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Prescription skin cream and pet toxicity

Q: I am heartbroken over the death of my dog after she chewed a tube of my skin cream. She apparently ingested the Efudex Cream I use for the precancerous skin condition on my forehead.

She developed seizures that wouldn’t stop even with aggressive treatment. If my doctor or pharmacist had told me how toxic this cream is to dogs, I would have secured it in my medicine cabinet.

A: Efudex contains 5-fluorouracil (5-FU), which also is marketed as Adrucil, Carac, Fluoroplex and Tolak. The active ingredient, 5-FU, is used topically in humans to treat actinic (or solar) keratosis, a precancerous skin disorder, and basal cell carcinoma, a type of skin cancer.

Unfortunately, 5-FU is extremely toxic to pets. Ingestion by dogs or cats, usually by chewing the tube but sometimes by licking the treated human’s skin, is most often fatal, even with optimal veterinary care.

Signs of toxicity, which begin within 30 to 60 minutes of ingestion, include vomiting, breathing difficulties, loss of coordination, tremors and seizures. 5-FU seizures are hard to control, and most dogs die of seizures or cardiopulmonary arrest within six to 24 hours.

Thank you for sharing your painful story and helping to prevent another tragedy. Our thoughts are with you.


Lee Pickett, V.M.D. practices companion animal medicine. Contact her at askdrlee@insurefigo.com.

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