If your dog’s skin appears to be losing its colour, they could have a de-pigmentation issue. There are a number of different conditions that can cause your dog to appear to lose the pigment (colour) in their skin or fur, many of which we will explore more in this article.
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First of all, what is depigmentation?
The colour of our pet’s skin and fur is controlled by melanocytes which are in the superficial layer of the skin, as well as around hair roots and in oil and sweat glands. These cells produce melanin, and they are controlled by hormones and genetics. Melanin’s function is to help protect cells from damaging UV rays emitted by the sun.
Dogs come in a variety of different shades, meaning that some naturally have less pigment than others to begin with e.g. white dogs have less melanin than black dogs. If your dog appears to be losing their natural colour, this is a concern – this is known as depigmentation.
Several conditions could cause your dog to lose pigment in their skin and fur, which we will explore next.
What causes depigmentation in dogs?
Depigmentation can occur in a generalised fashion (all over the body) or may be localised to one body area e.g. just the nose. It can involve the hair (known as leucotrichia) or the skin (known as leucodermia), or both.
Let’s look at just some of the many causes of depigmentation in dogs –
Age
Going grey is common in old age, in both people and dogs! As dogs get older their melanocytes become less active producing less melanin. This leads to a steady loss of skin and fur pigmentation. This age-related change is most noticeable in dogs with dark-coloured fur, and certain breeds like German Shepherds, Retrievers and Irish Setters (who go ginger with age! – Ed.).
Time of year
Some dogs seem to lose colour from their nose during the winter months, a phenomenon known as ‘snow nose’ or ‘winter nose’. It can affect many breeds including Labradors, Golden Retrievers and Siberian Huskies. Their normally black nose can fade to pink or brown during colder weather and shorter day lengths. It’s unknown why this occurs, but it is not harmful to your dog and no action is usually required. If the nose is looking sore, cracked or abnormal this may mean your dog has something other than snow nose – this definitely needs checking out by a vet.
Physical or chemical trauma
Previous physical or chemical trauma to your dog’s skin could lead to changes in the pigment. Cuts, burns and scrapes could all lead to depigmentation as your dog’s skin heals, leaving lighter or even white patches. This same issue is well recognised in people.
Neoplasia
Certain types of cancer (neoplasia) could cause depigmentation of the skin or nose. For example, in older dogs, a condition known as epitheliotropic lymphoma can cause loss of colour on the nasal planum (surface of your dog’s nose). Cancerous lymphocytes (a type of white blood cell) can cause damage to the melanocytes in this area leading to a blue-grey discoloration.
Drug reaction
Some dogs may experience drug reactions to certain medications which could lead to depigmentation. For example, toceranib phosphate (a drug used in the treatment of certain cancers) can cause depigmentation of the paw pads and nose. But many other commonly used drugs could also cause pigmentation issues in susceptible individuals including vaccines, sulfonamides, cephalosporins, penicillins, carprofen, and topically applied anti-parasite products and shampoos. This problem is known as a cutaneous adverse drug reaction (CADR).
Infection
Skin infections can disrupt skin pigmentation in some individuals. A condition known as nasal Aspergillosis can cause depigmentation around the nostrils as well as discharge from the nose, sneezing and facial swelling. This is caused by a fungus that has been inhaled by the dog and it can destroy the delicate nasal bones.
Vitiligo
Vitiligo is the most common pigmentation disorder in humans, affecting 0.5-2% of the world population. There is no firm data on the frequency of the condition in dogs, as it may be under-reported, but it is thought to be rare. In dogs it tends to be a cosmetic issue so many owners may not even present their dog to the vet. Vitiligo is believed to be immune-mediated, meaning the body is attacking its own melanocytes, however, there can be a hereditary component as well.
The condition causes affected dogs to develop clear patches of white or pink skin, making the dog’s fur look like it has been bleached. It is most striking in dogs with dark coloured fur, though can affect animals with lighter tones too. Patches are often symmetrical and predominantly affect the face and nose. The breeds that are most affected by this condition include Belgian Tervuren, German shepherd dogs, Doberman pinschers, rottweilers, German shorthaired pointer, Old English sheepdog, and Dachshunds.
Uveodermatologic syndrome (Vogt-Koyanagi-Harada-Like syndrome)
This is a rare disease in dogs that is not completely understood. Affected dogs can have depigmentation of the nose, lips, eyelids, scrotum, vulva, anus, footpads and roof of the mouth. There may also be ulcerations and crusting. Akitas are predisposed, but it can also affect many other dog breeds. The condition is thought to be both hereditary and immune-mediated. Before depigmentation occurs, the dog will suffer from sudden onset uveitis (severe inflammation in the eye). This could lead to blindness unless treatment is started promptly. The prognosis for the skin is good, again if treatment is started early.
Alopecia areata
Alopecia areata causes patchy areas of hair loss, which often affect the face, head and ears, but can be seen elsewhere too. In a small number of cases, the hair can become white in an affected patch before the hair loss occurs. Dachshunds seem to be commonly affected, but it can affect other breeds and crossbreeds too. Some dogs can have spontaneous hair regrowth, but others may require medication such as glucocorticoids (steroids) or cyclosporine. Humans and other mammals can also have this condition.
Discoid lupus erythematosus
Discoid lupus erythematosus (DLE) is an autoimmune condition in dogs. The body’s own immune system attacks cells within the skin, causing the surface to become damaged and die off. Scabs and crusting typically appear around the nose, alongside skin de-pigmentation. A black nose may become pink or blue-grey in colour. The nose may also become smooth (losing its normal cobblestone appearance) and bleeding from the lesions may occur.
In some dogs, lesions can affect the skin around the eyes, ears (pinnae) and the genitals, less commonly it can become generalised spreading across the whole body.
The cause is unknown, but sunlight (UV rays) seems to make the condition worse and it is more common in warm and sunny countries. Collies seem to be commonly affected. Treatment involves suppression of the immune system which can be a topical medication or systemic tablets.
How will my vet diagnose my dog’s skin issue?
Your vet will start by examining your dog. They will be looking at how widespread the depigmentation is, as well as looking for any crusting, sores or hair loss. Based on their examination they may recommend taking some samples to investigate the problem further. This could include tissue biopsies. Small samples of skin will be obtained surgically and sent away to the laboratory. Your pet will require an anaesthetic for this. The lab will process and examine the tissue, sending a report back to your vet.
Blood samples may also be required to check your pet’s overall health status, and diagnostic imaging such as X-rays could be required if issues like Aspergillosis are suspected.
Alternatively, your vet may suggest monitoring the situation without further testing, especially if they suspect normal age-related changes or a benign process like ‘snow nose’
What treatment options are available for my dog?
As the causes of depigmentation are varied, so will the treatment options. In some cases, no treatment is required at all. Some conditions are cosmetic, rather than harmful to the dog, such as vitiligo, alopecia areata and seasonal issues like ‘snow nose’
However, other conditions will require prompt intervention such as nasal Aspergillosis and Uveodermatologic syndrome. In cases where an autoimmune condition is suspected courses of immunosuppressive medication will be required.
Your vet will be able to advise you further based on their findings.
Summary
If your dog’s skin or fur appears to be losing its normal colour, and you aren’t sure what’s going on, then you should get them checked over by your vet. Some causes of depigmentation are not concerning at all such as age-related change, but others can be much more sinister. Warning signs include crusting, bleeding or discharge as well as changes in colouration. As with most conditions, the earlier you get your pet seen the more likely it is that treatment will be effective. Be aware that sometimes depigmentation changes are permanent though, depending on the condition.
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