Reovirus‐induced tenosynovitis in chickens: The effect of breed

Open Access
Publisher Website
Google Scholar
Abstract
The effect of breed of chicken on infection with an arthrotropic avian reovirus strain R2 was studied by oral or footpad inoculation of 1‐day‐old chicks of the following breeds: (1) specific pathogen‐free (SPF) light‐hybrid, (2) commercial White Leghorn egg‐layer, and (3) commercial Ross I broiler, and observed to 12 weeks of age. Although most inoculated birds of all three breeds developed swelling of one or both legs below the hock joint at 3 to 4 weeks of age, gross lesions of teno‐synovitis became progressively more severe and extended above the joints only in broilers, whereas in most orally‐infected SPF and commercial light chickens gross lesions were intermittently severe and regressed with time. Cloacal virus shedding continued up to 2 weeks in the lighter breeds and 3 weeks after infection in broilers. From a small proportion of infected chickens, reovirus was also reisolated from heart, pancreas and caecal tonsils. In all breeds, the tissue in which virus persisted longest was the hock joint/tendon. There was a poor correlation between isolation of virus and the presence of gross lesions in chickens of 12 weeks of age, especially in broilers. Virus‐neutralisation tests demonstrated that seroconversion in the lighter breeds occurred predominantly at 3 weeks and in broilers at 4 weeks after infection. In all three breeds the footpad infection gave significantly lower growth rates than were found in the control and oral‐infection groups. Oral infection had no apparent effect on growth rates. The greater susceptibility of broilers to reovirus infection is discussed.