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Age estimation in adult dogs can be performed by the radiographic measurement of the tooth pulp cavity, but the technique has hardly been described. In this study, the application of measuring pulp/tooth width ratios (P/T ratios) of the maxillary canine teeth was investigated. Pulp and tooth widths were measured at two locations on 166 maxillary canine teeth of the heads of 84 dog cadavers, using digital extraoral lateral oblique open mouth radiographs. The dogs belonged to different breeds and sexes and had a known age between 194 and 1907 days (approximately 6 months - 5 years). Both at the cemento-enamel junction (CE) and the half-height of the tooth, a comparable non-linear regression with age was demonstrated. Measuring at the CE location was less hindered by wear or superimposition. No statistically significant difference according to sex and breed size and no clinically significant difference according to skull type was found. The highest predictable capacity was found in the youngest dogs until the age of 448 days, of which 84.4% of the canine teeth had a P/T ratio above 0.39. Our results demonstrate that measuring P/T ratios of canine teeth can be used in practice to assign dogs to age categories, with the highest accuracy in young adult dogs., (© 2022 Wiley-VCH GmbH.)

Age is an important parameter to better understand wildlife populations, and is especially relevant for interpreting data for fecundity, health, and survival assessments. Estimating ages for marine mammals presents a particular challenge due to the environment they inhabit: accessibility is limited and, when temporarily restrained for assessment, the window of opportunity for data collection is relatively short. For wild dolphins, researchers have described a variety of age-determination techniques, but the gold-standard relies upon photo-identification to establish individual observational life histories from birth. However, there are few populations with such long-term data sets, therefore alternative techniques for age estimation are required for individual animals without a known birth period. While there are a variety of methods to estimate ages, each involves some combination of drawbacks, including a lack of precision across all ages, weeks-to-months of analysis time, logistical concerns for field applications, and/or novel techniques still in early development and validation. Here, we describe a non-invasive field technique to determine the age of small cetaceans using periapical dental radiography and subsequent measurement of pulp:tooth area ratios. The technique has been successfully applied for bottlenose dolphins briefly restrained during capture-release heath assessments in various locations in the Gulf of Mexico. Based on our comparisons of dental radiography data to life history ages, the pulp:tooth area ratio method can reliably provide same-day estimates for ages of dolphins up to about 10 years old., Competing Interests: J.M.H. owns and operates Companion Animal Dental Services, which has no commercial interests in the work described in this manuscript, and has no involvement in product development or marketing. This does not alter our adherence to PLOS ONE policies on sharing data and materials

Age determination of puppies represents a significant issue of animal welfare and forensic medicine, particularly for what concerns trade and imports of dogs. Despite the movement of puppy dogs before the age of 15 weeks is forbidden by Regulation (EU) No 576/2013, the occurrence of illegal transport of younger puppies is not uncommon. The illegal trade of puppies increases instances of falsified documentation, the counterfeit of vaccine certificates and discrepancies between the declared age and the real age of the puppies. Consequently, determining the exact age of animals and evaluating their welfare become legally crucial. Dental examination currently represents the most common approach to estimate the age of a puppy in clinical practice and in forensic investigations. In this work we addressed the legal, health and welfare issues associated with dogs' trade and import and we reviewed the existing literature referring to the assessment of age in dogs by dental examination. The imprecision and inaccuracy of this method make it poorly convincing in legal proceedings. The reasons for such vagueness are to be ascribed both to the lack of standardization and to many variability factors (size, breed, sex, diet, etc.) which influence dental eruption and development.

Objectives: Ecological factors, but also tooth-to-tooth contact over time, have a dramatic effect on tooth wear in primates. The aim of this study is to test whether incisor tooth wear changes predictably with age and can thus be used as an age estimation method in a wild population of mountain gorillas (Gorilla beringei beringei) from Volcanoes National Park, Rwanda., Materials and Methods: In mountain gorillas of confidently known chronological age (N = 24), we measured the crown height of all permanent maxillary and mandibular incisors (I 1 , I 1 , I 2 , I 2 ) as a proxy for incisal macrowear. Linear and quadratic regressions for each incisor were used to test whether age can be predicted by crown height. Using these models, we then predicted age at death of two individual mountain gorillas of probable identifications, based on their incisor crown height., Results: Age decreased significantly with incisor height for all teeth, but the upper first incisors (I 1 ) provided the best results, with the lowest Akaike's Information Criterion corrected for small sample size (AICc) and lowest Standard Error of the Estimate (SEE). When the best age equations for each sex were applied to gorillas with probable identifications, the predicted ages differed 1.58 and 3.33 years from the probable ages of these individuals., Conclusions: Our findings corroborate that incisor crown height, a proxy for incisal wear, varies predictably with age. This relationship can be used to estimate age at death of unknown gorillas in the skeletal collection, and in some cases, to corroborate the identity of individual gorillas recovered from the forest postmortem at an advanced state of decomposition. Such identifications help fill gaps in the demographic database and support research that requires individual-level data., (© 2018 Wiley Periodicals, Inc.)

