Griseofulvin

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Griseofulvin is an antifungal drug used for treatment of dermatophytes such as 'ringworm', a common dermatophytic skin infection in cats.

The absorption of griseofulvin is better when administered as a divided dose and with a fatty meal. Side effects are common in cats and include anorexia, depression, vomiting and diarrhoea. However, these can generally be avoided by dividing or lowering the dosage. Anecdotal reports indicate that Siamese, Himalayan, Abyssinian and Persian cats may be more prone.

Griseofulvin is also not recommended for use in kittens less than 12 weeks-of-age, although there are reports of its use in kittens as young as six weeks. Griseofulvin is highly teratogenic, especially in the first trimester of pregnancy and is therefore contraindicated in pregnant animals. Although teratogenic effects have not been documented after treatment of breeding male cats, griseofulvin can cause abnormalities in spermatozoa in experimental conditions in rodents. It is thus advisable to avoid using recently treated male cats for breeding.

Bone marrow suppression producing anaemia and leukopenia is a relatively uncommon, but severe and unpredictable, side effect of griseofulvin therapy[1]. These effects can reverse when treatment is withdrawn but irreversible idiosyncratic pancytopenia has been reported. Myelosuppression does not appear to depend on dose rate or breed of cat. Severe neutropenic reactions have been reported in cats with dermatophytosis associated with FIV infection. Griseofulvin should not be used in cats with FIV and, as such, all cats should be FIV-tested prior to griseofulvin therapy.

Griseofulvin does have anti-inflammatory and immunomodulatory properties and is known to suppress delayed hypersensitivity reactions in the skin. These properties can lead to important clinical misinterpretations. Some authors have noted dogs and cats with inflammatory skin disease (for example, bacterial pyoderma) have demonstrated significant clinical improvement while receiving griseofulvin for presumed dermatophytosis[2].

References

  1. Rottman JB et al (1991) Bone marrow hypoplasia in a cat treated with griseofulvin. J Am Vet Med Assoc 198(3):429-431
  2. Colombo S, Cornegliani, L and Vercelli A (2001) Efficacy of itraconazole as a combination therapy in feline dermatophytosis: preliminary results in nine cases. Veterinary Dermatology 12:347