Canine Rabies Virus Research Articles

BLACK-BACKED JACKAL EXPOSURE TO RABIES VIRUS, CANINE DISTEMPER VIRUS, AND BACILLUS ANTHRACIS IN ETOSHA NATIONAL PARK, NAMIBIA

Canine distemper virus (CDV) and rabies virus (RABV) occur worldwide in wild carnivore and domestic dog populations and pose threats to wildlife conservation and public health. In Etosha National Park (ENP), Namibia, anthrax is endemic and generates carcasses frequently fed on by an unusually dense population of black-backed jackals (Canis mesomelas). Using serology, phylogenetic analyses (on samples obtained from February 2009-July 2010), and historical mortality records (1975-2011), we assessed jackal exposure to Bacillus anthracis (BA; the causal bacterial agent of anthrax), CDV, and RABV. Prevalence of antibodies against BA (95%, n = 86) and CDV (71%, n = 80) was relatively high, while that of antibodies against RABV was low (9%, n = 81). Exposure to BA increased significantly with age, and all animals >6 mo old were antibody-positive. As with BA, prevalence of antibodies against CDV increased significantly with age, with similar age-specific trends during both years of the study. No significant effect of age was found on the prevalence of antibodies against RABV. Three of the seven animals with antibodies against RABV were monitored for more than 1 yr after sampling and showed no signs of active infection. Mortality records revealed that rabid animals are destroyed nearly every year inside the ENP tourist camps. Phylogenetic analyses demonstrated that jackal RABV in ENP is part of the same transmission cycle as other dog-jackal RABV cycles in Namibia.

Dog rabies in Africa: genetic analysis, geographic structure and dynamics

This work illustrates the studies that have provided a better understanding of the genetic and geographic structure of dog rabies virus and the dynamics of rabies in domestic dogs in Africa, the second largest continent most affected by this disease. These investigations are a key element to control the disease and identify effective strategies for eliminating rabies locally, nationally as well as internationally and could drastically reduce human deaths caused by this disease. They also allow for the first time the investigation of the role of humans in the canine rabies virus spreading.

Compendium of Animal Rabies Prevention and Control, 2011

the disease, and for purposes of this document, use of the term animal refers to mammals. The disease is an acute, progressive encephalitis caused by a lyssavirus. Rabies virus is the most important lyssavirus globally. In the United States, multiple rabies virus variants are maintained in wild mammalian reservoir populations, such as raccoons, skunks, foxes, and bats. Although the United States has been declared free from transmission of canine rabies virus variants, there is always a risk of reintroduction of these variants. 2–6 The virus is usually transmitted from animal to animal through bites. The incubation period is highly variable. In domestic animals, it is generally 3 to 12 weeks but can range from several days to months, rarely exceeding 6 months. 7 Rabies is communicable during the period of salivary shedding of rabies virus. Experimental and historic evidence document that dogs, cats, and ferrets shed virus a few days prior to clinical onset and during illness. Clinical signs of rabies are variable and include inappetence, dysphagia, cranial nerve deficits, abnormal behavior, ataxia, paralysis, altered vocalization, and seizures. Progression to death is rapid. There are currently no known effective rabies antiviral drugs.

Pathogenicity of different rabies virus isolates and protection test in vaccinated mice

This study was aimed to evaluate and compare the pathogenicity of rabies virus isolated from bats and dogs, and to verify the efficacy of a commercial rabies vaccine against these isolates. For evaluation of pathogenicity, mice were inoculated by the intramuscular route (IM) with 500MICLD₅₀/0.03 mL of the viruses. The cross-protection test was performed by vaccinating groups of mice by the subcutaneous route and challenged through the intracerebral (IC) route. Isolates were fully pathogenic when inoculated by the IC route. When inoculated intramuscularly, the pathogenicity observed showed different death rates: 60.0% for the Desmodus rotundus isolate; 50.0% for dog and Nyctinomops laticaudatus isolates; 40.0% for Artibeus lituratus isolate; 9.5% Molossus molossus isolate; and 5.2% for the Eptesicus furinalis isolate. Mice receiving two doses of the vaccine and challenged by the IC route with the isolates were fully protected. Mice receiving only one dose of vaccine were partially protected against the dog isolate. The isolates from bats were pathogenic by the IC route in mice. However, when inoculated through the intramuscular route, the same isolates were found with different degrees of pathogenicity. The results of this work suggest that a commercial vaccine protects mice from infection with bat rabies virus isolates, in addition to a canine rabies virus isolate.