Background: Equine incisors are often reduced in height during corrective dental procedures. Increased knowledge of subocclusal dentine thickness and pulp morphology may help prevent iatrogenic pulpar exposure. Although such data exist for equine cheek teeth, there are currently no reliable data for incisors., Objectives: To measure the distances between pulp cavities and the occlusal as well as the labial surfaces of equine incisors and to test if these distances change with age. Furthermore, pulp morphology with regard to number and orientation of pulp horns was investigated., Study Design: Observational study using cadaver material and high-resolution computed tomography., Methods: Upper and lower incisor arcades were removed from heads of 13 horses and scanned with high-resolution computed tomography. 3D Models were reconstructed and configuration as well as number of the pulp horns was evaluated. Anatomical marker points were set to measure distances between the pulp horn tips and the labial and occlusal surfaces., Results: Subocclusal dentine thickness ranged between 1.5 and 11.7 mm in upper and 0.7 and 6.7 mm in lower incisors. It decreased with tooth age. Distance to labial aspect ranged between 3.5 and 9.0 mm in upper and 3.8 and 8.1 mm in lower incisors and increased with tooth age., Main Limitations: Details of horse management, feeding and previous dental care were not available. Therefore, it remains unknown how these factors influenced the results., Conclusions: Although mean subocclusal dentine thickness of greater than 4.1 mm was found, equine incisors occasionally have less than 1 mm of thickness with potential for iatrogenic pulpar exposure during incisor reduction. Therefore, great care should be exercised by any practitioner during incisor reduction., (© 2018 EVJ Ltd.)

Introduction: The purpose of this study was to compare root and root canal width measurements between digital intraoral radiography (IOR) and micro-computed tomography (μCT). The accuracy of IOR measurements of canine mandibular molars was scrutinized to assess feasibility of developing a model to estimate animal age based on dentinal thickness., Materials and Methods: Thirty-nine canine mandibular first molars were imaged using μCT and IOR. For each tooth, the root and root canal width of the mesial and distal roots were measured by a single observer at 3 marked sites on μCT and IOR. Two different software programs were used to measure the radiographs. The radiograph measurements were compared to each other and to the μCT measurements. The μCT images were considered the anatomic reference standard for structural representation., Results: The data collected demonstrated IOR bias and variability throughout all measurement sites, with some sites being more affected than others. Neither IOR system produced unbiased measurements that closely reflected the μCT measurements consistently. The overall lack of agreement between measurements demonstrated the difficulties in developing a standardized protocol for measuring root and root canal width for the first molar teeth in dogs., Conclusion: Developing a protocol to accurately measure and compare μCT and IOR measurements is challenging. Designing a measurement system that would allow for universal application to age dogs would require continued research utilizing a standardized approach to overcome the limitations identified in this article.

In the Ngorongoro Conservation Area (NCA), Tanzania, where wildlife and livestock interaction is intense, greater potential for intra- and interspecies disease transmission is expected. We assessed the prevalence of bovine tuberculosis in African buffalo (Syncerus caffer) residing on the valley floor of the crater in the NCA. Apparently healthy animals were randomly selected from herds in nine sites of the Ngorongoro Crater. Syncerus caffer buffalo herds were located using very high-frequency radio-aided rangers positioned in various observation points around the crater in the NCA. A total of 102 African buffalo from 16 herds were immobilized from the ground using a cocktail of 4-10 mg etorphine hydrochloride (M99) and 60-150 mg azaperone tartrate. The M99 was reversed using 10-25 mg diprenorphine hydrochloride depending on age of animals. An interferon gamma assay was performed on harvested plasma samples using sandwich enzyme linked immunosorbent assay. Of the 102 animals sampled, two (2%) African buffalo tested positive for bovine tuberculosis. These results corroborate those of the skin test done recently in cattle in the NCA. The presence of bovine tuberculosis in livestock and wildlife suggested the possibility of cross-species transmission of the disease, indicating the need for appropriate intervention measures.

Oral papillomatosis was diagnosed in a gray wolf ( Canis lupus ) with sarcoptic mange from Minnesota, US found dead in February 2015. Intranuclear inclusion bodies were evident histologically, and papillomaviral antigens were confirmed using immunohistochemistry. Sequencing of the L1 papillomavirus gene showed closest similarity to Lambdapapillomavirus 2.

California has more reported human raccoon roundworm cases than any other state due to large and overlapping human and raccoon populations. Infection by this parasite, Baylisascaris procyonis , is relatively benign in raccoons but can cause severe pathology in other species. Disease risk is driven by environmental egg contamination which increases with raccoon density, worm intensity, and worm prevalence. To improve knowledge about risk to humans and other species, 189 raccoons from southern California were examined to investigate how host age and season affect worm abundance, demography, and fecundity. Adult worms were present in animals as young as 10 wk and 100% of 4-mo-old raccoons were infected. Although 80% of sampled raccoons hosted adult B. procyonis , prevalence and abundance were lower in older animals. There were more worms in juvenile than in adult raccoons, resulting in a convex age-intensity profile. Coupled with raccoon demography, this drove fall peaks in parasite abundance and egg production. Eggs per-gram feces averaged 4,606 ± 661 (SE), and this output increased with worm intensity, with no evidence that crowding reduced parasite size or fecundity. High parasite egg outputs from hosts in this California raccoon population increase human exposure risk, and this risk could be reduced by management strategies that target heavily infected juvenile raccoons.

