Toxicity to pets

One of the most dangerous pet toxins is 5-fluorouracil (5-FU), a prescription anti-cancer medication used topically to treat human skin cancers (e.g., superficial basal cell carcinoma) and actinic keratosis. While the injectable form of 5-FU can be safely administered to specific animal patients, the topical version is very poisonous if ingested by dogs, cats, and other pets. Small amounts – even a lick for some pets- are highly toxic resulting in acute gastrointestinal distress (e.g., vomiting, diarrhea), neurological signs (e.g., tremors, seizures), bone marrow suppression and, potentially, death. Clinical signs occur within 30 minutes to 6 hours. Immediate veterinary treatment is necessary for the best patient outcome after exposure to 5-FU.