Why Is My Cat Losing Weight?

Have you noticed your cat losing weight recently? Do you find it difficult to figure out what’s causing this? Sudden, unexplained weight loss in cats should always be diagnosed and checked thoroughly by your veterinarian. However, in the meantime, you may find yourself wondering what’s going on.

cat losing weight in port st. lucie, flIn the article below, you’ll find basic information to help you figure out why your cat might be losing weight. You can use this information to prepare for your cat’s vet visit and know what to expect as well as what to ask about your pet. Call Veterinary Medical Center of St. Lucie County at (772) 337-8570.


Just like humans, cats can develop diabetes, especially when they are either overweight or genetically predisposed to it. Diabetes may cause rapid weight loss in affected cats and may also cause an increase or decrease in appetite as well as excessive urination and thirst.

Your vet will need to perform blood work on your cat to diagnose diabetes. If your cat is diagnosed, there are many treatment options that can help your pet live a fulfilling life while managing the condition, just like a human can with the same diagnosis.


Cats are more prone to developing hyperthyroidism than some other animals. This condition is caused by a non-cancerous tumor that develops on the thyroid and causes changes in your cat’s body and wellbeing. It usually causes cats to become very hungry but lose weight, which is also known as wasting.

Although non-cancerous, this condition is very dangerous. It will eventually cause heart problems and organ failure in cats when left untreated. There are some treatment and management options available, but your vet will need to give you more information for your specific pet’s needs based on their health and age.

Digestive Issues or Parasites

Digestive problems can be as simple as irritable bowel syndrome or as serious as cancer of the stomach or intestines. Food allergies can also cause weight loss in cats as they are not able to gain enough nutrients from the food they eat.

Additionally, parasites may lead to weight loss in cats. If your cat is eating normally but still losing weight, parasites may be to blame. Your vet will need to perform a fecal exam to be sure that this is the cause rather than some of the other more severe problems on this list.


Cats can develop cancer, and it is unfortunately fairly common in cats as well. Different types of cancer may cause different symptoms, but all types are likely to cause weight loss. Cats who are losing weight due to cancer will likely not be hungry and will be uninterested in food.

Additionally, if your cat is going through chemotherapy treatments for cancer, they may be uninterested in food due to nausea from the chemo treatments. Your vet will be able to prescribe food that may encourage your cat to eat despite chemotherapy-related nausea, and may also be able to give your pet a medication to help too.


Normal aging may sometimes cause cats to lose weight. However, this should not be sudden or rapid if the cause is simply aging and a cat’s normal bodily changes. Aging cats can manage their weight loss by eating a high-quality food designed specifically for cats in their senior years.

Aging may cause organ failure in cats over time. This, in turn, may also cause your cat to lose weight as well as lose their appetite. Your vet will examine your senior cat thoroughly to determine whether or not organ failure or normal aging may be the cause of their weight loss.


Finally, a cat who is stressed or anxious may be less likely to want to eat than a cat who feels comfortable and calm. For example, if you have just brought home a new baby or even another new pet, your cat may be upset and may stop eating. This will cause your cat to lose weight quickly.

Talk to your vet if you think behavioral or emotional problems could be causing your pet’s weight loss. Your cat may need to take an antidepressant or an anxiety medication. Never give your pet a human medication for these problems.

Sudden, unexplained weight loss in cats is never a good thing, but some of the underlying causes may be more benign than others. It’s important to work with a trusted vet to figure out the cause of your pet’s weight loss so you can determine the best treatment or course of action moving forward.

If your pet is losing weight, don’t hesitate to contact your regular vet. This does not require an emergency vet (unless paired with other, more acute symptoms) but should still be checked out as soon as possible by your regular vet to ensure timely treatment solutions. Call us today at (772) 337-8570.