The European mink (Mustela lutreola) has undergone a dramatic decline and is one of the most endangered mammals in the world. The invasive American mink (Neovison vison) is considered the main factor for this decline. However, the American mink's introduction and the subsequent ecological concurrence of the two species cannot solely explain the decline or disappearance of the European mink. Aleutian mink disease virus (AMDV) is the main health problem in fur farming worldwide, causing varied clinical syndromes that depend on the viral strain and host factors. Infection with AMDV has been speculated to contribute to the decline of the European mink, but a detailed study has not been performed. To assess the potential effects of AMDV infection on the conservation of the European mink, we surveyed AMDV antibody in samples from 492 native European mink and 1,735 feral American mink collected over 16 yr. The antibody prevalence in European mink was 32%. There were no statistically significant differences in antibody prevalence between sexes, among years, or among weight classes. For recaptured European mink, incidence of seroconversion (negative to positive) was 0.46 cases per animal-year at risk. For positive animals, the incidence of conversion from positive to negative was 0.18 cases per animal-year at risk. In 1,735 feral American minks, the overall prevalence was 32.4% and varied among the six wild populations studied. Infection with AMDV appears to be endemic, distributed across the entire ranges of both species, and no effects on the population dynamics of either species were observed.

Objective: The knowledge of an animal's age is important for disease probability, prognoses, or epidemiological questions, but unfortunately, it is often unknown for dogs in animal shelters. A simple estimating procedure is preferable being quick and easy to perform, even for non-veterinarians., Material and Methods: In 295 dogs the dimension of light reflection (diameter in millimetres), visible on the posterior lens capsule using a penlight, the grade of dental abrasion and dental tartar were documented photographically and the exact weight and age in days were obtained. These photographs were evaluated blinded. The dogs were divided randomly into two groups. The first group was used to establish a model for age determination using linear and logistic regression models considering the documented parameters, which was then validated with the data of the second group., Results: The size of ocular light reflection and age correlated significantly (r = 0.781; p < 0.001; sy,x = 2.45 years [SD of y for given x]). The linear regression model gave the final equation: Estimated age [months] = 13.954 + 33.400 × lens reflection [mm] + 8.406 × dental abrasion [grade] + 8.871 × tartar [grade] with a standard error of estimation of 2.26 years., Conclusion and Clinical Relevance: Age determination, even based on three parameters results in a large standard deviation making age estimation in dogs very crude.

The purpose of this study was to evaluate the effect of age on the ratio of pulp cavity/tooth width (P/T ratio) in healthy cats. The dental radiographs of 32 cats (16 males and 16 females) were generated with a digital dental X-ray unit with the animals under general anesthesia. Standardized measurement of the canine teeth was performed by drawing a line on the radiograph perpendicular to the cemento- enamel junction (CEJ) of the tooth. There was an inversely proportional correlation between chronological age and the P/T ratio. Moreover, a strong Pearson squared correlation (γ(2) = 0.92) was identified by the curved regression model. No significant differences in the P/T ratio based on gender or breed were found. These results suggest that determination of age by P/T ratio could be clinically useful for estimating the chronological age of cats.

The methodology used to identify individuals in forensic anthropology requires a minimum degree of precision and accuracy and should be based on identified and representative samples. Achievement of these objectives in infant skeletons is hampered by the scarcity of appropriate samples. The dental age estimation methods of Liversidge et al. (Am J Phys Anthropol 90: 307-313, 1993) and Deutsch et al. (Growth 49: 207-17, 1985) were applied to the Granada osteological collection of identified infants (Granada, Spain) in order to evaluate its applicability in a Mediterranean population. Significant differences were found between the estimated and real ages in both cases. Based on the measurements obtained in 140 fetuses and infants, new regression formulas were developed to estimate age from the metric study on deciduous teeth. Independent functions are provided for each deciduous maxillary and mandibular tooth in each sex, along with the margin of error (95% confidence interval). These formulas appear to offer one of the best methods available for estimating the age of Mediterranean infants in forensic anthropology settings.

The first European interlaboratory comparison of tetracycline and age determination with red fox (Vulpes vulpes) tooth samples was organized by the European Union Reference Laboratory for rabies. Performance and procedures implemented by member states were compared. These techniques are widely used to monitor bait uptake in European oral rabies vaccination campaigns. A panel of five red fox half-mandibles comprising one weak positive juvenile sample, two positive adult samples, one negative juvenile sample, and one negative adult sample were sent, along with a technical questionnaire, to 12 laboratories participating on a voluntary basis. The results of only three laboratories (25%) were 100% correct. False-negative results were more frequently seen in weak positive juvenile samples (58%) but were infrequent in positive adult samples (4%), probably due to differences in the ease of reading the two groups of teeth. Four laboratories (44%) had correct results for age determination on all samples. Ages were incorrectly identified in both adult and juvenile samples, with 11 and 17% of discordant results, respectively. Analysis of the technical questionnaires in parallel with test results suggested that all laboratories cutting mandible sections between the canine and first premolar obtained false results. All the laboratories using longitudinal rather than transverse sections and those not using a mounting medium also produced false results. Section thickness appeared to affect the results; no mistakes were found in laboratories using sections <150 μm thick. Factors having a potential impact on the success of laboratories were discussed, and recommendations proposed. Such interlaboratory trials underline the importance of using standardized procedures for biomarker detection in oral rabies vaccination campaigns. Several changes can be made to improve analysis quality and increase the comparability of bait uptake frequencies among member states.

