Seroprevalence of canine distemper virus (CDV) in the free-roaming dog (Canis familiaris) population surrounding Chitwan National Park, Nepal

Canine distemper virus (CDV) is a global multi-host pathogen that is capable of causing considerable mortality in a range of species and is important in the field of conservation medicine. Nepal's Chitwan National Park is a protected area providing habitat for 32% of the country's mammal species including endangered carnivores such as the Bengal tiger (Panthera tigris tigris) that are susceptible to CDV. The presence of free-roaming dogs around protected areas could represent a source of infectious disease for transmission to local wildlife. A cross-sectional demographic and canine distemper virus seroprevalence study of 100 free-roaming dogs from the Chitwan National Park buffer zone and surrounding area was conducted in November 2019. The overall seroprevalence indicating past exposure to canine distemper virus was 80.0% (95% CI: 70.8-87.3). Of the host variables assessed, sex and age were positively associated with seroprevalence at the univariable level, with male dogs demonstrating lower seroprevalence than females (OR = 0.32, 95% CI: 0.11-0.91) and adult dogs demonstrating higher seroprevalence than juveniles (OR = 13.94, 95% CI: 1.37-142.29). The effect of sex was no longer significant at the multivariable level, but the direction of the effect remained the same. The effect of age remained significant after multivariable analysis (OR = 9.00, 95% CI: 1.03-192.75). No spatial associations were demonstrated in relation to the buffer zone area or boundary of Chitwan National Park. Free-roaming dog neutering and vaccination programmes can provide a useful baseline for future CDV studies in the region, and a proxy to monitor disease threats to susceptible wildlife.

Adding Nuance to Our Understanding of Dog-Wildlife Interactions and the Need for Management

The interactions of dogs and wildlife are receiving increasing attention across the globe. Evidence suggests that dogs can negatively affect wildlife in a variety of ways, including through the risk of predation, by hybridizing with other Canis species, by acting as a reservoir or vector of pathogens, and by competing with wildlife for resources. A multitude of observations and case studies for each of these interactions has led to calls to prioritize increased management of dogs, for instance, through population reduction, vaccination, movement restrictions, and enhanced care of the dogs themselves. Here, I argue that while the risks that dogs present to wildlife are real, they vary in their importance across the globe. Furthermore, often the approaches used to address these risks are championed without a full understanding of the likelihood of success given the necessary spatial scale of management, the availability of alternative management approaches, and the role dogs play in societies. For instance, culling, vaccination, and animal husbandry approaches in reducing the impacts of dogs on wildlife sometimes fail to recognize that local human populations actively recruit replacement dogs, that vaccination often fails to reach levels necessary for herd immunity, and that enhanced dog husbandry may have indirect impacts on wildlife by requiring environmentally impactful activities. I suggest there is a need for attention not only to identify the impacts of dogs but also to determine where and when such interactions with wildlife are problematic and the likelihood of success for any proposed management approach. The impacts of dogs should be mediated in a context-specific manner that accounts for factors such as the local density of dogs, the susceptibility of local wildlife populations to the risks that dog populations may represent, and the local societal norms that underpin how dogs might be managed.

Prevalence and risk factors for the presence of serum antibodies against canine distemper, canine parvovirus, and canine adenovirus in communities in mainland Ecuador

The purpose of this study was to estimate the apparent prevalence and identify risk factors for antibody levels (AL) against canine distemper virus (CDV), canine parvovirus (CPV), and canine adenovirus (CAV) in three communities in the metropolitan area of Quito, Ecuador that have limited access to regular veterinary care. Whole blood samples were collected from 154 dogs presenting to three veterinary field clinics in mainland Ecuador and tested for AL against CDV, CPV, and CAV by a commercially available point-of-care ELISA. Potential risk factors for the presence of AL were analyzed. A majority of dogs had AL against CDV (66%, 95% CI = 58-73%), CPV (95%, 95% CI = 91-98%) and CAV (60%, 95% CI = 52-67%). Dogs had significantly greater odds of AL against CDV if they were >2 years of age, from an urban community, and had previously received veterinary care. Dogs had significantly greater odds of AL against CAV if they were male, >2 years of age, and had previously received veterinary care. Results provide baseline estimates of AL within each community and allow for the targeting of future veterinary services to communities and dogs most at risk.

