Colitis and proctitis can cause a loss of nutrients, dehydration and pain in cats. Identifying the reason for the thickening in the digestive tract is critical in both diagnosing and treating colitis and proctitis.

Colonic inflammation, or colitis, occurs when the lining of the colon thickens, hindering the colon's ability to properly absorb water and store feces. Rectal inflammation, or proctitis, causes the lining of the lower part of the digestive tract, the anus and rectum, to thicken. Both types of inflammation typically occur when the digestive linings are infiltrated by various cells.

Symptoms may begin suddenly (acute) or develop slowly and worsen over time (chronic).

There are a variety of conditions that can cause colitis or proctitis to occur. These conditions include:

The veterinarian will need to know the cat's complete health history in order to diagnose and treat the cat. Explaining all of the cat's symptoms, as well as giving the approximate time that the symptoms first began, can help the veterinarian in diagnosing what is causing the colitis or proctitis. The veterinarian will gently examine the cat and perform a rectal palpation by using a gloved hand to feel inside the cat's rectum for any polyps or abnormalities.

Several labs will be performed in order for the veterinarian to see the impact that the inflammation is having on the cat's body and to determine why it is occurring. These labs include a complete blood count, urinalysis, and biochemical profile. The veterinarian will also want a stool sample from the cat in order to perform a fecal flotation test and a direct fecal smear. These tests will look for the presence of any parasites, bacteria, infectious organisms, and fungi.

An ultrasound and x-ray may be performed to help identify any tumors, physical abnormalities or impactions that may be causing the inflammation. A colonoscopy may also be performed. During the colonoscopy, the cat will be placed under general anesthesia while a thin tube with an attached camera is inserted into their colon through the rectum. The veterinarian can take tissue samples, remove any polyps and view any abnormalities from within the digestive tract during a colonoscopy. Tissues and polyps removed during the colonoscopy will be sent to an outside lab for further testing. 

Because colitis and proctitis can cause severe dehydration, the cat may need to be hospitalized in order to receive intravenous fluids. The cat will need to be hospitalized until their fluid levels have returned to normal. The cat's kidneys will be monitored during this time to ensure they are reacting well to the fluids.

If tumors or scar tissue are found in the colon or rectum during the examination, surgery will need to take place in order to remove the tumor or severely scarred sections. Fungal infections may also require surgery.

Anti-inflammatory medications, such as prednisone, may be prescribed in order to reduce the inflammation in the cat's digestive tract. Immunosuppressive drugs will be prescribed if the inflammation is the result of an autoimmune reaction. Fungal infections and parasites will also need to be treated with medications known as anthelmintics. Any other infections will be treated with antibiotics. 

The veterinarian may recommend that food be withheld from the cat for 24 to 48 hours in order to give the colon time to relax. After this, a low-residue, high protein diet will be prescribed. Food will first be given in small quantities and will be formulated to be digested easily. 

Cats with colitis or proctitis have a good prognosis with proper treatment. It's important to follow-up with the veterinarian to monitor medications, for follow-up testing and for treatment for any accompanying conditions, such as cancer. As environmental stress can cause relapses in colitis, it's important that the cat remains in a calm environment away from stressors, such as other animals or children, in order to prevent this from occurring.