Most dogs will have a bowel movement at least once a day; many of them will have bowel movements that correspond to the number of meals they eat each day. A constipated dog will have less frequent bowel movements and/or have difficulty passing the stool or feces, which is typically hard and dry. Constipation is usually a temporary condition and fairly easy to treat. This article discusses the diagnosis, causes, treatment, and prevention, including some home remedies for dog constipation.
Normal functioning of the colon
- Normal functioning of the colon
- Signs of constipation
- Diagnosis of constipation
- Causes of constipation
- Dietary causes
- Treatment, including home remedies for dietary causes of dog constipation
- Refusal to defecate
- Treatment for refusing to defecate
- Colonic Obstruction
- Colonic weakness
- Prevention of constipation
The colon, or large intestine, is located at the end of the gastrointestinal tract. By the time food reaches this point, it has been digested with the nutrients removed and is mostly liquid. The colon’s function is to remove the water from the food waste, leaving behind the solid parts, and then moving that dehydrated food waste to the rectum to be expelled from the body.
If something happens to slow down or even prevent the normal movement of food waste through the colon, water continues to be absorbed from the forming fecal material, causing it to become more and more dried out and firmer. This makes the stool more difficult to pass, and painful to do so.
Signs of constipation
Dogs with constipation will squat and attempt to pass stool multiple times, but will usually be unsuccessful. If any stool does pass, it may be extremely dried out and firm. They may also pass small amounts of very watery fecal material, with or without blood, or the fecal material may have mucus. Dogs may also circle excessively, scoot (drag their bottom along the ground), or cry out while attempting to defecate. Other possible signs include a decreased appetite, lethargy, vomiting, and abdominal discomfort. If the dog doesn’t produce a bowel movement within 2-3 days of the last bowel movement, it’s time to call the veterinarian.
Diagnosis of constipation
The veterinarian will ask some questions about any recent diet changes, if your dog has eaten any non-food items recently, or if your dog has been on any medications recently. The veterinarian will also ask the last time your dog had a normal bowel movement, and if your dog has been able to pass any stool or fecal material at all, and if so, what it looked like. They will also palpate your dog’s abdomen and feel for a firm, distended colon. If your dog is overweight, the veterinarian will not be able to perform the palpation and may need to take radiographs to confirm the presence of retained feces in the colon. Between the patient history and the confirmation of retained feces in the colon, the diagnosis can be made.
Once the general diagnosis has been made, it’s important to determine the cause of the constipation. Your veterinarian will likely perform a rectal examination on the dog, feeling for any tumors, enlarged sublumbar lymph nodes, an enlarged prostate, or any foreign objects near the rectum. A neurologic examination may also be helpful in ruling out some neurologic causes of constipation. Abdominal radiographs or ultrasound will be helpful in determining the extent of the constipation, whether a foreign body is obstructing the colon, or if there is another structure physically compressing the colon. Blood work may also be recommended, looking for signs of dehydration, low thyroid hormone, or low potassium or high calcium levels.
Causes of constipation
Some dogs like to eat items that are not food items, such as rocks, toys, corn cobs, etc., which can then block the colon and not allow fecal material to pass. Dogs with long hair or excessively groom themselves can cause an obstruction of the colon with the hair they ingest, thereby causing constipation. Dogs being fed a bones and raw food (BARF) diet produce very dried out and firm stool, which may put them at risk for constipation. Being dehydrated, especially in combination with a high fiber diet, can also cause constipation because the body will try to retain as much water as possible in order to stay hydrated, which means more water than usual is removed from the fecal material.
Treatment, including home remedies for dietary causes of dog constipation
The first step for any obstruction is to remove the obstruction. This can usually be accomplished with suppositories or enemas administered by veterinary staff. If those methods are unsuccessful, then it may be necessary to manually “milk” the obstruction through the colon while the dog is under general anesthesia. Rehydration is also an important step in the process, and may need to be accomplished by intravenous fluids.
