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Feline Constipation

duddyby Jean Duddy, DVM


Constipation is a common feline problem and is defined as infrequent or difficult evacuation of feces.  Acute constipation due to a one-time pelvic trauma or soft tissue pain can be handled best by resolving the underlying problem.

Chronic constipation often is not a dysfunction of the colon but a result of other factors:

Medical issues: (other than colon)

  • Dehydration is the most common cause
    • Increased losses ‑ chronic renal disease, vomiting, diarrhea, or polyuria from diuretics
    • Decreased intake ‑ lack of availability of water, nausea, or oral diseases
  • Orthopedic issues ‑ arthritis (which can also limit water availability) or narrowed pelvic canal from healed trauma
  • Neurologic disorders ‑ as chronic disc disease or other diseases causing ataxia
  • Excessive fecal matter (bulk) secondary to high fiber diet


  • Manx cats with sacral spinal cord deformities


  • Opiates
  • Anticholinergics
  • Sucralfate

Environmental Factors: Stressors

  • Litter box issues (litter type, box location, box covering, or other cat interactions at the box)
  • Changes in household (someone moves in, moves out, change in work hours, etc.)

Colon Factors:

  • Intraluminal masses (polyps or colonic masses)
  • Mural – intussusception or perineal hernia
  • Extraluminal masses (compressive lesions)
  • Idiopathic Megacolon – a generalized dysfuntion of the colonic smooth muscle.

feline-constipationObstipation is intractable constipation.  Multiple episodes of constipation and obstipation may cause the colon to dilate and be poorly responsive to medications, this is known as megacolon.

Many cases of constipation are not recognized by our clients.  Firm pellets are reported as normal stools by the owner or if it is a multiple cat household or outdoor cat; the owner may be unaware of what the stools look like at all.  Cats are often presented as the signs become more obvious

  • Posturing or straining (often thought by the owner to be associated with the urinary system)
  • Feces passed with mucus or fresh red blood on the outside
  • Vocalization in the litter box or as they leave the litter box
  • Vomiting (commonly seen associated with the straining)
  • Decreased appetite, lethargy, dehydration, and weight loss

Physical exam often confirms the large amount of firmly packed feces in the colon.  Some cats will also have abdominal pain on palpation of the colon.  Close examination for pelvic trauma or perineal pain should be done as well as a rectal to evaluate for anal gland problems or masses.

Simple cases may be easily managed, but repeat cases or moderate to severe constipation cases should have a minimum data base to evaluate for any underlying diseases.  A CBC, serum chemistries and urinalysis will assess hydration, electrolytes and metabolic diseases.  Abdominal radiographs will confirm the constipation and assess how severe it is, and also will evaluate the pelvic canal opening.  The diameter of the colon on the lateral view should be approximately the same length as the body of the 2nd lumber vertebrae.

Whenever possible, correct any underlying etiology.  For cats with recurrent constipation episodes, medical management is required.

Maintain optimal hydration:  IV or subcutaneous fluids are used to correct dehydration, and balance any electrolyte issues.  At home increased water intake should be encouraged.

  • Feed canned foods or mix water with dry diets 1:1
  • Feed smaller multiple meals instead of one large meal
  • Use multiple bowls or water fountains throughout the home, cleaned often
  • Use larger bowls so that cat’s whiskers do not touch the sides
  • Use bottled water or flavored water (fish, chicken or beef broths)

Remove the impacted feces:

For mild constipation, one or two of a 5ml microenema containing sodium lauryl sulfoacetate (Microlax) may produce the desired effects in 20-30 minutes.  Pediatric rectal suppositories may also be used; these include dioctyl sodium sulfosuccinate = DSS (Colace™), glycerin or bisacodyl (Ducolax™).

Moderate constipation or obstipation will require larger volume enemas which are given slowly using a red rubber catheter (usually 10-12 French).  Enemas given too rapidly may induce vomiting.  Water or isotonic saline solutions at 5-10ml/kg are given.  Safe additions to this are mineral oil (5-10ml/cat), DSS (5-10mls/cat), or lactulose (5-10ml/cat).  Do not use DSS and mineral oil together in the same enema, DSS will promote mucosal absorption of the mineral oil.

Do not use enema solutions containing sodium phosphate (Fleet™) as they predispose to life-threatening electrolyte imbalances (hypernatremia, hyperphosphatemia and hypocalcemia).

Manual removal of the feces while under anesthesia may be required if enemas fail to produce expected results.  All cats should be intubated due to the risk of vomiting when large amounts of warm water are infused into the colon with massage and breaking down of fecal material.

Oral polyethylene glycol (PEG3350) administration through a nasogastric tube has been used as an alternative to enemas.  It is given as a slow trickle at 6-10ml/kg/hour.  PEG 3350 (GoLytely, CoLyte) is an osmotic laxative, a large molecular weight water soluble polymer which is minimally absorbed in the gut.  It binds water and prevents its absorption out of the intestines.  Defecation occurs usually in 6-12 hours.

Dietary therapy, specifically high fiber diets or low residue diets, have been our first line of home therapies along with increased water consumption for constipation.  High fiber diets stimulate the production of short chain fatty acids and distend the colon with bulk both of which help stimulate normal colon contraction.  The ones often used are insoluble fiber sources: psyllium (Metamucil™) 1-4 tsp with food/12-24hr, canned pumpkin 1-4 tbsp with food/24hr and coarse wheat bran 1-2 tbsp/24hr.

Laxatives are used at home as part of medical management of constipation.  Lubricant laxatives impede water absorption and enable easier passage of stool.  Hairball remedies 1-5ml PO q24hrs are only advised in very mild cases of constipation.  Mineral oil is in this category, but due to the liquid having no flavor and therefore an increased risk of aspiration, it is better used as part of an enema.

Hyperosmotic laxatives are the most commonly prescribed laxatives and they stimulate colonic fluid secretion and propulsive motility.  Lactulose (0.5ml/kg/8-12 hrs)and Kristalose (3/4th tsp/12hr) are lactulose crystals that can be sprinkled over the food. Miralax (PG3350) 1/8-1/4tsp/cat 12hr can also be used.

Promotility drugs are also commonly used to help stimulate motility from the esophagus aborally.

Cisapride, a benzamide prokinetic drug may help with mild constipation, 2.5 – 5.0mg/cat /8-12 hr.  Newer promotility drugs are being evaluated for future use.

Other home improvements may also help cats with constipation.  Be sure there are enough litter boxes for the number of cats in the house.  If the cat has arthritis, be sure the litter box is in an accessible area that allows privacy.  Keep in mind the cat may not go up and down stairs well.  Try cutting down one end of the litterbox for easy access.  Be sure the area around the little box is well lit.

Cats with chronic constipation or megacolon, that are not responding to medical management, should be evaluated to see if they are candidates for subtotal colectomy.  Most patients do well with only a few weeks of diarrhea during the post op time period.

For more information, contact Angell’s Internal Medicine service at 617-541-5186 or

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