Feline Lungworm (Aelurostrongylus abstrusus)

Overview

A parasitic infection of the lungs, acquired through ingestion of infected intermediate hosts (typically small rodents, birds, or slugs/snails that cats might hunt or accidentally consume) — causes respiratory symptoms that can range from mild to more significant, requiring specific antiparasitic treatment.

Symptoms

• Coughing (moderate, uncommon)
• Breathing difficulty (significant infections) (moderate, uncommon)

Causes

Infection with Aelurostrongylus abstrusus, a lungworm parasite acquired by cats through consuming an infected intermediate host (commonly small rodents or birds that have themselves eaten infected slugs or snails, which serve as the parasite's primary intermediate host). Aelurostrongylus abstrusus, the most common feline lungworm, is transmitted through an intermediate host (slugs or snails), with cats acquiring infection either directly or by eating a prey animal (like a bird or rodent) that had itself eaten infected slugs/snails — genuinely one of the more commonly diagnosed feline lungworm species.

Risk Factors

Outdoor access with hunting behavior, particularly consuming rodents, birds, or accidentally ingesting slugs or snails.

Transmission

Acquired through ingestion of an infected intermediate or paratenic host; not directly contagious cat-to-cat.

Incubation Period

Can take several weeks from initial infection to when adult worms are established in the lungs and symptoms may become apparent.

Disease Stages & Progression

Following ingestion, larvae migrate to the lungs where they mature into adult worms, causing local irritation and inflammation that can result in coughing and other respiratory symptoms, with severity varying considerably between individual cats — some show minimal symptoms while others develop more significant respiratory compromise.

Early Warning Signs

Coughing, sometimes with mild breathing changes. Coughing, sometimes with increased respiratory effort, can range from mild to more significant depending on parasite burden, and can be difficult to distinguish from feline asthma or other respiratory conditions without specific testing.

Advanced Symptoms

More persistent coughing, breathing difficulty, and in significant infections, more pronounced respiratory compromise.

Diagnostic Methods

Fecal examination specifically looking for the characteristic larvae, combined with compatible respiratory symptoms and relevant hunting/outdoor exposure history, establishes diagnosis. Fecal examination using a specific technique (Baermann technique) is more sensitive for detecting lungworm larvae than a standard fecal float, and is the preferred testing method when this parasite is suspected.

Veterinary Examination Process

Assessment of respiratory symptoms and relevant exposure history.

Recommended Lab Tests

Fecal examination (sometimes requiring specific techniques to maximize larvae detection) for definitive diagnosis.

Diagnostic Imaging

Chest X-rays may show characteristic changes, though these aren't always distinctive enough alone for diagnosis.

Blood Test Indicators

Fecal examination (looking for larvae, since these parasites' offspring are coughed up, swallowed, and passed in stool) is the primary diagnostic approach.

Biopsy / Histopathology

Not typically needed given fecal examination's role as the primary diagnostic tool.

Differential Diagnoses

Feline asthma, other respiratory infections, and other causes of coughing — fecal examination specifically identifies this parasitic cause.

Home Monitoring Guidance

Not a substitute for veterinary evaluation and fecal testing of persistent coughing, particularly in a cat with outdoor hunting access.

Veterinary Treatment Options

Specific antiparasitic treatment effectively addresses this infection, typically resolving associated respiratory symptoms.

Surgery Requirements

Not applicable.

Recovery Timeline

Typically improves within several weeks of appropriate antiparasitic treatment.

Possible Complications

Genuinely uncommon with appropriate treatment; more significant respiratory compromise is possible in heavier infections if not promptly treated.

Long-Term Management

Not typically needed after successful treatment; reducing hunting exposure to intermediate hosts may help reduce reinfection risk.

Prevention

Reducing hunting behavior and consumption of rodents, birds, or slugs/snails through indoor living or supervised outdoor access reduces exposure risk; some broad-spectrum parasite prevention products may provide protection against this specific parasite.

Vaccination Availability

No vaccine exists against this parasitic infection.

Prognosis

Good with appropriate antiparasitic treatment.

References

Companion Animal Parasite Council (CAPC); American Association of Feline Practitioners (AAFP).

Medications Used

• Antiparasitic medication specifically effective against lungworm

Estimated Treatment Cost by Country

Frequently Asked Questions