Maxillary morphology of chimpanzees: Captive versus wild environments

Morphological studies typically avoid using osteological samples that derive from captive animals because it is assumed that their morphology is not representative of wild populations. Rearing environments indeed differ between wild and captive individuals. For example, mechanical properties of the diets provided to captive animals can be drastically different from the food present in their natural habitats, which could impact cranial morphology and dental health. Here, we examine morphological differences in the maxillae of wild versus captive chimpanzees (Pan troglodytes) given the prominence of this species in comparative samples used in human evolution research and the key role of the maxilla in such studies. Size and shape were analysed using three-dimensional geometric morphometric methods based on computed tomography scans of 94 wild and 30 captive specimens. Captive individuals have on average larger and more asymmetrical maxillae than wild chimpanzees, and significant differences are present in their maxillary shapes. A large proportion of these shape differences are attributable to static allometry, but wild and captive specimens still differ significantly from each other after allometric size adjustment of the shape data. Levels of shape variation are higher in the captive group, while the degree of size variation is likely similar in our two samples. Results are discussed in the context of ontogenetic growth trajectories, changes in dietary texture, an altered social environment, and generational differences. Additionally, sample simulations show that size and shape differences between chimpanzees and bonobos (Pan paniscus) are exaggerated when part of the wild sample is replaced with captive chimpanzees. Overall, this study confirms that maxillae of captive chimpanzees should not be included in morphological or taxonomic analyses when the objective is to characterise the species.

Evaluation of Dental and Oral Pathologies of 36 Captive Lions (Panthera leo) and Tigers (Panthera tigris)

The documented increase in the occurrence of dental diseases in captive big cats over the past decades has necessitated the need to target dental medical research accordingly. The aim of this study was the systematic evaluation of dental and oral pathologies of lions and tigers which included intraoral dental radiography. Thirty-six animals of both sexes, ranging in age from nine months to 18 years, predominantly in circus husbandry, served as the basis of the present study, and their dental health status was investigated. The preliminary report and history, adspection of the awake animal, and examination under anesthesia provided important information. Eight animals were specifically presented for oral examination because of known dental disease. The remaining 28 animals were anesthetized for other medically necessary procedures, and each animal's oral and dental health status was also evaluated while under anesthesia. In the 28 animals that underwent routine oral cavity examination, pathological changes that had not previously been noticed were found in two-thirds of the animals (19/28). One-quarter of all the animals (9/36) had no abnormal oral cavity findings. Dentoalveolar trauma such as tooth fractures and abrasion (24/36) were diagnosed most frequently. The results highlight the importance of regular oral examinations in big cats. Furthermore, the results suggest that there is a relationship between husbandry conditions and the incidence of dentoalveolar trauma in captive big cats.

The Cranial Morphology of the Black-Footed Ferret: A Comparison of Wild and Captive Specimens

The black-footed ferret (Mustela nigripes), a North American mustelid species, was once found abundantly throughout the Midwest until the extreme decline in prairie dogs (Cynomys spp.), the black-footed ferret's primary food source, brought the species to near-extinction. Subsequently, the Black-Footed Ferret Recovery Program was created in the 1980s with a goal of bringing all remaining individuals of the species into captivity in order to breed the species back to a sustainable population level for successful reintroduction into the wild. While many components of the ferrets' health were accounted for while in captivity-especially those affecting fecundity-this study aims to assess the effects that captivity may have had on their cranial morphology, something that has not been widely studied in the species. In a previous study, we showed that the captive ferrets had significant oral health problems, and here we aim to document how the captive diet also affected their skull shape. For this study, 23 cranial measurements were taken on the skulls of 271 adult black-footed ferrets and 53 specimens of two closely related species. Skulls were divided based on sex, species, captivity status and phase of captivity and compared for all measurements using stepwise discriminant analysis as well as principal component analysis derived from the combined variables. We found that there are significant differences between captive and wild specimens, some of which are larger than interspecific variation, and that a diet change in the captive specimens likely helped decrease some of these differences. The results suggest that captivity can cause unnatural cranial development and that diet likely has a major impact on cranial morphology.

