Why is my dog's skin turning dark?

Updated July 19, 2017

As your puppy matures into adulthood, its pink skin may begin to darken. In many cases, this is a normal occurrence. In others, this darkening effect is a sign of a more serious problem. If uncertain about your dog's condition, it is important to take it to see a veterinarian who can correctly diagnose the cause and prescribe any treatment if necessary.

Normal Occurrence

In a normal occurrence, a dog's skin will darken over time as it matures into adulthood and there will be no other side effects like scratching, hair loss or inflammation.

Causes for Concern

If your dog is experiencing skin darkening or lightening along with other symptoms such as inflammation, scratching, hair loss or thinning, lethargy, obesity, excessive thirst or increased urination, it should immediately be taken to a veterinarian.

Chronic Irritation Or Inflammation

Chronic irritation is indicated by darkening skin and thickening of the skin due to allergies and bacterial infections. It is treated on a case by case basis.

Lentigo and Vitiligo

As a genetic cause of hyperpigmentation, lentigo is a condition in which black spots called lentigines appear on the skin of the dog. Many people refer to these as tar spots, age spots or pigment spots. These spots appear in mature or ageing dogs, and can increase in number and become larger. Such spots are most commonly found in Shar-Peis.

Vitiligo is a skin disease marked by light or bleached spots on a dog's skin. Sometimes, the fur that grows over these spots will lighten or turn white. The majority of these spots will appear on the face; however, they are also seen on the inside of the mouth or on the nose.

Dudley Nose, or "Snow Nose" as it is sometimes called, is a syndrome sometimes associated with vitiligo. Though the cause is unknown, it is characterised by the fading of a dog's black nose to chocolate brown or dark pink. Some dogs recover the original dark colouring, while other dogs do not. This condition is not associated with any other symptoms and is not painful or harmful to a dog.

Cushing's Disease

Hyperadrenocorticism, more commonly known as canine Cushing's disease, mainly affects ageing dogs. This disease is caused by a pituitary tumour or an adrenal tumour. In other cases, Cushing's disease is caused by veterinary interference in which a vet is unknowingly poisoning a dog with too much cortisol, most likely in an attempt to treat a dog for another reason.

Characteristics of Cushing's disease include hyperpigmentation as well as hair loss, easy bruising, increased thirst and urination.


This hormonal disease is caused by a decreased production of thyroid hormone. It is signified by changes in skin pigmentation as well as hair loss, dry and brittle hair, obesity and lethargy. Hypothyroidism is treated through a lifetime of thyroid supplementation.


In dogs, melanoma is defined as a malignant tumour and is distinguished by a single dark-coloured lump. Once a vet identifies it as melanoma, the tumour is removed as is a large area surrounding the tumour.

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