Cat Constipation: Why Your Cat Can't Poop and How to Help
Follow Us
Introduction
Feline constipation can be a frustrating and distressing condition for both cats and their owners. Understanding the causes, symptoms, and treatment options is essential to ensuring your cat’s comfort and health. In this comprehensive guide, you’ll discover:
- The difference between constipation, obstipation, and megacolon
- Symptoms associated with constipation
- Causes and risk factors
- How veterinarians diagnose constipation
- Recommended workup and diagnostic tests
- Initial and long-term treatment strategies
- How to monitor your cat's progress
- The prognosis and what to expect
This guide is designed to empower you with the knowledge to understand and manage feline constipation effectively, helping your cat lead a happier, healthier life.
Definitions and Overview: What is Feline Constipation?
Constipation refers to difficulty or infrequent passing of stools, for example, defecating every 2-4 days rather than the typical once-a-day observed in healthy cats. Feces are often hard, dry, and reduced in volume. Constipation can affect cats of all ages but is more prevalent in middle-aged to older cats.
Although constipated cats experience difficulty defecating, they are still able to pass stools. However, feces retained in the colon for prolonged periods gradually become drier and harder to pass as one of the colon's primary functions is water absorption. If feces continue to accumulate and become drier and harder, they eventually form a complete obstruction. Once a cat is unable to produce any stools due to an impaction and blockage of feces in the colon, this is referred to as obstipation.
If a cat experiences repeat episodes of obstipation, the colon can become stretched, severely dilated, and lose its motility, increasing its tendency for fecal impaction. This condition is referred to as megacolon.
Idiopathic/primary megacolon occurs when there is a gradual loss of colonic smooth muscle function and motility. The colon is unable to contract and push feces along, causing a buildup of fecal material. Repeated episodes of constipation and obstipation damage and stretch the colon wall, leading to severe dilation and fecal impaction. The condition is not reversible, and function is permanently lost. The term "idiopathic' means there is no identifiable cause, and the exact reason idiopathic megacolon occurs is not yet fully understood.
Secondary megacolon occurs as a result of a condition that causes constipation, such as an obstruction (mass, stricture, pelvic fracture resulting in a narrowed pelvis), neurological disorder, or congenital hypothyroidism. If a cat becomes repeatedly obstipated, the muscles in the colon wall become increasingly stretched and damaged over time. This results in a severely dilated colon, which can no longer contract properly to move feces along. Although the damage is often permanent, colon function may improve if the underlying cause is addressed within 6 months.1
%2520megacolon%2520vs%2520secondary%2520megaolon%2520in%2520cats.webp)
Recognizing the Signs of Constipation in Cats
Signs of constipation can range from mild, such as a cat that has started defecating less often than normal, to severe, where a cat is unable to produce feces and becomes inappetent and lethargic.
It can be challenging to observe how often your cat defecates and if they are having difficulty passing stools, especially if they toilet outside or you have a multi-cat household. However, it is important to try to observe your cat's toileting behavior so issues can be identified and addressed early on.
Common symptoms of constipation in cats include:
- Straining: Prolonged or repeated attempts to defecate with increased effort that may be unproductive.
- Hard, dry stools: Feces are often hard, dry, and reduced in volume.
- Pain: Signs of discomfort or vocalization during defecation, or numerous aborted attempts to defecate.
- Reduced frequency: Healthy cats defecate approximately once per day. If they are defecating less often, or not at all, it could be a sign of constipation.
- Outside the litter box: If a cat associates painful defecation with litter box use, they may start defecating elsewhere.
- Blood or mucus: May be seen in the stool due to irritation of the intestinal tract lining or from prolonged straining.
- Reduced appetite: Cats often don't feel like eating due to the discomfort.
- Vomiting: Can occur if the intestines become blocked with feces preventing the flow of content through the gastrointestinal tract, the colon stretches and triggers the brain's vomiting center via the vagus nerve, or if toxins leak into the bloodstream from the buildup of waste products causing nausea.
- Lethargy: Cats may have reduced energy levels.
- Weight loss: If constipation has occurred for a while, they may lose weight.
- Protrusion of tissue: Tissue may protrude at the rectum (rectal prolapse) due to chronic straining.
- Motion-activated recording or watch live with two-way audio
- Night vision
- Monitor for signs of straining or difficulty defecating, helping you spot potential constipation issues.
- In multi-cat households, if hard, dry stools are found in the litter box, the camera helps determine which cat may be experiencing issues.
Feline Constipation Causes and Risk Factors
1. Idiopathic Megacolon
"Megacolon" refers to a large, dilated colon that has permanently lost its motility and ability to contract, leading to an accumulation of feces. "Idiopathic" means the cause is unknown but is suspected to be due to reduced smooth muscle function within the colon wall.
Before diagnosing idiopathic megacolon, it's crucial to rule out other causes of constipation to identify any treatable underlying issues.