Wild ruminants sharing pastures with domestic livestock are at risk of infection by liver trematodes. Detection of antibodies provides a very useful tool to gain more knowledge about the distribution of these parasites. Non-lethal methods are strongly encouraged for the analysis of the risk of infection among wild ruminants. A seroepidemiological survey was conducted to analyze exposure to hepatic trematodes ( Fasciola hepatica and Dicrocoelium dendriticum ) in wild ruminants from southern Spain. Blood samples were collected from 69 bovids (Mouflon + Spanish ibex) and 143 cervids (red deer + fallow deer) from Sierra de Cazorla, Segura and Las Villas Natural Park. The samples were analyzed using the excretory/secretory antigens of each trematode to determine the IgG response. All the animals were examined at necropsy for the presence of flukes, and the species, age, and gender of the animals were recorded. Fasciola hepatica were only observed in cervids (3%; 95% confidence interval [CI]  =  2-8), while D. dendriticum specimens were recorded in 1% (0-8) of bovids and 4% (CI  =  2-9) of the cervids. The IgG-seroprevalence against F. hepatica was significantly higher in the cervids. Statistical differences according to gender were observed. The bovids exhibited the greatest percentages of positive cases to D. dendriticum antigens, and the DdES-seroprevalence was related to age of the animals. When considering all the factors, the FhES-seroprevalence was initially distributed according to the type of ruminant (cervids), gender (male), and age (>2 yr).

Longitudinal studies have revealed how variation in resource use within consumer populations can impact their dynamics and functional significance in communities. Here, we investigate multi-decadal diet variations within individuals of a keystone megaherbivore species, the African elephant (Loxodonta africana), using serial stable isotope analysis of tusks from the Kruger National Park, South Africa. These records, representing the longest continuous diet histories documented for any extant species, reveal extensive seasonal and annual variations in isotopic--and hence dietary--niches of individuals, but little variation between them. Lack of niche distinction across individuals contrasts several recent studies, which found relatively high levels of individual niche specialization in various taxa. Our result is consistent with theory that individual mammal herbivores are nutritionally constrained to maintain broad diet niches. Individual diet specialization would also be a costly strategy for large-bodied taxa foraging over wide areas in spatio-temporally heterogeneous environments. High levels of within-individual diet variability occurred within and across seasons, and persisted despite an overall increase in inferred C(4) grass consumption through the twentieth century. We suggest that switching between C(3) browsing and C(4) grazing over extended time scales facilitates elephant survival through environmental change, and could even allow recovery of overused resources.

Advanced titanosaurian sauropods, such as nemegtosaurids and saltasaurids, were diverse and one of the most important groups of herbivores in the terrestrial biotas of the Late Cretaceous. However, little is known about their rise and diversification prior to the Late Cretaceous. Furthermore, the evolution of their highly-modified skull anatomy has been largely hindered by the scarcity of well-preserved cranial remains. A new sauropod dinosaur from the Early Cretaceous of Brazil represents the earliest advanced titanosaurian known to date, demonstrating that the initial diversification of advanced titanosaurians was well under way at least 30 million years before their known radiation in the latest Cretaceous. The new taxon also preserves the most complete skull among titanosaurians, further revealing that their low and elongated diplodocid-like skull morphology appeared much earlier than previously thought.

The authors give a short orientation about the age related parameters of the incisors based on the literature. They examined the question of breed differences with respect to the age determination of horses in the different counties, especially in regard to the English Thoroughbred. In this context they present a new parameter as well as a new approach in data-processing. The cup depth and the yearly abrasion showed high breed-specificity. The relative abrasion indicated that the most intensive wear out is typical for the Thoroughbred. The cup depth and the yearly wear out were different according to the incisor's type in respect to the merged Thoroughbred populations of the two countries. The deviations observed in the cup depth can be explained by body size differences of the breeds. The degree of the absolute and the relative abrasion of the cup can also be associated with the early utilisation (racing) and with the intensive feeding (concentrate). The authors assume that the selection for the early utilisation of the English Thoroughbred resulted in an automatic change of the well inherited chronology of dentition; i. e. the earlier maturity of dentition. In of the bone system manifests also in the narrowing of the teeth. As the recent cup depth values deviate from the earlier ones, the authors suggest correcting the age of the disappearance of the cup from the current 6-7-8 years to 5-7-9 years for the English Thoroughbred.

This research explores the relationship between generally accepted and alternative cattle age-prediction methods and chronological age. Cattle (n = 386) of documented ages ranging from 370 to 1,115 d of age were used. Dentition (DEN), USDA maturity score (MS), lens weight (LW), and lens total N (LN) content were used as possible predictors of age. Correlations with age were determined: LW (r = 0.77); DEN (r = 0.74); LN (r = 0.71); and MS (r = 0.64). Stepwise backward regression was used to generate an age prediction equation: Age (mo) = -21.79 + 17.23(LW, g) + 0.038(DEN). By this equation, 38% of cattle

The purpose of this study was to investigate the use of cheek tooth occlusal surface morphology as an indicator of age in the horse using a blinded cross-sectional design. Twenty horses of varying age, breed and sex were used. Horses of known age (foaling date) were euthanized for reasons other than dental disease. Following disarticulation of the head and sectioning of the mandibles, cheek teeth were cleaned using running water and photographs were taken of each arcade. Using a computer-based program, the total surface area of each premolar and molar, the outer enamel ridge perimeter distance, infundibular surface areas and perimeter distances were measured. Further anatomical data were calculated from these measurements and a statistical analysis of the relationship between horse age and cheek tooth occlusal morphology was performed. Results indicated that multiple anatomical regions within the occlusal surface of the equine cheek tooth can be used as an indicator of age. There are important differences between mandibular and maxillary teeth as well as between teeth in the same dental arcade. Horse size is also of significance. The mesial infundibular surface area as a percentage of the total surface area of tooth 111, and the mesiodistal length of 1/2/3/4 09 teeth, most closely approximates age within our mathematical model. Cheek tooth morphological data can be used to predict age in horses that possess all their permanent dentition. In cases in which the age of horses cannot be accurately determined from incisor examination, cheek teeth may be used.

