What is Hyperpigmentation in Dogs?

As pet owners, belly rubs and snuggles are a big part of having a furry companion. These moments usually allow us to connect with our pets and become familiar with their skin, including its color and texture.

However, you might notice some darkening on your dog's skin which might be a result of hyperpigmentation. Hyperpigmentation is a skin condition that affects dogs, yet most pet owners and dog caregivers have little information on this condition. 

This guide will equip you with a deep understanding of what hyperpigmentation is, and demystify some of the myths and misconceptions around the condition. We will highlight some of the signs and symptoms of hyperpigmentation.

We will also offer expert guidance on appropriate actions to take if you notice signs of hyperpigmentation in your furry friend.

Understanding Hyperpigmentation in Dogs

Hyperpigmentation is a term used to refer to the darkening and thickening/roughening of certain areas of your dog’s skin.

It can either be localized (in one specific area), multifocal (in several localized areas), or generalized (all over) in manifestation. You might notice that when you're stroking or petting your furry friend, certain parts of their skin feel velvety or rough.

Hyperpigmentation often affects the hairless or folded skin areas such as armpits, underbelly, groin, and inner thighs. If you notice dark brown to black patches on your pup’s skin in these areas then they are likely suffering from hyperpigmentation.

Hyperpigmentation is not always a diagnosis or disease itself but a reaction to another condition. It is usually a harmless condition, but for the well-being of your little furry bundle of joy, addressing any underlying causes is essential.

Types of Hyperpigmentation

Hyperpigmentation can affect dogs of all breeds, ages, and coat types. Two types of hyperpigmentation affect dogs. Let's quickly discuss them.

Primary Hyperpigmentation

Primary hyperpigmentation is uncommon and affects specific breeds of dogs, in particular Dachshunds. This type of hyperpigmentation usually doesn't have a cure but is manageable with treatments and medications. Symptoms of primary hyperpigmentation often start presenting themselves within the first year.

There are cases where primary hyperpigmentation occurs concurrently with secondary hyperpigmentation. In some instances, the condition only cosmetically affects the skin and doesn’t necessitate treatment.

Treatment with medicated shampoo and steroid ointments can be effective during the early stages if the hyperpigmentation presents with inflammation. Nonetheless, your veterinarian is the only one who can properly diagnose your pet and recommend the best treatment options.

Secondary Hyperpigmentation

This type of hyperpigmentation is more common and affects dogs of different breeds and ages. It is usually caused by inflammation or friction and can cause changes in the skin such as hair loss, thickened areas, odor, and signs of pain.

The inflamed areas can often be red around the edges, which points towards the presence of a secondary bacterial or yeast infection.

If left untreated, hyperpigmentation can spread to different parts of your pooch's body – including the groin region, abdomen, ears, and around the eyes. You'll also notice signs of increased itchiness and discomfort. Eventually, your dog could experience further loss of hair, fluid discharge, and infections.

The causes of secondary hyperpigmentation in your canine companion include skin allergies, skin infections, skin parasites such as demodicosis that cause inflammation, hormonal imbalances, UV exposure, certain medications, systemic lupus erythematosus (autoimmune disease), and Malassezia dermatitis (skin yeast infection).

Sometimes, hyperpigmentation may occur if your dog has a previous skin problem or infection and the skin is healing from a previous trauma.

Breeds Most Affected by Secondary Hyperpigmentation

Although secondary hyperpigmentation can affect all dog breeds, certain ones are prone to allergies, skin infections, hormonal imbalance, and obesity, and are more likely to be affected.

Breeds prone to skin allergies include: Golden retrievers, Labrador retrievers, Doodles, German shepherds, Bassett hounds, French and English bulldogs, Pit bulls, Dalmatians, Shih Tzus, Maltese, Boxers, Bichon Frise, Shar Pei, and Terriers, especially West Highland White and Yorkshire terriers.

Dog breeds prone to hormonal imbalances and obesity include Pugs, Irish setters, Labrador retrievers, Golden retrievers, Lhasa Apsos, and Bassett Hounds. Hairless dog breeds such as Chinese Crested or Mexican Hairless, have skin exposed to elements and are less protected than breeds with thicker coats, and will naturally have darker skin. For hairless dogs, avoiding direct sun exposure and protection is important.

