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Liposomal local anaesthetic solutions may provide extended duration analgesia postoperatively but have not been assessed following intra-peritoneal local infiltration in any species.To evaluate two doses of 1.33% liposomal bupivacaine (LB) versus 0.75% bupivacaine HCL (BHCl) for analgesia following laparoscopic ovariectomy in mares.Prospective cohort study.Fifteen healthy Quarter Horse mares (age 2-20 years) with normal bilateral ovarian palpation and appearance were enrolled. Horses were restrained in standing stocks and administered an α-2 agonist, butorphanol, and flunixin meglumine, followed by a variable rate infusion of sedation with α-2 agonists. Bilateral paralumbar fossa ovariectomies were performed. Treatment with either 30 mL 0.75% BHCl followed by 20 or 40mL LB 13.3% (LB20, LB40) volume expanded with saline to 80mL total (n=6/group) or 80mL BHCl alone (n=3, BCHL) was infused around incision sites and each mesovarium (LB or BHCl) prior to ovariectomy. Horses were monitored 72h by physical examination, algometry, and pain scoring (Composite Pain Scale by Bussieres et al., Horse Grimace Scale). Abdominocentesis with peritoneal fluid analysis was performed at 72h.Analgesia achieved with all treatment protocols allowed completion of ovariectomy procedures. Pressure algometry scores were lower in BHCl-treated horses versus both LB groups overall. Pain scores were improved with LB treated horses in a dose-dependent fashion (Horse Grimace Scale scores LB40LB20BHCL; Composite Pain Scale scores LB40BHCL, LB20BHCL, BHCL and LB20 did not differ). Peritoneal fluid total protein was lower in LB40 vs LB20 and BHCL horses. No complications from LB administration were appreciated.Small patient sample size, lack of follow-up past 72h or histopathology.Analgesia duration was extended, and pain scores improved postoperatively with LB vs. BHCl in a dose-dependent fashion. Further clinical evaluation of extended duration local anaesthetics in horses for improved postoperative pain management is warranted. This article is protected by copyright. All rights reserved.

Background Prophylactic perioperative antimicrobial protocols in equine synovial endoscopy have been described but not compared with respect to post‐operative outcomes and complications. Increasing antimicrobial resistance in equine practice and interest in promoting judicious use of antimicrobials has prompted reevaluation of drug selection and dosing strategies. Objectives To determine the frequency of and compare post‐operative complications following elective synovial endoscopy between horses receiving different perioperative antimicrobial protocols. Methods Records from the Colorado State University Veterinary Teaching Hospital were evaluated (2014–2018) and equine patients undergoing elective synovial endoscopy were identified. Patients undergoing endoscopy for sepsis or internal fixation were excluded. Patient signalment, clinician, joint and limb involved, perioperative antimicrobial regimen, number endoscopic portals and closure technique, and post‐operative complications including incidence of joint infection were recorded. Generalized linear models were used to estimate the odds of post‐operative complications. Results Elective synovial endoscopies of 516 horses in 537 procedures evaluating 761 synovial structures were performed. No horses developed post‐operative septic synovitis. Administration of post‐operative antimicrobials, type used and patient sex were all significantly associated with increased risk of complications, which were predominantly gastrointestinal‐related. Complication rates in horses receiving a single preoperative dose of cefazolin were lower than in horses receiving potassium penicillin, gentamicin or multiple doses. Complication rates were lower in females compared to castrated or intact males. Other factors evaluated (breed, age, surgeon, anaesthesia duration or hospitalization, joint/limb operated, number endoscopic portals) were not associated with increased risk of complications post‐operatively in this case population. Conclusions Prophylactic perioperative antimicrobial protocols in equine practice deserve periodic reconsideration due to increased antimicrobial resistance. Prolonged antimicrobial usage beyond the time of surgery was unnecessary to prevent septic synovitis following synovial endoscopy in this case population and was furthermore associated with an increased risk of gastrointestinal complications., Prophylactic perioperative antimicrobial protocols in equine practice deserve periodic reconsideration due to increased antimicrobial resistance. Prolonged antimicrobial usage beyond the time of surgery was unnecessary to prevent septic synovitis following synovial endoscopy in this case population and was furthermore associated with an increased risk of gastrointestinal complications.

Surgical intervention on cetaceans is rarely performed due to challenges including general anesthesia and post-operative wound healing. This report describes the evaluation and treatment of an adult female bottlenose dolphin (Tursiops truncatus) with the US Navy Marine Mammal Program, with a chronic ventral cervical abscess caused by Candida glabrata. Despite aspiration and lavage along with multiple antifungal drugs, the patient developed inspiratory stridor with decreased performance level and surgical treatment was pursued. Under general anesthesia with the dolphin in dorsal recumbency position a 12-cm longitudinal ventral midline neck incision was used for exploration. Intraoperative ultrasound aided the identification of surgical landmarks and the abscess cavity. After adequate drainage and curettage, a closed-suction drain was placed in the surgical site. Retention sutures were used to close the incision and the external drain bulb was secured to a pectoral fin strap. One-year post-op, the dolphin was clinically normal and follow-up imaging showed no significant recurrence of the abscess. This case demonstrates a novel surgical approach of managing abscesses in dolphins, including placement and management of a negative suction drain in a submerged patient. The successful collaboration between veterinary anesthesiology, veterinary medicine, radiology, and general surgery allowed the patient to continue her normal activities as a full-duty service member.

The objective of this study was to compare the biomechanical properties in a single cycle axial loading test and the types of failures in two constructs (a 3-hole 4.5-mm dynamic compression plate (DCP) and 7-hole 5.5-mm Y locking compression plate (Y-LCP)) in equine proximal interphalangeal joint (PIJ) arthrodesis. One limb in each pair was randomly assigned to PIJ arthrodesis using a 3-hole 4.5-mm DCP combined with two transarticular 5.5-mm cortical screws, whereas the contralateral limb was submitted to PIJ arthrodesis using a 7-hole Y-shaped 5.0-mm LCP in conjunction with one transarticular 4.5-mm cortical screw inserted through the central plate hole. Cortical screws were inserted in lag fashion. Constructs were submitted to a single axial load cycle to failure. Construct stiffness, load, and deformation were analyzed. Dynamic compression plate and Y-LCP arthrodesis constructs did not differ significantly and were equally resistant to axial loading under the conditions studied (DCP and Y-LCP group stiffness, 5685.22 N/mm and 6591.10 N/mm, respectively). Arthrodesis of the PIJ using a DCP and two transarticular 5.5-mm cortical screws or a Y-LCP yielded biomechanically equivalent outcomes under the test conditions considered. However, Y-LCP provides less impact in the palmar/plantar bone. Application of Y-LCP with unicortical screws has equivalent biomechanical characteristics of DCP and may be a safe option for PIJ arthrodesis, where potential trauma secondary to applying bicortical screws in the palmar/plantar aspect of the pastern can be avoided.

Injection of the equine navicular bursa can be technically challenging, and inadvertent penetration of other synovial structures is common using previously described techniques. When injecting the navicular bursa, inadvertent penetration of other synovial structures and hoof configuration can affect success rate, especially when performed by inexperienced operators. The aim of this study is to describe an alternate radiographic guided technique for injection of the equine navicular bursa that consistently avoids penetration of the distal interphalangeal joint using a 40 mm (1.5-inch) 20-gauge needle. This ex vivo pilot study compared the success rate, needle redirection rate, and rate of inadvertent synovial penetration of a novel injection technique for the equine navicular bursa between operators with three differing levels of experience in equine veterinary medicine (1 year, 8 years, >30 years). There was no significant difference in success rate between operators regardless of level of experience or hoof configuration, and inadvertent penetration of other synovial structures was highly unlikely. Thus, using the described technique, injection of the navicular bursa can be performed by individuals of various experience levels in equine veterinary practice, and can be achieved with a high success rate with little chance of inadvertent penetration of other synovial structures regardless of hoof configuration.