Understanding the way prosimian primates age can be helpful in inferring what the 'basal primate mode' of senescence may have been. Even though prosimians are known to be long-lived in captivity, relatively little is known about their reproductive senescence, and even less is known about how prosimians age in their natural habitats. Twenty years of observational data in Madagascar for four Propithecus edwardsi sifaka groups were used to analyze reproductive and behavioral trends of aging in the wild. Techniques using tooth wear were developed to establish ages of wild sifakas and to estimate the onset of their 'dental senescence', a proxy for the onset of decline in the ability to obtain nutrition. Estimated maximum longevity was 32 years for female sifakas. Based on the loss of dental functional morphology, and changes in tooth wear patterns and in chewing efficiency, dental senescence was estimated to set in at approximately 18 years of age. Of the adult females in the study groups, the yearly average of the number of dentally senescent females was 24%. There was no indication of a decline in fertility in the dentally senescent females (aged >18 years) compared to younger adult females (aged 4-18 years). The field data showed, however, that in years when rain was decreased during months of prime lactation, infants of dentally senescent mothers died before weaning. This may be because the nursing mother's worn teeth could not shear leaves and extract moisture, nor nutrition, both essential for successful lactation. Old females showed no clear signs of social disengagement, further suggesting that drought-induced stress plays a direct role in increased infant mortality. These data support earlier findings that prosimian females continue to cycle and give birth until death. The effect of environmental variation on infant survival, however, indicates an incipient age-linked decline in reproductive fitness. Therefore, whereas lemurs represent the condition of no menopause, changes in infant survival may uncover selective factors that have in part led to the evolution of menopause in other primates.

Ursid mortality data have long been used to evaluate associations between cave-bear remains (Ursus deningeri and U. spelaeus) and hominin (Homo sp.) remains. Typically, such ursid assemblages produce mortality patterns that indicate that juvenile and old bears died during hibernation, a pattern that is used to suggest that humans and bears occupied the same caves at different times. However, a different kind of mortality pattern can also be used to suggest human influence on cave bears, particularly under circumstances when bears and humans compete for habitat. In particular, data from Lawson Cave and Jerry Long Cave, Missouri indicate that young-adult North American black bears (Ursus americanus) are prone to capture in natural-trap caves. Similar faunal data from Sima de los Huesos in Spain, where cave-bear and hominin remains are found in the same deposit, might also suggest that the bears died from falling into a natural trap. It is concluded that mortality analysis of ursid remains from caves is a useful tool with which to evaluate accumulation histories of cave deposits and relations between humans, artifacts, and cave-bear remains. In particular, ursid mortality data are relevant to the Kurtén Response, a hypothesis reiterated in the recent literature that implicates human encroachment on ursid habitat (e.g., cave den sites) as a potential cause in cave-bear extinction.

We examined adaptive management (AM), applied as a science with testable and falsifiable hypothesis, in the context of a large carnivore population, specifically to wolf (Canis lupus lycaon) management in Algonquin Provincial Park, Ontario, Canada. Evidence of a population decline was based upon 12 years of data on 137 different radio-collared wolves. Because human killing accounted for an average of 66% of deaths, and most killing occurred adjacent to the park, a management prescription of complete protection for wolves around the park for 30 months was initiated in January 2001. We evaluated the probability of being able to test the null hypothesis, that protecting wolves adjacent to the park for 30 months would not result in a positive population response. Using preceding variances in population change, yearling recruitment, and mortality rates, we conducted this evaluation in two ways, the former involving a power analysis, the latter involving modeling. Both approaches showed the falsifiability of the hypothesis to be low. The reason, inherent in the application of AM to issues of population biology, especially of large carnivores, was stochasticity of the ecological system and time constraints of the human system. We discuss the political background that led up to the management prescription, and ways to avoid misapplication of a scientific approach to AM in such situations. For the latter, the merit of adjusting the relative probability levels of making Type I or Type II errors are discussed, along with recommendations that in the interests of conservation, avoiding a Type II error holds precedence.

Periodic growth incremental lines are found universally in dental hard tissues. This periodicity theoretically allows for estimation of age, even in days, which would be useful in studies of wild animals. In the present study, enamel and dentin increments of the sika deer (Cervus nippon) were observed in ground sections with a polarized light microscope, and their periodicity was examined by the use of a chronological labeling method with fluorochromes. Enamel increments occurred at a mean interval of 10.6 (SD=1.5) microm, and mean spacing of dentin increments was 17.3 (SD=1.8) microm. Fluorochromic marking revealed that incremental lines form each day in enamel and almost every second day in dentin. The fluorescence-labeled lines suggest that enamel formation of the first molar is complete by the age of 5 months. Due to its longer interval of incremental lines and longer term of formation, we conclude that dentin is more suitable than enamel for day-age estimation in sika deer. Experimental confirmation of incremental growth periodicity in various species can improve the reliability of use of tooth increments for age estimation and life history reconstruction.