2. Dehydration
Dehydration commonly causes constipation as the body attempts to maintain the correct water balance by absorbing extra water from the colon, making the stool dry and difficult to pass. Dehydration usually occurs due to an increase in water loss, or a reduction in water intake.
- Increased water loss: Diseases that cause an increase in urine production, such as chronic kidney disease and diabetes mellitus; medications that cause an increase in urine production, such as diuretics used to treat heart failure; or significant vomiting.
- Inadequate water intake: Water may be unavailable, difficult to access, or the cat may be reluctant to drink.
3. Obesity
Obese cats may make less frequent trips to the litter box if they find it difficult to enter, leading to drier, larger stools that are harder to pass. Carrying extra weight can also make it difficult for obese cats to posture correctly to defecate, leading to incomplete elimination of stools.
4. Inactivity
Inactivity may slow down intestinal motility and the passage of stools, leading to constipation. Cats may be inactive due to a sedentary lifestyle, confinement to a small space, for example, if they are hospitalized or boarding, or medical conditions that restrict their movement, such as a fractured limb or paralysis.
5. Intraluminal Obstruction
Constipation can occur due to an obstruction within the large intestine, with "intraluminal" meaning within the lumen of the intestine. Conditions that cause constipation due to a blockage or narrowing of the large intestine from the inside include:
- Mass: Masses associated with the intestinal wall, such as cancerous tumors (e.g. adenocarcinoma, lymphoma, mast cell tumor) or benign growths (e.g. polyps), can cause a complete or partial obstruction.
- Foreign body: If a cat consumes non-digestable or slowly digestible material, it will usually obstruct the stomach or small intestines, leading to vomiting. If an item has made it through the small intestine, it is unlikely to obstruct the large intestine, which has a wider diameter. However, large amounts of ingested hair, cat litter, string, bone, plastic, plant, and other material may become incorporated into feces in the colon, producing hard fecal balls that are difficult to eliminate. Additionally, a foreign body may get lodged prior to the anus, causing pain and an inability to defecate.
- Stricture: Narrowing of the rectum or colon that usually develops secondary to inflammation (e.g. colitis) or previous trauma (e.g. a foreign body). Rectal strictures can also be congenital (a kitten is born with the abnormality).
- Anal atresia: A congenital condition present at birth in kittens, where the anus develops abnormally. The anal opening may be narrow, completely closed, or appear normal but not connect to the rectum, instead ending in a blind pouch.
6. Extraluminal Obstruction Outside the Large Intestine
Constipation can occur due to an obstruction outside the large intestine, with "extraluminal" meaning outside the lumen of the intestines. Conditions that cause constipation due to a blockage or narrowing of the large intestine from the outside include:
- Pelvic canal narrowing: Usually occurs if a cat traumatically fractures their pelvis and it heals in an abnormal position (malunion) that is narrower than normal.
- Mass: Masses associated with structures adjacent to the large intestine, such as other abdominal organs, the anal glands, or pelvis, can compress or obstruct the intestines.
- Lymphadenopathy: The sublumbar lymph nodes (located near the lower spine) can become significantly enlarged due to cancer or a severe infection, compressing the colon.
- Matted hair: Also known as pseudocoprostasis, hair can become matted with feces around the anus, especially in long-haired or obese cats, or following an episode of diarrhea, which obstructs the passage of stools.
- Perineal hernia: Muscles around a cat's bottom weaken, allowing the rectum to push through (herniate), sometimes seen as a bulge next to the anus, which creates a pocket that traps fecal matter. Causes of perineal hernias include trauma, disorders that lead to persistent straining to urinate or defecate, or remains unknown.
7. Pain When Posturing
As well as making it harder to get into the litter box, painful conditions can make it difficult for cats to squat comfortably, leading to a reluctance to poop and the subsequent development of constipation. Painful conditions that may affect correct posturing include:
- Arthritis
- Hip dysplasia
- Back pain
- Fractures
- Dislocated joints
- Recent surgery
8. Pain When Passing Feces
Conditions that cause pain while defecating can lead to an avoidance of the litter box and pooping. Examples of such conditions include:
- Anal sac abscesses (an infection of the glands located just inside the anus at 4 and 8 'o'clock)
- Bite wounds around the anus from cat fights
- Rectal foreign bodies
Constipation itself and the passing of dry, hard, impacted stool is also painful, which can contribute to the worsening of clinical signs.
9. Disuse of the Litter Box
If a cat is unwilling to use their litter box, they may hold in their stools, leading to constipation. A cat may be dissuaded from using their litter box for the following reasons:
- Dislike the litter box or litter substrate: Cats may avoid using a litter box that is too dirty, too small, covered, or that they have developed a negative association with, for example, due to painful urination or defecation. Signs they dislike the litter substrate include avoiding touching the substrate by perching on the edge of the box or not digging, using the box and then quickly exiting, or eliminating next to the box.
