What Causes Constipation in Dogs and Cats?

What causes constipation in dogs and cats? Below, we provide the answer to this question that includes the most common factors that could be contributing to your pet’s constipation.

Poor Quality Food

The majority of processed pet foods contain highly refined and low-fiber ingredients. These often poor quality ingredients facilitate the condition of constipation in our dogs and cats. Very often ingredients such as tomato pomace or beet pulp are added to pet foods as a source of fiber, however, being by-products (or waste products) of the human food industry they generally make poor additions to pet foods. In the wild our canines and felines would consume fur, providing ample fiber, and bone, providing bulk, to provide normal stools and prevent constipation. Ingredients such as ground bone are found in commercially available raw foods and help to create healthy stools and naturally express anal glands.

In addition to the above, dry, kibble pet food often leads to constipation for another reason. Raw foods, as our dogs and cats have evolved to eat, contain high amounts of moisture. Compare this to kibble pet food that usually has a maximum moisture content of 10%, but is usually closer to 5%. This low level of moisture is necessary to preserve the food for extended shelf life, but is a major cause of constipation in dogs and cats. Kibble pet foods can be especially detrimental to cats that have evolved from desert felines that don’t drink very much water and should be getting the majority of their fluid intake from the food they eat. Kibble is yet another example of how large pet food corporations put shelf life and profits ahead of your dog or cat’s health.


As indicated above, dehydration is a major cause of constipation in our dogs and cats, and the major contributor is dry, kibble pet foods. Constipation due to low moisture occurs because fluids help to move waste through the digestive tract. By the time digestive waste gets to the colon much moisture has been lost, and it is in the colon where water is removed and stool is formed. When the waste is already dry it will become even dryer in the colon thereby slowing its elimination and causing a chronic condition of constipation.

Poor Digestion

Poorly digested food is a common problem in our dogs and cats and often contributes to constipation. This occurs because larger food particles are not broken down properly into their smaller constituents that allow for normal absorption through the digestive tract. These larger food particles can contribute to damage and disease in the digestive tract and the inefficient movement and elimination of waste.


As dogs and cats age, the wave-like movements that move waste through the digestive tract, called peristalsis, get weaker along with other tissue and organ systems within the body leading to constipation. Often, stimulant laxatives will be prescribed by the veterinarian leading to dependence on these drugs along with numerous potential side-effects. Exercise (as discussed below) alone, or when combined with a healthier diet, can often be very helpful if age is contributing to your pet’s constipation.


Certain drugs can cause constipation by increasing the amount of time it takes waste to move through the digestive system resulting in more moisture being removed and drier stool. Drugs can increase nonpropulsive contractions in the middle of the small intestine while decreasing beneficial propulsive peristalsis. Certain drugs can also partially paralyze the stomach so that food remains in this digestive organ for a longer period of time while at the same time reducing digestive secretions and the urge to defecate. All of these drug side-effects can result in food that fails to travel through the digestive tract properly and subsequent constipation. If your dog or cat’s elimination behavior changes soon after the addition of a new medication there is a very good possibility that the drug is contributing to the constipation. If you aren’t sure you can do an online search to check for the side effects of the medication you are using.

Imbalances / Disease

Various imbalances, or disease states, that our companion animals experience can contribute to constipation. This occurs for similar reasons to the use of certain medications. Different conditions can interfere with the normal movement of waste through the digestive tract and the formation of healthy stool in the colon. Conditions that may cause constipation include hormonal conditions like hypothyroidism, tumors in the colon or rectum, neurologic conditions, or injuries and painful conditions, like osteoarthritis, that can make it uncomfortable to pass stool.

Lack of Exercise

A dog or cat’s lack of exercise can contribute to constipation in a similar way to aging as described above. Muscle movement contributes to peristalsis and also lymphatic flow within an animal’s body. This is because these systems do not have a pump as the circulatory system has the heart to move blood around the body. Instead, peristalsis relies on smooth muscle movements, so when an animal becomes out of shape and lies around a lot with no exercise, lean muscle becomes weaker or is lost altogether. This contributes to an overall weaker animal, but as pertains to this topic, less effective peristalsis and the inefficient movement of waste through the digestive tract leading to constipation.

When Should I Bring My Dog to the Vet?

Bring your dog to the vet if your dog or cat does not have a normal bowel movement in 48 hours.

Natural Treatment for Constipation

Natural treatment for constipation can be as simple as changing over to a more natural diet, adding more fluid to your dog or cats food, adding a soluble fiber source to your pet’s food and/or making sure they get more exercise. We have a Natural Constipation Protocol we developed to assist you with some helpful product recommendations and lots of useful information. We are here to help so feel free to contact us by email or toll free at 888-683-3339 if you need more personalized attention.


Causes of Opioid-Induced Constipation (OIC). Retrieved from http://www.medicalnewstoday.com/info/oic/causes-of-opioid-induced-constipation.php

Constipation in Dogs. Retrieved from http://www.vcahospitals.com/main/pet-health-information/article/animal-health/constipation-in-dogs/7684

Hoffman, D. (2003). Medical herbalism: The science and practice of herbal medicine. Rochester, VT: Healing Arts Press.

Kidd, R. (2000). Dr. Kidd’s guide to herbal dog care. North Adams, MA: Storey Publishing.

Messonnier, S. (2001). Natural health bible for dogs & cats: You’re a-z guide to over 200 conditions, herbs, vitamins and supplements. New York, NY: Three Rivers Press.

Murray, M. T., & Pizzorno, J. E. (1998). Encyclopedia of natural medicine (2nd ed.). New York, NY: Three Rivers Press.

Pitcairn R. H., & Hubble-Pitcairn S. (1995). Dr. Pitcairn’s complete guide to natural health for dogs & cats. Emmaus, PA: Rodale Press, Inc.

Pitchford, P. (2002). Healing with whole foods: Asian traditions and modern nutrition (3rd ed.). Berkeley, CA: North Atlantic Books.

Puotinen, CJ. (2000). The encyclopedia of natural pet care (2nd ed.). Los Angeles, CA: Keats Publishing.

Tilford, G. L., & Wulff, M. L. (2009). Herbs for pets: The natural way to enhance your pet’s life. (2nd ed.). Irvine, CA: BowTie Press.

Thibodeau, G.A., & Patton, K.T. (2008). Structure & function of the body. St. Louis, MO: Mosby.

This information is for education only and is not meant to diagnose, treat or prescribe for any disease or medical condition.
Information on herbs and supplements has not been evaluated by the FDA.

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