The Role of Preventative Medicine Programs in Animal Welfare and Wellbeing in Zoological Institutions.

The overarching goal of a preventative medicine program is to minimize the chances of health problems developing and to maximize the chances of detecting health problems early, in a manner that best benefits the animals and the organization. The traditional paradigms of animal welfare, stemming from the five freedoms and being progressively fleshed out to five domains, the 24/7 approach and so forth do not apply perfectly to zoological collections and less so to animals undergoing veterinary treatments. The physiology and behaviour of animals undergoing veterinary treatments, including therapeutic, quarantine and preventative medicine, are derailed from their normal states and their choices and comfort are de facto limited. A paradigm separating animal wellbeing from animal welfare is necessary to instil clarity of thought and to guide actions in regard to the welfare of animals under human care. Using such a model, preventative medicine programs emerge as a cornerstone of zoo and aquarium animal welfare, all the more if it incorporates modern veterinary and husbandry techniques, including operant conditioning.

Evaluation of Vaccination Strategy Against Rabies in Hong Kong Macaques.

The objectives of this study were to assess the serological response to rabies vaccination in Hong Kong macaques and provide evidence-based recommendations for the vaccination interval implemented by the Government of Hong Kong. An inactivated rabies vaccine was administered subcutaneously to captured macaques under a mass sterilization program in Hong Kong. Blood samples from the animals were collected in a 2015 field survey and stored in -80°C freezer. In 2021, the frozen sera from vaccinated animals were prepared and tested for antibodies against the rabies virus using a commercial blocking enzyme-linked immunosorbent assay (ELISA) test. Sixty-five samples were available from the vaccinated macaques that had received at least one dose of the vaccine between 2008 and 2015. The interval between the first vaccination and blood sampling ranged from 21 to 2,779 days (median: 990). Only five macaques had a second vaccination record at the sampling time, all with high antibody levels. Among the remaining macaques, 77% (46/60) were positive for rabies antibodies. No specific association was observed between the post-vaccination period and the antibody titer of these macaques, and no adverse reactions were reported. Although the precise level of protection against a potential challenge with the rabies virus cannot be ascertained, the vaccination elicited rabies antibodies in 87% (21/24) of the macaques tested within 2.5 years of their first vaccination. Our findings indicate the potential benefits of the current vaccination strategy to protect the population from rabies and consequential mandatory culling of all macaques if a natural infection occurs.

Pathological manifestations of feline immunodeficiency virus (FIV) infection in wild African lions.

Feline immunodeficiency virus (FIV) causes AIDS in the domestic cat (Felis catus) but has not been explicitly associated with AIDS pathology in any of the eight free-ranging species of Felidae that are endemic with circulating FIV strains. African lion (Panthera leo) populations are infected with lion-specific FIV strains (FIVple), yet there remains uncertainty about the degree to which FIV infection impacts their health. Reported CD4+ T-lymphocyte depletion in FIVple-infected lions and anecdotal reports of lion morbidity associated with FIV seroprevalence emphasize the concern as to whether FIVple is innocuous or pathogenic. Here we monitored clinical, biochemical, histological and serological parameters among FIVple-positive (N=47) as compared to FIVple-negative (N=17) lions anesthetized and sampled on multiple occasions between 1999 and 2006 in Botswana. Relative to uninfected lions, FIVple-infected lions displayed a significant elevation in the prevalence of AIDS-defining conditions: lymphadenopathy, gingivitis, tongue papillomas, dehydration, and poor coat condition, as well as displaying abnormal red blood cell parameters, depressed serum albumin, and elevated liver enzymes and gamma globulin. Spleen and lymph node biopsies from free-ranging FIVple-infected lions (N=9) revealed evidence of lymphoid depletion, the hallmark pathology documented in immunodeficiency virus infections of humans (HIV-1), macaques, and domestic cats. We conclude that over time FIVple infections in free-ranging lions can lead to adverse clinical, immunological, and pathological outcomes in some individuals that parallel sequelae caused by lentivirus infection in humans (HIV), Asian macaques (SIV) and domestic cats (FIVfca).

A central role for venom in predation by Varanus komodoensis (Komodo Dragon) and the extinct giant Varanus (Megalania) priscus.

The predatory ecology of Varanus komodoensis (Komodo Dragon) has been a subject of long-standing interest and considerable conjecture. Here, we investigate the roles and potential interplay between cranial mechanics, toxic bacteria, and venom. Our analyses point to the presence of a sophisticated combined-arsenal killing apparatus. We find that the lightweight skull is relatively poorly adapted to generate high bite forces but better adapted to resist high pulling loads. We reject the popular notion regarding toxic bacteria utilization. Instead, we demonstrate that the effects of deep wounds inflicted are potentiated through venom with toxic activities including anticoagulation and shock induction. Anatomical comparisons of V. komodoensis with V. (Megalania) priscus fossils suggest that the closely related extinct giant was the largest venomous animal to have ever lived.

Pharmacokinetic behavior of enrofloxacin in estuarine crocodile (Crocodylus porosus) after single intravenous, intramuscular, and oral doses.

The disposition kinetics of enrofloxacin at a single dose of 5 mg/kg body weight were determined in clinically healthy captive-reared estuarine crocodiles (Crocodylus porosus) after intravenous (i.v.), intramuscular (i.m.), and oral (p.o.) administration. Enrofloxacin plasma concentrations were determined by diode array detection-high-performance liquid chromatography (limit of detection/limit of quantitation: 0.05 microg/ml). Data were subjected to noncompartmental analysis. The integrated pharmacokinetic-pharmacodynamic (PK-PD) variables showed that optimal area under the curve from the time of dosing to 24 hr:minimal inhibitory concentration (MIC) (>125) and peak plasma concentrations:MIC (>8) ratios, as reported for concentration-dependent bactericidal antimicrobials like fluoroquinolones, were achievable with both a single i.v. or i.m. dose for susceptible microorganisms with MIC values of < or =0.5 microg/ml, while the relatively slow onset of peak time allowed an effective plasma drug level only on day 3. The persistence of useful plasma concentrations indicated the possibility of redosing every 3 day for parenteral routes of administration, while further studies are needed for the oral route. Nevertheless, the absence of adverse reactions in the animals following i.v., i.m., or p.o. administration of enrofloxacin after a single dose of 5 mg/kg indicates the possibility of its safe and effective clinical use in captive estuarine crocodiles.