There are many different enzymes within your cat’s body that are used to break down food, liquids, and drugs into simpler, usable substances, or building blocks. When there is an insufficient quantity of these enzymes in your cat’s body, these substances accumulate in inappropriate ways, often causing cells to swell and as a result, no longer function properly. Metabolic enzyme deficiency is also referred to as lysosomal storage disease.

Metabolic enzyme deficiency will generally present at a very young age. Kittens or younger cats will begin to show symptoms as their systems require more energy and resources than their bodies are able to metabolize. Depending on the severity of the disease, symptoms may range from subtle to extreme and may include:

Metabolic enzyme deficiency can vary in severity and occurs when there is a lack, or deficiency, in the amount of enzymes needed to break down substances ingested by your cat. This condition is generally a genetic disorder that is inherited from generation to generation. The condition is usually a recessive trait, which means that both parents have to carry the gene for the disease in order to produce an affected kitten. Certain breeds of cats are more predisposed to this condition. These breeds include:

Diagnosis of metabolic enzyme deficiency in your cat will begin with a thorough physical exam. Given the genetic component, it will be important for you to provide a complete physical history of your cat to your veterinarian at the time of the exam. The combination of a susceptible breed, plus neurological and physical symptoms will be important in your veterinarian initially suspecting the condition. 

If your vet suspects an enzyme deficiency, he or she will follow up with other pathological tests. Blood profiles are likely to be unremarkable with the condition, meaning that elevated levels of white blood cells or various proteins aren’t generally seen. Blood and tissue smears are the preferred method for diagnosing the condition.

Blood smears are collected in the same manner as a blood draw. A needle is inserted into your cat and a blood sample is withdrawn. This procedure is generally quick and painless for your cat. The blood is then examined under a microscope for cellular changes that would indicate disease. Tissue samples are taken with either a fine needle biopsy, similar to a blood draw, or in some cases, with a more complicated incision that may require anesthesia.

Additional diagnostic tests, such as x-rays or similar imaging, will identify changes in the bony structures of your cat. For these types of tests your cat will most likely need some degree of anesthesia or sedation in order to get the most accurate images.

Treatment of metabolic enzyme deficiency in your cat will depend on the severity of the condition. The main goal of any course of treatment will be to regulate the levels of metabolic enzymes in your cat to improve the absorption of nutrients. This may be done by supplementing your cat with dietary or prescription enzymes. These enzymes are typically administered orally, although sometimes can be directly supplemented via special injections.

In less severe cases, your cat may be placed on a special diet. Your vet will need to carefully diagnose the exact enzyme that your cat is lacking or is not producing sufficient amounts of. This may require extensive additional testing. Once this enzyme is identified, your vet will be able to tailor a special prescription diet that will allow your pet to efficiently break down nutrients into useable products.

Finally, your veterinarian may also use special procedures to filter out your cat’s blood of any build up in harmful byproducts. This course of treatment may be needed regardless of whether nutritional or enzyme supplementation is done long term, as a means to correct severe buildup of byproducts in the blood and reset your cat to stable and balanced levels.

Prognosis for your cat’s long-term well-being will depend on the severity of the metabolic enzyme deficiency. The more severe the case, the more important it will be that you strictly follow any dietary or prescription regimen. Even slight changes or consumption of food or medication that your cat cannot metabolize may cause the condition to recur and could be potentially life-threatening.