Black patches on the skin - acanthosis nigricans in dogs

The condition known as acanthosis nigricans refers to black or brown patches of hyperpigmentation (darkening) on the skin of the dog, which often have a velvety texture to them and generally have rough or undefined borders.

It is a condition that is most commonly associated with people but can also affect dogs as well, and can be either primary or secondary in nature. In this article, we will look at canine acanthosis nigricans in more detail, how it is acquired, and what it means for affected dogs. Read on to learn more.

What causes acanthosis nigricans in dogs?

Acanthosis nigricans can affect dogs of any age or breed, although it is more prevalent in certain breeds than others, which we will cover later on.

The condition can either be genetic and hereditary, passing on from parent dogs to their offspring, which is known as genetic or primary acanthosis nigricans, or it may be secondary, which is the acquired form of the condition.

Primary or genetic acanthosis nigricans

Primary acanthosis nigricans tends to occur in dogs that are going to be affected by it prior to the dog reaching the age of one year old, and can potentially occur in any breed of dog. However, the Dachshund dog and dogs with some Dachshund ancestry are the most likely breed to be afflicted with the primary or hereditary form of the condition.

As part of the development of primary acanthosis nigricans, the skin in the affected areas will also become thickened as well as darker, and will be accompanied by seborrhoea, or scaly, flaky skin.

Secondary or acquired acanthosis nigricans

The more common form of acanthosis nigricans is the secondary, or acquired form of the condition, which is not considered to be hereditary and can potentially affect any dog of any age. It is thought that an excess of melanin in the skin, or darker skin pigmentation in certain areas cause the secondary condition, as these things make the skin darker than it would usually be on its own.

The causes for secondary acanthosis nigricans can be varied, but some of the most common conditions and problems that can lead to its development include:

• Hormone imbalances.
• Obesity and weight problems in the dog.
• Canine Cushing’s disease.
• Hypothyroidism.
• Food allergies, or other forms of allergies and hypersensitivities.

Secondary acanthosis nigricans can occur at any age, but rarely presents for the first time in dogs under the age of one year old.

Identifying acanthosis nigricans in your dog

It is a good idea to check your dog’s skin over regularly for any signs of problems in the making, as these can often be obscured by the dog’s fur. Some of the main indications of the condition in the dog include:

• Clearly visible blackening or darkening of the skin in certain areas.
• Inflamed skin in the affected area.
• Loss of hair in the affected areas.
• Thickening and toughening of the surface of the skin.
• Pruritus or itchy patches.
• Seborrheic patches, which may be flaky or irritable.
• Additional secondary complications, such as bacterial or fungal infections.

Diagnosing the condition

In order to make a definitive diagnosis of acanthosis nigricans in your dog, your vet will need to conduct a physical examination, and potentially take a skin biopsy. For the secondary form of the condition, your vet will also need to run a range of additional tests, to get to the root of the underlying issue.

Blood tests may be used to identify any underlying hormonal imbalance, and allergy testing may be performed to identify the presence of a certain allergenic trigger that may be causing the condition.

Treating acanthosis nigricans in dogs

What can be done to resolve the condition largely depends on whether or not it is primary or secondary in nature; for primary acanthosis nigricans, the darkening of the skin in the affected areas cannot be reversed, but the condition can be kept under control and kept from worsening, while at the same time helping to keep your dog comfortable.

Special shampoos or conditioners to reduce the skin’s production of seborrhoea may be prescribed, as may steroids or melatonin-based medications to improve the health of the skin on the whole.

For the secondary presentation of the condition, ascertaining the underlying cause of the condition and getting this under control is the best form of treatment, and this will often prove sufficient to resolve the issue and allow the affected skin to return to its normal colour.

The management of obesity or any underlying allergenic condition are often the keys to resolving the condition and preventing later flare-ups, and keeping the skin in good condition with conditioning baths and supplements such as vitamin E and essential fatty acids can all help to return your dog’s skin to its normal healthy state.