Hyperpigmentation In Dogs: Symptoms, Causes & Treatment

Key takeaway

Hyperpigmentation in dogs is characterized by dark spots on the skin. There are two types: primary and secondary. Secondary hyperpigmentation is the most common and is caused by an underlying illness.

If you're like most pet parents, you take pictures of your dog every week, watch them play, and know everything there is to know about them. That's why you might feel a little worried if you notice changes in their skin. Hyperpigmentation in dogs is a skin condition that appears as black spots on a dog's skin and is fairly common. This condition is typically a symptom of a primary health condition, and there are many potential causes of changes in your dog’s skin. 

Luckily, hyperpigmentation can be treated by treating the primary cause. Although, in some cases, there is no cure. Worried about changes in your dog's skin? This article will discuss everything you need to know about hyperpigmentation in dogs, including symptoms, causes, and treatment. 

What Is Hyperpigmentation In Dogs?

Dogs with black spots on their skin may be suffering from hyperpigmentation, one of many skin conditions in dogs. There are two types of hyperpigmentation: primary and secondary. Both types cause dark spots on dogs' skin that are noticeable on the belly, legs, and groin, but they can occur anywhere on the body and in any breed. The skin may also be thicker, but some dogs may not experience any other skin issues. 

Primary hyperpigmentation is thought to be breed-specific, while secondary pigmentation is a secondary condition caused by a primary underlying illness. Primary hyperpigmentation is common in Dachshunds, but any dog is at risk of secondary hyperpigmentation that is triggered by inflammation or friction, which can lead to further skin issues like hair loss, pain, and thickening of the skin.1

Hyperpigmentation in dogs can spread to other areas of the body if not treated, potentially causing further hair loss and infections.1

Symptoms of hyperpigmentation in dogs

Symptoms Of Hyperpigmentation In Dogs

Hyperpigmentation is not a disease; secondary hyperpigmentation is a symptom of a disease often characterized by: 

  • Discoloration of the skin
  • Velvety or thickened areas of the skin
  • Redness surrounding affected areas
  • Signs usually occur near the armpits, legs, or groin1

Dogs typically display signs of hyperpigmentation by the time they're one year of age and spread to other parts of the body, including the neck, hocks, eyes, and ears.1 

What Causes Primary Hyperpigmentation? 

Primary hyperpigmentation typically affects Dachshunds, which may show signs by the time they're one year old.1 However, some dogs may experience primary and secondary hyperpigmentation, so vets will need to rule out several potential underlying causes. 

What Causes Secondary Hyperpigmentation?

Secondary hyperpigmentation is a symptom of an underlying disease, so it's not breed-specific. It can occur in any dog, especially those prone to obesity, hormonal issues, allergies, dermatitis, and skin infections that cause inflammation.1

Obesity 

Recent statistics state that around 56% of dogs are overweight or obese.2 Unfortunately, obesity isn't the only problem. Overweight dogs are prone to more serious illnesses, such as:

  • Diabetes
  • Osteoarthritis
  • High blood pressure
  • Joint problems
  • Skin issues
  • Heart disease
  • Decreased life expectancy3

Some pet parents may not even realize their dogs need to lose weight unless a vet tells them. But many dogs only go to the vet once a year and may not be weighed at home. Luckily, there are other ways to tell if your dog is overweight, including:

  • Their body shape: Many dog food manufacturers offer a canine body-condition chart that can help you determine whether your dog is at a healthy weight. You can also ask for a chart at the vet. In general, healthy dogs have easy-to-see waists viewed from above with a tucked abdomen from the side.2 Dogs should not look oval from above. Instead, they should have a defined waist. 
  • Feeling for their ribs: If you can feel your dog's ribs by gently pressing them, they're likely a healthy weight. In overweight dogs, it's difficult to feel the ribs because they have too much fat covering them. 
  • Behavior: Overweight dogs are less active and spend their time eating or sleeping. If they have difficulty walking or breathing, it may indicate that they're overweight.4

Vets typically treat obesity with weight management plans, special diets, and exercise to help dogs lose weight. 

Hormonal Imbalance

Hormone imbalances are often characterized by skin conditions. You may notice changes in their skin, including color, consistency, and thickness. Dogs with hormonal imbalances may also lose fur or lick, scratch, and chew themselves due to skin irritation. Common hormonal imbalances in dogs include:

  • Cushing's disease: A disease in which the adrenal glands overproduce the stress hormone cortisol, with symptoms like increased thirst, urination, and appetite. Dogs with Cushing's disease are at higher risk of secondary skin infections and UTIs
  • Hypothyroidism: Hypothyroidism occurs when the body doesn't produce enough hormones, ultimately slowing down the metabolism. Dogs with this condition often gain weight, eat more, and experience skin conditions. 
  • Diabetes mellitus: Diabetes occurs when the body isn't producing enough insulin, preventing the dog's body from properly using carbs as energy. Diabetes results in increased thirst, urination, and weight loss. 

While there are other types of hormone issues in dogs, common signs of a hormonal imbalance include the following: 

  • Changes in the skin color
  • Changes in the consistency of the skin
  • Hair loss or bald patches
  • Irritation of the skin
  • Scratching 
  • Dull coat

Causes of secondary hyperpigmentation

Allergies

Many dogs experience allergies, which cause itching and several other symptoms. Common causes of skin allergies in dogs include: 

  • Food allergies: Food allergies can cause itchy, sensitive skin around the ears and paws with associated GI symptoms like diarrhea, gas, and vomiting. 
  • Fleas: Dogs are allergic to flea saliva, making them extremely itchy.
  • Environmental allergies: Environmental allergies, such as dust, pollen, and mold, can cause allergic reactions resulting in itchy skin.5

Unfortunately, allergies of any kind leave your dog susceptible to secondary infections because dogs typically scratch, bite, and lick at the skin, which can break the skin and cause an infection. 