Rabies surveillance in the United States during 2009

During 2009, 49 states and Puerto Rico reported 6,690 rabid animals and 4 human rabies cases to the CDC, representing a 2.2% decrease from the 6,841 rabid animals and 2 human cases reported in 2008. Approximately 92% of reported rabid animals were wildlife. Relative contributions by the major animal groups were as follows: 2,327 (34.8%) raccoons, 1,625 (24.3%) bats, 1,603 (24.0%) skunks, 504 (75%) foxes, 300 (4.5%) cats, 81 (1.2%) dogs, and 74 (1.1%) cattle. Compared with 2008, numbers of rabid raccoons and bats that were reported decreased, whereas numbers of rabid skunks, foxes, cats, cattle, dogs, and horses that were reported increased. Fewer rabid raccoons, compared with 2008, were reported by 12 of the 20 eastern states where raccoon rabies is enzootic, and number of rabid raccoons decreased by 2.6% overall nationally. Despite a 10% decrease in the number of rabid bats that were reported and a decrease in the total number of bats submitted for testing, bats were the second most commonly submitted animal, behind cats, during 2009. The number of rabid skunks that were reported increased by 0.9% overall. The proportion of rabid skunks in which infection was attributed to the raccoon rabies virus variant decreased from 473% in 2008 to 40.9% in 2009, resulting in a 12.7% increase in the number of rabid skunks infected with a skunk rabies virus variant. The number of rabid foxes increased 11.0% overall from the previous year. Four cases of rabies involving humans were reported from Texas, Indiana, Virginia, and Michigan. The Texas case represented the first presumptive abortive human rabies case, with the patient recovering after the onset of symptoms without intensive care. The Indiana and Michigan cases were associated with bat rabies virus variants. The human rabies case in Virginia was associated with a canine rabies virus variant acquired during the patient's travel to India.

Rabies virus pathogenesis in relationship to intervention with inactivated and attenuated rabies vaccines

Despite progress in vaccine development in the past century the mechanisms behind immune responses elicited by rabies biologics or via natural infection remain largely unknown. In this study, we compared protection elicited by standard, early, or delayed prophylaxis with a reduced number of vaccine doses using inactivated and live-attenuated vaccines. Two-month-old Syrian hamsters, 4-week-old ICR mice or adult rhesus macaques were inoculated with canine rabies virus variants. Thereafter, prophylaxis was initiated 6h, 1, 2, 3, 4, 5, 6 or 7 days post-exposure (p.e.). One or several doses of inactivated (HDCV), or reverse genetically attenuated (live), or gamma-irradiated (inactivated)-ERAG333 vaccines were administered intramuscularly. The dynamics of virus spread were measured over time in the rodent models. Rabies virus reached the spinal cord at day 4 and brain at day 6 p.e. All hamsters succumbed in groups in which live ERAG333 was delayed until days 5 and 6 p.e. However, 78%, 44%, 56% and 22% of hamsters survived when one dose of live ERAG333 was administered 6h, 1, 2, 3, and 4 days p.e., respectively. Similarly, 67% survived when inactivated ERAG333 was administered at 24h p.e. All hamsters succumbed when standard prophylaxis (the Essen regimen) was delayed until days 3–6, but 67% and 33% of hamsters survived when PEP began 1 or 2 days p.e., respectively. Macaques were protected by one dose of attenuated ERAG333 at 24h p.e. The highly attenuated (live) and inactivated ERAG333 vaccines elicited potent protective immune responses, even when prophylaxis initiation was delayed. When 2–5 doses of commercial vaccine and HRIG were administered according to the Essen scheme, 89–100% of the animals survived. Reduced vaccine schedules provided efficacious intervention, regardless of the total number of vaccine doses administered.

