More Than Skin Deep: Human Topical Medications Can Have Serious Effects on Pets

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.

  1. 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.


  1. 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.


  1. 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.


  1. 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.


  1. Patches: Used transdermal patches generally still contain significant amounts of drug, so proper disposal is crucial to preventing unintentional exposure to pets.
    1. 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.
    2. 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.
    3. 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.generic-products



The Dangers of the Sugar Substitute Xylitol


Recently, Longs Peak Animal Hospital has seen several cases of dogs experiencing toxicity from a substance called xylitol, and its effects can be life-threatening. Xylitol is a common sugar substitute found in many different food (and non-food) items from sugar-free gum and candy, to artificial sweetener for baking, to nut butters and vitamins and supplements. While it does not appear to have adverse effects in humans, dogs can experience toxic effects, even at seemingly low doses. To date, cats do not appear to be affected in the same way as dogs.

Xylitol is one of several common “sugar alcohols”. In dogs, it causes a massive release of insulin from the pancreas, which leads to a precipitous drop in blood sugar. If blood sugar becomes too low, a condition called hypoglycemia will develop, and may lead to weakness, lethargy, seizures, and death. Xylitol can also cause damage to the dog’s liver, known as acute liver necrosis. While liver necrosis is thought to occur at higher levels of intoxication, the exact level at which this occurs and the mechanism itself is unknown.

There is no known antidote for xylitol toxicity; treatment centers on supportive care. Treatment for xylitol ingestion may include induction of vomiting for recent ingestions, as long as the patient is conscious, followed by hospitalization for close monitoring of blood glucose values, glucose supplementation, and IV fluid administration as needed. Some patients may experience hypoglycemia for up to 72 hours after ingestion. Additionally, blood tests are performed periodically for at least 72 hours to assess liver health, and special medications for liver protection may be indicated.

The key to successful treatment of xylitol ingestion is early and aggressive intervention. If you suspect your dog may have ingested even as little as 1 to 2 sticks of gum containing xylitol, do not hesitate to seek immediate treatment.


  • Kristin Hrenchir, DVM
Longs Peak Animal Hospital, PC – 9727 Ute Highway – Longmont, CO 80504
303-776-6666  –

Marijuana Toxicity in Pets



Since the passage of two amendments to the state constitution in Colorado (Amendment 20 in 2000, allowing medical use of marijuana and Amendment 64 in 2012, allowing recreational use), exposure of pets to marijuana in our area has increased, and toxicity from these products can be serious in animals.

Pet exposure occurs most frequently in dogs, but cats and other pets are also at risk. Different forms of marijuana can contain drastically variable levels of THC (short for tetrahydrocannabinol, the main psychoactive component in marijuana and other cannabinoids). Exposure can occur to marijuana plants, loose leaf marijuana, edibles, oils, or second-hand smoke.

For pets who have ingested items containing THC or inhaled marijuana smoke, signs of toxicity can include nervous system changes, such as stumbling, sleepiness, mental dullness, and disorientation; rarely, an affected pet may show signs of CNS stimulation. Severely affected pets may go into a coma. Dogs usually display urine dribbling as a sign, and their third eyelids are usually prominent. Affected pets may also show an extreme sensitivity to stimuli such as touch or sound. Cannabinoids can cause vomiting, but this is rarely seen as they usually produce profound anti-nausea effects.

If a pet has consumed a large amount of edible product (i.e. – brownies, candy, cookies, etc.) or plant material, gastric lavage (aka “stomach pumping”) may be necessary, and it is important to seek veterinary care as soon as possible. Activated charcoal may be administered orally to minimize further absorption of THC. In more severely affected cases the pet may need to be hospitalized for supportive care, which can include warming, oxygen, IV fluids, and sedation if needed. There is no specific antidote for THC toxicity.

While marijuana toxicity is rarely fatal, it can indeed be serious, and immediate veterinary care is always best. Recovery time for pets is highly variable, but most pets are back to normal within 12 to 24 hours. If you have any specific questions about marijuana toxicity, ask your veterinarian or veterinary technician.

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  • Kristin Hrenchir, DVM