A Standard Method for Intraoral Dental Radiography With Dental Photo-Stimulative Phosphor (PSP) Plates in Big Cats

In recent years, dentistry has steadily gained more prominence in veterinary medicine, including exotic and wild animal medicine. It is known that dental diseases are among the most common diseases in captured big cats. However, so far, there is no standardized method for dental radiography in these animals. Therefore, this study aimed to develop a standardized procedure for the systematic radiographic examination of the teeth in big cats. In total, 34 big cats, including 21 lions and 13 tigers, of different ages were examined. Animals that needed treatment for known dental diseases and those that had to be anesthetized for other medically necessary procedures and dental health status examinations were included. Intraoral dental radiographs were captured with digital imaging plates designed for intraoral dental radiography in horses. Based on the intraoral dental radiography procedures used in domestic cats, both the bisecting angle technique and parallel technique were used. A hemisphere model originally developed for horses was used to describe the path and position of the x-ray beam as accurately as possible. The results demonstrated that it was possible to completely image all the teeth of big cat dentition on seven radiographs using the described method. This method can be used to acquire high-quality intraoral dental radiographs in big cats, aiding in the quick and reliable diagnosis of dental diseases.

Tusks, the extra-oral teeth

OBJECTIVE

The present review aims to: a) describe the features that support tusks in extra-oral position, and b) represent distinctive features of tusks, which provide insights into tusks adaptation to ambient conditions.

DESIGN

A comprehensive review of scientific literature relevant to tusks and comparable dental tissues was conducted.

RESULTS

The oral cavity provides a desirable condition which is conducive to tooth health. Therefore, it remains questionable how the bare (exposed) tusks resist the extra-oral conditions. The common features among tusked mammals indicate that the structural (e.g. the peculiar dentinal alignment), cellular (e.g. low or lack of cell populations in the tusk), hormonal (e.g. androgens), and behavioral traits have impact on a tusk's preservation and occurrence.

CONCLUSIONS

Understanding of bare mineralized structures, such as tusks and antlers, and their compatibility with different environments, can provide important insight into oral biology.

Drivers of stereotypic behaviour and physiological stress among captive jungle cat (Felis chaus Schreber, 1777) in India

Zoos play a vital role in managing and conserving a wide range of threatened species and in enhancing their populations in natural habitats through captive breeding and reintroduction programmes. Most small felids are poor breeders in zoos, owing to a range of issues such as spatial constraints, diet, disturbance from visitors, small population size, social grouping and other environmental factors in the exhibits. Many of these factors have also been found to influence the glucocorticoid levels among them. Chronic elevations in glucocorticoids can ultimately lead to psychological and physiological problems, eventually affecting reproduction and fitness. We assessed the influence of four biological and seven environmental factors on stress level linked to psychological (stereotype), and physiological (Faecal Glucocorticoid Metabolite, FGM) conditions and positive welfare behaviour (active and inactive) among 14 jungle cats Felis chaus managed at three zoos in Indian (two in Kerala and one in Maharashtra) during May 2014-March 2017. Stereotype, a behavioural indicator of stress, and welfare behaviour were assessed through 336 h daylight focal sampling and physiological stress following non-invasive FGM extraction using Enzyme-Immunoassay (EIA) from 63 fresh faecal samples. Overall, jungle cats spent more time on inactive (72%) compared to active behaviour (23%) and 5% on stereotypic behaviour. On average, the jungle cats had 43.3 ng/g of FGM. The Principal Component Analysis on 11 independent factors revealed that daylight hour did not influence active, inactive and stereotype behaviours. In addition, age also had no significant influence on FGM levels. Binary logistic regression revealed that active behaviour was more likely to be observed in cats fed live chicken, housed on natural substrate and in females. Inactive behaviour was significantly lower in younger cats, but higher in cats managed with hideouts. Our results suggest that cats housed with non-relatives and in enclosures lacking hideouts have higher rates of stereotype. Multiple regression analyses on behaviour indicate that active behaviour was significantly higher in cats when the arrival age at the zoo was <1 year, among females compared to males, fed live chicken compared to beef, when managed in natural compared to artificial enclosures and in enclosures without hideouts. Remarkably, inactive behaviour increased significantly with increase in visitor intensity and when cats fed beef compared to live chicken. The stereotypic behaviour was significantly lower in females and higher when the arrival age at the zoo was >1 year. It was also the case when the cats were fed beef vs. whole live chicken, when managed in enclosures without hideouts, and also when managed with unrelated conspecifics compared to those kept in enclosures with hideouts and in solitary condition. The FGM levels were significantly higher among males but lower among cats managed in natural and larger enclosures, and enclosures with hideouts, when compared to those managed in artificial, smaller enclosures and enclosures without hideouts. We recommend the provision of larger (>29 m²) natural enclosures with hideout facilities, management in solitary condition or in social groupings with related conspecifics and feeding of live prey to promote positive welfare and reduce psychological and physiological stress among the jungle cats in zoos.

