Acquired Fanconi syndrome in four cats treated with chlorambucil

Fanconi syndrome (FS) is well described in humans and dogs, but has not been reported in cats. This case series describes four cats with acquired FS. On the basis of clinical signs and intestinal biopsies, all cats were initially diagnosed with alimentary lymphoma or inflammatory bowel disease. Treatment with chlorambucil and corticosteroids was started at standard doses, based on published protocols. Within 2-26 months of the start of treatment, glucosuria, despite normoglycemia, was identified incidentally on routine biochemical screening; FS was diagnosed with urine metabolic assays, confirming aminoaciduria and glucosuria in all four cases. Neither polyuria nor polydipsia were noted in any case, and only 1/4 cats had any clinical signs at the time of diagnosis. Partial or complete resolution of FS was seen in 3/4 cases within 3 months of discontinuing chlorambucil therapy.

This is the first case series to document acquired FS in the cat, and the first to suggest a possible association between chlorambucil and acquired FS. Cats treated with chlorambucil should be monitored for the development of glucosuria, and discontinuation of chlorambucil should be considered if FS is identified. Further study into the association between chlorambucil and acquired FS in cats is warranted.