FELINE

Welcome to the Feline NAVLE Notes: Infectious Diseases section on AllVetsLink.

In this section, you'll find detailed notes on a wide range of infectious diseases affecting cats, including viral, bacterial, fungal, and parasitic infections.

Learn about key conditions such as Feline Infectious Peritonitis (FIP), FeLV, FIV, and more, with insights into diagnosis, treatment, and prevention. Prepare thoroughly for your NAVLE exam with a focus on feline infectious diseases.

Notes:

Cytauxzoon felis

Cytauxzoon felis is a tick-borne protozoan causing rapidly progressive and often fatal disease in cats, characterized by high fever, lethargy, icterus, and pancytopenia due to schizont-laden macrophages obstructing blood flow. Diagnosis is confirmed by blood smear or PCR, and treatment requires early administration of atovaquone and azithromycin with supportive care.

Toxoplasma gondii & Pregnancy

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Flash cards

Flashcard 1
Question:
Which protozoan is the causative agent of feline cytauxzoonosis, and what are its primary vectors in North America?

A. Babesia felis – Rhipicephalus sanguineus and Ixodes scapularis
B. Cytauxzoon felis – Amblyomma americanum and Dermacentor variabilis
C. Plasmodium felis – Culex spp. mosquitoes
D. Hepatozoon felis – Amblyomma maculatum and Rhipicephalus spp.

Flashcard 2
Question:
Which pathophysiologic mechanism is primarily responsible for the rapid deterioration observed in feline cytauxzoonosis?

A. Hemolytic anemia due to erythrocytic parasitism
B. Disseminated intravascular coagulation from thrombocytopenia
C. Vascular occlusion from macrophages containing schizonts
D. Myocarditis secondary to protozoal infiltration

Flashcard 3
Question:
What is the current most effective therapeutic protocol for feline cytauxzoonosis?

A. Imidocarb dipropionate (6 mg/kg IM once) + supportive care
B. Atovaquone (15 mg/kg PO q8h) + azithromycin (10 mg/kg PO q24h) for 10 days + supportive care
C. Doxycycline (10 mg/kg PO q12h) for 21 days + corticosteroids
D. Clindamycin (12.5 mg/kg PO q12h) + enrofloxacin (5 mg/kg PO q24h)

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Answer: B. Cytauxzoon felis – Amblyomma americanum and Dermacentor variabilis
Explanation: C. felis is transmitted primarily by the lone star tick (A. americanum) and occasionally D. variabilis. These vectors play a key role in the geographic distribution and seasonal prevalence of the disease.

Answer: C. Vascular occlusion from macrophages containing schizonts
Explanation: During the schizogenous phase, C. felis proliferates within macrophages, leading to their enlargement and aggregation within small blood vessels. This causes vascular obstruction, ischemia, and multi-organ dysfunction, which are the main drivers of the acute and often fatal presentation.

Answer: B. Atovaquone (15 mg/kg PO q8h) + azithromycin (10 mg/kg PO q24h) for 10 days + supportive care
Explanation: The atovaquone–azithromycin combination has shown the highest survival rates in clinical studies, especially when initiated early. Intensive supportive therapy, including IV fluids, heparin, oxygen supplementation, and nutritional support, is essential for improving prognosis.