# Prevalence of Pulmonary Nematodes in Cats and Lung Ultrasound Findings in Separate Animal Cohorts: A Coprological, Molecular and Clinical Study

## TL;DR

This study found that lungworms are common in Polish cats and that lung ultrasound can help detect and monitor these infections, especially when combined with other diagnostic methods.

## Contribution

The study introduces lung ultrasound as a useful tool for detecting lungworm infections in cats, particularly when used alongside traditional diagnostic methods.

## Key findings

- Lungworm infections, especially Aelurostrongylus abstrusus, were commonly detected in Polish cats.
- Lung ultrasound revealed lung changes even in cats without obvious symptoms and showed improvement after treatment.
- Lung ultrasound is a sensitive but non-specific tool that should be used with other diagnostic methods.

## Abstract

Pulmonary nematodes are an important but often overlooked cause of respiratory disease in cats. These parasites may cause a wide range of clinical presentations, from mild or absent signs to severe breathing difficulties. Diagnosis is challenging because infected cats may not consistently shed parasite larvae in their feces, and routine diagnostic methods may fail to detect the infection. This study investigated the occurrence of feline lungworms in cats in Poland and evaluated lung ultrasound as a complementary diagnostic and monitoring tool. Fecal samples from over one thousand cats were examined to assess the prevalence of pulmonary nematodes. Additionally, a separate group of cats with suspected lung disease underwent lung ultrasound examinations both before and after treatment. Lungworms were commonly detected, particularly Aelurostrongylus abstrusus, and infections were more frequent in younger cats, during autumn and winter. Lung ultrasound often revealed extensive lung changes even in cats without obvious respiratory symptoms. Importantly, these ultrasound abnormalities completely resolved after treatment with a moxidectin-based anthelmintic. These findings show that lungworm infections are present in cats in Poland. Lung ultrasound is a sensitive but non-specific adjunct that may support clinical suspicion of pulmonary helminthiasis and is particularly useful for monitoring recovery after treatment; however, it should not be used as a stand-alone diagnostic test and must be interpreted together with coprological/molecular results and clinical context and relevant patient information (e.g., age, lifestyle, indoor/outdoor status).

Background: Pulmonary nematodes are an underrecognized cause of respiratory disease in domestic cats, with diagnosis often complicated by nonspecific clinical signs and limitations of fecal-based testing. Methods: This study aimed to assess the prevalence of feline lungworms in Poland and to describe lung ultrasound findings in a separate clinical cohort of cats. A nationwide coprological survey was conducted using pooled fecal samples from 1058 cats examined with Baermann and flotation techniques, supported by molecular diagnostics where available. Results: Overall, 9.83% of cats were positive for at least one parasite. Aelurostrongylus abstrusus was the most frequently detected lungworm (7.18%), followed by Eucoleus aerophilus (2.17%) and Troglostrongylus brevior (0.47%). Lungworm infections were strongly associated with younger age and showed marked seasonal variation, with higher prevalence in autumn and winter. Lung ultrasound consistently revealed diffuse B-line artifacts and other signs of reduced lung aeration, often in the absence of severe respiratory signs. Following treatment with topical imidacloprid/moxidectin, complete resolution of ultrasonographic abnormalities and clinical signs was observed. Conclusions: These findings confirm that feline pulmonary nematodes are present in Poland and may be underdiagnosed. Lung ultrasound represents a sensitive and non-invasive tool for detecting and monitoring lung involvement, but should be interpreted in conjunction with epidemiological data, parasitological results and therapeutic response.