Serum prevalence to non-viral pathogens in wild felids of Southern Primorye, Russia

Serum prevalence to six different non-viral pathogens was estimated for big Russian cats (Amur tiger (Panthera tigris altaica) and the Far Eastern leopard (Panthera pardus orientalis)) in Southern Primorye, Russia (n = 26) in 2008–2016. Serum samples from smaller cats (Eurasian lynx (Lynx lynx) and Far Eastern wildcat (Prionailurus bengalensis euptilurus)) were also tested for these pathogens (n = 28) during the same period. Felids of Russian Southern Primorye showed serum prevalence to five out of six tested pathogens. Antibodies to Candida sp. and Trichinella sp. were found to be much more widespread in cats (47% and 42%) than antibodies to other tested pathogens (20% and less). Large cats demonstrated a higher serum prevalence to these pathogens than smaller ones. We did not detect animals seropositive to Coxiella burnetii

Distemper, extinction, and vaccination of the Amur tiger

Canine distemper virus (CDV) has recently emerged as an extinction threat for the endangered Amur tiger (Panthera tigris altaica). CDV is vaccine-preventable, and control strategies could require vaccination of domestic dogs and/or wildlife populations. However, vaccination of endangered wildlife remains controversial, which has led to a focus on interventions in domestic dogs, often assumed to be the source of infection. Effective decision making requires an understanding of the true reservoir dynamics, which poses substantial challenges in remote areas with diverse host communities. We carried out serological, demographic, and phylogenetic studies of dog and wildlife populations in the Russian Far East to show that a number of wildlife species are more important than dogs, both in maintaining CDV and as sources of infection for tigers. Critically, therefore, because CDV circulates among multiple wildlife sources, dog vaccination alone would not be effective at protecting tigers. We show, however, that low-coverage vaccination of tigers themselves is feasible and would produce substantive reductions in extinction risks. Vaccination of endangered wildlife provides a valuable component of conservation strategies for endangered species

Predator presence affects the reproductive success of prey in outdoor conditions

The reproductive outcomes of laboratory rats (Rattus norvegicus) housed at different distances (2, 20 and 80 m) from a predator (Lynx lynx) were investigated. Virgin female (n = 120) and m3ie (n = 40) rats of an outbred laboratory population were used for the experiments. Groups of rats (one male and three females) were housed in standard cages in close proximity to the predator Litter size, sex ratio. number of live pups, number of placental scars and corpora lurea were counted; and pre- and post-implantation losses were calculated for each female. The reproductive success of females, estimated as the number of live pups per female, was significantly higher in both control groups (20 and 80 m) than in both experimental Eraups (2 and 2 m). Equal numbers of corpora lutea in all groups but different numbers of placental scars between control and experimental groups indicated higher pre-implantation losses in the experimental groups. Post-implantation losses were also higher in both experimental groups. Total losses (calculated as a difference between the number of corpora lutea and live pups) were twice as high in experimental groups. Reproductive success of rats depended on concentrate/intensity of predator scents: when concentration/intensity was higher, the number of live pups was less and the total loss was higher

Size Matters: Zoo Data Analysis Shows that the White Blood Cell Ratio Differs between Large and Small Felids

The total number of white blood cells (WBCs) is related the immune system. In mammals, it is affected by the body mass, but it is unclear how the numbers of different WBC types correlate with this parameter. We analyzed the effect of body mass on WBC number and ratio in felids, where species are similar in diet (warm-blood vertebrates) and reproductive strategy (promiscuity). Based on zoo veterinary data (ZIMS database) we analyzed the effect of body mass on WBC number and neutrophils/lymphocytes ratio in 26 species of felids. The number of WBCs correlated with the body masses of animals: large cats had more WBC, which may be due to greater risks of infection associated with larger body surface, lifespan and home range size. For the first time we found obvious differences in the number of WBC types. Large cats also had more neutrophils and monocytes but fewer lymphocytes than smaller cats. The ratio of neutrophils to lymphocytes is greater in large felids. This phenomenon may be related to diet (relative prey size and kill utilization time), which suggests regular contact of large cats with bacterial and protozoal pathogens in contrast to the small cats

Comparison of tigers' fecal glucocorticoids level in two extreme habitats.

Application of different antibodies and extraction methods results in a wide range of steroid metabolite concentrations obtained during noninvasive hormones monitoring. It makes regional comparisons of steroid concentration very difficult. We compared three methods for extraction of glucocorticoids metabolites in tiger feces to examine correct stress level in Bengal and Amur tigers in India and Russia respectively. The results obtained with three different extraction methods correlate with each other positively and significantly. The highest concentration of fecal glucocorticoids metabolites (FGCM) was found after the extraction of wet feces samples with 90% methanol. The level of FGCM was significantly higher in Bengal tigers in India than in Amur tigers in Russian Far East. The reasons might be related to tigers' density or anthropogenic pressure

