Unraveling the causes of respiratory disease in the working equids of Ethiopia: A cross sectional survey

Abstract

Previous research has demonstrated that respiratory disease, particularly coughing and nasal discharge are consistently ranked in the top-three health concerns for working equid owners. However, there is little existing literature on the possible aetiology and these syndromes are poorly defined. This study aimed to better understand respiratory disease, including frequency of signs, in working equids and assess exposure to the major respiratory pathogens. A cross-sectional study was conducted across 19 sites in Central Ethiopia. Owners and horses were sampled using systematic random sampling from a selected focal point in the town. A brief questionnaire was administered to drivers/owners to ascertain horse details and history of respiratory signs or disease. A clinical examination was performed and a jugular blood sample was taken. Heat-treated serum was transported to the UK for testing. Serology for antibody titres to equine influenza virus (EIV) used a multispecies Influenza A competitive Enzyme-linked Immunosorbant Assay (ELISA). Samples showing a borderline negative result ( 0.3 on ELISA. Complement fixation was used to determine serum antibody titres to equine herpes viruses (EHV-1/4) and equine rhinitis viruses (ERAV/ERBV). Over 19 sites, 350 participants were selected. Owners reported 38% animals examined had recent history of coughing (last 30 days), 8% had a history of nasal discharge and 3% had suffered other breathing problems. In addition 11% horses examined had a clinically significant nasal discharge. Serology results for 350 horses suggested recent exposure to S equi in 23%, EAV 3.4%, but exposure to influenza virus was very rare. Low antibody titres to EHV-1/4 and ERAV/ERBV were also detected. Clinical signs of respiratory disease were relatively uncommon on examination of these working horses; however owners reported higher levels of respiratory signs in the previous 30 days, particularly coughing, consistent with results from the previous participatory studies. It appears S equi is endemic in the population and is likely to be a