CASE DESCRIPTION A 6-year-old Quarter Horse gelding used for barrel racing was evaluated for acute onset of non–weight-bearing lameness of the left hind limb following strenuous exercise. CLINICAL FINDINGS Nuclear scintigraphic imaging revealed focal increased radiopharmaceutical uptake centrally within the left talus. Subsequent standard radiographic and ultrasonographic examinations of the tarsus failed to identify the cause of the increased radiopharmaceutical uptake; however, the lameness was definitively localized to the tarsocrural joint by intra-articular anesthesia. Subsequent MRI sequences of the left tarsus revealed an incomplete fracture of the talus that extended distally from the trochlear groove and evidence of maladaptive stress remodeling of the trochlear groove of the talus and distal intermediate ridge of the tibia. TREATMENT AND OUTCOME The horse was treated conservatively, with management consisting of stall confinement, physical rehabilitation, therapeutic laser therapy, and intra-articular autologous conditioned serum administration. The lameness resolved, and the horse was competing at its previous level within 15 months after lameness onset. CLINICAL RELEVANCE Although rare, incomplete fracture of the talus should be considered as a differential diagnosis for horses that develop acute hind limb lameness following strenuous exercise, especially when that exercise involves abrupt changes in direction while the horse is traveling at maximal speed. Acquisition of additional oblique projections during radiographic evaluation of the tarsus might be useful for identification of such fractures, but definitive diagnosis may require advanced diagnostic imaging modalities such as CT and MRI. Horses with incomplete fractures of the talus can be successfully treated with conservative management.

The cause of transient post-operative pain in a subset of horses undergoing laparoscopy is unclear. The objective of this study was to evaluate if residual pneumoperitoneum is associated with transient post-operative pain in mares undergoing ovariectomy. Thirty-eight mares undergoing routine standing laparoscopic ovariectomy were randomly allocated into 2 groups. At the completion of laparoscopy, either the abdominal cavity was actively desufflated or the cannulas were opened to achieve ambient pressure before incisional closure. Assessments were performed for 18 hours after surgery using a validated visceral/somatic pain scale for horses. Overall, pain was minimal in both groups (median score 2/39) post-surgery. Active desufflation of the pneumoperitoneum at the completion of laparoscopy approached statistical significance (P = 0.07) in decreasing pain at 12 hours after laparoscopy. However, effects of active desuffation were not significant throughout the monitored 18-hour post-surgery period. We conclude that the decision to actively desufflate at the completion of laparoscopy should be based on surgeon’s preference.

The endangered Mexican blindcat (Prietella phreatophila, Carranza 1954) is one of only four described stygobitic ictalurid catfish in North America. Members of two monotypic genera (Satan eurystomus and Trogloglanis pattersoni) are known from the Edwards Aquifer in Texas and, until recently, Prietella (represented by P. lundbergi and P. phreatophila) was only known to occur in Mexico (northern Coahuila to southern Tamaulipas). The recent discovery of P. phreatophila in a cave on the Amistad National Recreation Area in Val Verde County, Texas is the result of decades of sporadic effort on both sides of the US/Mexican border and has stimulated a renewed effort to investigate the distribution, ecology, evolutionary history, and conservation status of this species. Collaborative efforts among The San Antonio Zoo, The University of Texas at Austin, Zara Environmental, and The National Park Service are currently focused on habitat surveys in Texas as well as captive husbandry and propagation. Ongoing efforts with collaborators from the Comisión Nacional de Áreas Naturales Protegidas, Área de Protección de Recursos Naturales Sabinas and the Laboratorio de Genética para la Conservación, Centro de Investigaciones Biológicas del Noroeste, La Paz include expanded fieldwork in Mexico, hydrogeologic studies, and surveys using environmental DNA.

Case Description—An 18-year-old Paint stallion (horse 1) and a 17-year-old Morgan gelding (horse 2) were evaluated because of an acute onset of severe unilateral forelimb lameness. Clinical Findings—Both horses were unable to bear weight on the affected forelimb and had a dropped elbow appearance. Radial nerve paralysis, triceps myopathy, and fractures of the humerus and ulna were ruled out. The caudal aspect of the affected antebrachium of each horse was very firm to palpation and became firmer when weight was shifted onto the limb. Ultrasonographic examination revealed swelling and suspected intramuscular hemorrhage of the caudal antebrachial muscles. On the basis of clinical examination and diagnostic imaging findings, both horses had antebrachial compartment syndrome diagnosed. Lameness did not substantially improve with medical treatment in either horse. Treatment and Outcome—Caudal antebrachial fasciotomy was performed in each horse. Following sedation and local anesthetic administration, a bistoury knife was inserted through small incisions to perform fasciotomy. Horses remained standing throughout the procedure and were immediately able to bear weight on the affected limb without signs of discomfort. Horse 1 developed colitis and horse 2 developed a mild incisional infection, but both fully recovered and returned to their previous activities. Clinical Relevance—Antebrachial compartment syndrome is a rare cause of severe unilateral forelimb lameness and should be considered as a differential diagnosis in horses with a dropped elbow appearance. Both horses of this report had a successful outcome following antebrachial fasciotomy.

Recent literature reviews of bioassessment methods raise questions about use of least-impacted reference sites to characterize natural conditions that no longer exist within contemporary landscapes. We explore an alternate approach for bioassessment that uses species site occupancy data from museum archives as input for species distribution models (SDMs) stacked to predict species assemblages of freshwater fishes in Texas. When data for estimating reference conditions are lacking, deviation between richness of contemporary versus modeled species assemblages could provide a means to infer relative biological integrity at appropriate spatial scales. We constructed SDMs for 100 freshwater fish species to compare predicted species assemblages to data on contemporary assemblages acquired by four independent surveys that sampled 269 sites. We then compared site-specific observed/predicted ratios of the number of species at sites to scores from a multimetric index of biotic integrity (IBI). Predicted numbers of species were moderately to strongly correlated with the numbers observed by the four surveys. We found significant, though weak, relationships between observed/predicted ratios and IBI scores. SDM-based assessments identified patterns of local assemblage change that were congruent with IBI inferences; however, modeling artifacts that likely contributed to over-prediction of species presence may restrict the stand-alone use of SDM-derived patterns for bioassessment and therefore warrant examination. Our results suggest that when extensive standardized survey data that include reference sites are lacking, as is commonly the case, SDMs derived from generally much more readily available species site occupancy data could be used to provide a complementary tool for bioassessment.

Assessments of growth can provide information needed to understand how fish populations respond to changing environmental conditions and management actions, including ecosystem experimentation. We estimated growth rates and parameter uncertainty from otoliths of endangered Humpback Chub Gila cypha from the Colorado River in Grand Canyon, Arizona. We then compared growth of Humpback Chub < age 2 that were 1) occupying the mainstem Colorado River during a period of variable discharge and cooler water temperatures (1980–1998; epoch 1), 2) occupying the Colorado River during a period of moderate discharge variability and warmer water (2001–2011; epoch 2), and 3) occupying the unregulated Little Colorado River. Because growth rates of juvenile Humpback Chub (< age 2) may be more sensitive to changes in environmental conditions than adult fish, we used analysis of covariance and linear models to compare growth of juvenile fish (slopes) between epochs and capture sites (mainstem Colorado River vs. Little Colorado River). Our analysis of covariance results were ambiguous (age × epoch × site interaction; P = 0.06). However, individual linear regressions of size and age by epoch and site suggest biologically important differences in growth, as evidenced by slower growth in the Colorado River in epoch 1 than in epoch 2, and slower growth in the Colorado River compared with the Little Colorado River for all time periods. Overall our results 1) provide information on growth and growth variability useful for parameterizing models to assess population viability and 2) provide empirical information on how growth of juvenile and adult Humpback Chub growth may respond to changing environmental conditions.

Behavioral studies have often examined parental care by measuring phenotypic plasticity of behavior within a species. Phylogenetic studies have compared parental care among species, but only at broad categories (e.g., care vs. no care). Here we provide a detailed account that integrates phylogenetic analysis with quantitative behavioral data to better understand parental care behavior in the Cuatro Cienegas cichlid, Herichthys minckleyi. We found that H. minckleyi occurs in a clade of sexually monochromatic or weakly dichromatic monogamous species, but that male and female H. minckleyi have dramatically different reproductive coloration patterns, likely as a result of sexual selection. Furthermore, we found that males are polygynous; large males guard large territories, and smaller males may attempt alternative mating tactics (sneaking). Finally, compared to the closely related monogamous Rio Grande cichlid, H. cyanoguttatus, males of H. minckleyi were present at their nests less often and performed lower rates of aggressive offspring defense, and females compensated for the absence of their mates by performing higher levels of offspring defense. Body color, mating system, and parental care in H. minckleyi appear to have evolved after it colonized Cuatro Cienegas, and are likely a result of evolution in an isolated, stable environment.