Predator odours as reproductive inhibitors for Norway rats

We examined the influence of predator odor on reproductive output of Norway rats (Rattus norvegicus). Naive laboratory rats responded to predator chemical cues with reduced litter sire and skewed sex ratio. We found that exposure to predator urine had its greatest effect on implantation and maintenance of implantation when predator urine was applied to the bedding of rats during the first third of gestation. Based on the physical appearance of corpora lutea and uterine implantation scars, we found that the reduction in litter sire was due to resolution of the embryos during the early part of gestation. Subsequently, we discovered that the reduction in litter sizes in rats exposed to predator urine could be attributed to suppressed progesterone levels affecting implantation of embryos. Chronically high corticoslerone levels did not suppress reproductive output. Suppression of reproduction also occurred when rats were exposed to urine of conspecifics housed under high population densities. The evolutionary adaptive response for reduced litter sire is to produce high-quality offspring in an environment where food resources are scarce. The fact that rats respond to certain chemical signals in predator urine in a similar fashion may be fortuitous, and may have more to do with the coincidence that the urine contains similar cues resulting from protein digestion in carnivores and protein catabolism in nutritionally deprived rodents, rather than specific predator-prey adaptations

Application of Felid Hair for Non-Invasive Tracking of Animal Reproductive Status and Adrenal Activity

Hair can be a useful matrix to examine the hormonal status of an animal, although it is difficult to correlate the results to a specific time point. The aim of this study was to evaluate seasonal changes in cortisol and testosterone levels in the hair of four feline species (lynx, Lynx lynx, n = 8; Amur wildcat, Prionailurus bengalensis euptilurus, n = 8; caracal, Caracal caracal, n = 6 and domestic cat, Felis catus, n = 17) with different breeding strategies. Animals of both sexes were sampled over the year, once per season (every three months), and the concentrations of hair testosterone and cortisol were measured by EIA. Both hormones showed annual dynamic changes, which coincided with the reproductive seasonality of the studied species. Sexual differences in testosterone level were found only during the mating season (spring for lynx and Amur wildcats, spring–summer for domestic cats), when testosterone levels were higher in males than in females. Cortisol levels were higher in males than in females in domestic cats and Amur wildcat, but also only during the mating season. Seasonal increases in testosterone were observed in three seasonal breeders (lynx, Amur wildcat and domestic cat) but not in caracal, which had high testosterone levels over the whole year. In lynx and Amur wildcat, it decreased sharply in the summer. Cortisol levels increased during the mating period in domestic cat males and lynx of both sexes; in caracal, an increase in cortisol was related to the transfer of animals to smaller winter cages. Measurements of steroids in hair can provide a reliable method for evaluating the reproductive status and the activity of the hypothalamus–pituitary–adrenal axis in several felid species

Stressed by Maternity: Changes of Cortisol Level in Lactating Domestic Cats

Lactation is the most energetically expensive component of maternal care in mammals. Increased reproductive investment can lead to physiological stress for the mothers, based on the exhaustion of energy resources and increase in glucocorticoids level. This study aimed to estimate the changes in cortisol concentrations during lactation in domestic cats and compared the differences among litter sizes. Eleven females gave birth to 27 litters, which were divided in two groups—small (1–3 kittens) and large (4–7 kittens) litters. Blood samples were collected from each female before mating, after parturition, at 4 and 8 weeks of lactation. We showed that the cortisol level in females changed significantly during lactation—the highest concentrations were observed at the peak of lactation at 4 weeks. Cortisol levels varied significantly among females but did not depend on their maternal experience. We also revealed that there were no differences in cortisol levels between females with small and large litters, but at 4 weeks of lactation, the hormone concentrations were higher in females with small litters. It is likely that these females initially invested less in reproduction, giving birth to fewer offspring

The First Case of Cytauxzoon spp. in Russia: The Parasite Conquers Eurasia

Over the last two decades, Cytauxzoon spp. has been conquering Eurasia, although this fact has only been brought to light through recent more intensive research after the discovery of C. manul in Pallas’ cat. In Europe, Cytauxzoon was detected mainly in southern countries and later in central Europe. This pathogen has now been found in Russia for the first time (50 km from Moscow), this being the most northern sighting in Eurasia. A captive serval (Leptailurus serval) was found to be infected. Hematological analysis showed a crucial decrease in the number of leukocytes and erythrocytes, as well as in hemoglobin concentration. Genetic analysis confirmed the presence of Cytauxzoon spp. in serval blood at the beginning of the disease period. The identical pathogen was found in one bobcat at the same breeding center. Two other haplotypes of Cytauxzoon spp. were obtained from domestic cats at the same location, identical to the samples from Italy. One new haplotype, which was sequenced for the first time, was found in 7/7 investigated Amur wildcats (100%). The high occurrence and diversity of these pathogens suggest that they are present in free-ranging domestic cats and wild felids in Russia, and may be considered a potential threat to the endangered species. Current research shows that the genetic diversity of this pathogen may be even higher than it was suggested previously. Further genetic research is necessary to describe the diversity and phylogeny of this pathogen in Eurasia