be life-threatening in pet rabbits. The four cases described provide information about clinical management, evolution over time, and potential etiology. [ABSTRACT FROM AUTHOR]

Gabapentin is used to treat seizures, neuropathic pain, and anxiety. Currently, dosage recommendations for rabbits are extrapolated from other species. The objective of this study was to determine the pharmacokinetics of gabapentin after single, oral administration in domestic rabbits. A randomized, crossover study was performed in male (n = 3) and female (n = 3) rabbits after administration of either 25 or 50 mg/kg gabapentin orally. Plasma concentrations of gabapentin were measured at 0, 0.25, 0.5, 1, 1.5, 2, 2.5, 3, 4, 8, 12, 24, and 48 hours post-administration via liquid chromatography. Mean maximum plasma concentrations were 17.70 and 16.83 µg/mL for the 25 and 50 mg/kg doses, respectively. Mean times to maximum plasma concentration were 1.75 and 1.5 hours, and mean terminal half-lives were 10.2 and 9.44 hours for the 25 and 50 mg/kg doses, respectively. No adverse effects observed at either dose. A single oral dose of gabapentin at 50 mg/kg did not result in higher plasma concentrations compared to the 25 mg/kg dose and no differences were observed between males and females for either dosing group (P > 0.9). [ABSTRACT FROM AUTHOR]

Rabbit haemorrhage disease virus 2 (RHDV2) is a highly pathogenic lagovirus that causes lethal disease in rabbits and hares (lagomorphs). Since its first detection in Europe in 2010, RHDV2 has spread worldwide and has been detected in over 35 countries so far. Here, we provide the first detailed report of the detection and subsequent circulation of RHDV2 in New Zealand. RHDV2 was first detected in New Zealand in 2018, with positive samples retrospectively identified in December 2017. Subsequent time-resolved phylogenetic analysis suggested a single introduction into the North Island between March and November 2016. Genetic analysis identified a GI.3P-GI.2 variant supporting a non-Australian origin for the incursion; however, more accurate identification of the source of the incursion remains challenging due to the wide global distribution of the GI.3P-GI.2 variant. Furthermore, our analysis suggests the spread of the virus between the North and South Islands of New Zealand at least twice, dated to mid-2017 and around 2018. Further phylogenetic analysis also revealed a strong phylogeographic pattern. So far, no recombination events with endemic benign New Zealand rabbit caliciviruses have been identified. This study highlights the need for further research and surveillance to monitor the distribution and diversity of lagoviruses in New Zealand and to detect incursions of novel variants.

Pathogenic lagoviruses (Rabbit hemorrhagic disease virus, RHDV) are widely spread across the world and are used in Australia and New Zealand to control populations of feral European rabbits. The spread of the non-pathogenic lagoviruses, e.g., rabbit calicivirus (RCV), is less well studied as the infection results in no clinical signs. Nonetheless, RCV has important implications for the spread of RHDV and rabbit biocontrol as it can provide varying levels of cross-protection against fatal infection with pathogenic lagoviruses. In Chile, where European rabbits are also an introduced species, myxoma virus was used for localised biocontrol of rabbits in the 1950s. To date, there have been no studies investigating the presence of lagoviruses in the Chilean feral rabbit population. In this study, liver and duodenum rabbit samples from central Chile were tested for the presence of lagoviruses and positive samples were subject to whole RNA sequencing and subsequent data analysis. Phylogenetic analysis revealed a novel RCV variant in duodenal samples that likely originated from European RCVs. Sequencing analysis also detected the presence of a rabbit astrovirus in one of the lagovirus-positive samples.