Minoxidil Toxicity in Cats

Minoxidil has Specific Toxicity to Cats

Minoxidil is a commonly used topical treatment for men and women with hair loss. It is not well known that minoxidil may have a unique toxicity to cats. Cats lack an enzyme to break down minoxidil. Given that 30% of households in the United States have cats and some 200 million or more cats are kept as pets worldwide, it’s important for cat owners to know a thing or two about minoxidil. Especially cat owners who live in a household where someone uses minoxidil. 

In 2004, DeClementini and colleagues reported 2 cats who died after cat owners applied minoxidil to areas of hair loss on their pets. The first cat was a 3 year old cat had only one drop applied to an area of hair loss. That cat had trouble breathing, high heart rate, water in the lungs (pulmonary edema and pleural effusion) and showed increased liver enzymes. The cat died 15 hours later.

The second cat was a 7 year old cat and the owners applied an unknown amount of 5 % minoxidil solution to an area of hair loss and left the home for three days. Upon returning to the home, the owners found the cat also having difficulty breathing. Veterinarians confirmed pulmonary edema and pleural effusions. That cat died 10 hours later despite supportive care.

Several other cases of minoxidil toxicity have been reported to various animal poison control centers. The stories are similar with affected cats showing lethargy followed by fluid in the lungs and heart failure. Intensive veterinary care saves the lives of some but not all cats. 

Cat owners can use minoxidil but not without common sense and appropriate precautions. Minoxidil must not be applied directly to cats and cats should not have the opportunity to play with or lick the hair (or pillows) of owners who have applied minoxidil to their scalps as a treatment for their own hair loss. Cats must never come into contact with the actual minoxidil bottle or canister.

Reference

Suspected toxicosis after topical administration of minoxidil in 2 cats. Journal of Veterinary Emergency and Critical Care 2004; 14:287-292