Hyperpigmentation in Dogs
Hyperpigmentation in dogs is a condition that causes dark spots on the skin. The human might notice red, purple, or crimson patches on the less hairy areas of the dog. Researchers discovered that hyperpigmentation does not usually happen on its own. It is usually associated with other underlying health issues. Veterinary researchers found it associated with problems ranging from allergies, to rare cases of lupus, to basic alopecia (hair loss) with no other physical health issues. The condition is either congenital (present from birth), or acquired from the environment.
Signs and Symptoms
The first sign of hyperpigmentation in dogs is the discolored skin mentioned above, sometimes accompanied by alopecia. The condition of discolored skin, if not paired with hair loss, will be noticed in areas with less hair, such as the groin, around the eyes, or inside the ears. It looks similar to bruising, but happens without a fall or other contact accident. Sometimes, the area is itchy, and accompanied by scaly or crusty skin. Owners may only notice the issue if the dog is worrying over it. The dog may or may not lick, scratch, or bite at the area. A pet owner should contact the veterinarian if the condition happens without any recent injuries or accidents.
Diagnosis and Prognosis
The vet will give the dog an initial assessment. If there is no apparent, immediate cause for the condition, more tests will be ordered. The vet will need to know about all changes to the dog’s diet and behavior to rule out conditions often associated with hyperpigmentation. Luckily, scientists have been researching this condition in dogs for a long time, helping today’s veterinarians with diagnosis and treatment. A study published in Environmental Toxicology in 2007 reviewed the case of hairless dogs who were found to have lesions on their skin. Other dogs with thicker coats did not have similar issues. Researchers found hyperpigmentation, as well as other skin issues, near the lesions. Results from testing found that the dogs were allergic to the stainless steel used to cage them during studies. After the irritant was removed, the conditions improved.
The prognosis for each case will depend on the underlying cause for the hyperpigmentation in the dog. For example, the case of a dog with nevus of ota, a benign eye condition, was presented in 2018 in Veterinary Ophthalmology. She was born with hyperpigmentation near her left eye. Her owner thought it was simply a part of the dog’s natural marking. The condition went undetected until other, non-related health issues emerged. The dog was given a positive prognosis, and was monitored by animal specialists every six months for the rest of her long life for her underlying issues. Other cases have even better prognoses, as the underlying cause is simply hair loss due to nervousness. As the hair falls away, the skin is exposed. This exposure may lead to darkening of the skin through simple environmental exposures, such as the sun. Simply covering the skin until the hair grows back gives the dog a positive prognosis.
Only a vet can deliver a proper diagnosis and prognosis. Taking the dog to a professional as soon as an issue appears is the best way to get a fast diagnosis and a plan for a good prognosis.
Treatment involves caring for any underlying illnesses as well as the skin condition. The vet will determine what combinations of medicines or therapies will work best for each unique case. Hydroquinone has been proven to be effective, according to a study published in Laboratory of Animal Science in 1998, for cases with no other underlying conditions. Mexican hairless dogs who were found to have hyperpigmentation received hydroquinone cream for a week. Their discoloration began to fade. After a month, the hyperpigmentation was corrected. If this treatment works with other medicines to treat underlying causes, it may be prescribed by the vet. The FDA deemed it safe for medicinal use in 2009 for humans and animals.
Follow-up care depends on the underlying issues. Hydroquinone cream works for dogs whose hyperpigmentation is one of only a few symptoms, such as the dogs with allergies mentioned above. Other cases may involve a neurological disorder, causing reactions in the skin. Follow-up care for such cases may involve behavioral changes. Still other dogs, such as the case of nevus of ota mentioned above, will need lifelong monitoring of their various conditions. Since hyperpigmentation in dogs is a sign of a wide range of possible problems, the follow-up care is uncertain.
Hyperpigmentation in dogs happens without injury, and surprises many pet owners. The dog will need a vet to find the real reason behind the skin change, which may get expensive. This is why many dog owners invest in pet insurance. With the right insurance, a pet owner is free to focus on what is best for the health of the pet, not on the price tag that comes with vet care.
- Contact hypersensitivity saved to computer found in Cornell library published 2007 in Environmental Toxicology
- Nevus of Ota… Cornell library published 2018 in Veterinary Ophthalmology
- Efficacy of hydroquinone…. abstract. Cornell Library website.
- Government Background (FDA) document on hydroquinone from 2009