Regardless of the symptoms your pooch might be exhibiting, the best course of action is to have them diagnosed by a vet so that in case of anything treatment can start sooner.

Symptoms of Hyperpigmentation

Hyperpigmentation is itself not a disease but a secondary reaction to a different underlying condition.

Hyperpigmentation is often characterized by:

• Skin discoloration from light brown to black
• Soreness or redness around affected areas of the skin
• Thick or velvety skin areas
• Loss of hair in affected areas
• Skin infection in affected areas if left untreated
• Odor and fluid discharge due to infection
• Causes of Hyperpigmentation

Hyperpigmentation can happen because of several reasons. As earlier mentioned, it isn’t a disease itself, but a secondary reaction to a different condition. 

The following are some of the causes of hyperpigmentation:

• Genetic disorders like Acanthosis Nigricans which commonly affects Dachshunds
• Skin allergies
• Reaction to certain medications
• Skin infections
• Hormonal disorders such as Cushing’s disease
• UV exposure, especially in hairless dogs
• Skin parasites such as demodicosis(parasitic mites) that cause skin inflammation
• Systemic lupus erythematosus (autoimmune disease)
• Obesity, especially in breeds prone to obesity like American bulldogs, Pugs, Dachshunds, Rottweilers, Labrador retrievers, Cairn terriers, and Beagles
• Malassezia dermatitis (skin yeast infection)
• Aging can also cause mild cases of hyperpigmentation, especially in dogs with light or white coats

Diagnosis of Hyperpigmentation

The most qualified person to give an accurate diagnosis depending on particular symptoms and the physical appearance of your dog is your veterinarian. For instance, if you have a young Dachshund, then it’s likely that it’s genetic and your vet will rule out other potential causes. They will use a thorough medical history and physical examination.

Some of the questions to expect from your vet include:

• What other signs have you noticed?
• When do they occur most often?
• How long have these signs been present?
• Have there been any environmental changes?
• What other changes have you noticed?
• Is your dog on medications or supplements?
• What foods or treats (protein sources) does your dog eat?

During the physical examination, your vet will run diagnostic tests such as:

• Blood work and blood chemistry
• Urinalysis
• Skin scrape (a sample of skin layers to detect parasites)
• Skin Cytology

For determining the underlying causes of hyperpigmentation such as Cushing's disease or hypothyroidism, advanced diagnostic tests are needed. Skin biopsies may be needed if first-line diagnostic tests don't give a diagnosis. It’s only after your vet has determined the underlying cause of the hyperpigmentation that they can formulate a treatment plan.

Treatment of Hyperpigmentation

Primary hyperpigmentation has no cure, but the signs can be effectively managed when detected early enough. Treatment may include steroid, antibiotic, or antifungal creams, sprays or mousses, and medicated shampoos. However, hyperpigmentation can be completely cosmetic in some dogs and requires no treatment. If the case worsens then additional treatment might be necessary.

Secondary hyperpigmentation can be treated and the skin returns to normal if diagnosed early enough. Nonetheless, pet parents should understand that resolving hyperpigmentation is a slow process, and it can take months before the skin returns to normal. 

Keep in mind that hyperpigmentation is a reaction to underlying conditions. The best way to resolve secondary hyperpigmentation is by handling the underlying disease or condition causing it.

Your vet could recommend treatment methods such as antibiotics and antifungals to treat any yeast or bacterial infections in your pup. Other topical treatments like medicated shampoos can also be effective in soothing and treating your dog’s skin. 

Food trials, allergen immunotherapy, and sun protection can also be used to treat your dog. For successful results, treatment needs to be consistent and it’s therefore advisable for pet parents to be patient. If the underlying cause is not dealt with or if you neglect the treatment instructions then you can expect a relapse to occur.

Some home remedies have proven effective, but it’s still important to get a vet’s input before administering them. For natural itch relief, you can consider a 15-minute oatmeal bath. Be careful to ensure that you consult your vet and don’t cause secondary infection. Fat-free yogurt has also been claimed to help boost a dog’s resistance to skin infection, but ensure that you consult your vet before you feed your dog anything.