- Difficult to access: If the litter box is in a location that is unnerving or difficult to access, they may stop using their litter box. Competition with other cats or fear of being ambushed can also prevent access.
- Environmental stress: A change to an unfamiliar environment, such as during hospitalization or boarding, can be stressful, and a cat may not use the litter box provided.
10. Electrolyte Abnormalities
Electrolyte imbalances can impair muscle function, including the smooth muscle in the intestinal wall, slowing down bowel movements and leading to constipation. The two most common electrolyte abnormalities that contribute to constipation are hypokalemia and hypercalcemia.
- Hypokalemia (low potassium): Conditions such as chronic kidney disease or prolonged anorexia can reduce potassium levels in the body. Cats with low potassium levels often also feel weak.
- Hypercalcemia (high calcium): Conditions such as kidney disease or cancer can increase calcium levels in the body, but in many cases, the cause is unknown (idiopathic). Other clinical signs may include increased thirst and urination, lethargy, anorexia, and vomiting, or the cat may show no other symptoms.
11. Hypothyroidism
Hypothyroidism occurs when the thyroid gland in the neck does not produce enough thyroid hormones, slowing metabolism and intestinal motility, which can lead to constipation.
Congenital hypothyroidism (present at birth) is a rare condition that becomes noticeable as kittens develop. They may show signs of constipation, lethargy, abnormal hair coat, and stunted growth.
It is extremely rare for adult cats to spontaneously and naturally develop hypothyroidism. Adult-onset hypothyroidism is typically associated with the over-treatment of hyperthyroidism with radioactive iodine, surgery, or drugs, known as iatrogenic hypothyroidism (caused by medical treatment). Signs may include decreased kidney function, lethargy, poor hair coat, and weight gain despite a poor appetite.
12. Neurological Disorders
Neurological disorders can impact a cat’s ability to regulate bodily functions, including defecation. The following neurological disorders can contribute to constipation in cats:
- Manx syndrome: Since the tail is an extension of the spine, breeding a cat to be tailless may result in abnormal development of the base of the spine and the associated nerves that innervate the hind limbs, colon, and bladder. This can lead to neurological problems, such as an abnormal hindlimb gait and loss of control over urination and defecation, usually becoming apparent during kittenhood.
- Lumbosacral disease: Disorders that affect the lower back, such as intervertebral disc disease (discs between the spinal vertebrae degenerate and herniate), may cause clinical signs such as hindlimb weakness, and loss of bladder and bowel control. In some cases, fecal incontinence (leakage of stools) may occur, while others may develop constipation, not only due to the impact on nerves responsible for bowel function but also due to pain and difficulty posturing to pass feces, and a lack of activity if their movement is restricted.4
- Pelvic nerve injury: Injuries to the pelvic area, such as tail-pull injuries from road traffic accidents, can damage nerves that control defecation, leading to urinary and fecal incontinence, constipation, and hindlimb weakness. Constipation can occur as a result of pelvic nerve damage, but defecating may also be inhibited due to pain, an inability to raise the tail, and an inability to posture correctly to defecate.
- Dysautonomia: A rare condition that causes degeneration of the autonomic nervous system, which controls involuntary body functions, leading to reduced gut motility and constipation. Other symptoms may include lethargy, anorexia, vomiting, difficulty swallowing, urine retention, dilated pupils, and dry eyes.
13. Medications
Certain drugs may result in constipation by slowing down colonic motility. A variety of drugs can potentially cause constipation, with some of the more commonly used ones including:
- Opioids
- Barium sulfate
- Iron supplements
- Antihistamines
- Aluminum hydroxide
- Sucralfate
- Fluoxetine
How Veterinarians Diagnose Constipation in Cats
A veterinarian will typically diagnose constipation by palpating (feeling) a cat’s abdomen (belly). The veterinarian may feel hard, impacted feces in the colon, either as a long tube or multiple lumps, and the abdomen may feel painful or uncomfortable.
Additionally, an abdominal radiograph (X-ray) may be taken to confirm the diagnosis and assess the extent of constipation. Radiographs are also helpful if the abdomen of a cat cannot be easily palpated, for example, if the cat is obese, frightened, has a fractured pelvis, or is recovering from recent abdominal surgery.
Cat A has no issues with defecation and produces normal stools once a day.
Cat B is still able to pass stools but frequently strains to defecate and has chronic constipation secondary to a previous pelvic fracture. Since he does not defecate regularly, the stools on the radiograph appear bunched up and more opaque (whiter) than normal, indicating they are dry.
Cat C is obstipated (unable to defecate due to fecal impaction) and was diagnosed with idiopathic megacolon. The colon is extremely dilated and filled with dense, dry stool. Research indicates that if the maximum diameter of the colon is greater than 1.48 times the length of the fifth lumbar (L5) vertebral body on a lateral abdominal radiograph, it suggests megacolon. A value greater than 1.62 is definitive for megacolon, while a value of <1.28 strong indicates a normal colon.⁵
Feline Constipation Workup: What to Expect
The diagnostic tests recommended by your veterinarian will depend on your cat's clinical signs, medical history, physical exam findings, and budget considerations.
