As with all mammals, the shedding of hair is a completely normal process for felines. Under normal circumstances, shedding occurs to allow older hair follicles to be replaced with new ones. Sometimes abnormal amounts of shedding can occur, and the causes can range from stress, to a reaction to detergents, to that cat's particular genetic history. This unusual hair loss is known medically as “alopecia”. Owners may notice "bald spots" (medically referred to as skin lesions), irritated underlying skin, and the pet abnormally licking itself. These feline hair loss scenarios typically indicate non-severe conditions, and usually require mild to moderate and non-invasive treatment. However, hair loss and related skin conditions can be signs of more rare conditions in cats, such as autoimmune disease, diabetes, thyroid conditions, and certain types of cancer. Because of this, it's important to take a cat suffering from hair and skin issues to a veterinarian for assessment as soon as possible.

Hair loss is not a typical symptom of cancer in cats. If hair loss is all that a cat's owner is observing, then even a veterinarian may dismiss it as not particularly alarming. Fairly particular and rare cancers in cats cause related hair-loss symptoms, and the specific condition is known as paraneoplastic alopecia. The condition is not believed to be directly caused by the cancer itself. Rather, it is believed that by the time the hair condition is visibly noticeable, cancerous tumors are present in the body, and the hair loss is an effect of compromised systems elsewhere in the body. So to distinguish hair loss as having cancerous as opposed to other causes, cat owners should be looking for symptoms besides hair loss, such as: 

In addition, a tell-tale indicator of the presence of paraneoplastic alopecia is the presence of very "shiny" bald patches on the animal that have the appearance of having been coated in cooking oil. This appearance is believed to be caused by the total loss of the cats' upper layers of skin, resulting in the skin's cholesterol literally being exposed. Cat owners may in fact find that this is the only dermatological symptom that they will see in such a situation, so when inexplicably "glistening" skin patches appear on a cat, immediate medical attention should be sought. 

The strongest cancer link to feline paraneoplastic alopecia appears to be pancreatic cancer, which affects the body's ability to produce insulin. Several other cancers have been linked to this condition as well. In general, very little is known about the root causes of feline cancer. Among the suspected contributing factors are:

Although studies have shown that age, gender, genetics, and breed seem to prove to be no deterrent to paraneoplastic alopecia, the condition does appear to be prevalent in older cats, generally around age twelve and older. 

While other mammals may abnormally shed for a variety of reasons, in felines, the two leading causes of hair loss are allergy (usually flea driven) and underlying disease. While hair loss in cats does not necessarily indicate a serious medical condition, it should not be ignored, especially if it is accompanied by any or all of the symptoms described above. When the cat is brought in for examination, its vet will most likely start with a dermatological approach, examining lesions and skin condition, checking for parasites, and inquiring about food habits. If parasites and allergies don't seem to be potential causes, the vet will move on to other testing, including skin biopsies and blood tests.

The cat's owner can be very helpful here by keeping diligent notes on the cat's symptoms and behavior prior to being brought in for examination. Because time is of the essence where small animal diagnoses is concerned, any information a pet owner can pass along on even seemingly trivial things can be helpful in steering a veterinarian towards a correct diagnoses. As always, it's helpful if the cat owner can give the vet a full "litter box report" even if symptoms don't indicate an underlying internal cause.

It's important that can owners understand that feline paraneoplastic alopecia is a symptom of late stage aggressive cancer, not a disease itself. There is no treatment for it alone. Generally, when "shiny" tell-tale skin lesions and hair loss are apparent, the cancer is far advanced in the cat, and its prognosis is very poor. However, feline cancers can be treated and managed with success, depending on the size of the tumors, and the metastasizing of systems within the body. 

Aggressive feline cancer treatment includes surgery in which tumors can be removed if not too large, and chemotherapy and radiation treatment. As with any treatment of an aggressive disease, the sooner that it is detected, the better the chances of a recovery. And owners should be aware that while the treatments described above can have effective results if the cancer is caught early enough, they also can cause injury and toxic side effects. There is also no guarantee that feline cancer won't recur. Treatment length depends on the severity of the disease, and can range from weeks to months, depending on the course chosen. 

A cat suffering from paraneoplastic alopecia that presents with shiny skin lesions and other symptoms is considered a poor candidate for aggressive cancer treatment. A course of palliative care is recommended instead, which includes pain medication and steroids among other choices. The objective here will not be to regain lost hair, but to prevent pain and infection in exposed areas. Owners should consult with their veterinarians as to their best options regarding the cat's comfort and quality of life considerations.