A retrospective cohort study of canid herpesvirus-1 seroprevalence and epidemiology in kennel dogs in Croatia.

Canid alphaherpesvirus-1 (CaHV-1) is an endemic pathogen of dogs worldwide. CaHV-1 is often related to abortions, neonatal mortality, and the death of puppies. Since the first description of the virus in 1965, there has been no generally accepted method for diagnosing CaHV-1. Many authors used the virus neutralisation test (VNT) as a 'reference standard' due to its high specificity. Nasal, vaginal, preputial swabs and serum samples for this study were collected in the population of kennel dogs in Croatia. To determine the optimal VNT protocol, three modifications of the VNT were compared. These modifications were: VNT using native serum samples, VNT using thermally inactivated serum samples, and VNT using thermally inactivated serum samples with the addition of the complement. The correlation between the results of the VNT methods was significant (P < 0.001). Of all three modifications of VNT, the one using native serum samples was the one that increased VNT sensitivity. The overall seroprevalence of CaHV-1 was 32.02%. The PCR did not confirm the CaHV-1 presence in collected swabs. According to analysed anamnestic data, significant risk factors for CaHV-1 infection were: kennel size, attendance at the dog shows, hunt trials, kennel disinfection protocols, and mating. The oestrus cycle had no significant effect on seropositivity. The study results indicate that CaHV-1 spreads horizontally between dams living in kennels and in males during mating. Although there was no correlation between seropositivity and a history of reproductive disorders, significantly more stillborn puppies were recorded in seronegative dames (P < 0.01).