Recovery and Cost of Hyperpigmentation

For a dog to recover from hyperpigmentation and the skin to return to normal, it might take months, so stick to the treatment routine recommended by your vet and be patient since the results will eventually show. It isn't a sprint race, but rather a marathon. Treatment cost often ranges between $200 and $800 with an average cost of $500. This is largely influenced by the treatment method adopted and the duration of treatment.

Dog Breeds Prone to Hyperpigmentation

As earlier mentioned, primary hyperpigmentation often results from an underlying genetic condition known as Acanthosis Nigricans. Hairless dog breeds such as Chinese Crested or the Mexican hairless breed are more prone to hyperpigmentation since their skins are more exposed to elements than hairy breeds.

However, secondary hyperpigmentation can affect dogs of all breeds and ages indiscriminately. Therefore, dog breeds that are prone to conditions that cause hyperpigmentation also make this list.

For example, breeds prone to skin allergies like:

• Golden and Labrador retrievers, 
• Doodles, 
• German shepherds, 
• Bassett hounds, 
• French and English bulldogs, 
• Pit bulls, 
• Dalmatians, 
• Shih Tzus, 
• Maltese, 
• Boxers, 
• Bichon Frise, 
• Shar Pei, and 
• Terriers, especially West Highland White and Yorkshire terriers.

Other dog breeds susceptible to hyperpigmentation are those prone to hormonal imbalances and obesity, such as Pugs, Irish setters, Labrador retrievers, Golden retrievers, Lhasa Apsos, and Bassett Hounds. 

However, hyperpigmentation is not contagious, since it is a symptom rather than an illness. Thus, secondary hyperpigmentation may be a sign of an underlying illness that may be contagious. For example, the hyperpigmentation may be a result of mites or ticks, which can be passed on to another dog.

Consult Your Vet

If you notice any signs that point towards hyperpigmentation in your pup, then the best course of action is to take them to your vet and have them checked immediately. Your vet will conduct a thorough diagnosis and determine the cause of the infection and therefore recommend the best treatment. Treating your dog’s hyperpigmentation without consulting an expert can aggravate it and even cause secondary infections. Only after diagnosis can a treatment plan be developed.

Treating the underlying cause is what’s important considering that hyperpigmentation is a secondary reaction to underlying conditions. For example, if your dog's hyperpigmentation is a result of allergies then your vet will treat the allergies with antihistamines or injections which will in turn clear out the hyperpigmentation. Early detection can help when it comes to treatment and even the preparation of treatment plans.

Final Notes

Hyperpigmentation itself is not a skin disease but rather a secondary reaction to an underlying condition causing skin issues. 

Secondary hyperpigmentation is the most common form and affects all dog breeds irrespective of age, coat type, or even age. It is caused by conditions such as allergies, obesity, infections, and endocrine disorders. On the other hand, primary hyperpigmentation is breed-specific, affecting Dachshunds and typically doesn't have any side effects.

Nonetheless, hyperpigmentation can cause extreme itchiness which can then progress into other infections especially if the dog scratches in response to the discomfort. Have your pup checked by a vet immediately if you notice any signs of hyperpigmentation or changes on their skin. 

Through effective treatment and medication, your pup can recover fully from secondary hyperpigmentation. Primary hyperpigmentation can also be managed effectively depending on your vet’s recommendations.

References

1. Bajwa, Jangi. "Cutaneous hyperpigmentation in dogs." The Canadian Veterinary Journal 63.1 (2022): 85.
2. Moriello, Karen A. “Hyperpigmentation (Acanthosis Nigricans) in Dogs - Dog Owners.” Merck Veterinary Manual, 18 Oct. 2022, https://www.merckvetmanual.com/dog-owners/skin-disorders-of-dogs/hyperpigmentation-acanthosis-nigricans-in-dogs
3. Wintersand, Anna, et al. "Allergens in dog extracts: implication for diagnosis and treatment." Allergy 74.8 (2019): 1472-1479.