1. History Taking
Your veterinarian will ask when your cat's signs of constipation started, if they are passing any feces, what the feces look like, and if your cat has experienced previous episodes of constipation. They will also want to know if your cat is showing any other signs of ill health, such as lethargy or vomiting, or if there have been any changes in eating and drinking habits, urination, gait, or body weight. Additionally, a vet may enquire about your cat's litter box setup, medication history, and previous trauma.
2. Physical Examination
- Body condition score: Obese cats are prone to constipation, while underweight cats may have an underlying disease contributing to constipation that needs to be identified.
- Abdominal palpation: A vet will feel a cat's belly to assess the severity of impacted feces. Masses or foreign bodies may also be palpated, although these can be difficult to distinguish from fecal balls.
- Hydration status: Dehydration is a common cause of constipation and by feeling your cat's gums and performing a skin tent test, your cat's hydration level can be estimated.
- Signs of pain: Pain due to a sore back, arthritis (painful joints), or wounds can cause difficulty defecating. If a cat is painful they may flinch, move away, or hiss when a painful area is touched during an exam.
- Coat condition: Overgrooming, for example, due to allergies and itchy skin, particularly in longhaired cats, may contribute to constipation. Hair matting around the anus should also be evaluated.
- Neurological examination: A complete neurological exam is performed with emphasis on the lower spinal cord and nerve function. This includes assessing for spinal pain, hindlimb coordination, proprioception (e.g., correcting a flipped paw indicating they are aware of where their limbs are positioned), decreased anal tone, and if the tail is limp or painful when elevated. Signs of dysautonomia, such as dilated pupils, protruding third eyelids, dry eyes and nose, and a slow heart rate, may also be assessed.
- Rectal examination: Often performed under sedation or general anesthesia as it's uncomfortable, to check for pelvic narrowing, perineal hernias, rectal strictures, masses, enlarged sublumbar lymph nodes, foreign bodies, anal gland abnormalities, and prostate abnormalities (rare in cats). Kittens should also be checked for anal atresia.
3. Blood Tests
- Electrolytes: Electrolyte imbalances, particularly high calcium and low potassium levels, are risk factors for constipation.
- Kidney function: Interpreting kidney parameters alongside a urinalysis is crucial. Elevated creatinine and urea with dilute urine indicate reduced kidney function. Elevated creatinine and urea with concentrated urine (USG ≥1.035) indicate dehydration. An elevated total protein and red blood cell count may also be noted in dehydrated patients.
- Thyroid function (T4/TSH): This test is for kittens suspected of congenital hypothyroidism (e.g., presenting as constipated with stunted growth) and adult cats potentially overtreated for hyperthyroidism.
4. Imaging
Imaging is often performed after fecal removal to improve visualization. Radiographs are commonly used, with additional diagnostic imaging techniques being case-dependent.
- Radiographs: Used to take images of the abdomen and pelvis, as well as the hindlimbs if indicated, to assess for megacolon, spinal abnormalities, pelvic narrowing, arthritis, fractures, luxations, masses, foreign objects, enlarged sublumbar lymph nodes, and perineal hernias.
- Ultrasound: Used to identify and sample masses in the abdomen, and evaluate the kidneys if renal disease is suspected.
- Colonoscopy: Allows for the identification of masses, polyps, foreign bodies, and strictures inside the colon.
- CT/MRI: Advanced spinal imaging may be warranted if neurological abnormalities are detected and spinal disease is suspected.
Initial Treatment to Relieve the Constipated Cat
Initial treatment of constipation in cats involves stabilization with fluids, correcting electrolyte imbalances, providing pain relief, addressing nausea, and carefully removing impacted feces. The exact treatment plan will depend on the severity of your cat's constipation and your veterinarian's assessment.
1. Correct Dehydration
Dehydration is both a cause and a complication of constipation since dehydration worsens stool hardness making defecation more difficult. If present, dehydration must be corrected before fecal removal to improve water content in the colon.
Subcutaneous fluids (under the skin) may be beneficial for mild cases of constipation. Intravenous fluids (directly into the vein) are preferred for moderate-severe cases of constipation and require hospitalization. Intravenous fluids can also be used to correct electrolyte abnormalities, for example, they can be supplemented with potassium if cats have low potassium levels due to chronic kidney disease or inappetence.
2. Pain Relief
Passing dry, hard feces can be painful, and untreated pain discourages cats from attempting to defecate. Opioids are commonly used to relieve pain, and while they may reduce bowel motility slightly, pain relief outweighs this concern during acute treatment.
3. Anti-Nausea
Straining to defecate can cause cats to feel nauseous, and they may abort their attempt to pass stool. Nausea can also deter cats from eating and drinking, which worsens their condition. Additionally, procedures to relieve constipation, such as enemas (especially when large volumes are administered quickly) and colonic massage under general anesthesia can trigger vomiting.