Objective: To assess perceived veterinary student confidence and surgical skill set following a live animal, nonrecovery porcine surgical laboratory and to assess veterinary alumni long-term surgical confidence benefits from this laboratory during their first few years in practice. Sample Population: Four hundred students pre- and post-laboratory self-assessment surveys were analyzed from veterinary students participating in the junior surgery laboratory (JSL) from 2009 to 2018. One hundred and fifty veterinary alumni surveys were analyzed from JSL participants graduating between 2014 and 2018. Materials and Methods : Procedures performed on swine culled from food production included wound closure, abdominal exploratory, abdominal closure, splenectomy, nephrectomy, gastrostomy, intestinal anastomosis, and cystotomy. Procedures performed aimed to facilitate development of atraumatic tissue handling, vessel ligation, and hollow organ surgery. Results: All participants demonstrated significant self-evaluation improvement (P

Case Description—A 7-year-old mixed-breed stallion was admitted because of colic. Clinical Findings—Entrapment of the left colon in the renosplenic space was diagnosed via rectal palpation and ultrasonographic examination, despite a renosplenic space ablation 6.5 years earlier. Treatment and Outcome—The renosplenic entrapment was corrected with a combination of phenylephrine administration, rolling, and ballottement of the horse's abdomen during general anesthesia. The following week, left flank laparoscopic renosplenic space ablation was performed with the horse standing. On examination of the previous surgical site, only 4 bands of fibrous adhesion remained of the original space ablation. The renosplenic space was again closed by suturing the perirenal fascia and renosplenic ligament to the splenic capsule. The horse was discharged from the hospital and recovered at home. No complications or recurrence of entrapment was reported following the procedure. Clinical Relevance—There have been no previous reports of recurrence of renosplenic entrapment following procedures to permanently ablate the renosplenic space. Recurrence in this patient may be attributed to the horse's young age at the time of initial surgery or inadequate size or spacing of the sutures through the perirenal fascia and splenic capsule.

To appraise conservation status of the Yaqui catfish Ictalurus pricei, we reviewed literature and unpublished records on a captive stock, examined voucher specimens at museums, re-sampled historical localities in the Yaqui, Mayo, and Fuerte river basins, and we surveyed rivers further south. A total of 72 specimens of native Ictalurus was collected in the Yaqui, Fuerte, Sinaloa, Culiacan, and San Lorenzo river basins. No native Ictalurus was collected in the Mayo Basin. Distribution of the Yaqui catfish appears restricted to the Yaqui, Mayo and Fuerte river basins, all of which now harbor nonnative blue (I. furcatus) and channel (I. punctatus) catfishes. The nonnative black bullhead (Ameiurus melas) is now known from the Yaqui Basin and the flathead catfish (Pylodictis olivaris) has been recorded anecdotally in the Yaqui Basin. Threats to the Yaqui catfish have increased in recent years and hybridization with the channel catfish now appears widespread. We conclude that the Yaqui catfish should be...

Case Description—An 11-year-old Quarter Horse stallion was admitted for intermittent hemospermia of 4 years' duration. Clinical Findings—A linear vertical defect had been detected endoscopically following multiple episodes of hemospermia on the caudodorsal convex surface of the urethra at the level of the ischial arch. Treatment and Outcome—When sexual rest alone did not result in complete healing of the urethral defect, a subischial urethrotomy and buccal mucosal urethroplasty were performed. The surgical site healed without complication. Four months of sexual rest was recommended after surgery. Repeat endoscopy at 4 months allowed inspection of the urethral graft site. Following endoscopic examination, resumption of semen collection was recommended on the basis of the apparent healing at the urethral defect site. Hemospermia did not reoccur following surgical repair. Clinical Relevance—Buccal mucosal urethroplasty resulted in a favorable outcome in a stallion with recurrent hemospermia. Buccal mucosal urethroplasty may be a useful surgical option in stallions that have hemospermia secondary to a urethral defect and do not heal with sexual rest alone.

We examined foraging behavior (microhabitat use and feeding behavior) in a trophically polymorphic cichlid fish, Herichthys minckleyi, to address several questions regarding resource partitioning in this threatened species. These include: (1) do morphotypes demonstrate different foraging behaviors? (2) do individuals within a morphotype vary in their foraging behavior (e.g. are some individuals specialists, only using a subset of available resources, while other are generalists)? (3) do foraging behaviors vary between isolated pools? (4) do foraging behaviors vary across seasons? We quantified microhabitat use and feeding behavior for over 100 individuals (of two morphotypes) feeding freely in two isolated pools (populations) and across two seasons (winter and summer). We found differences in foraging behavior between morphotypes and individual specializations within morphotypes; i.e. some individuals specialize on certain food resources by using a few feeding behaviors within a subset of microhabitats, whereas others employ a range feeding behaviors across many microhabitats. Foraging behavior also varied between pools and across seasons. This spatial and temporal variation in foraging behavior and resource use may serve to maintain this polymorphism, as the relative fitness of the each morph may vary over space and time.

Mesoamerica is famous for its complex biota assembled from diverse sources. The recent discovery of a highly distinct freshwater catfish, Lacantunia enigmatica (Lacantuniidae), in Chiapas, Mexico, added an unresolved taxon to this biogeographic puzzle. Morphology has not resolved the relationships of Lacantunia among the >3000 species of Siluriformes. We added Lacantunia to an expanding phylogenetic study of family-level taxa of living catfishes using >3.6 kilobases of nuclear DNA. We find that Lacantunia is derived from within a multi–family clade of African freshwater catfishes. Without living or fossil intermediates marking a wider lacantuniid distribution, this is an extraordinary case of biogeographic disjunction. Continental clades distributed in the New and Old World tropics are often explained by vicariance of Gondwanan ancestors of deep Mesozoic age. However, our fossil-calibrated, relaxed-clock molecular analyses estimate lacantuniid divergence between 75 to 94 mya, after separation of ...

Stromatolites, the dominant Precambrian life form, declined in the Phanerozoic to occur today in only a few sites. This decline has been attributed to evolution of metazoan grazers, but stromatolites in our study site, Cuatro Cienegas, Coahuila, Mexico, harbor diverse macroinvertebrates. Drawing on food chain theory, we hypothesized that fish predation on invertebrates controls invertebrate populations, allowing stromatolites to flourish in Cuatro Cienegas. Our experiment used small mesh (1 mm) cages to exclude all but larval fishes, and larger (6.5 mm) cages to exclude all larger fishes (including the molluscivorous and omnivorous endemic polymorphic cichlid, Herichthys minckleyi), but allow access to all sizes of the abundant endemic pupfish, Cyprinodon bifasciatus. No effects of treatments on invertebrate densities were noted at 6 week, but significant effects were observed on specific taxonomic groups after 3 month. In absence of fishes, hydrobiidae snails and ceratopogonids increased 3- and 5-fold, respectively, and invertebrate assemblage composition varied among treatments. Algal biomass was not affected by treatments, but algal species composition appeared to change. Overall results suggest that fish assemblages structure invertebrate assemblages, and that fishes may also be factors in determining algal communities.

