Has part of your dog’s skin become a certain darker colour lately? Does part of your dog’s skin feel or look abnormal compared to the rest of his or her body? There is a long list of signs and changes that are associated with skin conditions in dogs. One of these changes is called hyperpigmentation. Hyperpigmentation is an increase in dark pigmentation of the skin.
Hyperpigmentation is a sign, not a diagnosis. It is not a specific disease; rather, it is secondary change on a dog’s skin. Change in pigment can occur due to a number of reasons, and if darker skin pigment accumulates on the skin, this will cause darkening of the skin. Hyperpigmentation is a term used for increase in the pigmentation on dog skin, which is considered to be more than what is normal for that particular dog.
Hyperpigmentation may be the only change noted, or it may be accompanied by skin that feels velvety or rough to the touch. This may be due to areas of thickened skin where the skin feels rough or velvety. Other skin symptoms that can be noted along with hyperpigmentation include redness of the skin, hair loss, scaling, crusting, and itchiness. Hyper pigmented skin may also appear more moist or sweaty than usual, or may be dry to the touch along with the presence of scaling or dandruff.
Hyperpigmentation in Dogs: Primary or Secondary?
Generally speaking, hyperpigmentation is a secondary condition, thus it is a secondary effect. It happens most often when there is trauma to the skin for any reason. Skin inflammation such a redness of skin or scratching the skin are common causes of skin trauma.
When such skin trauma occurs, the skin repair cycle is activated. Part of skin repair involves increased melanin pigment as a protective effect for superficial skin layers. When this protective melanin pigment accumulates in the skin layers, skin is visibly darker to see. Causes such as skin allergy in dogs, scratching, skin infection due to bacteria, skin inflammation due to skin parasites, and self-trauma by dogs with activities such as scratching, rubbing, licking, and biting at their own skin are commonly seen in dogs with skin problems. These all can lead to hyperpigmentation.
Sometimes darker skin, i.e. hyperpigmentation of the skin, may occur after a skin problem has already occurred and the skin is healing from previous trauma to itself.
Other causes of hyper pigmented skin in dogs include breed-specific variations, hormonal disorders such as hypothyroidism or Cushing’s disease, effects of medications, physiological changes, etc. When other skin lesions such as hair loss or skin redness are evident, these signs are typically more helpful in finding the cause of the skin changes and correcting the signs including hyperpigmentation.
It is always key that the underlying skin problem is diagnosed and corrected as almost always, a dog with skin-related changes will have an underlying cause for it. Such underlying causes are best evaluated by a veterinary dermatologist or a family veterinarian so that it can be determined how the hyperpigmentation occurred and what would be the best treatment for the associated symptoms and causes.
Some hairless breeds of dogs such as the Chinese Crested dog or the Mexican hairless breed tend to have darker skin for the same reason, as their skin is more accessible to the elements and hence less protected than in hairy dog breeds.
Signs and Treatment
As mentioned earlier, there may be a long list of signs noted with hyperpigmentation, or it may be the only symptom noted. Typically, the symptoms are all evaluated as a whole so that appropriate treatment and diagnostic tests can be considered. If skin infection is present, it needs to be corrected. If underlying hormonal or allergic causes are present, these also need to be corrected. Occasionally, there may be clue of the cause based on presence of localized or full-body hyperpigmentation in a dog’s skin.
Also, it is important to find out if the hyperpigmentation is progressive or non-progressive. If itchiness or skin lesions are present, such as crusts, redness, etc., it is a good idea to act quickly and correct the problem before it progresses. Such crusting or redness of skin are often a sign of secondary bacterial or yeast infection.
After identifying and treating the underlying cause, affected areas of secondary hyperpigmentation can go away with time. If the primary problem and the secondary bacterial and yeast infections are not treated and controlled, then the hyperpigmentation will not go away. If partially controlled, there may be partial response followed by recurrence of the darker skin.
No matter the case, it may take time for darkening of the skin to resolve with whatever treatment program your vet dermatologist or family vet prescribes you. Unless if your pet is uncomfortable due to itchiness or pain, hyperpigmentation in dogs is not considered to be a severe symptom. With appropriate assessment and therapy, soon your dog should be comfortable and looking his or her best!
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Dr. Jangi Bajwa is a Board certified veterinary dermatologist at VetDERM Clinic in Surrey BC. He is also the dermatology feature editor for Canadian Veterinary Journal. Dr. Bajwa’s special interests include otitis and allergic disease in pets; as well as helping improve quality of life of pets and their families.