Causes of Pigment & Color Changes in the Skin & Coat of Cats

Orange cat with pigment changes on the nose due to lentigo

The skin and coat of a cat may sometimes change color or become lighter or darker. This may be a normal process, or may be due to a serious disease. If the skin or coat has a color other than white, it is said to be 'pigmented.' Colors include brown, black, red, purplish-blue, and yellow. If the skin is a darker color than normal, it is said to be 'hyperpigmented.' The table below provides a list of the majority of the conditions which are associated with pigment change. This extensive listing helps you understand why a quick diagnosis may be difficult to make, and various diagnostic tests may need to be performed. The most common conditions causing pigment or color changes are color-coded gray in the table (some may be more common in certain geographical areas).

Condition	Description	Symptoms	Diagnosis	Treatment
Apocrine sweat gland cyst	Rare in cats	Single, round, smooth nodules with no hair; may appear bluish; usually filled with a watery liquid; most common on head, neck, and limbs	Physical exam; biopsy	Surgical removal is optional
Basal cell tumors	Most common skin tumor in cats; benign tumors; may become cancerous, slow-growing tumors which rarely metastasize	Single, sometimes fluid-filled nodules which may ulcerate; usually on the head, neck, and chest; may be hyperpigmented	Biopsy	Surgical removal (if benign, surgical removal is optional)
Bowen's disease	A rare type of squamous cell carcinoma in which multiple lesions develop	Lesions start out as thickened, dark, raised, and well-delineated; progress to ulcers and crusts and bleed easily; found on the head, neck, shoulders, and forelegs	Biopsy	Lesions may come and go and are not always treated; some anti-cancer drugs and radiation have been tried with mixed results
Bruises	Generally the result of trauma; may indicate abnormally low platelets, clotting problems, or hormonal problems	Areas of bluish black discoloration of the skin	Medical history very important; blood tests if abnormality expected	None, if the result of trauma; in other cases, treat underlying cause
Chronic irritation/inflammation	Chronic atopy, allergies, bacterial infections	Darkening and sometimes thickening of the skin	History, physical exam; blood tests to determine cause	Treat/remove underlying cause
Cushing's disease (hyperadrenocorticism)	Caused by an increase in corticosteroids in the body - either due to increased production by the body or as a side effect of high doses or prolonged therapy with corticosteroids	Hair loss, thinning of skin, hyperpigmentation, easy bruising, seborrhea, comedones (black heads); lethargy, increased thirst and urination, pot-bellied appearance	Adrenal gland function tests, urinalysis, chemistry panel, CBC	If due to glandular tumors, selegiline, o,p-DDD (Mitotane), or surgical removal of tumor; if due to high steroid doses, withdraw use of steroids slowly
Epitheliotropic lymphoma (mycosis fungoides)	Rare cancer of T lymphocytes seen in older cats; may be associated with FeLV	Redness, itching, scales, ulcerated nodules	Needle or other biopsy	Poor response to treatments which include chemotherapy, surgical removal, retinoids, fatty acids
Follicular cyst	Most common cyst; may be called "sebaceous cysts" by some veterinarians	Single, round nodules on or underneath the skin; may appear bluish; may contain a thick, yellowish to gray material; usually found on the head, neck, and trunk	Biopsy	Surgical removal optional; do NOT squeeze these cysts since a severe skin reaction will occur
Hemangiosarcoma	Malignant, invasive tumor more common on sun-damaged skin	Blue to reddish black nodule; usually on ears, head, legs, groin, and axillae; often ulcerate	Biopsy	Surgical removal; need to remove large area around the tumor; if tumor is on a leg, amputation of the leg is commonly recommended
Hypothyroidism	Decreased production of thyroid hormone; uncommon in cats	Dry and brittle hair, seborrhea; secondary bacterial and yeast infections; lethargy, obesity, slow heart rate; changes in skin pigmentation may occur	Thyroid gland function tests, chemistry panel, CBC	Lifetime thyroid supplementation
Injection site alopecia	Hair loss at the site of an injection of a medication or vaccine; skin may become thickened; in cats, ulcers may develop	Hair loss occurs several months after injection; area may become hyperpigmented	History and physical examination	None; the condition is permanent
Jaundice	Generally results from liver disease	Yellowing of the skin, mucous membranes and whites of the eyes	Physical exam; blood tests to assess liver function	Treatment of underlying liver disease
Lentigo	Common on the lips and nose of orange cats	Circular brownish-black areas of coloration	Physical exam; skin biopsy to rule out other causes of hyperpigmentation	None
Malassezia	Usually follows some other underlying disease	Itching, redness, hair loss, greasy scales; if chronic, develop hyperpigmentation	Skin scraping/smear and microscopic examination, culture	Treat underlying disease; oral ketoconazole; miconazole shampoos
Mast cell tumor	Common cancer which is graded from 1-4: Grade 1 is one slow-growing tumor, and Grade 4 is rapidly growing malignant tumors with metastasis; in cats, most are Grade 1	Tumors may be of various sizes, appearances, and numbers	Biopsy to grade the tumors which determines treatment and prognosis	Depends upon grade; surgical removal, taking large area around tumor; chemotherapy; prednisone; radiation
Melanoma	Malignant tumor; uncommon in cats	Usually single, dark-colored nodule which often ulcerates	Biopsy	Surgical removal, taking large area around tumor
Mosquito bite hypersensitivity	Severe allergic reaction to mosquito bites; lesions most common on nose and ear tips - also footpads, lips, and chin	Acute lesions are red, raised, and oozing; with time develop hair loss, scales, nodules, and pigment changes; some cats develop fever and swollen lymph nodes	History of exposure to mosquitoes; lesions resolve when cat is hospitalized or otherwise restricted from exposure to mosquitoes	Restrict exposure to mosquitoes, insect repellents, prednisone
Pemphigus foliaceus	The most common form of pemphigus in the cat; an autoimmune disease	Often affects feet and head; starts with pustules and progresses to severe crusting; depigmentation of the nose is common; itching may occur; if footpads and nails affected often see lameness; symptoms wax and wane; severely affected cats may have fever and loss of appetite	History, physical exam, skin scraping and biopsy	Corticosteroids, other immunosuppressive therapy, gold injections
Post-clipping change in hair color (feline acromelanism)	More common in Siamese, Burmese, Himalayan, and Balinese; in these breeds, skin at higher temperatures has lighter colored hair, and cooler areas have darker hair; when area is clipped, it is cooler and hair grows in darker	Hair in a clipped area grows in with a darker color; after the next shed the hair returns to its normal color	Breed, history	None
Red/brown staining of hair	Often caused by body secretions such as tears and saliva from licking	Light colored hair turns a reddish brown	Clinical signs, history	Treat underlying condition
Skin cancer	See specific type, e.g., Basal cell tumor, Mast cell tumor, Melanoma
Stud tail (tail gland hyperplasia)	A sebaceous gland (on the top of the tail near its base) enlarges; most often occurs in confined, unneutered males	Oily area, hair loss, and crusts on area over gland; may become hyperpigmented	Clinical signs	Castration usually does not resolve the condition; antiseborrheic shampoos, retinoids; if confined, allow cat more freedom
Vitiligo (decreased pigment)	Can be hereditary or caused by an autoimmune reaction	Loss of pigment which may be temporary or permanent; usually on nose, lips, and face	Clinical signs, skin biopsy	None

* off-label use: medication used to treat a condition for which it was not developed (or licensed). A large number of medications fall under this category. Research has almost always been performed to determine the effectiveness and safety of the product, but the manufacturer has not undertaken the lengthy process required for licensure.