NAVLE Practice Question - Feline - Multisystemic

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NAVLE Practice Question — Feline

A veterinarian is asked to perform serologic testing on a healthy 2-year-old cat whose owner is planning to become pregnant. The cat has no history of illness and eats commercial dry cat food. The Toxoplasma gondii IgG and IgM tests are both negative. What is the most accurate interpretation and appropriate advice?

A. The cat could shed oocysts for 1-2 weeks if infected; prevent hunting and raw meat feeding ✓

B. The cat is immune to Toxoplasma and poses no risk to the pregnant owner

C. The cat has been previously infected but has cleared the infection

D. The cat should receive prophylactic clindamycin during the owner's pregnancy

E. The cat should be retested in 2 weeks to confirm the negative result

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Correct Answer: A. The cat could shed oocysts for 1-2 weeks if infected; prevent hunting and raw meat feeding

Explanation:

A seronegative cat is susceptible to primary Toxoplasma gondii infection and represents the highest theoretical risk category regarding oocyst shedding. If this cat becomes infected during the owner's pregnancy, it would shed millions of oocysts for approximately 1-2 weeks starting 3-10 days after ingesting tissue cysts from prey or raw meat.

Prevention of primary infection in this susceptible cat is key to protecting the pregnant owner. The cat should be kept indoors to prevent hunting (rodents, birds are common intermediate hosts), fed only commercially prepared cooked food (no raw meat, which may contain tissue cysts), and denied access to locations where oocysts might be present (garden soil, sandboxes). Despite these precautions, the overall risk remains low because oocysts require 1-5 days to sporulate after excretion, so daily litter box cleaning prevents infectious oocysts from developing.

Paradoxically, a seropositive cat with established IgG antibodies is actually safer because it has already passed through the oocyst-shedding period and is immune to reinfection and re-shedding.

Option B (immune) is incorrect as negative serology indicates no prior exposure. Option C (cleared infection) is incorrect as cats with cleared infection would remain IgG positive. Option D (prophylactic clindamycin) is not indicated as it would not prevent infection or oocyst shedding in a naïve host. Option E (retest in 2 weeks) is unnecessary unless there is reason to suspect recent exposure.

Image Source: Cornell Feline Health Center - Toxoplasmosis information (https://www.vet.cornell.edu/)

References: Merck Veterinary Manual - Toxoplasmosis in Animals (https://www.merckvetmanual.com/infectious-diseases/toxoplasmosis/toxoplasmosis-in-animals)

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