Heartworm infection in cats: 50 cases (1985–1997)

Abstract

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. (J Am Vet Med Assoc 2000;217: 355–358)

Effect of pre-cardiac and adult stages of Dirofilaria immitis in pulmonary disease of cats: CBC, bronchial lavage cytology, serology, radiographs, CT images, bronchial reactivity, and histopathology

“…By common definition, Dirofilaria immitis is discussed as having a 6-month life cycle (infection of host through development and sexual maturity) (Riley, 1922;McCall et al, 1992;Atkins et al, 2000;Bowman, 2009). The assumption that clinical disease does not develop until the parasite is a 6-month-old adult is incorrect.…”

Immunopathology of Dirofilaria immitis Infection

“…The development of the parasite takes longer compared to dogs and most infections are amicrofilaraemic. Additionally, the parasite burden is low and the infection is generally asymptomatic, although some cats present with severe disease or even sudden death in the presence of a small number of adult worms (1-3) (Genchi et al, 1992;McCall et al, 1994;Atkins et al, 2000). Humans are incidental hosts for D. immitis since the larvae do not normally develop into adult worms and microfilaraemia is absent.…”

Ectopic dirofilariosis in two dogs from Rio de Janeiro state, Brazil

“…The parasite has a worldwide distribution, and several endemic areas have been described in Brazil 2,3,5,8,10,15,16,18,21,22,36,40 . Canids are the most adapted definitive hosts and are the primary reservoir for parasite transmission, but reports about feline and human infection are becoming more frequent, including in Brazil 4,6,24,33,39,42 . Dirofilariosis is considered a zoonosis in human hosts since 1941, and although the parasite has been mostly described in the lungs, it has also been observed at the cardiovascular system, subcutaneous tissue, brain, testicle, eyeball, abdominal cavity and bladder 1,14,20,24,32 .…”

“…The species Dirofilaria immitis (Leidy, 1856) is a dixenic filarid parasite that infects dogs, cats and human beings among other animal hosts 6,43 . The intermediate hosts are mosquitoes from several genera, such as Culex, Aedes and Anopheles.…”