Symptoms of allergies in dogs typically vary depending on the cause. For example, food allergies are the only type that causes GI issues. However, in general, common symptoms include the following: 

  • Itchiness
  • Ear infections
  • Sneezing or coughing
  • Itchy, runny eyes
  • Inflamed skin
  • Swelling of the face
  • Hives
  • Diarrhea
  • Repeated licking at certain parts of the body5

Skin Infections

Skin infections can cause inflammation of the skin. Both bacterial and yeast infections are common in dogs and can be chronic, depending on the dog. Other skin infections, such as mange, can cause itchiness and discoloration of the skin. Common symptoms of skin infections in dogs include:

  • Itching and rashes
  • Patchy hair loss
  • Scabs
  • Crusty skin

Bacterial Infections

Bacterial infections occur when the immune system is weakened due to a poor diet, allergies, stress, or another illness. There are several types of bacterial infections, including Kennel cough, Lyme disease, bacterial ear and skin infections, Streptococcus, and Leptospirosis. Common symptoms of bacterial infections in dogs include:

  • Itching
  • Red patches on the skin
  • Hair loss
  • Scabs or pus
  • Skin crusting
  • Repeated licking on certain parts of the body

Checking With A Veterinarian 

The treatment plan for your dog's secondary hyperpigmentation varies based on the underlying cause. Since it's a secondary issue, treating the primary cause will help the symptoms clear up. However, there is no cure for primary pigmentation, which is a cosmetic issue in most cases. Still, unpleasant symptoms like itching can be treated to prevent discomfort. 

Diagnosing & Treating Hyperpigmentation

A veterinarian may diagnose the primary condition causing hyperpigmentation through a variety of methods, depending on the case. In all cases, they'll physically examine the dog and ask the pet parent questions about the symptoms. Then, depending on what they believe might be the cause, they may use the following:

  • Skin biopsies
  • Impression smears
  • Endocrine function tests
  • Food trials

Depending on the underlying disease, a veterinarian may suggest bathing your dog in medicated shampoos, making dietary changes, using antibiotics, or managing allergies with antihistamines and other medication. Ultimately, treatment depends on the diagnosis. However, primary hyperpigmentation is not curable and usually doesn't require treatment unless there's inflammation present. Meanwhile, secondary hyperpigmentation will resolve alongside any other symptoms of the primary illness. 

FAQs

Can you reverse hyperpigmentation in dogs? 

There is no cure for primary hyperpigmentation. However, secondary hyperpigmentation can be reversed once the primary illness is treated. Depending on the severity of a dog's symptoms, a vet may choose to treat the symptoms directly instead of waiting for the treatment for the primary illness to take effect. For example, dogs with extreme itchiness or skin infections may get antibiotics. 

Is dog hyperpigmentation contagious?

Hyperpigmentation is not contagious because it's a symptom rather than an illness. However, dogs with secondary hyperpigmentation may pass on an illness that causes the condition. For example, a dog can get hyperpigmentation due to fleas, which can be passed on to another dog. Therefore, setting your dog up for an appointment with a vet is important to rule out any possible contagions. 

What can I give my dog for hyperpigmentation?

If caught early enough, vets may treat hyperpigmentation with shampoo and topical steroid creams.1 However, depending on the cause, your vet may need to treat the underlying illness causing hyperpigmentation to have any real effect. For example, if your dog has allergies, your vet may treat your dog's allergies with antihistamines or injections, which will, in turn, treat hyperpigmentation. 

Puppy looking at laptop

Final Notes

Hyperpigmentation is not a skin disease. Rather, it's a side effect of an underlying condition causing skin inflammation. Secondary hyperpigmentation is the most common form, occurring because of an underlying primary condition, such as allergies, obesity, endocrine disorders, and infections. Meanwhile, primary hyperpigmentation is breed-specific, affecting dachshunds, and typically doesn't have any side effects. 

Since hyperpigmentation can cause extreme itching and lead to other infections, it must be treated as soon as possible. Talk to a Dutch vet if you notice dark spots on your dog's skin. We can help diagnose and treat skin issues such as hyperpigmentation in dogs to improve their symptoms and catch any underlying illnesses. Try Dutch today. 

References

  1. 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.

  2. “Understanding Obesity and Weight Loss in Dogs and Cats.” A Growing Problem – Obesity and Weight Loss in Dogs and Cats | Morris Animal Foundation, https://www.morrisanimalfoundation.org/article/weight-loss-in-cats-and-dogs.

  3. “Fat Dogs & Dog Obesity: How to Help Your Dog Lose Weight.” American Kennel Club, 4 June 2021, https://www.akc.org/expert-advice/health/fat-dogs-and-dog-obesity/.

  4. Paretts, Susan. “How to Tell If Your Dog Is Fat.” American Kennel Club, 29 Apr. 2021, https://www.akc.org/expert-advice/health/how-to-tell-if-your-dog-is-fat/.

  5. Burke, Anna. “Dog Allergies: Symptoms and Treatment.” American Kennel Club, 21 Sept. 2021, https://www.akc.org/expert-advice/health/dog-allergies-symptoms-treatment/.