Clinical and hematologic effects of experimental infection of dogs with recently identified Babesia gibsoni-like isolates from Oklahoma.
OBJECTIVE
To characterize clinical and hematologic responses in dogs following experimental inoculation with Babesia gibsoni-like isolates from infected dogs in Oklahoma.


METHODS
Prospective study.


METHODS
6 mixed-breed dogs.


METHODS
2 dogs were inoculated with organisms from a naturally infected dog, and 3 were inoculated with organisms from a second naturally infected dog (1 of these 3 dogs was splenectomized 1 week prior to inoculation). One dog was not inoculated. Complete blood counts were performed weekly.


RESULTS
In the 5 dogs inoculated with organisms, parasites were initially detected 1 to 5 weeks after inoculation, and severity of parasitemia peaked with 1.9 to 6.0% of RBC infected by 4 to 6 weeks after inoculation. Parasitemia was easily detectable (> 0.1% of RBC infected) for 3 to 4 weeks. Clinical abnormalities included lethargy, fever, and pale mucous membranes but were mild to nearly inapparent in 2 dogs. All dogs developed regenerative anemia and marked thrombocytopenia. Thrombocytopenia developed before and lasted longer than the parasitemia. Profound but transient neutropenia was detected in some dogs. The splenectomized dog developed more severe parasitemia and anemia and more pronounced clinical abnormalities. Three dogs with intact spleens recovered without treatment.


CONCLUSIONS
Results suggest that 2 or more genotypically distinct, but morphologically identical, small Babesia parasites can infect dogs in the United States. Compared with infection with small Babesia parasites from California, infection with these isolates resulted in less severe parasitemia and clinical abnormalities. Parasitemia was transient, indicating that identification of organisms in blood smears may be difficult in some dogs.
Department of Veterinary Pathobiology, College of Veterinary Medicine, Oklahoma State University, Stillwater 74078, USA.
James H
JH
Meinkoth
A Alan
AA
Kocan
Stephanie D
SD
Loud
Michael D
MD
Lorenz
D000740:Anemia / Q000662:veterinary; D000818:Animals; D001403:Babesia / Q000145:classification / Q000235:genetics / Q000472:pathogenicity; D001404:Babesiosis / Q000097:blood / Q000503:physiopathology / Q000662:veterinary*; D001772:Blood Cell Count / Q000662:veterinary; D004283:Dog Diseases / Q000097:blood* / Q000469:parasitology / Q000503:physiopathology; D004285:Dogs; D004912:Erythrocytes / Q000469:parasitology; D005334:Fever / Q000662:veterinary; D005838:Genotype; D006400:Hematocrit / Q000662:veterinary; D009825:Oklahoma; D018512:Parasitemia / Q000662:veterinary; D011446:Prospective Studies; D013156:Splenectomy / Q000662:veterinary; D013921:Thrombocytopenia / Q000662:veterinary; D013997:Time Factors