Dogs’ skin can have different pigmentations, ranging from pink to black, and different areas of the body can have different colors. “Why is my dog’s belly turning black” is a question that many pup parents grapple with at some point in the lifespan of their furry friends. In a nutshell, skin hyperpigmentation (Acanthosis Nigricans) in dogs are often secondary to other skin conditions or metabolic issues such as skin infections, allergies, or endocrine disorders.
The problem arises when areas of your dog’s skin that were originally cute pink begin to turn black. Unfortunately, many dog owners often think that such skin color variations happen suddenly. Hyperpigmentation often occurs over time. Perhaps it’s the bright light in the room on a particular day that caused you to notice the change, or maybe it was a weekend cuddling or grooming session when your pooch turned over and you suddenly noticed the pink belly having strange black spots.
The most common cause of the change in skin color on a dog’s belly is hyperpigmentation, which simply means a darkening of the skin. This is often more dramatic in dogs with light skin and fur.
But, note that skin discoloration doesn’t occur overnight — there is often some degree of incessant trauma or exposure for your dog’s stomach or belly area to turn black.
Think back to that redness that occurred at some point on your dog’s legs or when your pup spent a couple of weeks licking her belly. Perhaps these same patterns of itching happened over months or years, but the color change from that chronic trauma is only visible now.
Types of Hyperpigmentation in Dogs
Hyperpigmentation is not a specific disease but a reaction of your dog’s body to certain conditions. It may appear as light-brown-to-black, rough, and velvety areas of thickened, hairless skin.
The common sites are in the legs and groin areas, and it can be primary or secondary.
Primary diseases that trigger skin darkening can occur in any dog breed, but it is more prevalent in Dachshunds. The symptoms are usually evident by the time your dog reaches one year old.
Treating Primary Hyperpigmentation
Primary hyperpigmentation in Dachshunds is non-curable. In some pups, the condition is only cosmetic and often doesn’t require treatment. If there is inflammation, early cases may respond well to shampoo treatment.
As symptoms progress, other treatments, such as oral medications or injections, may be useful.
Secondary hyperpigmentation is relatively common and can affect any breed of dog, especially those breeds prone to obesity, allergies, hormonal abnormalities, skin infections, and contact dermatitis.
In most cases, secondary hyperpigmentation is triggered by friction and/or inflammation. Inflammation, in particular, leads to additional skin changes, such as hair loss, thickened skin, odor, and pain.
The edges of inflamed areas are usually red, a sign of secondary yeast or bacterial infection. With time, the discoloration may spread to the lower neck, abdomen, groin, hocks, ears, eyes, and the area between the external organs and the anus.
Itching is usually variable, and when it occurs, it is often caused by the underlying illness or by a secondary infection. As the situation progresses, other health issues may develop, such as secondary hair loss, infections, and fluid discharge.
Treating Secondary Hyperpigmentation
In secondary hyperpigmentation, the affected skin areas will go away on their own once the underlying cause is identified and treated. However, that will not happen if the secondary yeast and bacterial infections are not controlled and treated.
Many affected dogs usually benefit greatly from appropriate medicated shampoos (2 to 3 times per week) and antibiotics. Your vet may likely prescribe such treatments, but you need to be patient with the treatment programs.
More often, signs of skin darkening resolve slowly, and it may take several months for your dog’s skin to return to normal.
Fortunately, the concurrent treatments of secondary infections are helpful and should be explored before administering various medications. Medicated shampoos work well in removing excess oil and odor, but you must use them regularly for sustained results.
Diagnosing Hyperpigmentation in Dogs
Diagnosing hyperpigmentation is by the appearance of signs on the pet. In a young Dachshund, your veterinarian will seek to eliminate other causes of the signs.
Your veterinarians will basically ask the same questions you might be asking yourself already to arrive at an accurate diagnosis:
Why is my dog’s belly turning dark red or black? (Several causes are possible.)
Why is the area itchy? How itchy is it? (Most likely allergies?)
Why is the darkened skin smelly? How bad is the smell? (Yeast infection?)
Is my dog itchy only at certain seasons of the year? (Allergies?)
Do I have a thorough history of my dog since she was young? (Previous trauma or allergies?)
Once you’ve adequately answered these questions and evaluated your dog’s history, your vet may move on to other diagnostics such as skin scrapings, cytology, biopsy, and even food trials. This helps to identify the root cause of the problem and treat the issue that is causing your dog’s skin to turn black.
Previous Injury Or Trauma
If you’ve adopted a new dog that now has quiet skin but with obvious dark areas, it’s likely the pup suffered from skin trauma or allergies at a young age.
A careful evaluation of your pooch’s history and physical exam will help to identify any underlying cause. The presence of secondary hyperpigmentation more often suggests an underlying disease.
Your vet may also carry out skin scrapings to exclude other causes such as parasite infestation, especially in young pups, and impression smears may help to identify bacterial infections.
Depending on other available signs, your vet may carry out endocrine function tests for thyroid and adrenal disease to check for underlying hormonal abnormalities. Sometimes, skin testing, food trials, or both may be useful in testing for allergies.
Finally, skin biopsies may be taken to check for a condition known as seborrhea. In most cases, your vet will want to treat any secondary bacterial infection before proceeding with other diagnostic tests.
Allergies and Hyperpigmentation in Dogs
A dog’s skin turning black is most often associated with chronic itching. This is referred to as pruritus-induced hyperpigmentation, which means the darkening of the dog’s skin due to chronic itching.
You and your vet will have to manage the allergies triggering the itching and chronic inflammation to reverse the changes in skin color. Sometimes, it may be as simple as feeding hypoallergenic dog food.
