🐾 Vet’s Guide to Feline Nocardiosis: Symptoms, Treatment & Prevention in 2025 🐾

By Dr Duncan Houston BVSc

Nocardiosis is a rare but serious bacterial infection in cats, caused by Nocardia species. This guide provides comprehensive information on the symptoms, treatment, and prevention of feline nocardiosis, tailored for Australian cat owners in 2025.

🔬 What is Nocardiosis?

Nocardiosis is an infectious disease caused by filamentous, gram-positive bacteria of the genus Nocardia. These bacteria are commonly found in soil, decaying vegetation, compost, dust, and water sources. In cats, nocardiosis is often associated with an underlying immune system disorder, such as feline leukemia virus (FeLV) or feline immunodeficiency virus (FIV) infections. ^{Merck Veterinary Manual}

🦠 Causes and Transmission

Cats can become infected with Nocardia bacteria through:

• 🐾 Inhalation of contaminated dust or aerosols
• 🐾 Ingestion of contaminated material
• 🐾 Direct inoculation through skin wounds, such as bites or scratches

The bacteria are opportunistic pathogens, meaning they primarily cause disease in animals with compromised immune systems. ^{Merck Veterinary Manual}

🐱 Symptoms in Cats

Symptoms of nocardiosis in cats vary depending on the site of infection:

Cutaneous (Skin) Infections:

• 🐾 Non-healing wounds or abscesses
• 🐾 Draining sinus tracts
• 🐾 Swelling and inflammation of the skin
• 🐾 Lesions primarily on limbs, flanks, nose, and neck

Respiratory Infections:

• 🐾 Coughing, sometimes with blood
• 🐾 Nasal discharge
• 🐾 Difficulty breathing
• 🐾 Fever and lethargy

Disseminated Infections:

• 🐾 Abscesses in multiple organs
• 🐾 Pleuritis (inflammation of the chest cavity)
• 🐾 Peritonitis (inflammation of the abdominal cavity)
• 🐾 Neurological signs if the brain is affected

Common nonspecific signs include poor appetite, fever, lethargy, and weight loss. ^{Merck Veterinary Manual}

🩺 Diagnosis

Diagnosing nocardiosis involves a combination of clinical evaluation and laboratory tests:

• 🐾 Physical examination and assessment of clinical signs
• 🐾 Bacterial culture from affected tissues or fluids
• 🐾 Imaging studies (X-rays or ultrasounds) to detect internal abscesses or lesions
• 🐾 Blood tests to assess overall health and identify underlying conditions

It's important to note that Nocardia bacteria are resistant to some antibiotics, so culture and sensitivity testing are crucial for effective treatment planning. ^{Merck Veterinary Manual}

💊 Treatment Options

Treatment of nocardiosis in cats typically includes:

• 🐾 Long-term antibiotic therapy, often for 1 to 6 months, using medications such as trimethoprim-sulfamethoxazole
• 🐾 Surgical removal or drainage of abscesses when necessary
• 🐾 Supportive care, including fluid therapy and nutritional support
• 🐾 Management of underlying conditions, such as FeLV or FIV infections

Relapses are common with shorter treatments, so it's essential to follow the veterinarian's instructions and complete the full course of antibiotics. ^{Merck Veterinary Manual}

🛡️ Prevention Strategies

Preventing nocardiosis involves minimizing exposure to the bacteria and maintaining a healthy immune system:

• 🐾 Keeping cats indoors to reduce contact with contaminated soil and water
• 🐾 Promptly cleaning and treating any wounds or injuries
• 🐾 Regular veterinary check-ups to monitor for underlying health issues
• 🐾 Implementing flea and tick control measures to prevent skin trauma

While nocardiosis is not contagious between animals or from animals to humans, immunocompromised individuals should exercise caution when handling infected animals. ^{Merck Veterinary Manual}

📍 Regional Considerations in Australia

In Australia, nocardiosis in cats is rare but has been documented. A study reported 17 cases over 14 years in the eastern states, with most cats presenting with skin lesions associated with draining sinus tracts. The majority of infections were attributed to Nocardia nova. Predisposing factors included fight injuries and immunosuppressive conditions such as FIV infections. ^VetContact

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