Studies on actinobacillus seminis as a cause of ovine epididymo-orchitis on two ranches in Machakos and Kajiado Districts of Kenya

Abstract

A farmer in stony Athi, Machakos, reported testicular swellings in some rams in his dorper flock, and was worried about their subsequent fertility. Such swellings are often caused by contagious epididymitis and orchitis, a disease which commonly causes ram infertility reduced lamb crops. The disease causes lesions in the epididymis and testis, which are clinically expressed as low volume and poor quality of semen, and consequently, impaired fertility (Cameron et at, 1971). This work was undertaken to establish the aetiology, of the swellings in this free range flock, and compare the findings with flocks \11 Enkasit, Kajiado district. 140 dorper rams from the Machakos ranch and 500 red Maasai rams from the Enkasit group ranch, Kajiado, were evaluated for clinical epididymitis and orchitis by scrotal palpation. RaInS with scrotal injuries, testicular adhesions, swellings, abscesses, discharge or any other visible abnormalities were isolated for further examination. Six affected rams were selected and samples for serology, seminology, bacteriology and histopathology collected from them. The results from the six rams were compared with those obtained from 5 control rams that had been ascertained to be free from scrotal and testicular abnormalities. From 50 mature rams and 90 immature rams clinically examined on the Machakos farm, 14 mature rams (28%) had scrotal abnormalities, while 5 (5.5%) of the 90 immature rams had abnormalities. The agar gel immuno-diffusion test was found to be more sensitive than the bacterial agglutination test in the diagnosis of ram epididymitis and orchitis due to A. seminis. Both tests had limited specificity in diagnosis of chronic Actinobacillus seminis infections. Agar gel immuno-diffusion shows promise as a rapid screening test in acute infections of Actinobacillus seminis, but the low serum antibody levels in chronic infections makes it difficult to use both serological tests after two months of infection. This study concluded that there were potential causes of specific and non-specific ram epididymitis and orchitis and the swellings on the ram testes on the Machakos study ranch was Actinobacillus seminis. Indigenous Maasai rams which were reared with a few dorper rams, appear to have low incidence of testicular and epididymal diseases probably due to inherent genetic resistance or differences in management practices.