Anti-nausea medications, such as Cerenia (maropitant), may be administered to alleviate nausea and prevent vomiting.
4. Fecal Removal
Various procedures may be employed by a veterinarian to remove feces and alleviate discomfort. These methods range from mild, less invasive techniques to more intensive procedures, depending on the severity of the constipation.
- Rectal suppository laxatives: One to two doses of a 5 ml microenema, such as Pet-Ema, administered rectally may help lubricate and soften stools in mild cases of constipation. Results are usually seen within 20–30 minutes. Always follow veterinary guidance for proper dosing and use.
- Warm water enemas: A veterinarian may administer a warm water or isotonic saline enema (approximately 5-10 ml/kg) via a lubricated catheter inserted into the rectum. Lubricant gels and laxatives, such as lactulose, are typically added to the enema to improve its effectiveness. Depending on the severity of the constipation, the enema may be repeated 2-3 times over 12-24 hours. Enemas are administered slowly and cats are pre-treated with Cerenia (anti-nausea medication) to reduce the risk of vomiting.
- Oral PEG 3350 solution: In some cases, a cat may be hospitalized to receive an oral polyethylene glycol (PEG) 3350 solution (e.g., CoLyte or GoLytely). A veterinarian will place a nasogastric feeding tube, which enters the stomach through the nose, to slowly trickle-feed the solution at approximately 6–10ml/kg/hour. A study reported the median time to defecation was 8 hours.6
- Manual disimpaction: For severe impactions, feces may need to be manually removed by a veterinary professional. Careful abdominal massage with simultaneous administration of warm water enemas is used to break down the stools, which are then gently milked along the colon and extracted per the rectum. Since manipulation of the colon is uncomfortable and can trigger vomiting, the procedure is performed under general anesthesia with a cuffed endotracheal tube to protect the airway and prevent aspiration of any vomit into the lungs.
Long-term Management of Cats with Constipation
Chronic constipation requires ongoing care tailored to your cat's specific needs and adjustments based on their response. It's important to regularly communicate with your veterinary team to discuss if treatments are helping or worsening the constipation, or if there is a lack of response. Below are key points to consider for the long-term management of feline constipation to help keep cats comfortable and prevent future episodes.
1. Manage Any Underlying Medical or Surgical Conditions
Addressing any underlying medical or surgical conditions contributing to constipation is essential for improving outcomes. For instance, cats with arthritis may benefit from pain relief; those with chronic kidney disease may require management of fluid and electrolyte balance; cats with a narrowed pelvic canal due to a previous pelvic fracture may benefit from pelvic osteotomy surgery; and kittens with congenital hypothyroidism need thyroxine supplementation.
If a cat receives medication for a different condition that could be causing constipation, consult your veterinarian to discuss potential alternative options.
2. Diet
Dietary changes play a significant role in managing constipation but finding the most effective diet can involve trial and error. The best diet for your cat depends on the underlying cause and severity of their constipation, as well as any additional health concerns that need to be managed. It is always recommended to consult your veterinarian to discuss diet options.
There are two main feeding strategies for managing feline constipation:
- Fiber-Enhanced Diets: These diets include a combination of fibers (non-digestible carbohydrates) that are both insoluble (to increase fecal bulk and stimulate the urge to defecate) and soluble (to absorb water and form a gel that softens stools).
- Low-Residue Diets: These diets contain highly digestible ingredients and use appropriate processing techniques to maximize digestibility. This ensures that the majority of the diet is absorbed and utilized, leaving little waste. As a result, these diets produce smaller stools, which can help reduce the risk of fecal impaction.
A fiber-enhanced diet tends to be most beneficial for cats with mild constipation. For more severely affected cats, fiber may be detrimental, and low-residue diets may be a better choice.
Fiber-enhanced diets formulated for cats contain a mixture of soluble and insoluble fibers. Soluble fiber absorbs water and dissolves to form a gel, which helps soften and lubricate the stools for easier passage. Soluble fiber also increases the production of short-chain fatty acids (SCFAs), which stimulate colonic smooth muscle contractions. Insoluble fiber adds volume to the stool, which fills and distends the colon to stimulate colonic contractions and propel fecal content forward.
Royal Canin Gastrointestinal Fiber Response is a highly digestible formula, to which a moderate amount of fiber has been added. The main fiber source is psyllium husk, which is an excellent source of soluble fiber. In a feeding trial using this diet, 82% to 93% of cats that experienced recurrent constipation had a significant improvement in fecal consistency.7 Another fiber-enriched diet option is Hill's Gastrointestinal Biome, which contains a blend of fibers to help promote regular, healthy stools.
An alternative to transitioning a cat to a fiber-enhanced therapeutic diet is to add small amounts of fiber to their regular food. Psyllium husk powder, which contains approximately 70% soluble fiber and 30% insoluble fiber, can be mixed into their wet food, starting at 1/8–1/4 teaspoon per meal. The amount can be slowly increased if needed. Ensure the psyllium husk is plain and free of sweeteners or flavors.