Skulls and canines of 460 sea otters from Lopatka Cape, Kamchatka, were examined to assess development patterns, individual variation and sexual differences. An allometric formula was applied to morphometrical data, and the relative growth of each character to total length of skull was analyzed. In both sexes, most morphometrical characters ceased growth at about 2 years of age. Canine root length increased rapidly during the first year of life, while crown length decreased due to remarkable wear. There was large individual variation in the feeding and breathing/sniffing apparatus, while there was little variation in braincase size. There were sexual differences in most characteristics, although males and females showed similar growth patterns. The coronoid process of the mandible showed positive allometry in both sexes, and we attributed this finding to feeding habits. The fact that only male mastoids showed positive allometry may be due to the need for male otters to maintain a passing territory.

A method to obtain thin histological sections (4-5 microm thick) from teeth, using a conventional microtome, is described for incisors, molars and canines from Spanish red deer (Cervus elaphus hispanicus). Decalcifying solutions of formic acid and nitric acid at different concentrations were ineffective. This was not the case for a solution of 14% hypochloric acid and polyvinylpyrrolidone (TBD-1(R) of Shandon). However, the time needed to complete decalcification was longer than the time estimated by other authors. Incisors required between 4 and 6 days, molars between 7 and 15 days, and canines between 8 and 12 days. The preparation of histological thin-sections from teeth with a conventional microtome, required some training or prior specialization, because most of defective or lost material occurred during the preliminary stage of the study. However this technique is inexpensive enough to be implemented in any histological laboratory. The preparations obtained are suitable for growth mark observation in dentine and in cementum for dating studies. Nevertheless, they are not suitable for enamel change studies, because the enamel is completely destroyed during the decalcifying process.

The objective of this study was to examine the diameter, extent, orientation and contents of dentinal tubules in order to validate the hypothesis of pigment penetration into the dental star of equine incisival occlusal surfaces. The time of appearance and the configuration of the dental star on the incisival occlusal surface are macroscopically visible features that, along with other more reliable parameters, are used for the determination of horses' age. Although dental stars are an integral part of the equine incisor occlusive surface, the exact nature and microstructure of the dental star are poorly documented. Therefore, equine incisor dentine was examined macroscopically and by scanning electron microscopy to elucidate numerical density, diameter and 3-dimensional organisation of the dentinal tubules in the dental star. The dental star is surrounded by primary dentine and consists of a central core of tertiary dentine, an intermediate ring of pale secondary dentine and a peripheral rim of darker, yellowish-brown secondary dentine. The central core of tertiary dentine contains relatively few dentinal tubules (<8000/mm2) that have small diameters (mean +/- s.d. 1.67 +/- 034 microm) and are arranged in an irregular pattern. The surrounding pale ring of secondary dentine comprises manifestly more and wider tubules that lie almost parallel to the occlusal surface. The dark peripheral rim of the dental star contains high numbers of tubules (28,000-58,000/mm2) that have wide luminal diameters (mean +/- s.d. 3.09 +/- 0.31 microm) and open perpendicular to the occlusal surface. In contrast, the primary dentine surrounding the dental star is made up by a lower number of dentinal tubules (<25,000/mm2). The tubules of primary dentine, which are initially mean +/- s.d. 5.15 +/- 0.80 microm wide, are narrowed by circumferential deposits of peritubular dentine and are obliquely exposed at the occlusal surface. From these observations, it was concluded that the regional differences in numerical density, diameter and spatial orientation of the dentinal tubules may influence the penetration of food pigments into the equine occlusal surface and result in the particular staining of the dental star.

Two studies using commercially fed cattle were conducted to determine the relationship of the USDA bone ossification-based maturity system to one based on the number of permanent incisors present at slaughter. These studies showed that 91.5 to 100% of cattle with zero permanent incisors (< 23.8 mo of age), 89.1 to 97.5% of cattle with two permanent incisors (23.8 to 30.4 mo of age), 75 to 82.2% of cattle with four permanent incisors (30.4 to 38.0 mo of age), 64 to 72.5% of cattle with six permanent incisors (38.0 to 45.3 mo of age), and 40% of cattle with eight permanent incisors (> 45.3 mo of age) were graded as A maturity by the USDA maturity classification system. Kappa tests revealed no statistical relationship between the dentition- and skeletal ossification-based maturity systems. Dentition-based maturity agreed with ossification/lean maturity for only 162 of 1,264 carcasses in Exp. 1 and only 54 of 200 carcasses in Exp. 2. Cattle with two, four, six, or eight permanent incisors were classified in more youthful categories of USDA bone ossification/lean maturity than they should have been. Male cattle were more likely to be misclassified into a younger age category by the USDA system than were female cattle. It seems that determining physiological maturity by number of permanent incisors rather than by the current USDA method of subjectively evaluating skeletal and lean maturity may prove to be a more accurate technique of sorting beef carcasses into less-variable age groups.

