Pigmentation changes in a dog's skin and/or fur can be a sign of cancer or a side-effect of treatment. Most often however, it is due to a variety of non-cancer related causes.
- Dog fur changes color for many reasons. It is not an emergency, but it is a good idea to make a veterinary appointment to find out what is causing the changes.
- Certain cancers can cause pigment changes in dogs skin, coat, and fur.
- Certain chemotherapy drugs and radiation treatments can cause pigment changes.
Where Fur Changes Color
It can be a little concerning when you notice the color of your dog change, but it may not be an urgent problem. Dog fur changing color can occur in any location including the mucous membranes (e.g. lip, prepuce, vagina).1
- They can occur over most of the body (generalized) or in focal locations.
- Pigmentation lesions can be flat with the skin surface or raised above the normal surface of the skin.
- Skin changes are often brown to black in color, but they also can be red or bluish.
- Occasionally a loss of pigmentation occurs.
- In dogs, hyper- or increased pigmentation is the most likely change in skin color and often occurs in hairless or thinly haired areas of the skin.4,5
- Fur color changes can include a loss of color (turning white or gray) or increased color (turning dark or black).
Why It Changes Color
Pigment changes occur for a variety of reasons, the most often being in response to inflammatory and infectious processes.1 It is a natural response by the body to inflammation and often can resolve with time.
Other causes include, friction, genetic defects in some breeds, hormonal issues, and sun exposure, licking (saliva) which will not be discussed further in this article.1,4,5
Any color change in hair or skin should be evaluated by a veterinarian to determine what is causing the change.
Fur Changes Due to Cancer or Cancer Treatments
Pigmentation, primarily hyperpigmentation, can be related to cancer in two ways: drug, and tumor-related.
Drug-induced hyperpigmentation has been identified with mitotane (chemotherapeutic), minocycline (antibiotic), cabergoline (reproductive), and ketoconazole (an antifungal).1
In humans, cytotoxic agents, analgesics, anticoagulants, antimicrobials, antivirals, metals, and antiarrhythmics have been implicated in drug related pigmentation.3
Melanocytoma and melanoma tumors can cause hyperpigmentation.1 Senior Miniature Schnauzers, Standard Schnauzers, Scottish Terriers, and Irish Setters appear to be at higher risk.
Dog breeds predisposed to cutaneous hemangiosarcoma tended to be short haired and include: the whippet, American Staffordshire terrier, pit bull, and boxer.2,7,8,9
Various other pigmented tumors include:10
- Squamous cell carcinoma
- Basal cell tumors
- Epidermal nevi
- Epithelial nevi
Tumors can be other strange colors too. Apocrine gland cysts and tumors can be a bluish color while tumors that have a lot of blood vessels may appear red, red-blue, or a very dark blue or black.
Histiocytic, lymphocytic, and plasmacytic cutaneous (in the skin) tumors appear pink to purple in color.1 These may or may not be cancerous.
Additionally, hair color will often lighten after directed radiation therapy.
What to Do If You Notice Changes in Your Dog’s Skin, Coat, or Fur
If you notice changes in the skin or coat color of your dog, try to document the duration and progression of signs. Any change from normal in the skin or coat color of your dog should be evaluated by your veterinarian. Bring a list of any medications you are giving and a timeline of progression of your observations to help them diagnose the cause.
When to Call Your Vet
In general, this is not an emergent concern, however the pet should be evaluated within 1-2 weeks. General recommendations for a veterinary visit are:1
- Any changes that do not have an already known cause
- Worsening of discoloration
- New findings
- Changes in size, color, or appearance of previously identified masses.
Things that Help
Depending upon the cause for the fur changing color, your veterinarian will make recommendations or dispense medications. For example, there are therapies for inflammatory/infectious causes for pigment change.
Sun damage can be a contributing factor to some tumor types.6,7 Pet appropriate sunscreen can help.
Is Fur Changing Color a Sign of the End Approaching?
If your dogs fur is changing colors, it is not a sign that death is approaching. Drug related changes to skin color have not been associated with mortality in humans.3 No information is available for dogs, but it is assumed to be the same relationship.
Of course, dogs with new or changing pigment lesions should be evaluated by a veterinarian. Proper diagnosis and treatment in a timely manner can be curative. In other cases, further treatment may be warranted.
- Bajwa J. Cutaneous hyperpigmentation in dogs. Can Vet J. 2022;63(1):85-88. https://www.ncbi.nlm.nih.gov/pubmed/34975173
- Hargis AM, Ihrke PJ, Spangler WL, Stannard AA. A retrospective clinicopathologic study of 212 dogs with cutaneous hemangiomas and Hemangiosarcomas. Veterinary Pathology. 1992;29(4):316-328. doi:10.1177/030098589202900406
- Hassan S, Zhou XA. Drug Induced Pigmentation. StatPearls Publishing; 2022. Accessed January 27, 2023. https://www.ncbi.nlm.nih.gov/books/NBK542253/
- Moriello KA. Congenital and inherited skin disorders in dogs – dog owners. MSD Veterinary Manual. https://www.msdvetmanual.com/dog-owners/skin-disorders-of-dogs/congenital-and-inherited-skin-disorders-in-dogs. Published January 25, 2023. Accessed January 27, 2023.
- Moriello KA. Hyperpigmentation (acanthosis nigricans) in dogs – dog owners. Merck Veterinary Manual. https://www.merckvetmanual.com/dog-owners/skin-disorders-of-dogs/hyperpigmentation-acanthosis-nigricans-in-dogs. Published January 23, 2023. Accessed January 24, 2023.
- Nikula K, Benjamin S, Angleton G, Saunders W, Lee A. Ultraviolet radiation, solar dermatosis, and cutaneous neoplasia in beagle dogs. Radiation Research. 1992;129:11-18. https://pubmed.ncbi.nlm.nih.gov/1728052/.
- Nóbrega D, Sehaber V, Madureira R, Bracarense A. Canine cutaneous haemangiosarcoma: Biomarkers and survival. Journal of Comparative Pathology. 2018;166:87-96. doi:10.1016/j.jcpa.2018.10.181
- Szivek A, Burns RE, Gericota B, et al. Clinical outcome in 94 cases of dermal haemangiosarcoma in dogs treated with surgical excision: 1993-2007*. Veterinary and Comparative Oncology. 2011;10(1):65-73. doi:10.1111/j.1476-5829.2011.00282.x
- Ward H, Fox LE, Calderwood-Mays MB, Hammer AS, Couto CG. Cutaneous hemangiosarcoma in 25 dogs: A retrospective study. Journal of Veterinary Internal Medicine. 1994;8(5):345-348. doi:10.1111/j.1939-1676.1994.tb03248.x
- Yang Y, Go D-M, Jung J-H, et al. Subungual pigmented squamous cell carcinoma in a dog. Journal of Comparative Pathology. 2022;194:50-53. doi:10.1016/j.jcpa.2022.03.010
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