Abomasal coccidiosis (Eimeria gilruthi) in a goat kid
Emily Brouwer, Sebastian Ruszkowski
Animal Health Laboratory, University of Guelph, Guelph, ON (Brouwer);
Cheltenham Veterinary Services, Caledon, ON (Ruszkowski)
AHL Newsletter 2021;25(3):11.
A 3-month-old male Boer goat kid presented to the veterinarian for a history of coughing. The producer had noted that starting two weeks previously, the kids would start to cough and those affected would die within two days. Of the group of eleven kids, five were sick and two had died. The affected group had been treated with Draxxin, and this untreated kid was sacrificed for postmortem diagnostic workup.
On gross postmortem examination, the kid was in poor body condition, with visible bony protuberances of the scapulae and pelvis, and there was marked reduction in fat stores and mild dehydration. Approximately 50% of the right lung had marked cranioventral consolidation. On cut section, the pulmonary parenchyma was dark plum red, and there were irregular tan, necrotic foci throughout the affected tissue. A small amount of purulent exudate could be expressed from small airways. The forestomachs contained a small amount of finely ground plant fibres, and the small intestines contained brown-green fluid. The colon was empty.
Histologic examination identified a severe necrotizing bronchopneumonia, from which large numbers of bacteria including Bibersteinia trehalosi, Mannheimia haemolytica, Pasteurella multocida and Trueperella pyogenes were isolated. Large numbers of encysted apicomplexan parasites were identified within the abomasal mucosa, as well as within the small intestinal mucosa and the subcapsular sinus of a mesenteric lymph node in fewer numbers.
The apicomplexan parasites were contained within large schizonts (megaloschizonts) with thick eosinophilic walls that contained innumerable small round merozoites that were frequently arranged in circular blastophores. No inflammation was evident within the regional abomasal mucosa, nor was there any associated proliferation of the mucosa. In conjunction with anatomic location, the morphology of these megaloschizonts is consistent with Eimeria gilruthi.
Eimeria gilruthi is a poorly-characterized species of apicomplexan parasite that sporadically causes gastrointestinal disease in small ruminants. These parasites have been found incidentally on postmortem / microscopic examination, as in this case, but are capable of causing clinical disease. Clinical signs, if present, can include anemia, diarrhea, anorexia, and weakness.
Grossly, there is a range of potential lesions. The megaloschizonts may appear as small white raised foci throughout the abomasal mucosa in less severe cases. Proliferative abomasitis may be present in more severe cases, characterized by a thickened and nodular abomasal mucosa resembling infection by Teladorsagia spp.
Although this parasite is infrequently diagnosed, infection with Eimeria gilruthi should remain a differential diagnosis for small ruminants experiencing diarrhea and weight loss. AHL
Figure 1. Eimeria gilruthi megaloschizont in the abomasal mucosa with thick eosinophilic capsule, 10X magnification. H&E stain
Figure 2. Eimeria gilruthi megaloschizont in abomasal mucosa. Note merozoites arranged in circular blastophores, 40X magnification. H&E stain.
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