CANID HERPESVIRUS-1 IN ITALY: BIOMOLECULAR AND SEROLOGICAL SURVEY IN A BREEDING KENNEL

BACKGROUND AND OBJECTIVES Canid herpesvirus (CaHV-1) is a worldwide spread pathogen causing reproductive, respiratory and neurological disorders in adult dogs as well as neonatal death in puppies. According to studies, a higher seroprevalence exists in kenneled dogs than in household pets(1,2), however, there is a sparsity of prevalence studies reporting viral shedding and antibody titres. Additionally, the real prevalence of CaHV-1 in Italy is still unclear. The aims of this survey were to analyze immunological changes and detect CaHV-1 DNA in an at-risk dog population - a large breeding kennel - in order to find any evidence of circulation of the virus. MATERIALS AND METHODS For this survey we chose a breeding kennel in central Italy that hosted 243 dogs (160 breeders), which have never been vaccinated against CaHV-1. The experiment group consisted of 23 dogs (14 females and 9 males). All of the females were in heat contemporary. Blood samples and vaginal swabs were taken from bitches at three critical points: during estrus, before mating, and immediately after parturition. Blood samples were also taken from male dogs before and 3 weeks after mating. Aborted fetuses, stillborn pups, umbilical cords and placentas were collected as well. Serum neutralization (SN) assay was performed on serum while vaginal swabs and other samples were tested using nested PCR assay. The external genitals were examined for CaHV-1 associated lesions. RESULTS None of the dogs showed any external genital signs and none tested positive during the SN test. All of the other submitted samples tested PCR-negative. CONCLUSION CaHV-1 is maintained in nature by persistence in its canine host and by direct spread from infected animals. Viral shedding occurs sporadically and usually when animals are under stress, such as those in high population densities, those being transported or those that are pregnant. Serologic prevalence in domestic dogs has ranged from 30% to 100%(3,4,5,7), however, our survey showed no association between antibody titres and risk factors for CaHV-1 transmission despite the association of predisposing risk factors present in the kennel. Indeed, this dog population was large and animals were allowed to travel outside of the kennel and do various normal activities - such as contests or breeding - which may have exposed them to other infected dogs. An Italian study in 2014 showed a low seroprevalence (14.6%) in southern Italy(6), bringing attention to the problem of worldwide distribution of CaHV-1. In conclusion, similar values of seroprevalence obtained in canine populations of Italy imply the existence of a lesser circulation of CaHV-1 in our country when compared to the world mean, which attested between 40% and 93% with an incidence of 60-80%(7). Despite the low number of available bitches in heat contemporary in the kennel, it has been interesting to observe that there was no evidence of circulation or reactivation of viral infection in the population studied, neither before nor after breeding, rising new questions concerning the epidemiology of this pathogen. REFERENCES 1 Dahlbom M. et al 2009 Reprod Dom Anim 44:128-131 2 Ronsse V. et al 2002 Reprod Domest Anim 37:299-304 3 Erles K. et al 2005 Arch Virol 150:1493-1504 4 Nöthling JO. et al 2008 Theriogenology 69:276-282 5 Reading MJ. et al 1998 Arch Virol 143:1477-1488 6 Pratelli A. et al 2014 Vet J 200(2):257-60 7 Verstegen J. et al 2008 Theriogenology 70(3):304-19