Cats can suffer from some process of constipation throughout their lives, especially related to stressful conditions of which they are so sensitive, such as reforms, changes in their routine, introduction of a new animal or person at home, or it can be derived from some obstructive or neurological process that affects the colon and that usually has a favorable prognosis once the cause is resolved. However, on other occasions, chronic constipation caused by some cause of prolonged constipation over time that has not been resolved, some more serious, idiopathic or congenital pathological process can cause the cat to develop a megacolon or, what is the same, a dilation of the colon with accumulation of hard stools in it and hypomotility that produces severe constipation.
If you want to know the causes, symptoms, diagnosis and treatment of megacolon in cats, continue reading this article on our site.
What is megacolon in cats?
Megacolon in cats is defined as a severe and irreversible dilation of the colon with fecal retention and hypomotility of the colon. In other words, the colon increases in size, which causes feces to accumulate and lose tone, making defecation difficult and causing constipation in affected cats.
In cats, intestinal transit lasts between 12 and 24 hours from ingestion to evacuation of feces, and can sometimes be prolonged without adverse effects. However, if stool is retained for a long time, the colon will continue to extract water from the stool until it forms hard and painful concretions to pass, leading to to constipation. If this constipation is chronic, the deposit of feces generates a severe dilatation of the colon and it may lose the ability to contract, producing a megacolon.
For this reason, when faced with a cat with constipation, the cause must always be found, since untreated chronic constipation can lead to a megacolon.
Causes of megacolon in cats
Most cases of megacolon in cats, around 62%, are idiopathic, that is, they have no apparent cause, followed by obstructive cases of the colon (24%), produced by neurological damage (11%), congenital or by other causes that produce chronic constipation in cats.
Idiopathic megacolon
This megacolon occurs most often in elderly male cats over 8 years old in which no organic lesion is found. It is believed that it may be due to a primary neuromuscular degeneration of the smooth muscle of the colon, which causes chronic constipation and subsequent megacolon. It is diagnosed by excluding the rest of the causes.
Megacolon due to obstructive cause
Megacolon in cats can be caused by processes that trigger obstruction in the colon and make fecal evacuation difficult. Some pathologies that can produce this are the following:
- Pelvic canal stenosis secondary to fractures.
- Pelvic canal stenosis secondary to malformations such as rickets.
- Traumatic stenosis or intraluminal mass in colon, rectum, or anus.
- Extraluminal compression due to neoplasia or perineal hernia.
- Spinal injuries (cauda equina syndrome).
Megacolon due to neurological damage
In some cases, neurological damage can cause hypomotility of the colon, fecal retention, colonic dilation and the development of megacolon. These causes can be:
- Neuromuscular alteration due to sacro-coccygeal trauma.
- Alteration in the pelvic nerve and hypogastric due to trauma or dysautonomia.
Congenital megacolon
Sometimes a megacolon occurs in kittens, arriving for consultation in their first weeks of life due to severe fecal retention. In these cases, it is usually caused by the following congenital diseases:
- Anorectal agenesis.
- Aganglionosis: absence of contraction-inhibiting neurons, resulting in permanent contraction of the smooth muscle of the colon or rectum, causing obstruction and megacolon.
- In the Manx cat, due to partial or complete absence of the caudal and sacral spinal segment.
Megacolon due to chronic constipation
Finally, megacolon can be caused by chronic constipation due to:
- Stress/fear due to moving, renovations, introduction of other animals, changes in the arena, hospitalization, inactivity or aversion to the tray of sand. For more information, don't miss this other article on Stress in cats.
- Joint pain causing difficulty defecating or in the rectum or perineal area.
- Colon stricture due to foreign body, neoplasm, perineal hernia, rectal diverticulum or due to pelvic fractures, neoplasm, prostate disease, neoplasm or granuloma.
Symptoms of megacolon in cats
Cats with megacolon may exhibit the following clinical signs:
- Painful attempt to defecate (manifested with meowing) and tenesmus (sensation of needing to defecate).
- Prolonged constipation (chronic).
- Feces out of the litter box because they feel rejection of it because they relate it to suffering pain when defecating when they use it.
