Megacolon in Cats
The colon is the section of large intestine that begins at the cecum, the sac that joins the colon to the end of the small intestine (ileum). From there it proceeds to the rectum in the digestive tract. The main purpose of the colon is to serve as a temporary storage conduit for waste products, extracting water and salt from the waste as it passes through and out of the body. When a condition causes the diameter of the colon to become abnormally enlarged, it is medically referred to as megacolon. This condition is associated with chronic constipation, and with obstipation – severe, obstinate constipation that blocks the passage of gas as well as feces. Minimal colonic activity, where the colon is not releasing its contents, is another condition that can lead to abnormal enlargement of the colon.
Megacolon can be a congenital or acquired condition. Cats with congenital megacolon lack normal smooth muscle function of the colon. Megacolon can also be acquired, such as when feces is chronically retained and the fecal water is completely absorbed. The water and matter bond, and the feces becomes solidified within the colon. If concreted feces remains lodged in the colon for a prolonged period of time, distention of the colon will occur, resulting in irreversible colonic inertia (inactivity). Colonic inertia is characterized by the smooth muscle of the colon no longer contracting or expanding to void feces.
Symptoms and Types
Constipation: feces is trapped in the colon
Obstipation: severe blockage that impedes both feces and gas, keeping them trapped in the colon
Infrequent defecation
Straining to defecate with small or no fecal volume
Small amount of diarrhea may occur after prolonged straining
Hard, dry feces
Hard colon felt with abdominal examination (palpation)
Fecal impaction can be felt when a gloved finger is inserted into the rectum
Occasional vomiting, anorexia and/or depression
Weight loss
Dehydration
Scruffy, unkempt hair coat
Causes
Unknown (idiopathic) in most cats
Congenital (present at birth); the Manx breed appears ot be at higher risk
Mechanical obstruction of feces
Trauma to the body
Limb and/or pelvic fractures
Metabolic disorders
Low serum potassium
Severe dehydration
Drugs
Vincristine: used for lymphoma and leukemia
Barium: used for enhancing x-ray images
Sucralfate: used for treating ulcers
Antacids
Neurologic/neuromuscular disease
Spinal cord disease
Intervertebral disk disease
Disease of the anus and/or rectum
Diagnosis
Your veterinarian will perform a thorough physical exam. A complete blood profile will be conducted, including a chemical blood profile, a complete blood count, an electrolyte panel, and a urinalysis. The doctor will also perform an abdominal palpation (examination by touch) of the colon, and a manual examination of the rectum, by digital (finger) rectal penetration. You will need to give a thorough history of your cat’s health, including a background history, onset of symptoms, and possible incidents that might have precipitated this condition.
Abdominal radiograph imaging is useful for a visual examination of the colon. Recorded images will show whether the colon is full of feces, if there is a mass blockage in the colon, or if there are any other underlying causes of megacolon. An internal examination of the colon, using a lighted tubular instrument called a colonoscope may be performed if obstructive lesions inside the colon, or in the wall of the colon, cannot be ruled out.
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neuromuscular
The area found between the muscles and the endings of the nerves
megacolon
The term for a colon that is enlarged abnormally
lymphoma
A term for a type of neoplasm that is made up of lymphoid tissue; these masses are usually malignant in nature
palpation
Examination through feeling
radiograph
A record of body structures using an x-ray
urinalysis
An in-depth examination of the properties of urine; used to determine the presence or absence of illness
rectum
The very end of the large intestine
leukemia
An increase in the number of bad white blood cells
inject
To mechanically introduce a substance into a living thing
dehydration
A medical condition in which the body has lost fluid or water in excessive amounts
defecation
The exiting of excrement from the body; bowel movements.
digestive tract
The whole system involved in digestion from mouth to anus
distention
The process of making something larger by dilating or stretching it
ileum
The term for the last part of the small intestine, between the jejunum and the large intestine.
idiopathic
Relating to a disease of unknown origin, which may or may not have arisen spontaneously
anus
The end of the gastrointestinal tract; the opening at the end of the tract.
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