Objective—To compare intraoperative pain responses following intraovarian versus mesovarian injection of lidocaine in mares undergoing laparoscopic ovariectomy. Design—Randomized controlled trial. Animals—15 mares between 4 and 20 years old. Procedure—Standard bilateral laparoscopic ovariectomy was performed. Prior to manipulation of the ovary, 2% lidocaine (10 mL) was injected into the ovary and saline (0.9% NaCl) solution (10 mL) was injected into the mesovarium on 1 side, with saline solution (10 mL) injected into the ovary and 2% lidocaine (10 mL) injected into the mesovarium on the other side. Presence (yes vs no) and severity (visual analogue scale) of pain were scored at 5 times (grasping of the ovary, dissection of the mesosalpinx, tightening of the first loop ligature, tightening of the second loop ligature, and transection of the ovarian pedicle) by 2 individuals blinded to treatment and each other's observations. Results—During 4 of the 5 observation periods, significantly fewer mares had signs of pain following mesovarian injection of lidocaine, and during 2 of the 5 observation periods, visual analogue scale score was significantly lower. Conclusions and Clinical Relevance—Results suggest that mesovarian injection of lidocaine is associated with significantly lower pain responses, compared with intraovarian injection, in horses undergoing laparoscopic ovariectomy. (J Am Vet Med Assoc 2005;227:593–596)

A recent survey of benthic macroinvertebrates of the Cuatro Cienegas basin found 118 species in the 21 sites collected. Four exotic macroinvertebrates that could threaten the native biota were found within or near the basin.

Though adults and older juveniles of some species are commonly encountered in freshwater reaches of coastal streams and rivers, pipefishes in general are believed to be either amphidromous or marine. In 1992, Gulf pipefish (Syngnathus scovelli) were reported in Lake Texana, a reservoir on the Navidad River near Edna, Jackson County, Texas. In June 2011, we collected an adult male with embryos and a juvenile from the same lake. This strongly suggests reproduction and persistence of the population at Lake Texana, which does not have access to saline waters. Though presence of a viable, reproducing population was not absolutely confirmed this appears likely to be the first known landlocked, freshwater population of any species of pipefish.

Nymphophilus minckleyi is a hydrobiid snail endemic to the freshwater spring ecosystem of Cuatro Cienegas, Mexico. We used seven allozyme loci to examine the genetic substructure of N. minckleyi from 14 sites (subpopulations) in the basin and to test the hypothesis that spring pools in Cuatro Cienegas are separated into seven hydrologically distinct drainages. Hierarchical F-statistics suggest significant population structure exists among the fourteen populations but not among the seven proposed drainages. Cluster analysis of Nei’s genetic distance did not show populations grouping according to drainages, although it did reveal alternative clusters. We found two distinct morphotypes that were supported as genetically distinct groups by the allozyme data. Genetic studies of vagile species in desert spring ecosystems can be used to reveal hydrologic connections and identify genetically unique sub-populations.

Two horses were examined for large head wounds suspected to be the result of trauma and characterized by extensive necrosis of the skin and subcutaneous tissue, with abundant purulent exudate. Corynebacterium pseudotuberculosis was isolated from the facial wounds in both horses. Histopathologic examination revealed severe suppurative cellulitis and panniculitis with fistulous tracts and granulation tissue in 1 horse. Both horses were treated with local wound care, nonsteroidal anti-inflammatory drugs, and administration of antimicrobials. The concept of moist wound care was used in the second horse, with products that have recently become available for veterinary wound management. Outcome in both horses was good.

Resource polymorphisms, or morphological variations related to resource use, are common in fishes and are thought to be a possible step in speciation. This study experimentally tests the hypothesis that fitness (as estimated by growth rates) is increased by the presence of multiple trophic morphotypes (or morphs) within a population. Cage experiments were used to quantify the intraspecific competitive interactions between morphs of the polymorphic cichlid Herichthys minckleyi in Cuatro Cienegas, Mexico. Results sug- gest that competition is reduced between morphs in mixed-morph treatments relative to equal-density single-morph treatments. Field studies revealed that the morphs feed in dif- ferent microhabitats and use different feeding behaviors within these microhabitats. These results suggest that the polymorphism is maintained in the population because it decreases competition between the morphs, and that differences in feeding behavior facilitate resource partitioning.

Several small, enclosed reserves in southern Africa are experiencing significant elephant population growth, which has resulted in associated environmental damage and changes in biodiversity. Although several techniques exist to control elephant populations, e.g., culling, relocation, and immunocontraception, the technique of laparoscopic vasectomy of free-ranging bull elephants was investigated. Bilateral vasectomies were performed in 45 elephants. Of these elephants, one died within 24 hr of recovery and two had complications during surgery but recovered uneventfully. Histologic examination confirmed the resected tissue as ductus deferens in all the bulls. Most animals recovered uneventfully and showed no abnormal behavior after surgery. Complications recorded included incisional dehiscence, 1 full-thickness and 2 partial-thickness lacerations of the large intestine, and initial sling-associated complications, for example, deep radial nerve paresis. One bull was found dead 6 weeks after surgery without showing any prior abnormal signs. Vasectomy in free-ranging African bull elephants may be effectively performed in their normal environment. The surgical procedure can be used as a realistic population management tool in free-ranging elephants without major anesthetic, surgical, or postoperative complications.

Since Barbour proposed sympatric speciation to explain evolution of silversides in the Lerma-Santiago basin, relatively little subsequent study has been done. We assessed foraging patterns of four sympatric silversides species (Chirostoma estor, Chirostoma grandocule, Chirostoma attenuatum and Chirostoma patzcuaro) in Lago de Pátzcuaro to understand resource partitioning and their sympatric coexistence. We assessed the abundance of invertebrate prey in three feeding habitats and measured physical and chemical habitat parameters at two study sites. Fish were collected during the wet (September 1987) and dry (March 1988) seasons; a total of 242 gut contents were analyzed. We evaluated the trophic guild of each species using the index of relative importance (IRI), prey selectivity with the Ivlev Electivity Index (E), dietary diversity using Shannon and Wiener diversity index (H’), and diet overlap using Morisita index. All silverside species were determined to be predacious carnivores that feed mainly on nekton and periphyton. Dietary diversity and prey selectivity patterns were similar among species and diet overlap was >70%. Our data do not support the proposition that coexistence of these four fish species is maintained by dietary specialization. We hypothesize that sympatric coexistence of atherinopsids in Lago de Pátzcuaro is explained by food resource availability and ontogenetic variation in their diets. This study highlights the importance of analyzing ecological patterns and mechanisms as basic elements for designing conservation strategies of species flocks, especially under habitat loss and introduction of exotic species. Conservation efforts are urgent to preserve the rare evolutionary process of sympatric speciation (habitat segregation) that is occurring in other lakes in central Mexico, and probably already lost in the Lago de Pátzcuaro, as a result of poor management and inadequate conservation strategies. KEY WORDS: Atherinopsidae, feeding interactions, species flocks, evolutionary process, conservation. RESUMEN: Los patrones de forrajeo de cuatro especies simpátricas del género Chirostoma (Chirostoma estor, Chirostoma grandocule, Chirostoma attenuatum y Chirostoma patzcuaro) fueron evaluadas en el Lago de Pátzcuaro, para entender la repartición de recursos alimenticios y su coexistencia simpátrica. La abundancia de invertebrados presa fue estimada en distintos hábitat alimenticios y se midieron parámetros físicos y químicos del hábitat en dos sitios de estudio. Los peces fueron recolectados durante las temporadas de lluvias (Septiembre 1987) y estiaje (Marzo 1988); 242 tractos digestivos fueron analizados. Se revaluó el gremio trófico, la selectividad de las presas, la diversidad y el traslape de dieta. Las cuatro especies fueron determinadas como carnívoros depredadores que se alimentan principalmente de necton y perifiton. La diversidad de la dieta y los patrones de selectividad de presas fueron similares entre los atherinopsidos y el traslape de dieta fue >70%. Los resultados no apoyan la propuesta de que la coexistencia de estas cuatro especies se mantiene por medio de la especialización de su dieta. Se hipotetizó que la coexistencia simpátrica de los atherinopsidos del Lago de Pátzcuaro se explica por la alta disponibilidad de recursos alimenticios y la variación ontogénica de su dieta. Este estudio resalta la importancia de analizar los patrones y mecanismos ecológicos como elementos básicos para el diseño de estrategias de conservación en bandadas de especies, bajo efectos antropogénicos como la pérdida del hábitat y la introducción de especies exóticas. Los esfuerzos de conservación son urgentes para preservar el raro proceso evolutivo de la especiación simpátrica (segregación del hábitat) que ocurre en otros lagos del centro de México, y que posiblemente se ha perdido en el Lago de Pátzcuaro, como resultado del manejo deficiente y estrategias de conservación inadecuadas. PALABRAS CLAVE: Atherinopsidae, interacciones alimenticias, bandadas de especies, procesos evolutivos, conservación.

