Seroprevalence of Canine Herpesvirus-1 in Breeding Dogs with or Without Vaccination in Northwest Italy

Abstract

Canine herpesvirus-1 (CHV-1) can cause abortion and foetal and neonatal deaths in the bitch. The reactivation of latent infections with asymptomatic virus shedding represents a mechanism, whereby the virus can persist in a dog population. The aim of this study was to investigate the seroprevalence of CHV-1 in a population of breeding dogs in Piedmont, Northern Italy, and to investigate the distribution of herpesvirus vaccination. The study was carried out in 370 animals that were housed in 33 breeding kennels. Antibodies against CHV-1 in serum samples were measured by means of serum neutralization. Vaccination had been performed in 21.2% of the kennels and 8.4% of the dogs. The overall seroprevalence of CHV-1 was 50.3%. In ten kennels (30.3%), no seropositive dogs were identified. The percentage of seropositive dogs ranged from 7.1% to 100% in positive kennels. More than 40% of the seropositive dogs showed high titres. Sex had no significant effect on either seroprevalence or the category of the serum titre. The number of positive animals was significantly lower in the groups of prepuberal bitches and animals younger than 1.5 years. The majority of younger animals showed very high titres, suggesting recent contact with the virus. Our data show that CHV-1 is a common infection in breeding dogs in Piedmont. Vaccination is rarely performed but might be an option, because, although many animals of breeding age already show high antibody titres, seronegative pregnant bitches will be at high risk of contracting the infection due to viral circulation in kennels where the virus is enzootic.

Keywords: breeding kennels; canine herpesvirus-1; dog; vaccination.

Figure 1

Distribution of CHV-1 antibody titres in the groups of nonvaccinated (No vax; n = 178) and vaccinated animals (Vax; n = 7). The percentage of animals showing the different antibody titres (1:4, 1:8, 1:16, 1:32, 1:64, 1:128, ≥1:126) appears on the y-axis, while the number in each category is written on the histogram.

Figure 2

Distribution of serum titres among bitches in different reproductive conditions (Prepuberal, Pregnancy, Lactation) or cycle phases (Anestrus, Estrus, Diestrus). Different grey scales show different titre categories: 1:4–1:8 weakly positive; 1:64–1:128 positive; ≥1:256 strongly positive.

Figure 3

Distribution of serum titres among prepuberal bitches and animals in other life stages. Different grey scales show different titre categories: 1:4–1:8 weakly positive; 1:64–1:128 positive; ≥1:256 strongly positive.

Figure 4

Relative percentage of seropositive (positive) and seronegative (negative) animals in the different age classes (<1.5 years; 1.5–3.5 years; >3.5–6 years; >6 years). The number of animals in each category appears in the histogram.