Rabies surveillance in the United States during 2008

During 2008, 49 states and Puerto Rico reported 6,841 cases of rabies in animals and 2 cases in humans to the CDC, representing a 3.1% decrease from the 7,060 cases in animals and 1 case in a human reported in 2007. Approximately 93% of the cases were in wildlife, and 7% were in domestic animals. Relative contributions by the major animal groups were as follows: 2,389 (34.9%) raccoons, 1,806 (26.4%) bats, 1,589 (23.2%) skunks, 454 (6.6%) foxes, 294 (4.3%) cats, 75 (1.1%) dogs, and 59 (0.9%) cattle. Compared with numbers of cases reported in 2007, numbers of cases reported in 2008 increased among cats, cattle, and skunks and decreased among dogs, raccoons, bats, and foxes. Numbers of rabid raccoons reported during 2008 decreased in 11 of the 20 eastern states where raccoon rabies was enzootic; overall number of rabid raccoons reported decreased by 8.6% during 2008, compared with 2007. On a national level, the number of rabies cases involving skunks increased by 7.7% during 2008, compared with the number reported in 2007; this was the first increase in the number of reported rabid skunks since 2006. The total number of cases of rabies reported nationally in foxes decreased 1.7% in 2008, compared with 2007. The 1,806 cases of rabies reported in bats represented a 6.7% decrease, compared with the number reported in 2007. One case of rabies in a dog imported from Iraq was reported at a quarantine station in New Jersey during 2008. Follow-up of potentially exposed animals in the same shipment did not reveal any secondary transmission. The United States remained free from dog-to-dog transmission of canine rabies virus variants. Total number of rabid dogs reported decreased 19.4% in 2008, compared with 2007. Two human rabies cases were reported from California and Missouri during 2008. The California case involved a recent immigrant from Mexico and was attributed to a newly identified rabies virus variant most likely associated with Mexican free-tailed bats. The case in Missouri was attributed to a rabies virus variant associated with eastern pipistrelle and silver-haired bats.

Rabies surveillance in the United States during 2007

During 2007, 49 states and Puerto Rico reported 7,258 cases of rabies in animals and 1 case in a human to the CDC, representing a 4.6% increase from the 6,940 cases in animals and 3 cases in humans reported in 2006. Approximately 93% of the cases were in wildlife, and 7% were in domestic animals. Relative contributions by the major animal groups were as follows: 2,659 raccoons (36.6%), 1,973 bats (27.2%), 1,478 skunks (20.4%), 489 foxes (6.7%), 274 cats (3.8%), 93 dogs (1.3%), and 57 cattle (0.8%). Compared with numbers of reported cases in 2006, cases in 2007 increased among dogs, bats, foxes, and skunks while decreases were reported among cattle, cats, and skunks. Increases in numbers of rabid raccoons during 2007 were reported by 11 of the 20 eastern states where raccoon rabies was enzootic, and reported cases increased by 1.7% overall, compared with 2006. On a national level, the number of rabies cases in skunks during 2007 decreased by 1.1% from the number reported in 2006. Texas reported the greatest number (n = 362) of rabid skunks and the greatest overall state total of animal rabies cases (969). No cases of rabies associated with the dog/coyote rabies virus variant were reported. The United States remains free of dog-to-dog transmission of canine rabies virus variants. The total number of cases of rabies reported nationally in foxes increased 14.5%, compared with 2006. Increases in the number of reported rabid foxes were attributable to greater numbers of foxes reported with the Arctic fox rabies virus variant in Alaska, the Texas gray fox rabies virus variant in Texas, and the raccoon rabies virus variant in Virginia. The 1,973 cases of rabies reported in bats represented a 16.6% increase over numbers reported in 2006. Cases of rabies in dogs and in sheep and goats increased 17.7% and 18.2%, respectively, whereas cases reported in cattle, cats, and horses and mules decreased 30.5%, 13.8%, and 20.8%, respectively. In Puerto Rico, reported cases of rabies in mongooses decreased 51.5%, and rabies in domestic animals, presumably attributable to spillover infection from mongooses, increased 25%. One human rabies case was reported from Minnesota during 2007. Although typing of the rabies virus variant in this case was not possible, an investigation of this case indicated a bat as the most likely source of exposure.

Importation of Dogs into the United States: Risks from Rabies and Other Zoonotic Diseases

The importation of dogs into the United States poses a risk for the introduction of rabies and other zoonotic diseases. Federal regulations (42 CFR 71.51) currently require proof of valid rabies vaccination for imported dogs, but allow the importation of some unvaccinated dogs, including dogs less than 3 months of age, provided certain requirements for confinement are met until the dog is vaccinated. Although there are no accurate surveillance data on the number of dogs imported each year, it is estimated based on extrapolated data that over 287,000 dogs were imported into the United States during 2006. Of these, approximately 25% were either too young to be vaccinated or lacked proof of valid rabies vaccination. Import trends suggest that an increasing number of unvaccinated puppies are being imported into the United States, many through commercial resale or rescue operations. Since 2004, foreign canine rabies virus variants have been documented in at least two imported puppies. Federal regulations are currently being reviewed by the Centers for Disease Control and Prevention to determine if they can be updated to address current import trends and disease risks, such as requiring a health screen and valid rabies vaccinations for all dogs prior to entry.

