Respiratory Parasites in Cats: A Vet’s 2025 Guide to Recognition, Diagnosis & Care 🐾💨

Hello! I’m Dr. Duncan Houston BVSc, veterinarian and founder of Ask A Vet. In 2025, we understand the threat of respiratory parasites—like lungworms (Aelurostrongylus abstrusus, Capillaria aerophila) and Troglostrongylus species—more clearly. Though these parasites may be under-recognized, they can cause significant breathing issues, illness, and even life-threatening complications. This guide covers everything you need to confidently identify, diagnose, treat, and prevent these infections, ensuring your cat breathes easy and thrives.

📘 What Are Respiratory Parasites?

Respiratory parasites, commonly called lungworms, are nematodes that infect the lungs, trachea, and bronchial airways. The most important species in cats include:

• Aelurostrongylus abstrusus: affects lung tissues, causing coughing, wheezing, and sometimes pneumonia :contentReference[oaicite:3]{index=3}.
• Capillaria aerophila: infects the trachea and bronchi, leading to chronic cough and respiratory discomfort :contentReference[oaicite:4]{index=4}.
• Troglostrongylus brevior: more common in Mediterranean regions, can cause severe infection, especially in outdoor or feral kittens :contentReference[oaicite:5]{index=5}.

🌍 Why It Matters in 2025

• Respiratory parasite cases are rising globally due to climate change and vector expansion :contentReference[oaicite:6]{index=6}.
• Outdoor and indoor/outdoor cats are at higher risk—especially those who hunt or eat intermediate hosts like snails, rodents, or birds :contentReference[oaicite:7]{index=7}.
• Early recognition helps avoid complications like pneumonia, airway obstruction, or pulmonary hypertension :contentReference[oaicite:8]{index=8}.

👀 Recognizing Signs Early

The symptoms of lungworm infection vary by parasite, cat age, and immune status:

• Chronic dry cough, often mistaken for hairballs or asthma :contentReference[oaicite:9]{index=9}.
• Wheezing or audible respiratory noises, especially on exertion :contentReference[oaicite:10]{index=10}.
• Dyspnea or open-mouth breathing, particularly severe in kittens or immunocompromised cats :contentReference[oaicite:11]{index=11}.
• Exercise intolerance & lethargy, lack of appetite.
• Nasal discharge or occasional cough up mucus or blood-tinged sputum :contentReference[oaicite:12]{index=12}.
• Radiographic changes: bronchial/alveolar lung patterns :contentReference[oaicite:13]{index=13}.

🧭 Diagnostic Roadmap

1. History + Physical Exam: note outdoor habits, coughing patterns, and respiratory effort.
2. Imaging: chest X-rays often reveal interstitial or bronchial patterns and, occasionally, pulmonary hypertension :contentReference[oaicite:14]{index=14}.
3. Baermann fecal test: gold standard for detecting larvae :contentReference[oaicite:15]{index=15}.
4. Tracheal wash: useful in severe bronchial disease to detect larvae :contentReference[oaicite:16]{index=16}.
5. ELISA serology: available for some lungworms to support diagnosis :contentReference[oaicite:17]{index=17}.
6. PCR: emerging method for improved parasite identification.

🛠️ Treatment Protocols

Effective treatment targets both adult parasites and larvae:

• Topical Macrocyclic Lactones

• Moxidectin/imidacloprid (Advocate®): effective prevention and treatment for A. abstrusus and C. aerophila :contentReference[oaicite:18]{index=18}.
• Selamectin, emodepside/praziquantel (Profender®): useful against certain species :contentReference[oaicite:19]{index=19}.
• Repeated dosing may be required—consult your vet.

• Oral Anthelmintics

• Fenbendazole: 50 mg/kg daily for 5–7 days, sometimes extended.
• Milbemycin oxime: off-label but effective in some cases :contentReference[oaicite:20]{index=20}.

• Supportive Care

• Oxygen therapy for respiratory distress.
• Corticosteroids to reduce airway inflammation.
• Antibiotics for secondary bacterial pneumonia.
• Hydration, nutritional support, and rest.

🏠 Prevention Strategies

• Prevent hunting and outdoor roaming.
• Use regular parasite preventatives: Advocate®, Profender®, or selamectin monthly.
• Regular fecal screenings: at least annually for outdoor cats.

📈 Monitoring & Prognosis

• Repeat fecal/BAERMANN testing 2–4 weeks post-treatment to confirm parasite clearance.
• Follow-up chest X-rays if cough or lung changes persist.
• Prognosis is excellent with early detection—guarded if complications occur.

📚 Case Series

“Ella,” a 2-year-old outdoor tabby, developed chronic cough and wheezing. Baermann test showed A. abstrusus larvae. Treated with Advocate® monthly × 3 months and a 7-day fenbendazole course. Clinical and radiographic resolution occurred in 6 weeks. Annual prevention ensures no recurrence.

🚨 When to Seek Vet Emergency

• Open-mouth breathing, severe dyspnea.
• Collapse or severe lethargy.
• Poor response to initial therapy or antibiotics.
• Cough in kittens, outdoor cats, or immunocompromised individuals.

✨ Final Thoughts

Respiratory parasites in cats are often overlooked but can lead to serious illness. With awareness of signs, precise diagnostics, and effective treatments—including macrocyclic lactones and supportive care—most cats recover fully. Prevention via indoor living and year-round parasite control is essential. Ask A Vet offers tele-support, medication reminders, and monitoring tools to keep your cat breathing easy. 🐾❤️

For personalized care plans, follow-up guidance, and respiratory-health support, visit AskAVet.com or download the Ask A Vet app. We’re with you every breath of the way.