Haemonchosis in a Brahman calf in the high tropics of the Antioquian Northeast

Abstract

Haemonchosis is a parasitic disease that in cattle, unlike small ruminants,rarely causes mortality. However, parasitic burdens that are usually subclinicalin well-fed calves may become clinical causing death when bodycondition is poor. This report describes a case of fatal haemonchosis in a7-month-old Brahman calf and the results of treatment with albendazole(10 mg/kg PO) in 17 cohort calves. The farm, dedicated to breeding andrearing beef calves, was located in the high tropics of the Andes, municipalityof Yarumal (Antioquia), at 2,353 meters of altitude with an annual meantemperature of 14 °C. Apart from vaccination for foot and mouth disease,the animals are not subjected to any other treatments. The diagnosis wasinitially suspected based on clinico-pathological observations of a severeanemia with hypoproteinemia of non-inflammatory etiology, and wasconfirmed in the postmortem examination by the presence of hundreds ofadult nematodes of Haemonchus spp. in the abomasum and a count of 19,200eggs per gram of feces (EPG) of trichostrongylids. Stool culture showed that70, 20, and 10% of these eggs belonged to Haemonchus, Coperia and othernematode genera, respectively. Albendazole treatment was effective in reducingparasitic loads in 17 treated calves from moderate (200-700 OPG)and high levels (> 700 EPG) to low levels (16-100 EPG). The infection wascompletely eliminated in half of the treated animals and was reduced tobelow 90% in only 3 animals. Because the mean egg reduction percentagewas 95%, it can be inferred that there is no resistance to albendazole. Inconclusion, this case reveals that haemonchosis should be included in thedifferential diagnosis of mortality in calves in the Colombian tropics, andthat necropsies and periodic coprological examinations are necessary toestablish preventive and control measures of this parasitosis.