Capillaria Infection in Cats: A Vet’s 2025 Guide to Bladder & Lung Worms 🐾🩺
In this article
Capillaria Infection in Cats: A Vet’s 2025 Guide to Bladder & Lung Worms 🐾🩺
By Dr Duncan Houston, BVSc
🔍 What Are Capillaria Worms?
Capillaria are slender parasitic nematodes that can infect cats—commonly in the urinary bladder (Capillaria plica/feliscati) and, less often, in lungs or nasal passages (Capillaria aerophila) :contentReference[oaicite:3]{index=3}.
🐾 Where They Live & Who They Affect
- Bladder worms (C. plica/feliscati) attach to bladder or ureter walls :contentReference[oaicite:4]{index=4}.
- Lung worms (C. aerophila) inhabit airways, rare in cats but more common in foxes/dogs :contentReference[oaicite:5]{index=5}.
- All ages can be infected, but bladder cases often seen in cats >8 months old :contentReference[oaicite:6]{index=6}.
⚠️ Symptoms to Watch For
Urinary Signs (Bladder Worms)
- Frequent urination or straining to urinate
- Blood in urine, painful urination
- Accidents outside litter box :contentReference[oaicite:7]{index=7}
- Possible urinary obstruction in heavy infections :contentReference[oaicite:8]{index=8}
Respiratory Signs (Lung Worms)
- Coughing, sneezing, wheezing, difficulty breathing :contentReference[oaicite:9]{index=9}
- Poor appetite, lethargy, fever :contentReference[oaicite:10]{index=10}
Other Variants
- Capillaria boehmi (nasal worm): sneezing, nasal discharge :contentReference[oaicite:11]{index=11}
- Gastrointestinal forms (e.g., C. putorii): vomiting or diarrhea—rare :contentReference[oaicite:12]{index=12}
🔬 How Cats Get Infected
All species share a similar lifecycle:
- Eggs from urine or feces embryonate in environment.
- Earthworms eat eggs—larvae develop inside.
- Cat ingests earthworm, transport host, or contaminated material :contentReference[oaicite:13]{index=13}.
- Larvae migrate → bladder (urinary species) or lungs (respiratory) and mature.
🩺 Diagnosis
- Urinalysis: bladder worms are diagnosed by detecting characteristic eggs in urine sediment :contentReference[oaicite:14]{index=14}.
- Fecal exam or airway lavage: respiratory species diagnosed via feces or nasal/tracheal samples :contentReference[oaicite:15]{index=15}.
- Repeat testing may be needed—eggs often shed intermittently :contentReference[oaicite:16]{index=16}.
- Imaging: used if complications like bladder thickening or lung inflammation are suspected.
- Bloodwork: help evaluate overall health and support diagnostics.
💊 Treatment Options
- Fenbendazole: off-label, commonly prescribed; effective for most Capillaria worms :contentReference[oaicite:17]{index=17}.
- Ivermectin or levamisole: alternatives when appropriate :contentReference[oaicite:18]{index=18}.
- Anti-inflammatories: prednisolone for symptomatic bladder inflammation :contentReference[oaicite:19]{index=19}.
- Supportive care: fluids, pain relief, rest if respiratory distress or obstruction occurs.
- Monitor: follow-up urine/fecal testing ensures complete clearance.
📅 Prognosis & Follow-Up
- Generally good: most cats recover fully after deworming :contentReference[oaicite:20]{index=20}.
- Severe bladder infections: may cause temporary urinary obstruction or cystitis :contentReference[oaicite:21]{index=21}.
- Respiratory cases: usually mild; heavy infections may lead to bronchitis or pneumonia :contentReference[oaicite:22]{index=22}.
- Retesting: recommended a few weeks post-treatment to confirm eradication.
🛡️ Prevention Tips
- Keep cats indoors to reduce exposure to earthworms or rodents :contentReference[oaicite:23]{index=23}.
- Avoid feeding raw prey or allowing outdoor hunting.
- Maintain clean litter boxes and environments.
- Regular deworming helps prevent uptake of parasites :contentReference[oaicite:24]{index=24}.
- Yearly wellness exams include urine/fecal screening—early detection is key.
🐾 Tips for Cat Parents
- Record changes in urination frequency, behavior or respiratory symptoms.
- Ensure full medication course; never skip doses.
- Follow your vet’s instructions on follow-up testing.
- Provide supportive care—ease stress and comfort your cat during recovery.
- Stay in touch via Ask A Vet for advice between visits; use calming Woopf & Purrz products.
📝 Consolidated Summary
| Aspect | Bladder Worms | Lung/Nasal Worms |
|---|---|---|
| Species | C. plica / C. feliscati | C. aerophila / C. boehmi |
| Main Site | Bladder, ureter | Airways, lungs, nasal passages |
| Symptoms | Straining, hematuria, accidents | Coughing, wheezing, sneezing |
| Diagnosis | Urine eggs | Feces or airway sample eggs |
| Treatment | Fenbendazole, ivermectin | Fenbendazole, levamisole |
| Outlook | Good with treatment | Generally mild & treatable |
| Prevention | Indoor life, deworming | Same + minimize hunting |