Oral health correlates of captivity

The predominant diet fed to captive carnivores in North America consists of ground meat formulated to provide full nutritional requirements. However, this ground meat diet completely lacks the mechanical properties (i.e., toughness and hardness) of the foods these animals would consume in the wild. The goal of this study is to evaluate the effect of captivity on oral health by comparing the prevalence of periodontal disease and dental calculus accumulation in wild and captive lions and tigers (Panthera leo and Panthera tigris), and to also correlate oral health with cranial morphology in these specimens. To achieve this, 34 adult lion and 29 adult tiger skulls were scored for the presence and extent of dental calculus and periodontal disease. These oral health scores were also compared to cranial deformations examined in a previous study. We found that the occurrence and severity of calculus buildup and periodontal disease was significantly higher in captive felids compared to their wild counterparts. Further, higher calculus accumulation occurred on the posterior teeth when compared to the anterior teeth, while an opposite trend for periodontal disease was observed. We also found a significant correlation between oral health and cranial morphology of lions and tigers. The results suggest that food mechanical properties are significant factors contributing to oral health in felids.

Effect of dietary vitamin E and prey supplementation on semen quality in male black-footed ferrets (Mustela nigripes)

Over the recent years, the captive population of the endangered black-footed ferret (Mustela nigripes; ferret) has experienced a decline in normal sperm (NS) morphology (from 50% to 16%), which may be linked to inbreeding depression or it may have been a dietary change. We examined the role of dietary vitamin E, selenium (SE), and vitamin A on serum levels of vitamin E, SE, and vitamin A and semen quality. Ferrets (n = 55 males) were randomly assigned to one of five diet treatments (n = 11 per treatment): (1) horsemeat diet (control); (2) horsemeat diet + vitamin E (400 IU/kg Dry Matter) daily; (3) horsemeat diet + whole prey; (4) horsemeat diet + vitamin E daily + whole prey; and (5) beef diet. Both blood (prediet and postdiet change) and diets were analyzed for vitamin E, vitamin A, and SE concentrations. Electroejaculates were collected monthly and evaluated for sperm concentration, sperm motility index (includes percent motile and forward progression), and percent NS. Results reveal that the beef and horsemeat diets had comparable (P = 0.05) vitamin E and SE concentrations and all diets met most nutrient requirements for small carnivores; however, the horsemeat diet was excessive in vitamin A and the beef diet was deficient in vitamin A. Vitamin E supplementation increased (χ1(2)=25.83; P < 0.001) serum vitamin E. Ferrets fed the beef diet or prey had improved (H4 = 15.596; P = 0.004) sperm motility index than the horsemeat control group, and ferrets fed the horsemeat diet supplemented with vitamin E had the lowest (H4 = 18.408; P = 0.001) NS. In conclusion, the high levels of vitamin A in the horsemeat diet could compete with vitamin E as evidence by serum levels, which may reduce reproductive success in this endangered species.