Efficacy and safety of a live canine adenovirus-vectored rabies virus vaccine in swine

Rabies infections in swine have been reported occasionally in recent years in certain geographic locations. Although a protective vaccine consisting of inactivated rabies virus is available for use in swine, searching for a more economically viable formulation for use in developing countries is always a priority. This work describes the testing of a canine adenovirus that expresses a rabies viral epitope (CAV-2-E3Δ-RGP) in a porcine rabies model. The data presented here show that the recombinant viral vaccine was effective in protecting swine against rabies if administered intramuscularly, but not orally or intranasally, and that protection was probably related to the development of a humoral response that lasted at least 28 weeks. Following vaccination, no behavioral abnormalities were observed in vaccinated swine and virus particles were not detected in either tissues or body fluids, indicating that this formulation was safe. The recombinant virus stimulated an effective level of antibody response in the immunized swine after a single intramuscular inoculation.

Compendium of Animal Rabies Prevention and Control, 2008

sive encephalitis caused by a Lyssavirus. Although the United States has been declared free of canine rabies virus variant transmission, multiple viral variants are maintained in wild mammal populations, and there is always a risk of reintroduction of canine rabies. 2 All mammals are believed to be susceptible to the disease, and for purposes of this document, use of the term animal refers to mammals. The recommendations in this compendium serve as a basis for animal rabies-prevention and -control programs throughout the United States and facilitate standardization of procedures among jurisdictions, thereby contributing to an effective national rabies-control program. This document is reviewed annually and revised as necessary, and the most current version replaces all previous versions. These recommendations do not supersede state and local laws or requirements. Principles of rabies prevention and control are detailed in Part I; Part II contains recommendations for parenteral vaccination procedures; all animal rabies vaccines licensed by the USDA and marketed in the United States are listed in Part III.

Rabies surveillance in the United States during 2006

During 2006, 49 states and Puerto Rico reported 6,940 cases of rabies in animals and 3 cases in humans to the CDC, representing an 8.2% increase from the 6,417 cases in animals and 1 case in a human reported in 2005. Approximately 92% of the cases were in wildlife, and 8% were in domestic animals. Relative contributions by the major animal groups were as follows: 2,615 raccoons (37.7%), 1,692 bats (24.4%), 1,494 skunks (21.5%), 427 foxes (6.2%), 318 cats (4.6%), 82 cattle (1.2%), and 79 dogs (1.1%). Compared with numbers of reported cases in 2005, cases in 2006 increased among all groups except cattle. Increases in numbers of rabid raccoons during 2006 were reported by 11 of the 20 eastern states where raccoon rabies was enzootic, and reported cases increased by 3.2% overall, compared with 2005. On a national level, the number of rabies cases in skunks during 2006 increased by 6.1% from the number reported in 2005. Once again, Texas reported the greatest number (n = 351) of rabid skunks and the greatest overall state total of animal rabies cases (889). No cases of rabies associated with the dog/coyote rabies virus variant were reported. The last identified case of this canine rabies virus variant was identified in March 2004, along the US/Mexico border. With 2006 marking the second year of no apparent transmission of the dog/coyote variant, these findings from surveillance data support the contention that the canine rabies virus variant is no longer in circulation in the United States. Total number of cases of rabies reported nationally in foxes increased 13.6%, compared with 2005. Increases in the number of reported rabid foxes were attributable to greater numbers of foxes reported with the Arctic fox rabies virus variant in Alaska, the Texas gray fox rabies virus variant in Texas, and the raccoon rabies virus variant in Virginia. The 1,692 cases of rabies reported in bats represented a 14.5% increase, compared with numbers reported in 2005, making bats the second most reported rabid animal behind raccoons. Cases of rabies in cats, dogs, horses and mules, and sheep and goats increased 18.2%, 3.9%, 12.8%, and 22.2%, respectively, whereas cases reported in cattle decreased 11.8%. In Puerto Rico, reported cases of rabies in mongooses increased 9.2%, and rabies in domestic animals, presumably attributable to spillover infection from mongooses, increased 20%. Three cases of human rabies were reported from Texas, Indiana, and California during 2006. The cases in Indiana and Texas were attributed to bat rabies virus variants, whereas the case in California was attributed to an exposure to a dog in the Philippines.