- Secretion of bloody liquid content due to irritation of the colonic mucosa.
- Ptyalism (excessive salivation).
- Vomiting in cats with severe conditions due to irritation of the colon and absorption of toxins.
- Anorexia, lethargy and weakness.
- Dehydration.
- Electrolyte Imbalances.
- Hard tubular mass throughout the abdomen on palpation.
- Sometimes diarrhea, sometimes with blood and mucus.
Diagnosis of megacolon in cats
Megacolon must be diagnosed through the use of several diagnostic tests without neglecting a good medical history, anamnesis and general examination of the cat to assess its general state of he alth, hydration status, body condition and mental status, while obtaining information on the possible cause or causes that are producing this chronic constipation due to megacolon. It will be necessary to perform a complete blood and urine analysis
The diagnostic technique of choice for diagnosing a case of megacolon in cats is abdominal radiography With this imaging technique too pelvic canal strictures and masses can be ruled out. With radiography it can also be differentiated from severe chronic constipation by comparing the ratio between the thickness of the colon and the length of the body of the L5:
- A ratio <1.28 is an indicator of a normal colon.
- A ratio between 1.28-1.48 suggests constipation.
- A ratio >1.48 good indicator of megacolon
- A ratio >1.6 is diagnostic of megacolon
Other imaging techniques useful for diagnosis can be abdominal ultrasound, colonoscopyand the magnetic resonance imaging , especially for cases of obstructive megacolon.
Treatment for megacolon in cats
The treatment of a feline megacolon must combine dietary therapy with medical therapy through the use of drugs and products that facilitate the exit of the feces In some cases, surgical treatment will be necessary.
Feline megacolon dietary treatment
The diet for a cat with megacolon should be high in moisture, increasing the water content in the diet by using wet complete food, wet snacks such as milk for adult cats or soups (also suitable for cats), as well as adding water to dry diets with feed.
It can also be a good option to add insoluble fibers such as Pysillium, which increase the water content of the stool and the frequency of defecation. However, they add bulk to the faeces, which can be detrimental to an already damaged colon, so they should be given only early in the disease and in well-hydrated cats.
Medical treatment of feline megacolon
If you wonder how to treat megacolon in cats, you should know that a specialist must prescribe the appropriate medications. Thus, the medical treatment to treat feline megacolon when diet is not enough consists of the use of the following groups of drugs:
- Laxatives: added when diet modification is not enough. Lactulose can be used at a dose of 0.5 ml/kg every 8-12 hours, polyethylene glycol 3350 (Movicol Pediatric powder for solution®) at a dose of 1/8 to 1/4 teaspoon, every 12 hours on food or bisacodyl (Dulcolaxo 5 mg) at a dose of 5 mg/24 hours orally. They stimulate mucosal secretion and colonic contractility, but continued use can damage enteric neurons
- Prokinetics such as ranitidine can help, but once the accumulation of feces is corrected to stimulate colonic motility.
- Enemas: to facilitate passage of stool by introducing fluids that facilitate passage, such as 5 mL of lauryl sulfoacetate (Micralax ®) or bisacodyl (Dulcolaxo suppositories ®) in mild cases. If the case is severe, enemas should be applied through a well-lubricated 10-12 French feeding tube of warm water (5-10 ml/kg) with mild soap or mineral oil (5-10 ml/cat) (Hodernal®) or lactulose (5-10 ml/cat) (Duphalac syrup®).
- Manual extraction: This procedure will only be performed in very severe cases and always with the cat generally anesthetized and hydrated. After the administration of an enema, the stool is manipulated through the abdominal wall or through the rectum. This can damage the mucosa of the colon with the increased risk of absorption of toxins and bacteria into the blood, so prophylactic antibiotics should always be administered.
Surgical treatment of feline megacolon
When the cat suffers from recurrent megacolon, a surgery called ' subtotal colectomy' can be performed, which consists of removing between 95 -85% colon and has a generally good prognosis. Stools may be liquid at first after surgery, but improve in 1 to 6 weeks if you don't have other illnesses that cause diarrhea, such as small intestinal bacterial overgrowth (SIBO) or inflammatory bowel disease (IBD).
