Prevalence of heartworm infection in healthy cats in the lower peninsula of Michigan

Objective-To determine prevalence of heartworm infection among healthy, cli ent-owned cats in the lower peninsula of Michigan. Design-Cross-sectional prevalence study. Animals-1,348 healthy cats examined at private veterinary practices through out the lower peninsula of Michigan. Procedure-Sera were tested by use of an ELISA-based antigen test kit to det ermine infection and 2 commercially available antibody detection kits to de termine exposure. A questionnaire was used to collect data to assess risk f actors associated with infection. Results-25 cats had positive results for heartworm antigen, yielding an obs erved prevalence of 1.9%. Neither antibody test was reliable or provided re producible results, and neither yielded positive results for more than 20% of the antigen-positive heartworm-infected cats. Multivariate regression in dicated that cats from southeastern Michigan and cats 2 2 years old had a h igher risk of infection. Conclusions and Clinical Relevance-Results indicated that most (80%) heartw orm-infected cats in the lower peninsula of Michigan were from the southeas tern part of the state, a pattern that closely paralleled the prevalence of heartworm infection in dogs. Therefore, knowledge of the regional prevalen ce of heartworm infection in dogs may be useful in assessing the risk of in fection in cats. Results also suggest ed that currently available in-clinic heartworm antibody detection kits have limited utility in the diagnosis of heartworm infection in cais.