Home remedies, suitable only for mild constipation include using a high fiber diet, or by supplementing the regular diet with bulk-forming laxatives. Commercial high-fiber diets are available, such as Hill’s w/d, but it is often just as easy and perhaps less expensive to supplement the dog’s regular diet. Supplements that can be used include coarse wheat bran (1-3 tbsp per pound of food), psyllium (Metamucil) (1-2 tsp per pound of food), or plain canned pumpkin (not spiced!) (1-3 tbsp/day). Milk and ice cream can also be used, but since most dogs don’t have the enzyme to break down lactose, using milk or ice cream can also cause gas, just like with lactose-intolerant people, so consult with your veterinarian before going that route. Too much fiber can cause excessive stools, so it may be necessary to adjust the amount of fiber supplementation to find that happy medium.
Also important while using a high fiber diet or supplementation is to make certain the dog has access to plenty of water, otherwise the fiber will cause harder-than-normal stools. A little bit of low-sodium chicken or beef broth can be added to the dog’s water to give it a little flavor and encourage drinking. Canned food also has a higher water content than kibble, which may also help move things along.
Your veterinarian may also choose to treat mild constipation with a liquid drug called lactulose. It is particularly useful in softening feces. If lactulose is used, it may take some trial and error to get the right dose that will produce stool of the desired consistency.
It is particularly important to not use fiber supplementation if the colon is partially or completely obstructed because that can lead to impaction of the fecal material, which is more difficult to correct. Have a veterinarian examine your dog to make sure fiber supplementation is safe before proceeding.
Refusal to defecate
Some dogs will refuse to defecate for various reasons. Sometimes stress can be a factor – if something scared the dog while doing his business, he might be anxious or fearful about repeating the experience. The dog might not want to defecate because it’s painful to do so. Things that could cause pain near the rectum include perianal fistulae (chronic draining abscesses around the anus; German shepherds make up 80% of cases), tumor, pelvic fracture, or proctitis (inflammation of the rectum). Other dogs may refuse to defecate because they are unable to assume the position due to orthopedic or neurologic problems.
Treatment for refusing to defecate
Taking the dog to a new and different place to defecate may be helpful in the case of stress. Irritant laxatives such as Dulcolax or glycerin suppositories stimulate defecation and may be useful if a change of scenery is not possible – talk to your veterinarian about dosage. Short-acting, as-needed anti-anxiety medications such as alprazolam or trazodone may also be beneficial.
Causes of pain should be investigated thoroughly. Treatment of perianal fistulae is a long and difficult process, and not always successful in fully curing the disease, but it starts with immune-modulating drugs such as tacrolimus and cyclosporine. Antibiotics may be used to treat secondary infections, and a hypoallergenic diet may be recommended since there is some evidence food allergies may be an underlying cause. Increasing ventilation of the area around the anus is helpful, especially for long-haired breeds such as the German shepherd, and careful bathing and cleaning of the area can also help.
Treatment of tumors will depend on the type of tumor, which is usually diagnosed with a procedure called a fine needle aspiration, if the tumor is in a location that allows relatively easy access. With fine needle aspiration, a needle is inserted into the tumor and the plunger of the attached syringe is drawn back, which suctions some of the cells inside the tumor into the barrel of the syringe. The cells are then placed on a microscope slide and sent off to the laboratory where they are stained and examined by a veterinary pathologist. While the diagnosis is being made, an anti-inflammatory drug may be useful in reducing any associated pain or inflammation. Treatment of the tumor itself could include surgery, chemotherapy, radiation, or some combination of those therapies.
Other cases of pain and inflammation such as pelvic fractures or proctitis may be alleviated by non-steroidal anti-inflammatory medications such as carprofen, or steroids such as prednisone. Most pelvic fracture cases (75%) can recover without surgery, especially in small dogs, but surgery may be recommended depending on the severity of the fracture. However, surgery should occur within 48-72 hours of the injury; after 7 days, early healing and muscle rigidity prevents surgical correction of the fracture.
For dogs unable to posture or unable to stay postured due to neurologic issues, using a harness such as the Help ‘Em Up harness allows the owner to provide support to the dog while they defecate.
There are a number of things that could obstruct or block the colon either partially or completely, and those things can cause the blockage either from the inside of the colon or from the outside. Examples include perineal hernias, tumors, rectal foreign bodies, congenital strictures, poorly healed pelvic fractures, enlarged prostate gland, and enlarged sublumbar lymph nodes.