The three-dimensional morphological effects of captivity

Many captive animals are fed diets that are drastically different in mechanical properties than their wild diet. Most captive pantherines are fed a nutritionally supplemented diet consisting almost entirely of ground meat. While many zoos supplement this diet with bones, the fact remains that large captive felids are fed diets that require substantially less masticatory effort than those of their wild counterparts. The osteological effects of this dietary difference have not been fully evaluated. To this end, we compared linear measurements and 3D geometric morphometric landmarks of captive and wild lions and tigers. Using Principal Component (PC) analysis of the linear measurements, not only were the sexes and species statistically distinct, but so too was the population clearly divisible in terms of captivity status. The 3D analysis supported these findings: although the most influential variable in the sample (PC1, 21.5% of the variation) separates the two species, the second most influential contributor (PC2) to the overall skull shape is driven not by the sex differences in these highly dimorphic species, but rather by their captivity status. In fact, captivity status drives nearly twice as much of the 3D variation as sexual dimorphism (14.8% vs. 8.0% for PC2 vs. PC3). Thus the shape is influenced nearly twice as much by whether the animal was captive or wild than by whether it was male or female. If a causal relationship can be demonstrated between dietary mechanical properties and morphology, people who oversee the diets of captive carnivores should consider modifying these diets to account for not only nutritional but also the mechanical properties of a carcass-based diet as well. In addition to the husbandry implications, our analyses show the ways in which captive specimens are different than their wild counterparts--ndings that have implications for morphologists when considering anatomical samples.

Comparison of several types of enrichment for captive felids

Enrichment can increase the complexity of the captive environment and possibly enhance captive animals' well-being by stimulating active behaviors and reducing stereotypical behaviors commonly seen in zoo felids. In this study, three different enrichment items were added to outdoor enclosures of felids at the Montgomery Zoo to test their effects on activity levels and stereotypic pacing. Bones, frozen fish, and spices (cinnamon, chili powder, and cumin) were presented over a 3-month period to six species of felids: cheetah, cougar, jaguar, lion, ocelot, and tiger. Proportion of time spent engaging in active behaviors and stereotypic pacing were compared before, during, and after treatments. All treatments resulted in a significant increase in activity level from baseline (bones: +15.59%; frozen fish: +35.7%; spices: +12.38%). Effects of enrichment items on activity levels were not sustained 7 days after removal. Proportion of time spent pacing significantly decreased during presentation of spices (-21.25%) and frozen fish (-26.58%), but not with the addition of bones. However, only the effect of frozen fish on stereotypic behavior was sustained 7 days after removal of the enrichment item. In conclusion, bones, spices, and frozen fish are inexpensive and easy-to-administer enrichment items that may be used to increase active behaviors of captive felids. Zoo Biol 26:371-381, 2007. (c) 2007 Wiley-Liss, Inc.

Diet and periodontal disease in dogs and cats

A review of relevant literature was undertaken because of concerns about a possible relationship between pet foods, development of periodontal disease, and secondary adverse effects on general health. It was concluded that, while changes in feeding methods in recent decades have arguably improved pet health by reducing or preventing diseases associated with nutritional deficiencies and excesses, periodontal disease remains a serious, diet-related problem. There is reasonable evidence that soft diets are associated with increased frequency and severity of periodontal disease, and that harder foods requiring vigorous prehension and mastication are preferable for dogs and cats. While it is plausible that periodontal disease could cause diseases in other organs and tissues, the evidence for this is limited at present. Further research is needed to better define the relationship between diet types and oral health. In the meantime, veterinarians and pet owners should pay attention to the physical qualities (textures, abrasiveness, 'chewiness') of foods they provide for dogs and cats, as well as to their nutrient content, and should consider additional methods to control plaque and prevent periodontal disease where necessary.