Coccidioidomycosis (Valley Fever) in Cats: A Vet’s 2025 Guide to Diagnosis, Treatment & Prevention 🐱🌵
In this article
Coccidioidomycosis in Cats: A Vet’s 2025 Guide to Diagnosis, Treatment & Prevention 🐱🌵
By Dr Duncan Houston, BVSc
🔍 What Is Coccidioidomycosis (Valley Fever)?
Coccidioidomycosis—also called Valley Fever—is a fungal infection caused by Coccidioides immitis or C. posadasii, endemic in sandy soils of the U.S. Southwest, northern Mexico, and parts of Central/South America :contentReference[oaicite:3]{index=3}. Cats inhale microscopic spores that settle in the lungs and may spread through the bloodstream.
⚠️ Who’s at Risk & How Infection Occurs
- Outdoor cats in endemic regions: Disturbance of dry soil during rain/dust storms releases spores :contentReference[oaicite:4]{index=4}.
- Young or outdoor-exposed cats: Greater activity) and inhalation risk :contentReference[oaicite:5]{index=5}.
- Immunocompromised individuals: Stress, illness, or predisposed breeds increase risk for dissemination :contentReference[oaicite:6]{index=6}.
🚩 Clinical Signs to Watch For
- Respiratory: Chronic cough, difficulty breathing, fever, lethargy, appetite loss :contentReference[oaicite:7]{index=7}.
- Disseminated signs (~50% of cases): Skin lesions, draining wounds, musculoskeletal pain, lameness, neurological signs (seizures, weakness), eye issues, blindness :contentReference[oaicite:8]{index=8}.
🔬 How Veterinarians Diagnose It
- History & exam: Lives in endemic zone + chronic signs :contentReference[oaicite:9]{index=9}.
- Blood work: Antibody titers (IgM/IgG), chemistry/CBC to assess organ function :contentReference[oaicite:10]{index=10}.
- Imaging: Chest X-ray or CT for lung nodules or pleural disease; advanced imaging for lesions elsewhere :contentReference[oaicite:11]{index=11}.
- Microbiology: Biopsy or skin lesion cytology for characteristic spherules; airway wash for pulmonary diagnosis :contentReference[oaicite:12]{index=12}.
- Diagnosis by response: Sometimes supportive diagnosis if antifungal therapy leads to improvement :contentReference[oaicite:13]{index=13}.
🛠️ Treatment & Medical Management
1. Antifungal Medications
- Fluconazole is the first-line choice (10 mg/kg once daily)—high bioavailability, well tolerated :contentReference[oaicite:14]{index=14}.
- Itraconazole for tissue-invasive or bone/joint involvement; serum level monitoring may be necessary :contentReference[oaicite:15]{index=15}.
- Ketoconazole has been replaced by triazoles due to safety and efficacy issues :contentReference[oaicite:16]{index=16}.
- Amphotericin B reserved for severe or refractory cases—nephrotoxicity caution :contentReference[oaicite:17]{index=17}.
2. Supportive Care
- Oxygen and IV fluids for respiratory compromise :contentReference[oaicite:18]{index=18}.
- Pain management, anti-inflammatories, appetite stimulants, liver-supportive therapy as needed.
- Regular bloodwork to monitor liver function during prolonged therapy :contentReference[oaicite:19]{index=19}.
3. Treatment Duration & Monitoring
- Typical therapy lasts months to over a year; continue 1–2 months after antibody titers normalize or clinical signs resolve :contentReference[oaicite:20]{index=20}.
- Recheck with imaging and serology every 3–6 months :contentReference[oaicite:21]{index=21}.
🏡 Prevention & Environmental Control
- Keep cats indoors during dust storms or dry conditions in endemic areas :contentReference[oaicite:22]{index=22}.
- Reduce indoor/outdoor dust; use air filters to minimize spore exposure.
- Prevent outdoor digging; wipe paws after exposure.
- Early vet review if respiratory signs appear in at-risk cats.
📅 Prognosis & Follow-Up
- Localized lung disease: Good prognosis—recovery in ~90% with treatment :contentReference[oaicite:23]{index=23}.
- Disseminated disease: Guarded—relapses common; long-term follow-up essential :contentReference[oaicite:24]{index=24}.
- Relapse risk if therapy is shortened prematurely.
- Lifelong monitoring with bloodwork and imaging may be needed.
📝 Quick Reference Table
| Aspect | Detail |
|---|---|
| Cause | Inhaled Coccidioides spores from soil in arid regions |
| Signs | Cough, fever, skin lesions, lameness, neuro signs |
| Diagnosis | History, titers, imaging, biopsy/spherules, response to therapy |
| Treatment | Long-term azoles (fluconazole/itraconazole), supportive care |
| Prevention | Limit dust exposure, indoor housing |
| Prognosis | Excellent in localized disease, guarded in systemic forms |