What causes a dog's skin to turn black, and why might dark patches appear on your pup's skin? In today's post, our Irvine vets discuss hyperpigmentation in dogs and the signs, causes, and treatment options for this condition.
Canine Hyperpigmentation
Hyperpigmentation is an increase in the dark pigmentation of the skin. If you've recently noticed dark patches have appeared on your dog's skin or that areas of your dog's skin look or feel different compared to the rest of the body, you may be seeing hyperpigmentation.
Similar to other mammals, skin color in dogs is related to how much melanin (pigment) is present. This is how the body reacts to some conditions, but is not in itself a specific diagnosis or disease. Numerous conditions can cause hyperpigmentation on a dog's belly or elsewhere on their body.
Darkening of a dog's skin is highly variable and can be:
- Progressive or static
- Generalized
- Localized to a specific area
- Multifocal
- A single symptom
- Accompanied by other symptoms
- Primary (genetic)
- Secondary (caused by an underlying condition)
Signs & Symptoms of Hyperpigmentation
If you've noticed the color of your dog's skin has changed and are wondering, "What are these black spots on my dog's skin?', or "Why is my dog's skin turning black?", you're not alone. The spots often appear light-brown to black in color. Though hyperpigmentation may be the singular symptom of a skin condition, it sometimes appears on areas of the skin that feel velvety or rough to touch. This may be caused by thickening of the skin in some areas.
Several factors can cause the skin's pigment to change. If darker skin pigment accumulates on the skin, the skin will become significantly darker than the rest of the skin on your dog's body.
You might also notice other symptoms such as crusting, itchiness, scaling, redness, and hair loss. The sin may also be abnormally moist or sweaty. Conversely, it may also have dandruff and be dry to the touch.
The two types of hyperpigmentation are primary and secondary.
Primary Hyperpigmentation
Typically, this type of pigmentation develops due to primary disease, such as a genetic disorder called Acanthosis Nigricans. The disorder is especially prevalent in Dachshunds but can affect dogs of any breed. This form of hyperpigmentation typically appears by the time a dog is one year old and is incurable. It primarily affects the armpits and upper front legs.
Secondary Hyperpigmentation
A common sign, secondary hyperpigmentation can happen in any dog breed and is caused by friction and/or inflammation that leads to additional changes in the skin like hair loss, odor, thickened skin, and pain.
Hyperpigmentation due to chronic inflammation is typically worse on the armpits and belly, itchy, and accompanied by secondary bacterial or fungal infections.
Secondary pigmentation is most often seen in breeds that are susceptible to skin infections, allergies, and contact dermatitis (Dobermans, Great Danes, border collies, dalmations, Labradors, golden retrievers, Irish setters, Yorkshire terriers, basset hounds, and German shepherds), hormonal abnormalities, and obesity (Lhasa Apsos, basset hounds, Irish setters, Jack Russell terriers, golden retrievers, Labrador retrievers, and pugs).
What causes a dog's skin to turn black?
Causes of hyperpigmentation in dogs can vary. Many dogs gradually develop darker areas of the skin as they age. In many cases, this is purely a cosmetic concern and no treatment is necessary. In other circumstances, hyperpigmentation can indicate larger medical issues your dog is experiencing, including:
- Allergies – May lead to hyperpigmented areas on the skin.
- Hypothyroidism – Hyperpigmentation appears in some dogs with hypothyroidism.
- Injury - The amount of melanin in a dog's skin may increase when the skin heals from an injury.
- Pseudo-Cushing's Syndrome - This endocrine disorder is common in middle-aged and older dogs and can result in hyperpigmentation.
- Systemic Lupus Erythematosus - Some dogs with this chronic, fairly rare immune-mediated disease will also have hyperpigmentation.
- Malassezia - Hyperpigmentation is one symptom of this type of yeast infection.
- Demodicosis - A lesser-known cause of hyperpigmentation, this condition is due to a parasitic mite.
- Cancer – Melanocytic (skin and toe cancers), melanomas (often found on a dog's lips, mouth, and nail bed), trichoblastomas (hair follicle tumors), and other tumors may cause hyperpigmentation on a dog's skin.
As you can see, some conditions associated with hyperpigmentation are severe, so it's critical to have your dog examined by a veterinarian if you notice any changes in the skin.
Diagnosing Canine Hyperpigmentation
To diagnose hyperpigmentation, your veterinarian in Irvine will examine your dog for typical symptoms of this skin issue and gently scrape the skin for samples to identify any underlying causes such as infections or parasites.
A full physical exam and review of your dog's medical history may be performed. If your veterinarian suspects allergies may be the culprit, food trials may be conducted to isolate the cause of your pet's symptoms.
Diagnostic testing may also be done to ensure the underlying cause of your dog's symptoms has been correctly identified.
Treating Hyperpigmentation in Dogs
While there is no cure for primary hyperpigmentation when detected early enough symptoms can be managed with steroid ointments and special shampoos. Other medications can be used as symptoms intensify or worsen. If any infections occur, your veterinarian can also treat those.
Our veterinarians at Irvine Pet Hospital are experienced in diagnosing and treating various health issues in dogs and cats and are dedicated to developing effective treatment plans.
If your veterinarian has diagnosed your dog with secondary hyperpigmentation, your pup's skin will feel normal again once the underlying issue has been treated. Hyperpigmentation may go away once a minor injury heals. However, when skin is chronically injured, the change is often permanent.
In addition to hyperpigmentation, it will also be important to treat any yeast or bacterial infections.
Antifungal medications or antibiotics may be prescribed to treat yeast or bacterial infections on your pooch's skin. Medicated shampoos may also be recommended for application two to three times a week. Be prepared for slow progress. The risk of relapse of hyperpigmentation will only be high if the underlying cause hasn't been correctly treated.
The Recovery Process
As indicated above, progress may be slow and can take weeks or months before your dog's skin gets back to normal. Your veterinarian will tell you whether any follow-up appointments are required. Most follow-ups will focus on continuing to treat the underlying cause of your dog's hyperpigmentation.
Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets. Please make an appointment with your vet for an accurate diagnosis of your pet's condition.
