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Heartworm infection in cats: 50 cases (1985-1997)
C E Atkins1, T C DeFrancesco, J R Coats
1Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh 27606, USA.
Insights
Heartworm infection (HWI) in cats is more common in domestic shorthairs, with respiratory signs being key indicators. Antibody screening is effective for diagnosis, though indoor housing offers limited protection against this feline disease.
Area of Science:
- Veterinary Medicine
- Parasitology
- Feline Health
Background:
- Heartworm infection (HWI) in cats, caused by Dirofilaria immitis, presents unique diagnostic and prognostic challenges.
- Understanding risk factors and clinical manifestations is crucial for effective feline heartworm management.
Purpose of the Study:
- To identify risk factors associated with feline heartworm infection (HWI).
- To characterize clinical findings, diagnostic test utility, and prognosis in cats with naturally occurring HWI.
Main Methods:
- A retrospective study analyzing medical records of 50 cats diagnosed with Dirofilaria immitis infection.
- Review of thoracic radiographs and echocardiograms, comparing findings with reference populations.
Main Results:
- Domestic shorthair cats showed increased risk; indoor housing provided only partial protection.
- Respiratory signs and vomiting were common; sudden death occurred in 10% of cases.
- Serologic tests, radiography, and echocardiography proved useful for diagnosis, with eosinophilia as a supporting indicator.
Conclusions:
- Feline heartworm infection (HWI) risk is not linked to sex; indoor living offers incomplete protection.
- Respiratory signs like dyspnea and cough are strong indicators of HWI in cats.
- Antibody screening is effective, while antigen testing and echocardiography aid definitive antemortem diagnosis.
Objective:
To characterize risk factors, clinical findings, usefulness of diagnostic tests, and prognosis in cats with naturally occurring heartworm infection (HWI).
Design:
Retrospective study.
Animals:
50 cats with Dirofilaria immitis infection.
Procedure:
Medical records, thoracic radiographs, and echocardiograms were reviewed and findings compared with appropriate reference populations.
Results:
Findings suggested that male cats were not predisposed to HWI, domestic shorthair cats were at increased risk, and indoor housing was only partially protective. Fewer cases of HWI were identified in the final quarter of the year, compared with other periods, and prevalence is not apparently increasing. Signs of respiratory tract disease were most common, followed by vomiting. Infection was diagnosed incidentally in > 25% of cats; conversely, 10% of infected cats died suddenly without other clinical signs. Serologic tests were most useful for diagnosis, followed by radiography and echocardiography. Eosinophilia supported the diagnosis. Overall median survival time was 1.5 years but exceeded 4 years in cats surviving beyond the day of diagnosis.
Conclusions And Clinical Relevance:
Sex does not appear to be a risk factor for HWI in cats, and indoor housing provides only incomplete protection. Signs of respiratory tract disease (dyspnea and cough) are the strongest indicators of HWI in cats, and some radiographic evidence of infection is detected in most cases. Antibody screening for HWI in cats is efficacious, and antigen testing and echocardiography are most useful for making a definitive antemortem diagnosis.