Feline heartworm disease in endemic settings: an integrated diagnostic approach

Feline heartworm disease, caused by Dirofilaria immitis, is an emerging concern in endemic regions, although its epidemiology remains poorly defined due to diagnostic limitations. In Italy, available data on feline D. immitis infection are limited and largely based on serological investigations. The aim of the present study was to provide an epidemiological assessment of infection in cats across Sardinia, a region where canine dirofilariosis is endemic. A total of 141 cats were evaluated using a multimodal diagnostic approach including echocardiography, antigen detection, and the modified Knott's test. In addition, antibody detection by in-house ELISA and PCR targeting the 16S rRNA gene of endosymbiont Wolbachia pipientis were performed to deeply investigate the infection features. All cats underwent physical examination and clinical findings were recorded. Evidence of D. immitis infection was detected in 2.8% of cats by echocardiography, corresponding to the overall prevalence observed in the study, and in 2.1% by antigen detection, while microfilariae of D. immitis were detected in 0.7% of cats. Antibodies to Dirofilaria spp. were found in 14.9% of animals, indicating broader exposure. Wolbachia DNA was identified in 1.4% of samples. A significant association was observed between D. immitis positivity and the presence of compatible clinical signs such as coughing, dyspnea, and vomiting (P = 0.016). These findings confirm the presence of feline heartworm infection in Sardinia, highlighting the diagnostic complexity of the disease and the importance of prevention in endemic areas, given the severity of this parasitosis in cats and the current lack of an effective therapy.