Published anatomic studies of North American river otters (Lontra canadensis) include only comparative reviews of single anatomic systems, but this paper includes multiple clinically relevant anatomic features. Both captive and free-ranging North American river otters were studied by gross dissection of nine specimens, radiography of 18 live otters, and physical examination of 170 otters. Body fat in North American river otters is stored primarily subcutaneously at the base of the tail and in the axillae, so lack of visceral detail on abdominal radiographs is due to a lack of coelomic fat. The heart and great vessels are oriented as in the dog. The cardiac radiographic silhouette measures three intercostal spaces laterally between the fourth and sixth ribs and 4-4.5 intercostal spaces between the seventh through 11th ribs on the ventrodorsal projection. Subjective estimation of age by evaluation of tooth wear is confirmed by histologic examination of cementum annuli. Structures of the feet were imaged by high-resolution mammographic technique. The adult thymus was prominent, but the gland was small in the one juvenile animal studied. The spleen was unexpectedly large but consistent with findings in European otters (Lutra lutra). As in other otters and mammals, kidneys are reniculated.

The accuracy of ageing mini-Shetland ponies and donkeys was assessed by correlating the appearance of specific dental features with the known ages of 106 mini-Shetland ponies and 63 donkeys. The ages of the animals ranged between 2 days and 26 years. In both species the eruption of the deciduous and permanent incisors occurred later than in horses. On the other hand, the appearance of the dental stars on the permanent incisors of mini-Shetlands and donkeys was seen at a younger age than in horses. As in most horse breeds, the disappearance of the cups, the clinical crown lengths, the presence of hooks on the upper corner and the presence of a Galvayne's groove are unreliable features for dental age determination in the pony and the donkey. Specific dental characteristics of both the mini-Shetland pony and the donkey are discussed.

The lesser mouse deer (Tragulus javanicus) is one of the most primitive ruminants. Skulls of lesser mouse deer were measured to evaluate their growth. The age was estimated from the eruption and attrition of molars on the mandible. A total of 95 specimens was divided into five age groups, and the growth pattern in each sex was established for some measurements. The relative growth coefficients were calculated for the head and body length and several parts of the cranium and mandible against the profile length. Sexual dimorphism could not be found on the skull in any age group except for measurements related to the upper canine. However, females showed a higher value in head and body length in the oldest group. This feature was consistent with an interpretation of mouse deer society as monogamous. Growth was more rapid in length than in width. Various statistical analyses showed that the visceral cranium related to masticatory facility was much better developed than the neurocranium. However, observations on the shape of the mandible ramus and of the premolars implied that the masticatory function was not suitable for taking roughage. This speculation agreed with previous reports on the feeding habits and digestive organs of the mouse deer.

Equine practitioners should be knowledgeable of dental anatomy and development to enhance their skill of age estimation of horses. The permanent teeth of horses are continually undergoing changes in shape and appearance. These changes may be used to suggest a reasonable age range for a horse.

The dentition of 170 Arab horses of known ages was examined and compared with the dental characteristics of trotter horses and Belgian draft horses of the same ages. The results indicated that inaccuracies in the determination of the age of horses by their dentition may result, at least partly, from differences between the breeds of horse involved because there were some major differences between the three breeds examined. These differences increased as the horses' true age increased. In general, the rate of dental wear was slower in the Arab horses than in trotter horses and Belgian draft horses.

Methods of cutting and staining thin sections of Cape fur seal canines are described. The accuracy of age determination from the histology of the prepared sections and the suitability of the sectioning method is assessed. Known-age canines were used to validate age determination. Longitudinal sections along the midline enable growth layer groups (GLGs) in the dentine to be counted along the length of the canine root. GLGs in the cementum were either absent, or returned estimates of age that were too low. Only GLGs in the dentine of female upper canines could be used to determine age reliably, and only for the < 10 year age-classes.

During winter 1994-95, four and three sperm whales (Physeter macrocephalus) were stranded along the Belgian and the Dutch coasts, respectively. Necropsies and tissue samplings were collected 24 hrs post mortem. Lesions on several whales included round and linear skin scars, ventral skin abrasions, acute skin ulcers, acute ulcerative stomatitides, acute to chronic external otitides, and passive visceral congestion. In addition, these sperm whales appeared to be debilitated with severe weight deficit, had blubber thickness reduction, the absence of abdominal fat, and the intestinal tracts were almost empty. Three categories of lesions and their possible relation with the stranding were evaluated. Cutaneous scars observed on the seven whales appeared to have no relation with the stranding. The poor body condition and acute integument ulcerative lesions were present before the stranding. Ventral skin abrasions and visceral passive congestion were caused by the strandings. Absence of food in the alimentary tracts, evidence of weight loss and blubber thickness reduction were compatible with an extended presence of the sperm whales in the North Sea, where adequate food is not available. This might lead to progressive weakness, predisposing the animals to secondary pathogens such as viral diseases. Finally, the coastal configuration of the southern North Sea makes it a trap for sperm whales which have entered the area during their wanderings.

Sixty seven serum samples collected from 43 European brown bears (Ursus arctos) from Croatia were tested for < or = 31 serum chemistry parameters. Results were grouped and compared by bears origin (method of capture), sex, age, mass, and season sampled. Greatest differences were found between captive and free-living bears, and minor differences were found when sex, age, mass, or season of sampling were compared. Creatine kinase was significantly different among three categories of bears with the highest mean value of 924 IU/l in snare captured free-living bears compared to 67.8 IU/l in captive ones. Results of these tests provide reference values for European brown bears.