Interactions Between Carnivores in Madagascar and the Risk of Disease Transmission

Introduced carnivores exert considerable pressure on native predators through predation, competition and disease transmission. Recent research shows that exotic carnivores negatively affect the distribution and abundance of the native and endangered carnivores of Madagascar. In this study, we provide information about the frequency and distribution of interactions between exotic (dogs and cats) and native carnivores (Eupleridae) in the Betampona Natural Reserve (BNR), Madagascar, using noninvasive camera trap surveys. Domestic dogs (Canis familiaris) were the most frequently detected carnivore species within the BNR, and we found that indirect interactions between exotic and native carnivores were frequent (n = 236). Indirect interactions were more likely to occur near the research station (incidence rate ratio = 0.91), which may constitute a disease transmission hot spot for carnivores at BNR. The intervals between capture of native and exotic carnivores suggest that there is potential for pathogen transmission between species in BNR. These capture intervals were significantly shorter near the edge of the reserve (P = 0.04). These data could be used to implement biosecurity measures to monitor interactions and prevent disease transmission between species at the domestic animal and wildlife interface.

Urban dogs in rural areas: Human-mediated movement defines dog populations in southern Chile

Management strategies for dog populations and their diseases include reproductive control, euthanasia and vaccination, among others. However, the effectiveness of these strategies can be severely affected by human-mediated dog movement. If immigration is important, then the location of origin of dogs imported by humans will be fundamental to define the spatial scales over which population management and research should apply. In this context, the main objective of our study was to determine the spatial extent of dog demographic processes in rural areas and the proportion of dogs that could be labeled as immigrants at multiple spatial scales. To address our objective we conducted surveys in households located in a rural landscape in southern Chile. Interviews allowed us to obtain information on the demographic characteristics of dogs in these rural settings, human influence on dog mortality and births, the localities of origin of dogs living in rural areas, and the spatial extent of human-mediated dog movement. We found that most rural dogs (64.1%) were either urban dogs that had been brought to rural areas (40.0%), or adopted dogs that had been previously abandoned in rural roads (24.1%). Some dogs were brought from areas located as far as ∼700km away from the study area. Human-mediated movement of dogs, especially from urban areas, seems to play a fundamental role in the population dynamics of dogs in rural areas. Consequently, local scale efforts to manage dog populations or their diseases are unlikely to succeed if implemented in isolation, simply because dogs can be brought from surrounding urban areas or even distant locations. We suggest that efforts to manage or study dog populations and related diseases should be implemented using a multi-scale approach.

PREVALENCE OF ANTIBODIES TO SELECTED VIRUSES AND PARASITES IN INTRODUCED AND ENDEMIC CARNIVORES IN WESTERN MADAGASCAR

Introduced animals impact endemic populations through predation, competition, and disease transmission. Populations of endemic carnivores in Madagascar are declining, and pathogens transmitted from introduced species may further endanger these unique species. We assessed the exposure of introduced and endemic carnivores to common viral and parasitic pathogens in two national parks of Madagascar (Kirindy Mitea National Park and Ankarafantsika National Park) and their neighboring villages. We also identified variables associated with the presence of antibodies to these pathogens in fosa ( Cryptoprocta ferox ). Introduced and endemic species were exposed to canine parvovirus, canine herpesvirus, feline calicivirus, and Toxoplasma gondii . Domestic dogs ( Canis familiaris ) and cats ( Felis catus ) may be sources of infection for these pathogens. Prevalence of antibodies to Toxoplasma in captured fosa was >93%, and adults were more likely to be exposed than immature individuals. Our data provide a basis upon which to evaluate and manage risks of pathogen transmission between species.