Fish Scale Disease in Cats

The disease is called “fish scale disease” because of the lesions’ appearance, which is similar to fish scales. Twenty types of ichthyosis have been identified to date. The most common form of this disease is responsible for about 90 percent of all cases. Cats with this condition have inherited it in an autosomal recessive manner; both parents must have the gene in order for the kitten to inherit the disease.

Pet owners and vets can recognize fish scale disease, or ichthyosis, by the characteristic, thick, scaly skin on the cat’s body. The condition causes an abnormality in how the skin grows, which causes drying and scaling of the skin. 

Fish scale disease causes the following symptoms:

• Thickened, rough skin
• Seborrhea (red, itchy skin)
• Skin can crack and bleed, causing pain
• Greasy, scaly fur
• Swollen and painful footpads in severe cases
• Smelly skin and fur
• Worsening symptoms with age

Symptoms of fish scale disease can be intense and are difficult to treat.

Fish scale disease it is an inherited condition passed on by both parents. When the gene is passed to the kitten, it is referred to as an “autosomal recessive” gene. The kitten may develop one of several versions of ichthyosis, showing varied symptoms that progress differently. The skin lesions appear in different areas of the cat’s body, depending on the version of the disease it has inherited.

Vets diagnose fish scale disease by taking a complete history of the affected cat. They also make note of the clinical signs (symptoms and appearance of the skin lesions) during the cat’s physical. If the cat’s skin has developed a bad odor, the vet will also make note of this, which helps to narrow down the list of potential skin diseases the cat could have. Because the disease is inherited, symptoms begin appearing while the cat is still a kitten.

After completing the physical, the vet will perform basic skin tests. These include impression smears and skin scrapings. A skin biopsy should also be carried out to help rule out other skin conditions. The biopsy also helps to confirm a diagnosis of ichthyosis.

Ichthyosis is rare because it has to be passed on to the kitten by its parents. The condition cannot be spread through casual cat-to-cat contact, even though the lesions look like they could be contagious.

Since ichthyosis is a genetic disorder, vets can treat only the symptoms of fish scale disease. Methods include the use of medicated shampoos that help to soothe and moisturize the skin. The vet also may prescribe topical phytosphingosine and propylene glycol sprays for the skin lesions. In addition to these medications, vets may also prescribe retinoids, which are closely related to vitamin A. These may help to keep the cat’s skin pores from becoming clogged with dead skin cells and help reduce the inflammation that results from fish scale disease.

In some cases, vets prescribe glucocorticoids (a form of corticosteroid) and oral cyclosporine, both of which help to relieve symptoms. Medications only help to relieve and control symptoms. They won’t cure the skin condition.

Vets may also suggest or prescribe oral fatty acids that may help to add moisture to the skin from within. Most vets try to treat the rashy, itchy skin to help the kitten or cat get relief from its symptoms.

Fish scale disease is incurable. The most that vets and pet owners can hope for is to treat and control the symptoms, offering some relief to their cats. Cats can live a long life, but the presence of this disease can make them feel miserable until they are diagnosed and begin receiving treatment for their skin symptoms.

Pet owners have to treat the cat’s symptoms daily, administering everything the vet has prescribed. The cat can live a relatively normal life, aside from the discomfort caused by the condition, skin lesions, rash, and itching. Depending on the form of ichthyosis the cat has, the vet may prescribe different medications to treat the symptoms and give relief to the cat.

To keep this disease from moving into new litters of kittens, affected cats and their first-degree relatives should not be bred to other healthy cats. This is the only known form of prevention at this time.