Why Do Dogs Have Black Spots on Their Tongue? Is It Normal?

Black spots on dogs’ tongues are most often perfectly normal and harmless, especially if they were born with them. If black spots appear suddenly, your dog may have a health problem. The most common medical conditions that cause black spots on dogs’ tongues are oral ulcers, cancer, kidney or lung problems, and vitamin deficiencies.

Every dog is unique, and so is its tongue. They can be pink, have black spots, or be completely black. 

Most of the time, black spots on a dog’s tongue are perfectly normal, a result of hyperpigmentation. Black spots can also be found on the gums and inside the lips.

Although these spots are normally caused by hyperpigmentation, they also appear in relation to some medical conditions.

In this article, you will learn what black spots are, why they appear, what dog breeds have spotted tongues, and whether you should do something.

Why Do Dogs Have Black Spots on Their Tongue?

Black spots on the tongue of some dogs are normally caused by hyperpigmentation. These spots are flat with many shapes, sizes, and shades. In other situations, the black spots are the symptom of a medical condition.

A healthy tongue is generally pink. Healthy tongues can also have black spots or be completely blue-black. 

There are dog breeds that are born with a spotted tongue, which is normal. The color of the spots varies from blue to black. They often have different shapes and sizes as well.

It is important to periodically check your dog’s mouth and look for changes, including the color and texture of the tongue.

Normal and harmless dark spots are flat with the same texture as the surrounding tissue. These spots are areas of hyperpigmentation. 

Hyperpigmentation occurs due to the excess of melanin, a pigment that gives color to the eyes, skin, and hair.^[1]

For dogs born with black spots on their tongue, these are beauty marks or freckles (similar to those on humans). These beauty marks can also develop later in dogs’ lives.

They aren’t always harmless though. Contact your veterinarian in the following cases:

• The spots appeared suddenly.
• The spots are prominent, not flat.
• The dog is bleeding from the spots.
• The spots are infected.

What Dog Breeds Have Black Spots on Their Tongue?

Black spots on dogs’ tongues are a completely normal trait. They can occur in all dogs, whether pure or mixed breed.

When these black spots are present from birth, they are usually nothing to worry about.

Some of these breeds can have completely blue or black tongues.

Are Black Spots on Dogs’ Tongues Ever a Problem?

Black spots on a dog’s tongue represent a problem when they are not flat, bleed, painful, have appeared suddenly, or have a different texture than the rest of the tongue.

Black or blue spots on some dogs’ tongues are perfectly normal. Healthy spots have the same texture as the rest of the tongue and don’t change in size over time. 

In addition, dark spots that suddenly appear in your dog’s mouth and skin can also indicate an issue.

To avoid complications, it is best to be vigilant and pay attention to any changes that appear in your dog’s mouth, including its tongue. 

Brush your dog’s teeth regularly and inspect its mouth for any changes.

If new spots appear, mention them to the vet. They will determine whether the black spots need to be evaluated or not.

Causes of Black Dots on Your Dog’s Tongue

There are several reasons why some dogs have black spots on their tongues. The most common cause is harmless hyperpigmentation. Black spots can also appear in certain types of cancer, kidney or lung problems, due to oral ulcers, or vitamin deficiencies though.

The most common cause of the black spots on your dog’s tongue is hyperpigmentation, which is normal for many breeds. 

If spots are not caused by hyperpigmentation, they can be caused by the following health issues:

• Kidney diseases
• Lung diseases
• Heart disease
• Oral ulcers
• Vitamin B3 deficiency
• Cancer

Kidney Diseases

Acute renal failure can cause black spots on the tongue. These spots are areas of necrosis (dead tissue). The tongue may also appear discolored.^[2]

Look for other symptoms caused by acute renal failure:

• Depression
• Dehydration
• Oral ulcers
• Decreased body temperature (hypothermia)
• Bad breath (ammonia smell)
• Increased heart rate
• Abdominal pain
• Heavy breathing
• Seizures

Lung and Heart Diseases

In lung and heart diseases in dogs, the tongue of dogs can become purple. In rare cases, it also causes black-bluish spots. 

This occurs due to the lack of oxygen distributed in the body.

Pulmonary and heart diseases can also be accompanied by the following symptoms:

• Difficult breathing.
• Panting, especially after the slightest effort.

Oral Ulcers     

Mouth ulcers are caused by a number of health problems. Ulcers can increase the risk of secondary infections in the mouth if left untreated.

Oral ulcers appear as red or white spots. The ulcers are painful and can bleed. They are generally bumpy, unlike black spots caused by hyperpigmentation. Oral ulcers are prominent, with the shape of a mushroom or cauliflower.

Oral ulcers can occur in the whole mouth^[3], not only on the tongue:

• On the roof of the mouth (hard palate)
• Lips
• Gums

The most common symptoms of oral ulcers include:

• Refusal of food or the dog has an appetite but struggles to eat.
• Blood in the saliva.
• Pawing at the mouth.
• Smelly breath.

Vitamin B3 Deficiency

Vitamin B3 (niacin) deficiency is also known as “black tongue disease” in dogs. As the name implies, the surface of the tongue turns black as a symptom of the deficiency.

Niacin deficiency is caused by a lack of vitamin B3. Symptoms of this condition include:^[4]

• Weight loss
• Redness of the oral mucosa
• Oral inflammation and ulceration
• The surface of the tongue becomes black
• Diarrhea

Niacin deficiency can lead to death if not treated.

Cancer

Black spots on the dog’s tongue can appear suddenly in relation to cancer, especially in old dogs. These spots are prominent, textured, painful, and can bleed.

There are two common types of oral cancer:

• Melanoma
• Squamous cell carcinoma

These tumors can appear as dark masses on the dog’s tongue or mucous membranes.