Topical medications (creams, gels, sprays, patches) are commonly prescribed and used for many conditions in human medicine. They are often incredibly effective for the conditions they treat, but if pets are inadvertently exposed to them (through casual contact/petting, or by the pet ingesting the product), they can be hazardous. The following list is not meant to be all-inclusive, but contains some of the more common and/or dangerous medications.
- Fluorouracil (Efudex®, Carac®, Fluoroplex®): This topical medication, usually supplied as a cream, is used to treat human skin conditions including solar and actinic keratosis, as well as some superficial skin tumors. It is particularly dangerous for dogs and cats exposed to it, as it is very rapidly absorbed, and low doses may be fatal. It causes seizures, stumbling, tremors, vomiting, heart rhythm abnormalities, diarrhea, and respiratory issues, usually within an hour of ingestion. If the pet survives the initial illness caused by this medication, they aren’t out of the woods yet – bone marrow suppression may occur and persist for up to three weeks.
- Calcipotriene (Dovonex®): This topical psoriasis treatment causes high blood calcium levels if ingested and may result in kidney failure, heart failure, and may lead to death. Lethargy, weakness, and decreased appetite are usually seen within one to two days of ingestion.
- Hormonal preparations (Evamist®, Estrogel®, Divigell®, Estrasorb®): Hormone replacement creams and sprays are often prescribed to lessen the adverse symptoms associated with menopause. They typically contain estrogen and/or progestin, which may be absorbed by pets after the product is applied – usually to the owner’s arms or legs. The pet can then exhibit signs of “feminization” – including enlarged nipples, mammary glands, and vulva, and possibly vulvar bleeding in female pets, or enlarged nipples and mammary glands in males. Pets may also exhibit patterns of hair thinning or hair loss. These effects are reversible once the exposure is halted, but it can take up to several months for the pet to fully recover.
- NSAIDs (Non-steroidal anti-inflammatories): Used for topical pain relief, these usually contain diclofenac or ketoprofen, and may be supplied as a cream or a patch. If a dog ingests only a small amount, the only sign may be gastrointestinal upset; however, if a larger amount is ingested, or if a cat ingests some of the product, then gastrointestinal bleeding, perforating stomach/GI ulcers, kidney failure, and death are possible.
- Patches: Used transdermal patches generally still contain significant amounts of drug, so proper disposal is crucial to preventing unintentional exposure to pets.
- Nicotine – These smoking cessation aids can be dangerous. Ingestion initially causes drooling and vomiting, and can progress to high blood pressure, rapid heart rate and breathing, tremors, and seizures. Some signs can show later, and include central nervous system depression, respiratory distress, stumbling, and seizures; if enough has been ingested, it can be fatal.
- Lidocaine – Patches containing lidocaine are generally applied to or near painful areas. Ingestion may cause seizures, stumbling, low heart rate, low blood pressure, and cardiac arrest or death at very high doses.
- Fentanyl – This potent pain medication is related to morphine. Effects have been seen in small pets after they have simply licked their owner’s skin in an area where a patch was previously applied. Initially, a mildly affected pet may only appear “drunk” – sleepy, stumbling – and recover within a few hours; in more severe cases with higher ingestion/exposure, the pet may have a low heart rate and low body temperature, become unconscious and severe respiratory depression may lead to death.
If you have been prescribed any of these medications, discuss with your physician best practices to ensure no pets (or children) will be exposed. If you think your pet may be affected by or might have ingested a medication you have been prescribed, please do not hesitate to contact your veterinarian.