When Treating Your Skin Cancer, Protect Your Pets


Creams containing the chemotherapy 5-fluorouracil can be fatal to animals, the FDA warns.

CERTAIN TOPICAL SKIN CANCER creams can sicken or kill animals that ingest even a small amount of them, and the Food and Drug Administration is cautioning patients to keep these creams out of the reach of their pets.

As of January 2017, creams containing fluorouracil 5 percent (5-FU), a chemotherapy sold under the brand names Carac, Efudex and Fluoroplex, had killed five dogs following accidental ingestion. There had been no reports of ingestion in cats, but health officials warned that the medication would be harmful to them, as well.

The FDA explained that, in one case, a dog punctured a tube of the cream while playing with it, and within two hours the dog “began vomiting, experienced seizure and died 12 hours later.” In a second case, a pet owner rushed her dog to the veterinarian immediately after noticing that the dog had ingested the medication, but the dog got sick and had to be euthanized three days later.

Considered by the World Health Organization to be an “essential medicine,” the drug works by killing fastgrowing skin cancer cells and pre-cancerous skin cells.

Administered as either an injection or a cream, it is used in superficial, or early-stage, basal cell and squamous cell carcinomas.

The FDA has provided guidance about how to help prevent pets from coming into contact with the medication:

- Store all medications safely out of the reach of pets.

- Make sure medications/toxic materials are labeled clearly so others will not unknowingly leave them in unsafe places.

- Safely discard or clean any cloth or applicator that may retain medication, and avoid leaving any residue of the medication on hands, clothing, carpeting or furniture.

- Consult health care providers about whether the treated area should be or can be covered.

- Seek immediate veterinary care for pets that show signs of vomiting or illness.

After hearing about the danger the cream poses to pets, Tom Rohrer, M.D., a member of the American Society for Dermatologic Surgery, said, “We will have to make special recommendations (to clients) to keep (this medication) away from pets, and to wash their hands (after using this drug) before petting their pets.”

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