Although your dog’s skin may never return to its previous light color, treating chronic skin conditions and the underlying causes of itching and self-trauma is critical for your dog’s overall health and comfort.
Dog’s Skin Turning Black May Indicate an Inflammatory Process
If your dog consistently licks at a particular area of her skin, she might experience darkening of the pigment there. If she has light fur in that area, it will soon turn brown or dark red due to the licking. The skin can also turn black and thicken over time.
Inflammation and infections from a variety of sources can trigger local or widespread hyperpigmentation of your dog’s skin. Some of these triggers include:
Demodex mite infection
Dog’s Skin Turning Black Might Indicate a Hormonal Problem
Dogs with hyperadrenocorticism or Cushing’s syndrome experience heightened levels of adrenal hormones in their bodies. One of the physical signs of this condition is increased skin pigmentation, especially around the abdomen. This condition may also be accompanied by calcinosis cutis, or tiny, hard lumps in the skin over the abdomen.
An underactive thyroid gland or hypothyroidism can sometimes cause your dog’s skin to turn black, especially around the abdomen and flanks. Other skin and coat problems associated with this condition may include hair loss or poor regrowth when you shave a patch.
Investigate Skin Cancer When Your Dog’s Skin Turns Black
Mast cell and melanoma tumors may appear as black spots on the skin. They usually show up as small, individual masses and not just large areas of smooth, hyperpigmented skin. It’s always important to have your vet investigate such skin issues to clear doubts about skin cancer.
Bruising Can Make Areas of your Dog’s Skin to Turn Black
Bruises can appear as dark blotches on your dog’s skin, which can be widespread if your pooch suffered trauma, platelet disorder, or rat poison toxicity. If certain areas of your dog’s skin suddenly become darker than before, get him to a veterinarian right away as it could be an emergency.
Skin Infections Can Cause Your Dog’s Skin to Darken
Skin infections can crop up on their own or can be as a result of secondary allergies. No matter the cause, if your dog’s skin is infected, it can lead to hyperpigmentation.
Common skin infections such as allergies can be chronic, but your vet should get to the bottom of it and treat the underlying cause accordingly. Bacterial and yeast infections are the most prevalent causes of skin infections in dogs.
Mange (Sarcoptic and Demodex mange) can cause your dog’s skin to turn dark. Demodex lesions are usually local, but Sarcoptes can become generalized. Either way, the discoloration can resolve once the mange is effectively treated, unless the condition had developed to a severe level.
Ringworm (dermatophytosis) may also cause temporary or permanent hyperpigmentation in dogs.
Endocrine Disorders and Hyperpigmentation in Dogs
Hypothyroidism, sex hormone imbalances, or hyperadrenocorticism (Cushing’s disease) can all cause hyperpigmentation in dogs. If your pooch has any hormone imbalance, there are generally many other things going on other than just the black tummy.
Along with hyperpigmentation, a dog with an endocrine disorder can have large areas of fur missing. Secondary skin infections, patchy fur loss, thinning hair, and thinning or thickening skin may also occur. Some dogs even exhibit changes in appetite, thirst, and energy.
Generally, your vet will need to carry out a blood test to diagnose endocrine disorders.
Genetic Disorders and Hyperpigmentation in Dogs
Here are a few dog breeds that are susceptible to hyperpigmentation:
Dachshunds: This breed is prone to a rare disease known as acanthosis nigricans that causes their skin to turn black followed by alopecia and lichenification.
Huskies and related breeds: These breeds are prone to alopecia X, a genetic syndrome that causes hair loss and hyperpigmentation.
Silkies, Yorkies, and crosses: These dog breeds are prone to melanoderma, a skin anomaly that causes hair loss and hyperpigmentation around the ears. The situation may be accompanied by color dilution alopecia, which causing fur thinning and darkening of their skin.
Miscellaneous Causes of Hyperpigmentation in Dogs
Is your dog’s skin turning black after shaving? Some dogs often suffer post-clipper alopecia, meaning “no fur regrowth after shaving or clipping.” This condition can result in hyperpigmentation.
If fur does not grow back after thorough grooming or clipping due to surgery, the skin around that area can become darkened. However, the darkening may fade over time, and the fur may regrow after several months.
This scenario is particularly true in Nordic breeds. Vets don’t often recommend shaving close to the skin of these wonderful fluffy beauties, like Akitas and Samoyeds.
Saliva from excessive licking can also cause pigment changes on your dog’s skin and fur, particularly in pups with light-colored coats. The white Poodle, for example, can develop brown-stained feet due to chronic licking. As a result, their fur and the underlying skin can grow darker.
Fortunately, you can control and lessen foot-licking due to allergy by addressing the underlying cause. Consider changing your pup’s food or grooming shampoo.
When Hyperpigmentation is Considered Normal
Your dog’s skin turning dark can be considered normal when your dog ages. Mild darkening of the skin due to exposure to the sun and elements can always occur. This is particularly true in pups with light or white coats.
Any significant fluctuations in hair cycle arrest, especially in plush-coated dog breeds, can cause skin darkening.
Changes in hormones triggered by certain muscle building drugs for urinary incontinence for spayed females can also cause hyperpigmentation.
If your dog is not exhibiting any licking, scratching, or biting of the affected area, or has no obvious lesions on their skin other than the darkening in color, you should bring up the issue at your next vet visit for an accurate diagnosis.
Only a qualified vet can do a complete exam to determine if there is a potential cause of hyperpigmentation or if it’s just a normal process.