Objective—To evaluate the outcome of horses with large fragments of the extensor process of the distal phalanx that were removed by use of arthrotomy. Design—Retrospective study. Animals—14 horses with large fragments of the extensor process of the distal phalanx. Procedure—Medical records for horses with large fragments of the extensor process that were removed by use of arthrotomy were reviewed. Data retrieved from medical records included signalment, use of horse, affected limb, lameness history, lameness examination findings, radiographic findings, surgical technique, and outcome. Follow-up evaluation was obtained by telephone interview. Results—Most affected horses were < 5 years old and had a history of chronic lameness. Lameness grade ranged from 1/5 to 4/5. Fragments involved 20 to 45% of the dorsopalmar articular surface of the distal phalanx. Eight of 14 horses had a successful outcome. Outcome was not associated with age, duration or severity of lameness, or fragment size. Conclusions and Clinical Relevance—Despite involvement of a large portion of the articular surface and use of arthrotomy, joint instability and permanent soft tissue injury was not a problem in most horses. Outcome may be improved by selection of horses with lameness of < 2 years' duration and careful management after surgery. A fair prognosis may be anticipated for removal of large fragments of the extensor process via arthrotomy. (J Am Vet Med Assoc 2000; 217:1351–1355)

Transrectal ultrasonography of a 35-yr-old captive female southern white rhinoceros (Ceratotherium simum simum) with a history of chronic mucohemorrhagic vulvar discharge revealed right transmural uterine horn enlargement. Abdominal laparoscopic surgery, although extremely difficult because of inadequate instrumentation, permitted uterine visualization and biopsy. Standing anesthesia, incorporating butorphanol and azaperone together with local anesthetic infiltration, facilitated the laparoscopy. A leiomyoma was suspected on the basis of history, physical examination, ultrasonographic appearance, and histopathology. Prior rhinoceros laparoscopies have failed, primarily from limitations imposed by recumbency.

Minimally invasive surgery in the human was first identified in mid 900’s. The procedure as is more commonly practiced now was first reported in 1912. There have been many advances and new techniques developed in the past 100 years. Equine laparoscopy, was first reported in the 1970’s, and similarly has undergone much transformation in the last 40 years. It is now considered the standard of care in many surgical techniques such as cryptorchidectomy, ovariectomy, nephrosplenic space ablation, standing abdominal exploratory, and many other reproductive surgeries. This manuscript describes the history of minimally invasive surgery, and highlights many of the techniques that are currently performed in equine surgery. Special attention is given to instrumentation, ligating techniques, and the surgical principles of equine minimally invasive surgery.

Species range expansions are often difficult to determine (West 1968, Smida and Wilson 1985, Dennis 2001). Spatial -ly and temporally comprehensive surveys allow strong infer-ences regarding absences with minimal subjectivity, but typi-cally surveys are inadequately comprehensive either spatially or temporally for use in detecting range expansions. Large datasets that cover long time periods and large geographic space are needed for this purpose. The Fishes of Texas Proj-ect database (FoTX; Hendrickson and Cohen 2011), which has been highly controlled as to quality and represents the most complete database of historical fish occurrences in Texas, is the best source for data to address range expansions and contractions for Texas’ fish species. Museum data clearly and unambiguously document presence (Chapman 2005) but typically cannot rigorously address absences (West 1968). For various reasons specimens deposited in museums do not always represent the entire community present at a given lo-cation (West 1968). Susceptibility to capture varies among species, among collecting methods, and as a function of ef-fort. Furthermore, sampling methods and effort are inconsis -tently reported in museum records. Additionally, collectors may deposit only selected specimens from their collections, thus creating pseudoabsences. However, the museum data are numerous, cover a large time span, and specimens can be examined for positive identification. Museum data are thus often the best data readily available for assessing changes in distributions.We used FoTX’s database of museum—vouchered species occurrences to examine potential range expansions. A “spe-cies occurrence” is the presence of a species from a single collecting event, which is defined by a unique combination of collector(s), location and date. Species occurrences were garnered from the FoTX database of records from 40 do-nor institutions, coupled with the same project’s database of species occurrences gathered from published literature, and our own post—2007 collections from the lower coastal plain of Texas. These are used in an attempt to detect recent spatial changes in fish distributions. Our recent collections are all backed by museum voucher specimens and are other-wise typical of museum specimen—based occurrence data in that they come from collecting events conducted irregularly over space and time using non—standardized methods and effort. Our preliminary analyses of these combined data sets identified

Accurate establishment of baseline conditions is critical to successful management and habitat restoration. We demonstrate the ability to robustly estimate historical fish community composition and assess the current status of the urbanized Barton Creek watershed in central Texas, U.S.A. Fish species were surveyed in 2008 and the resulting data compared to three sources of fish occurrence information: (i) historical records from a museum specimen database and literature searches; (ii) a nearly identical survey conducted 15 years earlier; and (iii) a modeled historical community constructed with species distribution models (SDMs). This holistic approach, and especially the application of SDMs, allowed us to discover that the fish community in Barton Creek was more diverse than the historical data and survey methods alone indicated. Sixteen native species with high modeled probability of occurrence within the watershed were not found in the 2008 survey, seven of these were not found in either survey or in any of the historical collection records. Our approach allowed us to more rigorously establish the true baseline for the pre-development fish fauna and then to more accurately assess trends and develop hypotheses regarding factors driving current fish community composition to better inform management decisions and future restoration efforts. Smaller, urbanized freshwater systems, like Barton Creek, typically have a relatively poor historical biodiversity inventory coupled with long histories of alteration, and thus there is a propensity for land managers and researchers to apply inaccurate baseline standards. Our methods provide a way around that limitation by using SDMs derived from larger and richer biodiversity databases of a broader geographic scope. Broadly applied, we propose that this technique has potential to overcome limitations of popular bioassessment metrics (e.g., IBI) to become a versatile and robust management tool for determining status of freshwater biotic communities.

A 364-kg (800-lb) 1-year-old mixed-breed horse was admitted for treatment of uncontrolled bleeding after castration. Multiple attempts to ligate the testicular artery through the scrotal incisions prior to referral had been unsuccessful. Because of the owner's concerns about cost, an attempt was made to control the bleeding by applying pressure to the inguinal region and administering formalin IV. However, hemorrhage continued. A decision was made to use laparoscopy to ligate the testicular artery. The horse was anesthetized and positioned in dorsal recumbency, and a routine ventral laparoscopic approach was used. The horse recovered without further complications. Laparoscopy should be considered for ligation of the testicular artery in horses with uncontrolled bleeding after castration.

Objective—To compare efficacy and safety of paste formulations of firocoxib and phenylbutazone in horses with naturally occurring osteoarthritis. Design—Randomized controlled clinical trial. Animals—253 client-owned horses with naturally occurring osteoarthritis. Procedures—Horses were treated with firocoxib (0.1 mg/kg [0.045 mg/lb], PO, q 24 h) or phenylbutazone (4.4 mg/kg [2 mg/lb], PO, q 24 h) for 14 days. Physical examinations and lameness evaluations were performed prior to treatment and after 7 and 14 days. Clinical improvement was defined as a reduction of at least 1 lameness grade or a combined reduction of at least 3 points in scores for pain during manipulation or palpation, joint swelling, joint circumference, and range of motion. Results—Proportion of horses clinically improved on day 14 for the firocoxib group (104/123 [84.6%]) was not significantly different from the proportion for the phenylbutazone group (103/119 [86.6%]). Proportion of horses that were improved on day 14 was significantly greater for horses treated with firocoxib than for horses treated with phenylbutazone with regard to score for pain on manipulation or palpation (P = 0.028), joint circumference score (P = 0.026), and range of motion score (P = 0.012), but not for overall lameness score or joint swelling score. No direct treatment-related adverse effects were detected during the study. Conclusions and Clinical Relevance—Results suggested that overall clinical efficacy of a paste formulation of firocoxib in horses with naturally occurring osteoarthritis was comparable to efficacy of a paste formulation of phenylbutazone.