The accuracy of ageing horses by their dentition was assessed by comparing the dental features with the known dates of birth of 212 trotter horses and 189 Belgian draft horses. The horses ranged in age from two to 25 years. In both breeds it was observed that the shedding of the incisors and the appearance of the dental stars were the most reliable features for age determination. In young animals, the dental configuration was similar in both breeds. With increasing age the incisor teeth of draft horses were more liable to abrasion than those of trotter horses. The sequential changes in appearance of the permanent incisors occurred earlier in draft horses than in trotters.

Two age-determining methods were conducted on representatives of known age from the Order Carnivora (4 red foxes, 3 tree martens, 3 stone martens, 2 racoons, 2 badgers, 2 polecat and one otter). Age determination employed with the aid of tooth wear nearly agrees with the real age of the animals. Dating based on the formation of the age-dependent cement zone coincided well with the known ages of the individual specimens. However, in real foxes the figure one must be added to the number of cementum layers counted determining the definitive age of individuals. For representation of the cementum layers transverse sections of the apical part of the tooth root of canini, P2 and P3, stained with methylene blue, should be used. It is important to note that the dentino-cemental line should not be considered when counting the year rings in the cement.

Sixty-six (18%) cases of widely metastatic carcinoma of probable transitional cell origin were identified in 370 California sea lions (Zalophus californianus) stranded alive along the central California (USA) coast, between January 1979 and December 1994. Live animals were usually emaciated and anorectic, with perineal edema and occasionally hind-flipper paralysis or paresis. Large yellow caseous masses were observed in the sub-lumbar lymph nodes, often extending around the ureters resulting in hydroureter. Histologically, metastases were usually widespread, and the primary neoplastic focus undetectable. This is the highest reported prevalence among necropsied animals of neoplasia in a pinniped population to date.

The skull of an adult male Antarctic fur seal (Arctocephalus gazella) collected at Heard Island, Southern Ocean, October 1992, had chronic changes attributable to a fracture of the left lower canine, luxation of the mental symphysis, osteomyelitis of the left and right mandibles, and periostitis of the left maxilla.

It is generally considered that the age of a horse can be determined by examining its incisor teeth. However, the criteria used to determine age from dental configurations differ widely. The existence of this variety of rules and guidelines was the challenge for the present examination. Detailed descriptions of the incisor teeth of 212 horses of registered age were recorded and the results were compared with the age criteria of various authors. The time at which teeth were shed and the appearance of dental stars seemed to be more reliable features than the disappearance of the cups. The disappearance of the marks occurred four years later than usually stated. Other criteria, such as the presence of the seven-year notch and Galvayne's groove, were too variable and inconsistent to be reliable for the determination of age.

We tested 644 serum samples from 480 grizzly bears and 40 black bears from Alaska (USA), collected between 1988 and 1991, for Toxoplasma gondii antibodies, using a commercially available latex agglutination test (LAT). A titer > or = 64 was considered positive. Serum antibody prevalence for T. gondii in grizzly bears (Ursus arctos) was 18% (87 of 480). Prevalence ranged from 9% (seven of 77) on Kodiak Island to 28% (15 of 54) in northern Alaska. Prevalence was directly correlated to age. No grizzly bears < 2-year-old had T. gondii antibody. High antibody titers were found mainly in grizzly bears captured north of the Arctic Circle. Antibody prevalence in black bears (Ursus americanus) from Interior Alaska was 15% (six of 40), similar to the prevalence in grizzly bears from the same area (13%; five of 40).

The prediction of the age of a horse from its dentition has been widely accepted as an accurate technique, but recent reports have questioned this belief. In this study the dental features of 434 thoroughbreds of known age were documented and a multiple regression equation was calculated from the 13 dental features which had the highest correlation with true age. The accuracy of the ages assessed by a computer model were compared with the ages estimated by experienced equine clinicians. There was little difference between the accuracy of the computer model and the human observers, and neither method provided an acceptable level of accuracy for ageing horses from their dentition.

Dental features are commonly expected to provide an accurate estimate of a horse's age. In this study the dentition of 434 thoroughbreds was photographed and the individual dental features documented, the true age of all the horses was known. For each dental feature the correlation with true age was determined. The eruption of the incisor teeth was the most consistent feature but it was not totally reliable. The presence of a hook on the upper corner incisor and Galvayne's groove proved to be of no value when estimating age and, of the attritional features studied, the dental star showed the highest correlation with age. The results show that specific ages cannot be assigned to these dental criteria owing to the wide variation between horses, and that as a result the estimation of age from dentition can never be precise.

There is a widely held belief that a horse can be accurately aged by an examination of its teeth but this belief has recently been questioned. In this study photographs were taken of the dentition of 434 thoroughbreds of known age. Four experienced equine clinicians provided estimates of the ages of the horses from the photographs. A comparison of the estimated and true ages showed large discrepancies in many cases and the discrepancies increased as the horse's true age increased. The results show that the ageing of horses from their dentition is an imprecise science. It is suggested that written records of the dental features are made on each occasion when a dental examination is made and that veterinary surgeons advise clients that estimating a horse's age from dental criteria can provide no more than an 'informed guess'.