Why Has My Cat’s Fur Gone Lumpy? Solutions for Greasy, Clumpy Cat Fur

Healthy cats have healthy coats. And you’ll know it when you see it–the hair is fluffy, shiny and soft to the touch.  

Veterinary clients ask, “Why has my cat’s fur gone lumpy?” These cat patients have separated, greasy and clumpy fur that I take as a sign that something is not quite right with their health. Let’s go over some of the reasons a cat’s fur becomes greasy and clumpy…

Causes of Greasy, Clumpy Cat Fur

A healthy cat’s coat and skin are constantly being renewed. Follicles grow a new hair then after a while, it falls out only to be replaced by another new one. 

The cells of the skin also go through a normal life cycle. New cells form in the deep skin layers and work their way to the surface. Old skin cells are eventually shed and replaced by fresh, new ones from below.

A cat’s diet and underlying health conditions affect the normal transition of hair and skin cells, as well as skin moisture. The shedding cycle can become too slow or too fast. Oil glands might produce too much or too little moisture. All of these abnormalities contribute to the appearance of greasy, oily, clumpy fur mats.

Pastel tortie cat with matted fur (why has my cat's fur gone lumpy)
Separated cat fur with matting

Primary or Secondary Seborrhea

Seborrhea is a condition in cats that causes greasy, matted fur and increased dandruff. The condition happens when dead skin cells fail to shed normally. (1) 

Primary seborrhea is an inherited disease that affects Persian cats and often causes a “dirty” appearance in the facial folds of the short-nosed breed.

The term secondary seborrhea is used for cats who develop this skin condition secondary to some other disease. 

Diseases associated with secondary seborrhea include a type of tumor called thymoma, skin allergies, skin infection and diseases of the endocrine system. Some of these are discussed below.

Ringworm Fungal Infection

Ringworm is the common name for a fungal skin infection that is fairly common in U.S. cats. Veterinarians call the condition dermatophytosis. 

Ringworm fungi like Microsporum and Trichophyton are present in the environment, but most cats pick up the infection from another cat. It is contagious to most mammals including dogs and humans.

The fungus infects the hair follicle and the top layer of the skin. The organisms cause changes in the hair, follicles and skin including hair loss, increased dandruff, oil and mats. 

Dermatophytosis is diagnosed by culturing skin and/or hair samples. Treatment may include topical and oral antifungal medication. 

Parasites: Fleas, Mites & Lice 

Parasites are organisms that take their nutrition from another living organism. Fleas, mites and lice just love getting a free ride from a nice, juicy cat. When they bite or burrow into a cat’s skin it causes skin and coat changes as the cat’s immune system reacts to the invaders. 

Common symptoms cats show in response to parasites include scratching, increased licking of the body, scabs, hair loss, skin bumps, greasy fur, lumpy fur and dandruff.

Just because you can’t see any parasites doesn’t mean they aren’t there.  Some, like fleas, are big enough for us to see with the naked eye but others are microscopic. Your vet can collect a sample for analysis under a microscope. 

Environmental Allergies

Cats can develop allergies to pollen, dust, and even things they come in contact with. When the immune system responds to these normal substances as an invader, inflammation, and itchy skin develops.

The classic symptoms of skin allergy in cats are the presence of tiny scabs on the skin, hair loss, and changes in coat quality. You may or may not see your cat licking and grooming more often. Dandruff can be severe due to scratching inflamed skin.

Skin allergy symptoms tend to be seasonal and are worse in the spring and fall when pollen counts go up. In warm climates, symptoms may persist throughout the year.

Nutritional Deficiencies & Food Sensitivity

Have you ever seen an alley cat who lives his life outside, snatching food wherever he can find it? Most feral cats have dirty, clumpy coats with excessive dandruff. It’s due in part to poor nutrition.

Even cats who eat a high-quality diet can have skin and coat problems due to food sensitivities. Some cats do better with different proteins, different levels of fat and different mixes of vitamins and minerals.

Consult your veterinarian about whether a different type of food might help your cat’s skin condition.

cat fur greasy and clumpy
Greasy, clumpy fur on an old cat with hyperthyroidism


The thyroid gland is part of a cat’s endocrine system. Located on the neck in the area of the “Adam’s apple,” the thyroid gland produces hormones that help control metabolism.

Hyperthyroidism is a common problem in senior cats and is caused by excessive production of thyroid hormones. Symptoms of hyperthyroidism include weight loss, scruffy fur, and changes in behavior (usually grouchiness).

Hyperthyroidism is diagnosed with blood testing. There are several effective treatments available and your cat’s fur should start looking healthier after a few months of treatment.

Decreased Mobility

Many senior cats have some degree of degenerative changes in their spine. Twisting and bending become difficult so they’re unable to groom themselves as they once did. That’s why elderly cats develop clumpy, oily fur on their mid-to-lower back areas. They can’t reach it anymore!

Mouth pain also interferes with a cat’s grooming ability. Dental disease is very common in older cats. A cat with a sore mouth, tongue and gums may be unable to groom themselves effectively.