Objective—To compare pain responses in stallions undergoing standing laparoscopic cryptorchidectomy following intratesticular or mesorchial infiltration of lidocaine. Design—Clinical trial. Animals—20 stallions with 1 or 2 undescended testes. Procedures—Standing horses were administered a nonsteroidal anti-inflammatory drug and a caudal epidural injection of detomidine hydrochloride and underwent laparoscopic cryptorchidectomy. The undescended testis (1/horse) was grasped to determine the preoperative pain response (present vs absent) and assess severity of pain (by use of a visual analog scale [VAS]). The undescended testis or its mesorchium was injected with 2% lidocaine (10 mL); saline (0.9% NaCl) solution (10 mL) was injected in the untreated structure. Presence and severity of pain was determined by 2 individuals as the testis was grasped following infiltration and at the times of ligature placement and transection of the spermatic cord. Serum cortisol concentration was analyzed preoperatively, after ligation, and after transection. Presence or absence of signs of pain, severity of pain, and serum cortisol concentrations were compared within and between treatment groups. Results—Detection of signs of pain and VAS pain scores did not differ between observers at any time point. Perceived pain responses associated with ligature placement differed significantly from preoperative responses. Pain responses and serum cortisol concentrations after intratesticular and mesorchial infiltration of lidocaine did not differ. Conclusions and Clinical Relevance—Results suggested that intratesticular or mesorchial infiltration of lidocaine combined with administration of a nonsteroidal anti-inflammatory drug and caudal epidural injection of detomidine provides adequate analgesia in standing stallions undergoing laparoscopic cryptorchidectomy.

