The pathogenicity of some avian reoviruses with particular reference to tenosynovitis

In two experiments, 13 avian reoviruses from different sources were tested in specific pathogen-free (SPF) light hybrid chicks at 1-day-old for their pathogenicity with particular respect to tenosynovitis. All strains including two from commercial ducks and another from a wedge-tail eagle caused tenosynovitis. In most cases the lesions were macroscopic but in a few only microscopic abnormalities were observed after footpad or oral inoculation. In the first experiment with six British strains, infection by contact also resulted in tenosynovitis, and in most cases virus persisted longer in the hock joint/tendons than in the gut. Among the 13 viruses, two strains, R14 and Lasswade 126/75 were the mildest, producing only slight microscopic lesions of the disease, while strain WVU 2937 was the most virulent for joints/tendons. Five strains caused mortalities when inoculated at high concentration, deaths being due to hepatic necrosis. However, infection at a 1:10 dilution of this dose resulted in tenosynovitis lesions only. None of the strains tested caused signs of stunting or malabsorption syndromes.