Within the abdomen, there is a wall of muscle called the pelvic diaphragm. This structure supports the end of the colon (the rectum), away from the rest of the structures in the pelvis such as the bladder and prostate gland. If a weakness develops in the pelvic diaphragm, the bladder or prostate gland can push through the diaphragm and push against the rectum, preventing fecal material from passing through. It is uncertain what causes the hernia, but the majority of the cases are seen in intact middle-aged to older male dogs. Treatment is surgical repair of the hernia.
Similarly, an enlarged prostate gland (found only in males) can place pressure on the rectum without actually herniating through the pelvic diaphragm. There are multiple causes of an enlarged prostate gland. Hormonal causes can usually be treated by neutering the dog – the prostate gland will return to normal size within a month. Abscesses or cysts are usually surgically drained and removed. Bacterial infections are treated with aggressive and lengthy courses of antibiotics since antibiotics have a difficult time penetrating the prostate gland. Prostatic tumors generally don’t respond well to current therapies, but targeted radiation and some chemotherapies may help; however, the prognosis is poor. Stool softeners or laxatives may be used to help with constipation while other treatments are pursued.
Tumors either inside or outside the colon may obstruct the passage of fecal material, and treatment will depend on the type of tumor present. In general, abdominal tumors don’t have a good prognosis; the possible exception to this is lymphoma causing enlarged sublumbar lymph nodes. Lymphoma can be treated with chemotherapy, which reduces the size of the lymph nodes. Most dogs will survive about a year before the disease returns, at which point it becomes more difficult to achieve remission again.
Rectal foreign bodies may be able to be “milked” out of the colon while the dog is under general anesthesia, or if that is not possible, surgical removal is necessary.
Congenital strictures are malformations of the colon causing a narrowing of the colon; these are present from birth. Surgery to ease the constriction may be possible, or even complete removal of the narrowed part of the colon may be possible. Otherwise, stool softeners may be the treatment of choice.
A poorly healed, previously broken pelvis may place pressure on the rectum. Unfortunately, once the pelvis has healed, treating the pelvis itself may be impossible. Stool softeners are likely to be the treatment of the constipation in order to allow fecal material to pass by the constricted part of the colon.
The colon has muscles in it to move the fecal material along its length. If the colon is not able to move material along as well as it should, it may be due to neuromuscular conditions such as hypothyroidism, high calcium, low potassium, spinal cord trauma, or pelvic nerve damage. Hypothyroidism, high calcium, and low potassium can be treated with medications or supplementation, though the causes of high calcium or low potassium should be investigated thoroughly as they are highly unusual and may indicate a larger underlying problem such as cancer.
Spinal cord trauma may be able to be treated, depending on the cause of the trauma. If it is an intervertebral disc or tumor pressing on the spinal cord in the low back, surgery may be an option to remove the disc or tumor to relieve pressure on the spinal cord. Pelvic nerve damage is generally not able to be treated. Consultation with a veterinary neurologist is very helpful in determining your options for treating nervous system disorders.
Some drugs can cause the slowing down of movement of food through the gastrointestinal tract, which may lead to constipation. Some of the drugs that can potentially cause constipation include opioids, antihistamines, diuretics, sucralfate, and potassium bromide.
If you notice constipation as a side effect of a drug, talk to your veterinarian about the possibility of using another drug that will still treat the condition for which it was prescribed but not cause constipation. If it’s not possible to change the drug, then your veterinarian may recommend an additional medication to help increase motility of the colon.
Prevention of constipation
As mentioned above, there are some things you can do to prevent constipation in your dog. Make sure that your dog has free access to water at all times. Consider using some canned/wet food in your dog’s diet, or adding a little bit of water to their kibble, especially if they don’t tend to drink much water. Make sure your dog doesn’t eat non-food items. If they have long hair, groom them frequently to decrease the chance they will ingest a lot of hair as they groom themselves. If you notice their stools unexpectedly increasing in firmness, consider using a fiber supplement to help soften the stool.
While most constipation is due to diet-related issues, there are some important and serious underlying conditions that may be the cause. Diagnosis of the underlying cause of constipation is generally straight-forward, and together you and your veterinarian can come up with a plan to treat the current episode and prevent future episodes from happening again.