Veterinary Medicine Expert Janet Tobiassen Crosby, DVM notes that common mosquito repellents are not intended for use on dogs, and advises that pet owners should use dog-only insect and parasite repellents, such as K9 Advantix, instead. Dog specific repellents are formulated to be pet-safe and when applied topically, are effective in repelling mosquitoes, ticks and other pests. It is recommended to consult a veterinarian before buying any repellent.
Insect repellents that contain DEET are meant for human-only use and should not be applied to dogs or other animals. DEET is toxic if consumed in large amounts, and dogs and cats are likely to lick the product off their coats. Some dog-only insect repellents contain the chemical permethrin, which is extremely hazardous to cats. Dogs treated with these repellents must be kept separate from cats until the treated areas on the dog's coat are dry.