Why Is My Cat Thin at The Back End?

Why Is My Cat Thin at The Back End

We’re all attracted to affectionate cats that are pudgy and healthy. But sometimes it can be deceiving as a cat can look big but it’s actually mostly fur. If our pet cats start to get thin, especially at the back it is best to try to find the cause for the loss of weight as it may be a sign of even serious health issues.

How to determine if your cat is thin at the back end 

A healthy cat’s back end gives an impression of support and strength. The entire back end including the buttocks and thigh should be covered with fur, sturdy and well-muscled. It is where most of the vital organs are located such as the kidney, small intestine, colon, stomach, liver, and spleen.

If you notice that your pet’s back end is saggy, sunken, and looks abnormal it may be an indication of a health issue.

Why do cats usually get thin including the back end?

Cats have varied eating habits and patterns. Some like to eat a lot, some are finicky when it comes to food while still others like to eat at various times during the day. Following are the most common for a cat to lose weight and get thin at the back end:

1. It may be due to an underlying illness or disease.

You may think that your pet is okay because it’s eating normally and doesn’t manifest major behavioral changes except for weight loss. If this is the case then your pet may have a disease or illness. These include the following:


It results from the inability to produce insulin which balances glucose levels. Other signs aside from weight loss include urinating more than usual, drinking lots of water, and looking sluggish. 


It is caused by a benign tumor in the thyroid glands resulting in elevated thyroid hormone levels. Older felines are more prone to this illness. Other signs that your pet has this illness include frequent drinking of water, excessive urination, diarrhea, and vomiting. 


Certain cancers such as soft tissue sarcoma and lymphoma are common in cats. Aside from getting thin, other signs may include difficulty in urinating, defecating, and the appearance of lumps or tumors. 

Gastrointestinal tract and digestive disease

This disorder minimizes the digestion and absorption of food and modifies its passage to the digestive system. The types of gastrointestinal disorders include colitis, pancreatitis, and irritable bowel syndrome. The presence of parasites or worms is also under this category and could be the culprit. Other symptoms may include vomiting, diarrhea, constipation, and flatulence.

Feline infectious peritonitis

This is a viral disease caused by a coronavirus that attacks the intestinal walls. The symptoms include weight loss, excessive urination, and a distended abdomen. 

It may be due to an underlying illness or disease.
Image: istockphoto.com / hadkhanong_Thailand

2. Due to loss of appetite.

If your pet is showing a loss of appetite and doesn’t show interest in food it’s a cause for concern. Loss of appetite or anorexia is characterized by a change in eating habits and/or a consistent refusal to eat. Potential reasons include: 

  • The cat has dental issues and its tooth or mouth may be painful.
  • The cat is not feeling well. 
  • Something is stuck in the airways, such as a hairball or the cat may have ingested a foreign object. 
  • The cat doesn’t like the texture, flavor or taste of the food. 

3. Due to stress, depression, or anxiety.

Pet cats may also lose weight because of psychological depression, stress and anxiety.  They may get depressed due to loneliness, changes in their environment or routines and even the death of a companion animal or family member. The usual causes of stress in cats include a dirty litter box, a noisy environment such as remodeling projects and loud parties at home as well as being in unknown places. Competition for resources and inadequate territory are also possible causes, especially in a multi-pet household. 

Cat breeds with a slender physique

There are cases where your pet cat, although it may have a thin back end, is perfectly okay and has no weight problems after all. Some cat breeds have a natural slender physique even to the extent that they appear to be too thin for some people. These breeds include:

Devon Rex

This hypoallergenic breed originated in Europe. Aside from being slender, it has big ears, short hair, a thin tail, thin limbs, and extrovert and affectionate nature. 


This breed originated in Russia. It has a thin tail, big ears and is hairless. It’s referred to as the oriental version of the Sphynx and has a calm, affectionate and extroverted character. 

Oriental shorthair

This cat breed originated in Thailand. It is said to be a cross-breed of the Siamese and British or American shorthair breeds. It has a muscular body, usually weighs 5 kgs., is affectionate, and makes powerful vocalizations or sounds. 

Cornish Rex

It originated in the United Kingdom and is best known for its striking looks and endearing personality. Its life expectancy is 15 to 18 years.

Russian blue

This is one of the most popular cat breeds because of its striking bright blue color and intense green eyes. It has a calm, affectionate, curious, and intelligent personality. 

What to do if your cat is thin at the back end

What to do if your cat is thin at the back end
Image: istockphoto.com / Tatiana Plotnikova

If your cat looks and acts normal but has a thin back end you should address the situation promptly:

1. Visit the veterinarian.

A visit to your vet is the first step you should take. Your vet will perform a physical examination along with laboratory and blood tests which are needed to come up with the diagnosis.

2. Give your pet high-calorie and nutrient-rich food.

Sometimes all it takes is nutritious and protein-rich food to help your cat gain weight again. Try Iams Proactive Health High Protein Chicken and Salmon Recipe Dry Cat Food. It’s enriched with fatty acids for shiny fur, has no artificial preservatives, and contains minerals for strong bones and teeth. High-calorie supplements that come in gel form may also be given but make sure to consult your vet first. 

3. Administer an appetite stimulant. 

An appetite stimulant like Mirtazapine may be given to your cat. It comes in pill form and transdermal formula which makes it easy to absorb. However, make sure you have the nod from your vet before giving it to your pet. 

4. Make food more flavorful and delectable. 

Encourage your pet cat to eat by enhancing the flavor and using add-ons. These may be in the form of tuna or clam juice, dried tuna flakes, powdered tuna, and oregano flavoring. 

5. Keep your pet cat hydrated.

Be sure to have ample water nearby so your pet can drink anytime and stay hydrated. Usually, dehydration can lead to a loss of interest in eating. Placing an automatic water dispenser in a strategic location can also encourage your pet cat to drink water anytime.