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Neosporosis in cats.
J P Dubey1, D S Lindsay, T P Lipscomb
1US Department of Agriculture, Agricultural Research Service, Beltsville, MD.
Veterinary Pathology
|September 1, 1990
Summary
Methylprednisolone acetate immunosuppression exacerbated Neospora caninum infection in cats, leading to severe disease and death. Unimmunosuppressed cats showed milder symptoms, highlighting the role of immune status in disease outcome.
Area of Science:
- Veterinary Parasitology
- Immunology
- Feline Infectious Diseases
Background:
- Neospora caninum is an apicomplexan parasite causing significant disease in various animal species.
- The impact of immunosuppression on Neospora caninum infection in domestic cats is not well understood.
- Corticosteroids like methylprednisolone acetate are commonly used for their anti-inflammatory properties but can suppress the immune system.
Purpose of the Study:
- To investigate the effect of methylprednisolone acetate-induced immunosuppression on the pathogenesis of Neospora caninum infection in cats.
- To evaluate the clinical and pathological outcomes of experimental Neospora caninum infection in immunosuppressed versus non-immunosuppressed cats.
Main Methods:
- Six cats were inoculated with Neospora caninum tachyzoites.
- Three cats received methylprednisolone acetate prior to and on the day of inoculation.
- Three cats served as non-immunosuppressed controls.
- Clinical signs, gross lesions, and histopathological findings were assessed.
Main Results:
- Two immunosuppressed cats died acutely (8 and 16 days post-inoculation) with severe systemic lesions, including bacterial septicemia and necrotizing encephalitis.
- The third immunosuppressed cat, euthanatized at 21 days, also exhibited significant necrotizing lesions in multiple organs.
- Non-immunosuppressed cats remained largely asymptomatic, with only mild myositis and encephalitis observed upon euthanasia at 55 days post-inoculation.
- Control cats without Neospora caninum inoculation showed no lesions.
Conclusions:
- Methylprednisolone acetate administration significantly exacerbates Neospora caninum infection in cats, leading to severe, rapidly progressive, and often fatal disease.
- Immunosuppression compromises the host's ability to control Neospora caninum, resulting in widespread tissue damage.
- These findings underscore the critical role of the host immune response in determining the outcome of Neospora caninum infections and suggest caution when using corticosteroids in potentially exposed felines.