Lacantunia enigmatica n. sp. Rodiles-Hernández, Hendrickson & Lundberg Table 1 Holotype. ECO-SC 3859 (Fig. 1), male, 427 mm SL, México, Chiapas, Río Usumacinta basin, Río Lacantún, Selva Lacandona, Reserva de la Biosfera Montes Azules, 16°08.083' N, 90°55.317' W (Fig. 3), Rodiles-Hernández, 8 November 2002. Paratypes. All Chiapas, México, Río Usumacinta basin. Museum code (following Leviton et al. (1985) but adding here ECO-SC [ECOSUR San Cristóbal, address as for first author] and ENCB-IPN [Escuela Nacional de Ciencias Biológicas - Instituto Politéc- nico Nacional - address as for IPN in Leviton et al.]) and number is followed when data are available by sex, SL mm, collection date, Reserve (Reserva de la Biosfera Montes Azules = RIBMA; Selva Lacandona = SLac [Río Lacantún basin]), Municipio (Benemerito de las Américas [BA], Marqués de Comillas [MdC]), specific locality, Lat. N, Long. W, collector (CCS=Celedonio Chan-Salas; EVV=Ernesto Velázquez-Velázquez; SDC=Sara Domínguez-Cisneros; RRH= Rocío Rodiles-Hernández). * indicates articulated and disarticulated material; ** cleared and stained preparation; *** HRXCT data examined: ANSP 178696**, female, 280 mm, 14 May 1996, RIBMA, Río Lacanjá, 16° 25.92’ N, 90° 51.8’ W, RRH; ANSP 178697, female, 280 mm, 19 May 1997, RIBMA, Río Lacanjá, 16° 26.75’ N, 90° 51.63’ W, CCS; ANSP 178698*, male, 318 mm, 20 May 1997, SLac, MdC, Zamora Pico de Oro, 16° 20.10’ N, 90° 50.58’ W, RRH; ECO-SC 1166, female, 406 mm, 01 Mar. 1997, SLac, MdC, Zamora Pico de Oro, 16° 22.8’ N, 90° 44.99’ W, RRH; ECO-SC 3856, female, 384 mm, 20 May 2001, SLac, MdC, entre Reforma Agraria y Zamora Pico de Oro, 16° 20.10’ N, 90° 50.58’ W, RRH; ECO-SC 3858, male, 320 mm, 3 May 2002, SLac, MdC, Reforma Agraria, 16° 15.31’ N, 90° 51.99’ W, RRH; ENCB-IPN 5787, male, 353 mm, 20 May 1997, SLac, MdC, Zamora Pico de Oro, 16° 20.10’ N, 90° 50.58’ W, RRH; IBUNAM 12739, female, 282 mm, 20 May 2001, SLac, MdC, entre Reforma Agraria y Zamora Pico de Oro, 16° 15.31’ N, 90° 51.99’ W, RRH; TNHC 29071***, female, 347 mm, 5 Dec. 1998, SLac, BA, Puente Lacantún, 16° 32.45’ N, 90° 41.7’ W, EVV; TNHC 29072***, female, 223 mm, 20 May 1997, SLac, MdC, Zamora Pico de Oro, 16° 20.10’ N, 90° 50.58’ W, RRH; UANL 15259, female, 351 mm, 21 Aug. 1998, SLac, MdC, Río Chajulillo, 16° 5.57’ N, 90° 57.47’ W, EVV; UMMZ 243699, female, 295 mm, 20 Mar. 1997, RIBMA, Río Lacanjá, 16° 24.45’ N, 90° 49.46’ W, CCS; USNM 378035, male, 354 mm, 11 Dec. 1997, RIBMA, Río Lacanjá, 16° 25.525’ N, 90° 50.986’ W, EVV. Non-type specimens of Lacantunia enigmatica. ANSP 178695, female, 330 mm, 21 Aug. 1998, SLac, MdC, Río Chajulillo, 16° 5.57’ N, 90° 57.47’ W, EVV; CAS220134, female, 290 mm, 21 Sep. 1997, SLac, MdC, Ejido Reforma Agraria, 16° 15.31’ N, 90° 51.99’ W, CCS; ECO-SC 1239-2, male, 314 mm, 21 Sep. 1997, SLac, MdC, Ejido Reforma Agraria, 16° 15.31’ N, 90° 51.99’ W, CCS; ECO-SC 1363-3, female, 308 mm, 20 May 1997, SLac, MdC, Ejido Zamora Pico de Oro, 16° 20.10’ N, 90° 50.58’ W, RRH; ECO-SC 1368-2, 274 mm, 19 May 1997, RIBMA, Río Lacanjá, 16° 26.75’ N, 90° 51.63’ W, CCS; ECO-SC 1426, female, 319 mm, 19 May 1997, RIBMA, Río Lacanjá, 16° 26.94’ N, 90° 51.84’ W, EVV; ECO-SC 1511-2, female, 302 mm, 11 Dec. 1997, RIBMA, Río Lacanjá, 16° 25.525’ N, 90° 50.986’ W, EVV; ECO-SC 2138, male, 356 mm, 21 Mar. 1998, RIBMA, Río Lacanjá, 16° 24.581’ N, 90° 49.502’ W, EVV; ECO-SC 2582-1, male, 384 mm, 9 Sep. 1998, SLac, MdC, Arroyo Caribe, 16° 34.577’ N, 90° 42.342’ W, EVV; ECO-SC 2582-2, female, 344 mm, 9 Sep. 1998, SLac, MdC, Arroyo Caribe, 16° 34.577’ N, 90° 42.342’ W, EVV; ECO-SC 4005, 360 mm, 7 Feb. 2003, SLac, MdC, Reforma Agraria, 16° 15.31’ N, 90° 51.99’ W, CCS; ECO-SC 4006**, male, 370 mm, 15 May 2003, SLac, MdC, Reforma Agraria, 16° 15.31’ N, 90° 51.99’ W, CCS; ECO-SC 4008, female, 340 mm, 15 Jun. 1997, RIBMA, Río Tzendales, CCS; ECO-SC 4009**, female, 322 mm, 12 Jun. 1977, SLac, MdC, not specified, CCS; ECO-SC 4125, female, 340 mm, 24 Nov. 2003, SLac, MdC, Reforma Agraria, 16° 15.31’ N, 90° 51.99’ W, CCS; ECO-SC 4126, male, 330 mm, 30 Jan. 2004, SLac, MdC, Reforma Agraria, 16° 15.31’ N, 90° 51.99’ W, CCS. Diagnosis: Same as genus. Description: Maximum size exceeding 400 mm SL. Proportional measurements are given in Table 1. Body moderately elongate, markedly depressed anteriorly, strongly compressed posteriorly. Dorsal profile rises vertically from nearly terminal mouth on snout, then in a sharply convex curve from snout to above orbit, then straight and rising gently to occiput; most specimens with low nuchal hump before dorsal-fin origin; profile continuing horizontally below and behind dorsal fin to adipose-fin origin; falling gently below adipose to caudal-fin base. Ventral profile abruptly convex downward from mandible tip to mental barbels; gently convex or straight along head, pectoral girdle and abdomen to pelvic girdle; straight to anal-fin origin, finally rising in straight line to slightly concave curve to caudal-fin base. Cross-sectional shape flattened oval at vertical through middle of eye; head depth at mid-eye much less than head width at same level, about equal to distance between posterior nares, and contained 3 times in bony HL. Maximum body width across cleithra at pectoral spine insertions always greater than body depth, about 3.6-4.6 times in SL. Cross sectional shape becoming sub-quadrangular and deeper behind eye to pelvic-fin insertions, body depth about equal to width near posterior insertion of dorsal fin, increasingly compressed posteriorly onto laterally-flattened caudal peduncle and fin. In dorsal and ventral views, snout very broad and bluntly rounded, projecting slightly beyond mandibular symphysis. Mouth scarcely subterminal, opening anteriorly; margins of closed mouth smoothly curved; no teeth exposed when mouth closed; rictus below eye; gape width about 1.3-1.6 in membranous HL; 1.8-2.1 in predorsal distance. Lips moderately papillate, more so in larger fish; lips set off by grooves from bands of jaw teeth and without accessory folds parallel to tooth rows. Fleshy rictal fold in a shallow pocket behind corner of mouth, protruding a little above general surface of head below maxillary barbel; ventral to rictal fold, a thin submandibular groove extends less than 1/2 distance to symphysis; dorsal to rictal fold a shallow groove extends anteriorly to terminate at insertion of maxillary barbel. Each premaxillary tooth patch broad, its width about 3 times its symphyseal length; premaxillary teeth very fine, needle-like, tall and gently curved inward, especially the inner teeth; teeth arranged in irregular rows, about18 teeth along transect near symphysis in specimens about 30 cm SL. Dentary teeth like those on premaxillary; tooth band broadest near symphysis, tapering laterally onto coronoid process. No teeth on palate. Head skin thick, concealing skull roofing bones and narrowly open cranial fontanelles, yet skull roof near midline not buried by masses of jaw musculature dorsolaterally and laterally on head and masses of epaxial muscle on nape. Supraoccipital process not evident on surface behind occiput; process very short and remote from dorsal fin base. Four pairs of proximally flattened barbels. Maxillary barbels inserted above lip midway between verticals through posterior nostril and eye; reaching to below dorsal fin. Maxillary barbels free from upper lip, laterally compressed basally, lying in shallow groove below eye and on cheek. Nasal barbel arises from anterior rim of posterior nostril; reaching a point 3-4 times eye diameter behind eye and about equal to distance between posterior nares. Inner mental barbels closer to margin of lower jaw than to gular fold apex, not reaching edge of gill membrane and about equal to or a little greater in length than distance between their bases. Outer mental barbels inserted at level of gular fold apex; tips of outer mental barbels reach onto depressed pectoral fin to a point slightly less than length of inner fin ray. Gular fold defining a deep groove in front of hyoid arch, its sides meeting apex at less than right angle. Gill membranes anteriorly united to each other, then diverging without overlap, supported by 11-12 branchiostegal rays (two on posterior ceratohyal, 1 or 2 on joint between ceratohyals, 8 on anterior ceratohyal). Gill rakers stiffly-ossified, sharp and slender; rakers on first branchial arch 14-15, (4 upper, 10-11 lower); first, second and fifth branchial arches with single anterior rows of gill rakers, third and fourth arches with anterior and posterior rows. Anterior nostril tubular, located dorsally on snout, remote from snout tip by about 3 times its own diameter, anterior to a line between anterior edges of maxillary barbel bases. Posterior nostril as close to anterior nostril as to eye (ca. twice its own diameter in front of eye); medially offset from a line between midpoint of anterior border of eye and anterior nostril; nostril rim a thin, hyaline membrane low or incomplete posteriorly and produced anteriorly as thick nasal barbel; aperture ovoid with its long axis parallel to longitudinal body axis. Eye dorsolateral, centered on a vertical at about first third of bony HL, without a free orbital rim, clear corneal skin defines ocular surface and shape of eye. Ocular surface ovoid to nearly circular; pupil less than 50% of ocular surface. Eye relatively small: horizontal ocular diameter 11.2-14.2 in HL, 5.6-7.5 in interocular, 4-6.3 in snout. Cephalic sensory canals thin; supratemporal, supraorbital, infraorbital, and preopercular canals lead to short, multiple-branched cutaneous canals and clusters of small pores on sides and top of head; cutaneous canal branches of mandibular and nasal canals not dendritic on chin and snout, respectively. Lateral line canal straight and superficial with simple, short tubes and pores, ending over hypurals. Dorsal fin inserted a little anterior of first third of SL; its origin near a vertical at tip of inner pectoral-fin rays. 10-12 dorsal-fin rays: spinelet, spine, and 8-10 soft, branched rays; 9-11 pterygiophores. Dorsal-fin base embedded in thick tissue especially at its anterior insertion. Spinelet small, with a shallow anteromedial cavity and its limbs widely diverging at ca. 60° angle. Dorsal spine short, slender, straight, not denticulate; ossified for about half its length, otherwise segmented. Distal margin of dorsal fin rounded, secondfourth soft rays longest, last dorsal-fin ray more than 2/3 length of second soft ray. Adipose fin large, thick; its anterior insertion at about 70% of SL, remote from dorsal fin base, by about 1.1-1.8 times dorsal base. Adipose-fin margin gently rounded, its apex at a vertical just behind middle of anal fin, ending without a short, free lobe at a weak notch in front of upper caudal fin lobe. Adipose-fin length 2.7-3.8 in SL, about 0.8-1 in HL, 2.2-2.7 in length of dorsal-fin base and 1.3-1.8 in length of anal-fin base; adipose-fin height 6-12 times in adipose fin length, 1.7-4.5 in least caudal peduncle depth. Caudal fin slightly rounded to truncate with rounded corners. Principal caudal rays 1,7,9,1; 10-12 upper and 11-13 lower procurrent caudal-fin rays. Anal fin inserted a little behind a vertical at adipose fin origin; fin margin rounded; middle rays the longest. Anal-fin rays 22-26 (9-10 simple). Last two anal-fin rays closely separate; 22-25 anal-fin pterygiophores. Anal-fin base embedded in thick tissue especially at its anterior insertion. Pectoral fin with a spine and 10-11 branched rays; its margin gently rounded, third soft ray longest; no fleshy membrane along medial edge of inner ray; depressed pectoral fin reaches to a vertical between second and third dorsal -fin soft rays. Pectoral spine formed from basal half of first lepidotrich; distal half filamentous and segmented. Pectoral spine articulating base with typical siluriform dorsal, anterior and ventral processes. Shaft of spine without dentations or serrae, and terminating bluntly at transition to segmented ray. Posterior cleithral process narrow, short and moderately sharp; surface buried in skin and weakly ornamented with few subparallel ridges. Axillary pore below postcleithral process. Pelvic fin inserted a little behind a vertical at middle body and below midpoint of depressed last dorsal-fin ray; containing 6 rays, first simple, third longest; no fleshy membrane along medial edge of inner ray; pelvic-fin margin gently rounded; pelvic-fin length contained 6-8 times in SL and separated from anal-fin origin by half its length. Pelvic splint absent. Total vertebrae 55-57, 22-25 precaudals and 31-33 caudals. Weberian complex including 6 vertebrae, first rib on sixth vertebra. Urogenital papilla located in a shallow depression immediately behind anus between pelvic fins about midway along length of inner fin rays. No apparent sexual dimorphism. Distance from anus to anal fin origin about equal to length of inner pelvic ray. Pigmentation. Back, upper sides, nape, and tympanic area laterally over swim bladder medium to dark brown in life and in alcohol pale to dark gray or grayish blue. Upper sides with small dark and irregularly scattered freckles or spots that fade in larger fish; no stripes. Lower sides and venter much lighter, cream to white anteriorly changing to light to medium gray posterior to anus and urogenital papilla or at anal-fin origin. Dorsal fin with or without dark margin, and darker pigment concentrated in membranes between fin rays. Caudal and anal fins with broad dark margins. Adipose pigmentation like that of adjacent back and sides, with vague freckles or spots. Pectoral and pelvic fins with dorsal surfaces mostly pigmented brown to gray proximally; anterior and distal margins pallid, often strikingly so; ventral surfaces of both paired fins lighter; some individuals with evenly dark pectoral and pelvic fins. Dorsum of head and opercles (except for light membranous margin) nearly uniform brown in life or dark gray in alcohol; no light spots over cranial fontanelles. Maxillary barbels dusky gray dorsally; often much lighter anteriorly and ventrally; increasingly lighter distally. Nasal barbels gray proximally grading to lighter tips. Membranous rim of posterior naris and tubular rim of anterior naris white. Lower sides and venter of head and inner mental barbels light cream to white. Outer mental barbels proximally with dark posterior edge, lighter distally. Additional descriptive information on L. enigmatica, including video animations from high-resolution X-ray computed tomography (HRXCT) is available at http://www.digimorph.org and http://clade.acnatsci.org/catfishbone/. Distribution and habitat. Lacantunia enigmatica occurs in the Ríos Lacantún and Lacanjá, tributaries of Río Usumacinta basin, Chiapas, México, inhabiting deep (to 18 m) river channels and pools with rocks and strong eddy currents. Few specimens were taken in stream mouths. Specimens were collected in both high and low water seasons, and generally during the night. Gut contents include fishes, crabs, prawns and large, tough seeds. Etymology. The name enigmatica is Latin for baffling or inexplicable in reference to the unexpected discovery, obscure relationships and origin of the new catfish. We suggest the common name “Chiapas Catfish” (= “Bagre de Chiapas”) for L. enigmatica. Discussion The major phylogenetic lines of Siluriformes are unevenly resolved. South American Diplomystidae are the sister-group to all other catfishes or Siluroidei (Grande 1987, Arratia1987). The North American fossil Hypsidoridae (Grande 1987) are a deep clade subtending the remaining extant siluroid catfishes. The Neotropical extant Cetopsidae may also be among the most basal catfish lines (de Pinna & Vari 1995). The many remaining catfishes are placed in 31 well-supported, monophyletic families, yet few multi-family groups (Arratia et al. 2003). Phylogenetic resolution is high within many families (de Pinna 1993, Arratia et al. 2003), whereas most family interrelationships remain to be determined. Lacantunia is not a basal catfish within or below Diplomystidae. Instead, the new catfish shares derived characters uniting all non-diplomystid catfishes into the Siluroidei (Grande 1987). These synapomorphies are: 8 upper principal caudal-fin rays (cf. primitively9 in diplomystids); barbels on the chin (cf. no mental barbels); fifth vertebra sutured to compound second-fourth (Weberian) fused vertebrae and partly covered by lamellar bone (cf. fifth vertebra with non-sutural joints and lacking covering of lamellar bone). In Siluroidei, Lacantunia and non-hypsidorid catfishes share a reduced distal maxillary arm and short medial maxillary process (cf. in diplomystids and hypsidorids maxillary arm primitively expanded and maxillary process elongated), loss of maxillary teeth (cf. teeth present), and sutures uniting anterior and posterior ceratohyals (cf. synchondral joint between ceratohyals (Grande 1987, de Pinna 1993)). Also among Siluroidei, the development of interdigitating coracoid symphyseal sutures places Lacantunia with non-cetopsid as well as non-diplomystid catfishes (cf. primitively in diplomystids and cetopsids coracoid symphyseal sutures not present; although the sutures secondarily lost in Siluridae and some Trichomycteridae) (de Pinna 1993, de Pinna & Vari 1995). Other Río Usumacinta basin catfishes belong to three families: Ictaluridae, Heptapteridae and Ariidae. Discovery of a new catfish belonging to any of these families would be unsurprising, but such is not the case. Lacantunia resembles ictalurids more than it does heptapterids or ariids, however, Lacantunia lacks the synapomorphies uniting crown group Ictaluridae (Lundberg 1982, Lundberg 1992, Grande & de Pinna 1998): skull roof covered by jaw adductor muscles attached to prominent sagittal crest (cf. primitively, as in Lacantunia, muscles not on skull roof and sagittal crest not developed); infraorbital canal exits frontal bone (cf. canal exits sphenotic); supracleithrum with subpterotic process (cf. process absent). Lacantunia also lacks synapomorphies that place the fossil genus Astephus, an early Tertiary North American catfish, as the sister lineage to crown group Ictaluridae(Lundberg 1992, Grande & de Pinna 1998): loss of bony posterior process on pelvic girdle (cf. primitively ossified posterior process present as in Lacantunia); continuous cartilage along posterior edge of pelvic girdle (cf. cartilage in two parts interrupted by bone); pelvic-fin rays 7 or more and intraspecifically variable (cf. pelvic-fin rays invariably 6). We found no characters suggesting a deeper sister group relationship between Lacantunia and all Ictaluridae. Lacantunia also lacks synapomorphies of Heptapteridae a

