Cytauxzoonosis in Cats 🐱🦠

By Dr Duncan Houston, BVSc

Cytauxzoonosis is a rapidly progressing, often fatal disease in cats caused by a tick-borne parasite called Cytauxzoon felis. With cases rising in spring and early summer, awareness, prevention, and early intervention are crucial. In this 2025 guide, Dr Duncan Houston explains everything cat owners need to know. 🕷️

🔬 What Is Cytauxzoonosis?

Cytauxzoon felis is a single-celled parasite that infects both blood cells and tissues. It was first identified in the U.S. in 1976, and the natural host is the bobcat. While bobcats usually carry the infection without signs, domestic cats can suffer severe, often deadly illness. 🐾

There are two parasite stages in the cat:

• 🧬 Piroplasms (in red blood cells) – less harmful
• 💥 Schizonts (in body tissues) – responsible for severe inflammation and blood vessel blockage

🦟 How Is It Transmitted?

Transmission occurs through tick bites—specifically from the Lone Star Tick (Amblyomma americanum) and the American Dog Tick (Dermacentor variabilis). Ticks pick up the parasite from bobcats and transmit it to domestic cats. ❗

Important Notes:

• ⛔ Cats cannot get Cytauxzoonosis without a tick bite
• 🐅 Bobcats are the main wildlife reservoir for the parasite

📋 Signs and Symptoms

Early signs are vague, but the condition deteriorates quickly. Look for:

• 🌡️ High fever and fatigue
• 🚫 Loss of appetite (anorexia)
• 💩 Vomiting and diarrhea
• 💛 Jaundice (yellow gums, eyes, or skin)
• 😿 Pain and weight loss
• 🫁 Labored breathing
• 🧠 Neurologic signs or collapse

Without treatment, many cats die within a week of symptom onset. Time is critical. ⏳

🩺 Diagnosis

• 💉 Blood smear – checks for piroplasms in red blood cells
• 🧪 PCR test – detects parasite DNA
• 🧫 Urinalysis and bloodwork – assess liver, kidneys, and clotting
• 📸 Imaging (X-rays) – evaluate lung and organ health

Note: Early infection may not show parasites in the blood—repeat testing may be required. 🔍

💊 Treatment

Prompt treatment and hospitalization are vital. Treatment typically includes:

• 💊 Atovaquone + Azithromycin – the most effective combo
• 💉 Imidocarb – used when other meds are unavailable
• 💧 IV fluids for hydration
• 🍽️ Assisted feeding and oxygen therapy
• 🧴 Anti-coagulants to reduce blood vessel blockage
• ⚠️ Pain relief (but avoid NSAIDs)

Improvement may take 4–7 days. Daily monitoring and supportive care are essential. 🏥

📈 Prognosis

The mortality rate is high without early treatment. However, survival is possible with rapid diagnosis and therapy. Some cats may become long-term carriers with no symptoms. 🐱

Newer research also suggests that milder strains may exist—but this remains under investigation. 🧬

🛡️ Prevention

Prevention is your cat’s best protection:

• 🏠 Keep your cat indoors—no ticks = no infection
• 🧴 Use feline-approved tick preventives—never dog products
• 🚫 Avoid wooded or grassy tick-heavy areas
• 🔬 Monitor for ticks during peak seasons (spring/summer)

Ask your veterinarian about safe tick control options for your cat. There are fewer products for cats than for dogs, so professional advice is key. 🧑‍⚕️

📱 Ask A Vet App Support

Worried about fever, lethargy, or ticks? The Ask A Vet app offers:

• 📸 Share photos or videos of symptoms
• 🩺 Chat with licensed vets 24/7
• 🧾 Get help with tick product selection
• 📊 Receive support during hospitalization or aftercare

🏁 Final Takeaway

Cytauxzoonosis is rare but deadly. Early detection, aggressive treatment, and prevention through tick control can save lives. If your cat shows signs during tick season—don’t wait. Seek immediate veterinary care and ask your vet about tick prevention tailored for cats. 🐱🛡️