It's important to note that in cats with megacolon (a colon that has lost its motility and become severely dilated), obstipation (unable to defecate due to severe fecal impaction), or an obstruction (such as a narrowed pelvis), adding fiber and thus increasing fecal bulk may worsen clinical signs.8 Additionally, since fiber draws water into the colon, cats should be well-hydrated before starting fiber supplementation to prevent worsening clinical signs or fiber impaction.
| Product | Empty | Features | Price |
|---|---|---|---|
 | Biome |
| View on AmazonView on Chewy |
 | Response | Royal Canin Gastrointestinal Fiber Response
| View on AmazonView on Chewy |
 | Psyllium | Yerba Prima Psyllium Husk Powder
| View on Amazon |
Low-residue diets reduce stool volume. They are made from highly digestible proteins, fats, and carbohydrates, are low in non-digestible fiber, and are energy-dense to provide essential nutrition in smaller meals. With less undigested material entering the colon, these diets produce smaller stools, lowering the risk of fecal impaction—particularly important for cats suffering from constipation due to an obstruction or those with megacolon.
Low-residue diets tend to be those formulated specifically for intestinal issues, such as Purina EN or Hill's i/d. Veterinary intestinal diets undergo feeding trials to ensure they provide adequate nutrition and are highly digestible. Ingredients are carefully selected, including highly digestible proteins like muscle and organ meats, while avoiding difficult-to-digest proteins such as tendons and cartilage. Processing also plays a critical role in digestibility, for example, overcooked proteins can lose some of their digestibility, while undercooked starches remain poorly digestible. These factors are considered when formulating and preparing high-quality low-residue diets.
Another option is preparing a low-residue home-cooked diet. However, it is essential to consult a veterinary nutrition specialist to ensure the recipe is balanced and tailored to your cat’s specific needs. Without proper guidance, there is a risk of nutritional deficiencies or causing additional health problems.
| Product | Empty | Features | Price |
|---|---|---|---|
 | i/d |
| View on AmazonView on Chewy |
 | EN |
| View on AmazonView on Chewy |
3. Hydration
It's important cats with constipation remain well-hydrated to help keep stools moist and easier to pass. Feeding canned (wet) food is an effective way to help ensure cats remain hydrated. If your cat refuses wet food, read 'How to Get a Cat to Eat Wet Food.'
Other techniques to keep cats hydrated include providing fresh water in multiple locations and offering water fountains. Cats with chronic kidney disease (CKD), who do not concentrate their urine appropriately, may benefit from subcutaneous (under the skin) fluids administered at home. The technique should be demonstrated by a veterinary professional. For more tips on how to keep your cat hydrated, read 'How to Get a Cat to Drink More Water.'
4. Weight Management and Encouraging Activity
Since obesity is a risk factor for constipation, overweight cats may benefit from a weight loss plan, involving both diet changes and increased exercise. Encouraging activity with regular playtime can also promote intestinal motility and help move poop along. Always work closely with your veterinarian to help your cat safely lose weight, and for more information, read 'How to Help a Cat Lose Weight - An Effective Weight Loss Plan.'
5. Grooming
Although a cat's digestive tract is adapted to handle the ingestion of hair—from grooming themselves, each other, or consuming small prey—frequent brushing of longhaired cats prone to constipation may help reduce hair ingestion and lower the risk of recurrence. While grooming alone is unlikely to resolve constipation, it can be incorporated into a broader management plan.
6. Ideal Litter Box Setup
Providing the ideal litter box setup for your cat will minimize any litter tray avoidance issues that could be causing them to hold in their stools and contributing to constipation. While every cat will have their personal preferences some points to consider include:
- Location: A quiet, undisturbed area that is easy for your cat to access.
- Cleanliness: Scooped twice daily and emptied, cleaned, and refilled every 1–2 weeks, depending on usage.
- Type of Litter: Fine, unscented, clumping litter that resembles sand in texture.
- Size: Large boxes that are at least 1.5 times the length of your cat (measured from their nose to the base of the tail).
- Number: At least one tray per cat plus one extra, placed in different locations to avoid territorial blocking in multi-cat households.
- Special Considerations: Older or arthritic cats may benefit from trays with lower sides for easier entry. Some cats may also avoid covered or automatic boxes.
7. Oral Laxatives
The most commonly used oral laxatives are osmotic laxatives, which work by creating an osmotic gradient that retains water within the colon. This helps to increase the water content in stools, making them softer and easier to pass. Therefore, a cat must remain adequately hydrated while receiving oral laxatives. Oral laxatives should also be started at the lower end of the dose and gradually increased if necessary to avoid diarrhea. Since it can take several days for the full effect to be observed, dose increases should be made gradually.