A method for performing laparoscopic ovariectomy with high-power ultrasonic shears in mares is described, along with results in 10 mares. Briefly, after epidural administration of detomidine and local anesthesia with mepivacaine, 3 cannulas were placed in each paralumbar fossa. A laparoscope was placed through the most dorsal cannula, and a grasping forceps was placed through the most ventral cannula and used to grasp and manipulate the ovary. The ultrasonic shears was then placed through the middle cannula. The jaws of the ultrasonic shears were closed across a portion of the ovarian pedicle, and the instrument was discharged until tissue within the jaws was transected; the process was repeated until the entire ovarian pedicle was transected. Following removal of the right ovary, it was passed to the left side of the abdomen and both ovaries were removed through an incision in the left paralumbar fossa. No major complications were identified in any of the 10 mares. However, excessive bleeding necessitating reapplication of the ultrasonic shears (2 ovaries) or application of ligating clips (8) was encountered with 10 of the 20 ovaries. Laparoscopic ovariectomy with a high-power ultrasonic shears appears to be safe in mares.

Objective—To evaluate μ-opioid receptors in synovial membranes of horses and determine whether these receptors are up-regulated in nerve endings during inflammation. Sample Population—Synovial tissue obtained from 39 client-owned horses during arthroscopy and 14 research horses during necropsy; brain and synovial tissues were obtained during necropsy from 1 horse, and control tissues were obtained from a mouse. Procedure—Horses were classified into 7 groups on the basis of histologically determined degree of inflammation. Binding of primary rabbit antibody developed against μ-opioid receptors in equine synovial tissue was studied, using western blot analysis. Synovial membranes were tested for μ-opioid receptors by immunohistochemical staining, using a diaminobenzidine-cobalt chloride chromogen. Homogenates of synovial membranes were evaluated by use of radioligand binding. Results—Examination of western blots of equine thalamus revealed that rabbit antibody developed against μ-opioid receptors yielded a band (molecular weight, 55 kd) that corresponded with that of other opioid receptors. Use of immunohistochemical staining of synovial tissue revealed considerable staining in the proliferative lining layer and in regions surrounding vascular structures. Specific radioligand binding of tissue homogenates was found in all groups. We did not detect significant differences in binding between horses with inflammation and horses without inflammation. Conclusions and Clinical Relevance—Results of immunohistochemical analysis and radioligand binding of tissue homogenates suggest that there are opioid receptors in synovial membranes of horses. Our results support the practice of intra-articular administration of opioids to relieve pain after arthroscopic surgery in horses. (Am J Vet Res 2001;62:1408–1412).