Obesity is a very common problem in pet cats. Excessive abdominal and body fat seriously limits a cat’s ability to groom every part of their body leading to separated, greasy fur on the back half of their bodies.

Other Systemic Diseases

A cat’s fur is the tip of the health iceberg. When something is going wrong inside the body, it will eventually show up as changes in the coat. 

Cat diseases that can cause secondary skin and coat symptoms include: 

  • cancer
  • dental disease
  • diabetes
  • inflammatory bowel disease
  • kidney disease
  • liver disease

By the time you see changes in your cat’s coat, the primary disease has been present for several months.

How to Fix Greasy Clumpy Cat Fur

No matter the age, habits or history of your cat, there are some general steps you can take to improve their coat quality.

  1. Diagnose and treat underlying diseases
  2. Improve the diet
  3. Help with grooming
  4. Use degreasing shampoo 
  5. Be patient–coat changes take months, not days!

1. Diagnose & Treat Underlying Disease

Unless you identify and treat your cat’s underlying health problems, you will be fighting an uphill battle. 

Your veterinarian can recommend the necessary tests after they examine your cat and review her history with you. Most cats will need a urinalysis, thyroid screen, CBC, and a blood chemistry profile. 

Viral testing for feline leukemia and immunodeficiency virus may be included. Radiographs can also be very helpful in identifying skeletal issues as well as problems in the chest and abdomen.

Once your vet has all the test results, they will make recommendations for treating any problems found. Follow their advice and you should see an improvement in your cat’s coat over a few months of treatment.

greasy clumpy cat fur of feral cat
This feral cat’s coat would benefit from a better diet.

2. Improve Nutrition

If you’re feeding a cheaper brand of cat food, try upgrading to a premium brand. Try adding canned or fresh/cooked food to the rotation for added moisture.

Fish oil in the appropriate amount can improve skin health but it takes a couple of months to see the full benefits. I recommend using a supplement made specifically for pets. One good product is Nordic Natural Omega-3 Pet fish oil. Follow the dosing directions on the label.

Your vet may recommend a food allergy trial using prescription cat food like Royal Canin Limited Ingredient Diets or Purina HA. Don’t try to do a food trial on your own–you’ll see much better results with the help of a veterinarian.

grooming a cat
Be very careful trimming mats!

3. Help With Grooming

Older arthritic cats with mobility problems and overweight cats have trouble reaching all parts of their body with their tongue. You can help with both health and appearance by brushing your cat frequently,

Hopefully, your cat already enjoys grooming. If he doesn’t you’ll have to get him used to it gradually. 

Start with a soft-bristled brush and use it lightly. Give lots of verbal praise and tidbits of delicious food like cooked chicken when he lets you brush him even for a second. I find it helps to have someone distract them by gently stroking another part of the cat’s body like the cheeks or top of the head.

Furminator combs work great to remove dead hair. But be careful not to overdo it. I’ve seen cats who were practically bald after a cat owner went too far with the Furminator!

When you see body language indicating that your kitty is getting annoyed, stop and try again another day. Once you can brush your cat for a few minutes at a time, do it several times a week to help him keep his coat nice.

If your cat has a lot of mats, the best solution may be to clip them off. If you’ve never used a clipper before, let a professional help you. It’s super easy to cut a cat’s skin with scissors or clippers. Get help from your veterinarian or a good cat groomer.

4. Use Degreasing Shampoo

No matter the reason for excessive oil in your cat’s coat, shampooing can help. Use a degreasing shampoo such as DermaBenSS or Keratolux brands. These shampoos can also improve dandruff by normalizing the turnover of skin cells.

Watch out for skin redness and irritation because degreasing shampoos occasionally irritate a sensitive cat’s skin. Stop using it if you see irritation and switch to a gentler shampoo.

If your vet suspects a bacterial or fungal infection, they may recommend an antibacterial/antifungal shampoo like MiconaHex+Triz. It has a couple of different ingredients from DermaBenSS and is good for cats with milder symptoms.

I tell my cat owners to let the lather soak on the cat’s body for at least five minutes before rinsing. Depending on the severity of the problem, you may be instructed to bathe your cat twice a week to every other week.

Get professional help if you aren’t able to bathe your cat at home. Some cats need a sedative to be comfortable with bathing. That’s best done under a vet’s watchful eye.

5. Exercise Patience

Be prepared to wait several months to see improvements in your cat’s coat. As skin health improves, old diseased cells and hairs will slough off and be replaced by healthy ones.

If you haven’t noticed improvements after three months of following your vet’s recommendations, re-evaluate the plan. You can request a referral to see a veterinary dermatologist. These professionals are very efficient at getting to the bottom of skin problems. 

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  1. Campbell, K. L. (2012). An approach to keratinization disorders. In BSAVA Manual of Canine and Feline Dermatology (pp. 46-52). BSAVA Library.
  2. Miller W H, Griffin C E, Campbell K L: Congenital and hereditary defects. Muller and Kirk’s Small Animal Dermatology, 7th ed. Saunders Elsevier, St. Louis 2013 p. 232.
  3. Resnick A W: Food Allergy: Dr. Google Debunked. Wild West Veterinary Conference 2019.

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