The evolutionary dynamics of canid and mongoose rabies virus in southern Africa

Two variants of rabies virus (RABV) currently circulate in southern Africa: canid RABV, mainly associated with dogs, jackals, and bat-eared foxes, and mongoose RABV. To investigate the evolutionary dynamics of these variants, we performed coalescent-based analyses of the G-L inter-genic region, allowing for rate variation among viral lineages through the use of a relaxed molecular clock. This revealed that mongoose RABV is evolving more slowly than canid RABV, with mean evolutionary rates of 0.826 and 1.676 x 10(-3) nucleotide substitutions per site, per year, respectively. Additionally, mongoose RABV exhibits older genetic diversity than canid RABV, with common ancestors dating to 73 and 30 years, respectively, and while mongoose RABV has experienced exponential population growth over its evolutionary history in Africa, populations of canid RABV have maintained a constant size. Hence, despite circulating in the same geographic region, these two variants of RABV exhibit striking differences in evolutionary dynamics which are likely to reflect differences in their underlying ecology.

Identification of novel canine rabies virus clades in the Middle East and North Africa

Four novel phylogenetic clades of canine rabies virus (RABV) variants have been identified in the Middle East and North Africa. The three novel Middle Eastern clades comprise RABV isolates from the borders between Israel and neighbouring countries. The North African clade (Africa 4) comprises four RABV isolates from Egypt and one from Israel. We characterized various RABV lineages antigenically by using a panel of monoclonal antibodies to the nucleoprotein (N) and phylogenetically by analysis of entire N gene sequences. The estimated mean substitution rate for the N gene alignment (2.7x10(-4) substitutions per site per year) is comparable with previous estimates for RABV. The application of a molecular clock indicates the emergence of current canine RABV diversity to have occurred at about the same time (approx. 1870) in the Middle East and Europe, following divergence from established lineages in Africa and Asia.

Phylogenetic Characterization of Rabies Virus Isolates from Carnivora in Brazil

The incidence of canine rabies has been widely reported in Brazil, and new rabies virus (RV) variants, genetically similar to canine RV, have recently been isolated from foxes. In order to derive the epidemiological characteristics of Brazilian Carnivora RV, Brazilian RVs isolated from dogs, cats, and foxes were genetically analyzed. Brazilian Carnivora RV isolates were divided into 2 main lineages. The predominant lineage was found in dogs and cats, which included the Argentinean and Bolivian Carnivora RV isolates, and was extensively distributed throughout Brazil and surrounding countries. The other lineage consisted of three sublineages containing Brazilian dog and fox RV isolates, with the dog sublineages located on an internal branch of 2 fox sublineages, suggesting that RV transmission events might have occurred between foxes and dogs in the past. These results suggest that contact between dogs and wildlife has the potential to generate new rabies variants and that it is important to control RV infection cycles in both dogs and wildlife to prevent spread of rabies infection.

Screening of Upregulated Genes in Suckling Mouse Central Nervous System during the Disease Stage of Rabies Virus Infection

The pathogenesis of hydrophobia remains unclear. The aim of this study was to identify the differentially upregulated genes that correlated with disease development in an experimental mouse model to provide better understanding of pathological mechanisms in rabies. The present work employed Clontech mouse array 1.2 II containing 1,176 gene transcripts. Suckling mice were intracerebrally infected with canine rabies virus. The gene expression profiles on day 2, 4 and 6 post inoculation were followed. The results show genes whose expression increased at least twofold above the control, mock-infected brain. The numbers of genes showing altered expression level were 29, 109 and 98 genes on day 2, 4 and 6, respectively. The genes with altered expression were classified into eight major groups, namely immune response, metabolism, receptor and transporter, growth factors, death mediated factors, transcription and translation factors, proteases, and kinases. The numbers of upregulated genes during the disease stage was much higher than during the asymptomatic stage. This suggested that direct interaction between RABV and target cells induced massive destruction of a cellular homeostasis which may lead to functional termination of the CNS.