Lactulose can be prescribed by a vet and is typically administered 2-3 times per day. However, it usually comes in a liquid form, which can be a fairly large volume and is also thick, sticky, and poor tasting, making it challenging to administer.
Unflavoured MiraLAX, also known as Polyethylene Glycol (PEG) 3350, is a powder that can be mixed into food and is usually not noticed by the cat, making it easy to administer. It can be titrated to effect, and the starting dose is 1/8–1/4 teaspoon twice per day. In a study involving 6 cats, PEG3350 was found to be a safe, effective, palatable and easy to administer oral laxative.9
- Oral osmotic laxative powder (Polyethylene Glycol [PEG] 3350)
- Easily mixed into your cat's food, making it typically unnoticeable
- Starting dose: 1/8–1/4 teaspoon twice per day, then adjust as needed
- Electrolyte-free to reduce the risk of causing electrolyte imbalances
8. Rectal Suppository Laxatives
Microenemas (5 ml volume), such as Pet-Ema, can be administered rectally, and stools are usually passed within 20–30 minutes. Microenemas will be ineffective for severely impacted cats.
Veterinary-administered enemas are preferred for safety and efficacy in a clinical setting. If an owner chooses to administer an enema at home, it's advisable to have the technique demonstrated by a veterinary professional and to abandon the attempt if it is not tolerated by the cat, as it could potentially result in stress, injury, or damage to your bond.
Avoid phosphate-containing enemas (e.g., certain Fleet® brand enemas), which can cause life-threatening electrolyte abnormalities in cats.
- A rectally administered enema that acts as both a lubricant and laxative to relieve mild constipation in cats
- Contains dioctyl sodium sulfosuccinate, glycerin, and sorbic acid
- Recommended for use by or under the supervision of a licensed veterinarian
- Always follow veterinary and product guidelines for dosage and instructions
- Before insertion, lubricate the outside tube with the contents, then carefully insert and administer the enema
- Only to be used in compliant cats to avoid injury or stress
9. Prokinetics
A veterinarian may prescribe a prokinetic, a drug that stimulates smooth muscle contractions in the gastrointestinal tract and promotes motility. The most commonly prescribed prokinetic is cisapride, which, unlike some prokinetic drugs that only affect the stomach and small intestine, also promotes motility in the colon. Cisapride is usually given twice a day and is better absorbed when administered with food.
Cisapride can be difficult to obtain because it was withdrawn from the human market due to the development of heart arrhythmias in human patients (not observed in cats). However, it is available through some compounding pharmacies, which can provide appropriately sized tablets for cats. Cisapride should not be used in cats with an intestinal obstruction, such as severe fecal impaction, a stricture, or a narrowed pelvic canal.
10. Subtotal Colectomy (Surgery)
For cats with recurring obstipation that are not responding to medical management, surgery may be recommended to remove the majority of the colon and connect the remaining sections of the intestine. In general, the prognosis is good, but there can be complications postoperatively, such as the rare but serious breakdown of the anastomosed intestines and leakage of bacteria into the abdomen, to the common complication of diarrhea, which in the majority of individuals improves within one to six weeks.10
If surgery is being considered, it is advisable to consult with a veterinary surgeon who is familiar with the procedure or to be referred to a specialist surgeon.
Monitoring Cats with Constipation
It's important to monitor your cat's bowel movements, including stool consistency and frequency of defecation.
Stools should be moist but well-formed. Very hard, dry, or crumbly stools indicate ongoing constipation, while unformed, very soft, or liquid stools indicate diarrhea, which may suggest overuse of laxatives or other complications. For more information on scoring cat feces, review the Royal Canin Fecal Scoring System.
On average, most cats defecate once a day. While some cats may have slightly different normal patterns, any reduction in frequency from their normal defecation pattern warrants veterinary attention.
In addition, monitor for signs of discomfort when defecating, such as straining, vocalizing, or unsuccessful attempts.
If you notice abnormalities in any of the above, or if your cat goes more than 48 hours without defecating, consult your veterinarian promptly. Constipation is much more manageable when it is addressed early rather than allowing it to progress to a stage that requires more invasive interventions.
Use the scoring chart to monitor your cat's stools and assess if they are optimal, too dry or, too wet.
Prognosis: What is the Likely Outcome for My Constipated Cat?
The prognosis for cats with constipation depends on the severity, underlying cause, and duration.
Cats with mild constipation, or those where the underlying cause can be identified and managed (e.g., diet changes or treating dehydration), may have a good prognosis without further recurrence.
Cats with recurrent episodes of constipation can progress to obstipation (severe constipation with complete blockage of stools) or acquired megacolon (a large, dilated colon with a lack of motility), requiring intensive medical management, with some eventually requiring surgery.
In summary, early and proactive management is critical for improving outcomes. While some cats may only experience one or two episodes, others require continuous lifelong treatment and monitoring. Owners should prepare for the possibility of progressive disease, which may necessitate surgery. With appropriate management, many cats can maintain a good quality of life.