Importation of canid rabies in a horse relocated from Zimbabwe to South Africa : research communication

In July 2003 a 2-year-old Thoroughbred colt was imported from Harare, Zimbabwe to the Ashburton Training Centre, Pietermaritzburg, South Africa. Five months after importation, the colt presented with clinical signs suggestive of rabies: it was uncoordinated, showed muscle tremors and was biting at itself. Brain tissue was submitted for analysis and the clinical diagnosis was confirmed by the fluorescent antibody test and reverse-transcription polymerase chain reaction (RT-PCR). Phylogenetic analysis of the nucleotide sequence of the cytoplasmic domain of the glycoprotein and the G-L intergenic region of the rabies virus confirmed it to be an infection with a canid rabies virus, originating from an area in Zimbabwe endemic for the domestic dog (Canis familiaris) and side-striped jackal (Canis adustus) rabies.

A phylogenetic reconstruction of the epidemiological history of canine rabies virus variants in Colombia

Historically, canine rabies in Colombia has been caused by two geographically distinct canine variants of rabies virus (RV) which between 1992 and 2002 accounted for ∼95% of Colombian rabies cases. Genetic variant 1 (GV1) has been isolated up until 1997 in the Central Region and the Department of Arauca, and is now considered extinct through a successful vaccination program. Genetic variant 2 (GV2) has been isolated from the northern Caribbean Region and continues to circulate at present. Here we have analyzed two sets of sequence data based upon either a 147 nucleotide region of the glycoprotein (G) gene or a 258 nucleotide region that combines a fragment of the non-coding intergenic region and a fragment of the polymerase gene. Using both maximum likelihood (ML) and Markov chain Monte Carlo (MCMC) methods we have estimated the time of the most recent common ancestor (MRCA) of the two variants to be between 1983 and 1988. Reconstructions of the population history suggest that GV2 has been circulating in Colombia since the 1960s and that GV1 evolved as a separate lineage from GV2. Estimations of the effective population size at present show the GV2 outbreak to be ∼20 times greater than that of GV1. Demographic reconstructions were unable to detect a decrease in population size concurrent with the elimination of GV1. We find a raised rate of nucleotide substitution for GV1 gene sequences when compared to that of GV2, although all estimates have wide confidence limits. We demonstrate that phylogenetic reconstructions and sequence analysis can be used to support incidence data from the field in the assessment of RV epidemiology.

Reactivation of Nedd-2, a developmentally down-regulated apoptotic gene, in apoptosis induced by a street strain of rabies virus.

A laboratory strain of rabies virus has been reported to induce apoptosis in experimental animals. The present study demonstrated that a bat strain and a primary canine rabies virus isolate also induced apoptosis in vivo. This death process involved reactivation of the caspase gene, Nedd-2, a developmentally down-regulated apoptotic gene. Expression of Nedd-2 was significantly up-regulated in infected adult and suckling mice. Reactivation of Nedd-2 in infected adult mice started at around day 3 and was prominent on day 5. The level of expression was constantly high up to the time that mice showed signs of illness. Expression of Nedd-2 correlated with the appearance of apoptotic nuclei within the infected brain, suggesting that reactivation of a developmentally down-regulated gene, Nedd-2, may be required for apoptotic elimination of cells damaged by infection.

Serologic survey of selected viral agents in recently captured wild North American river otters (Lontra canadensis).

Blood samples were collected from 64 wild North American river otters (Lontra [Lutra] canadensis) from northern and eastern New York State and analyzed for serologic evidence of exposure to selected viral agents during a 1995 1996 translocation program. No clinical signs of disease nor lesions suggestive of prior viral exposure were seen. Titers were detected for antibodies against canine distemper virus, canine herpesvirus-1, and canine parvovirus-2 but not for antibodies against canine adenovirus-1, canine coronavirus, canine parainfluenza virus, rabies virus, feline herpesvirus-1, feline calicivirus, or feline coronavirus. This is the first report of titers for antibodies against canine herpesvirus-1 in North American river otters, and it suggests a low prevalence of antibody titers against most canine viruses in otter populations in northern and eastern New York. Confounding variables in this study could include exposure to domestic dogs associated with the project, prolonged time spent in captivity, and concurrent bacterial or parasitic infection. Stress-associated humoral immune suppression could have altered serologic profiles, especially in otters exposed to dogs after trapping but before venipuncture.