Summary: Key Points on Feline Constipation
Definitions:
- Constipation: Difficulty passing stools or infrequent defecation
- Obstipation: Complete blockage of the colon with impacted stools
- Megacolon: Severely dilated colon that no longer functions, which may be primary (loss of colonic smooth muscle function) or secondary to an underlying cause, such as a narrowed pelvis, stricture, or neurological disorder.
Symptoms:
- Straining to defecate
- Hard, dry stools
- Pain or vocalization during defecation
- Reduced defecation frequency
- Defecating outside the litter box
- Blood or mucus in stools
- Rectal prolapse (tissue protruding)
- Reduced appetite
- Vomiting
- Lethargy
- Weight loss
Causes & Risk Factors:
- Idiopathic megacolon
- Dehydration
- Obesity
- Inactivity
- Intraluminal obstruction (e.g. a mass or stricture causing an obstruction inside the colon)
- Extraluminal obstruction (e.g. a narrowed pelvis causing an obstruction from outside the colon)
- Painful posturing
- Pain during defecation
- Litter box avoidance
- Electrolyte imbalances
- Hypothyroidism
- Neurological disorders
- Medications
Diagnosis:
- Abdominal palpation
- Abdominal radiographs
Workup:
- History
- Physical exam
- Blood tests (case dependent)
- Imaging (case dependent)
Initial Treatment:
- Correct dehydration
- Pain relief
- Anti-nausea
- Fecal removal:
- Rectal suppository laxatives (microenemas) for mild cases.
- Warm water or saline enemas for more severe cases.
- Oral PEG 3350 solution via a feeding tube while hospitalized.
- Manual disimpaction for very severe cases under anesthesia.
- Sodium phosphate enemas should be avoided due to the risk of life-threatening electrolyte imbalances.
Long-term Management:
- Address any underlying medical or surgical conditions
- Diet change (fiber-enriched vs low-residue)
- Ensure proper hydration
- Weight management if overweight
- Encourage activity
- Regular grooming
- Create the ideal litter box setup
- Oral laxatives (MiraLAX)
- Rectal suppository laxatives (Pet-Ema) for compliant owners and cats
- Prokinetic drugs (cisapride)
- Surgery (for cases refractory to medical management)
Monitoring:
- Stool consistency
- Frequency of defecation
- Signs of discomfort while defecating
- Promptly report abnormalities to your vet
Prognosis:
- Cats with mild constipation may have a good prognosis with appropriate management.
- Recurrent constipation can lead to obstipation or megacolon, requiring intensive treatment or surgery.
- Early and consistent management improves outcomes and quality of life.
References:
- Schrader SC. Pelvic osteotomy as a treatment for obstipation in cats with acquired stenosis of the pelvic canal: six cases (1978-1989). J Am Vet Med Assoc. 1992 Jan 15;200(2):208-13.
- Washabau RJ, Holt D. Pathogenesis, diagnosis, and therapy of feline idiopathic megacolon. Vet Clin North Am Small Anim Pract. 1999 Mar;29(2):589-603. ISSN: 0195-5616.
- Benjamin SE, Drobatz KJ. Retrospective evaluation of risk factors and treatment outcome predictors in cats presenting to the emergency room for constipation. Journal of Feline Medicine and Surgery. 2020;22(2):153-160.
- Thanaboonnipat C, Kumjumroon K, Boonkwang K, Tangsutthichai N, Sukserm W, Choisunirachon N. Radiographic lumbosacral vertebral abnormalities and constipation in cats. Vet World. 2021 Feb;14(2):492-8.
- Trevail T, Gunn-Moore D, Carrera I, Courcier E, Sullivan M. Radiographic diameter of the colon in normal and constipated cats and in cats with megacolon. Vet Radiol Ultrasound. 2011 Sep-Oct;52(5):516-20.
- Carr AP, Gaunt MC. Constipation resolution with administration of polyethylene glycol solution in cats (abstract). J Vet Intern Med 2010;24:753–754.
- Freiche V, Houston D, Weese H, Evason M, Deswarte G, Ettinger G, Soulard Y, Biourge V, German AJ. Uncontrolled study assessing the impact of a psyllium-enriched extruded dry diet on faecal consistency in cats with constipation. J Feline Med Surg. 2011
- Moreno AA, Parker VJ, Winston JA, Rudinsky AJ. Dietary fiber aids in the management of canine and feline gastrointestinal disease. J Am Vet Med Assoc. 2022 Oct;260(S3):S3-S10.
- Tam FM, Carr AP, Myers SL. Safety and palatability of polyethylene glycol 3350 as an oral laxative in cats. J Feline Med Surg. 2011 Oct;13(10):694-7. doi: 10.1016/j.jfms.2011.05.017. Epub 2011 Aug 5.
- White RN. Surgical management of constipation. J Feline Med Surg. 2002 Sep;4(3):129-38.
