The Causes Of Irritable Bowel Syndrome In Animals

Posted on May 16th, 2013

This post was originally posted in Nutricula Magazine on May 3rd, 2013

-by Al Plechner, DVM and Bob Berger, MS, MVSc, PhD

Dr. Plechner-

All dogs and cats that have IBS all have a measurable deficiency in the mucous membrane antibody referred to as IgA which occurs throughout the body, including in the gut.

This IgA deficiency occurs due to a deficient, bound, or defective cortisol which causes the pituitary gland to over-release its hormone called ACTH. The excessive secretion of ACTH over stimulates the inner layer adrenal cortex, which then will produce excess sex hormones, including excess adrenal estrogen.

This excess production of adrenal estrogen is easily measured with a total estrogen test. This is not just a partial test for ovarian estrogen and is not just measuring estradiol in males. It has been proven that the deregulation of the B lymphocytes leads to this IgA deficiency.

Unfortunately, this IgA deficiency will cause the patient to have reduced normal bacteria in the gut, which in turn, will cause chronic diarrhea. This chronic diarrhea leads to IBS, (Irritable Bowel Syndrome).

Once a patient has this identifiable imbalance, quite often, food, vaccine, and stinging insect sensitivity will occur.

In a dog or cat, (and I also expect in humans), if a food sensitivity is suspected in the patient, a simple injection of a fluorinated steroid can be administered. If there is no improvement after 3-4 days post steroid administration, the patient most probably has a food sensitivity.

Wheat is a very common reactant with IBS, and as genetically modified products (GMOs) are added to animal and human foods, more cases of IBD can be expected to occur.

For more information on how to control identify this hormone antibody imbalance, please go to

Dr. Berger-

Another factor to consider as a cause of IBS in dogs, cats and other domestic and non-domestic animals is the overproduction of histamine from mast cells that line the entire gastrointestinal tract. (Also called a mastocyte, a mast cell is a resident cell of several types of tissues that contains histamine and heparin. It plays a significant role in allergy and anaphylaxis, as well as a protective role in wound healing and defense against invading pathogens.)

Mast cells are vital components of the gastrointestinal tract and are often considered important in the pathogenesis of many G.I./gut diseases, i.e., bacterial and parasitic infections, ulcers, ulcerative colitis, inflammatory polyps, etc.1 Any type of pathology, regardless of origin, can cause a number of inflammatory responses. These may result in the overproduction of histamine, mucosal secretions, G.I tract hyper-motility, and auto-immune attacks on the G.I system itself. An auto-immune attack can be directly related to mast cell over-secretion and can lead to IBS as well.1

It has been suggested that hypersensitivity type 1 reactions, (reactions that are provoked by the re-exposure to a specific protein allergen), may be involved in the pathogenesis of canine inflammatory bowel disease (IBD), and the cells which are mainly effected are mast cells.2 Thus, controlling mast cell production may be a very effective treatment for IBD in animals.

Along with IBS, chronic idiopathic large bowel diarrhea is a diagnosis reached by the exclusion of the most common diseases that are associated with chronic idiopathic large bowel diarrhea. Many canines with CILBD may experience behavioral problems, who are (or may have been), exposed to a stressful environment at one time or another.3 Most dogs and cats do respond positively to not only a less stressful environment, but also to a dietary change and even fiber supplementation. Some animals also may benefit from behavior-modification therapy as well.3

The basic goal here is to identify the cause of IBS and other related bowel problems and resolving them completely. The only way to do this is to find out what the initiating factor or factors are, and eliminating them. Simply treating the symptoms and/or stopping the effects is not going to solve the problem, and for health issues like IBS, IBD, and CILBD, eliminating causal factors are vital; otherwise you are just practicing palliative therapy.

Note: An important concept here is that many times the inflammation from these G.I. issues may be overwhelming at first. Attempting to subside a major inflammatory or diarrheal attack by diet, fiber, certain natural supplements, etc., may be futile if the inflammation is too advanced. This could be like trying to stop a 26o lb fullback running at full speed with the opposing team’s 100 lb ball-girl. Many times a short course of a small dose of an oral corticosteroid may have to be employed just to “subside” the inflammation so it is not overwhelming. It’s “OK” to do this, as this would not be for long term, but could subside/control the inflammatory problem so it is manageable; and most vets would probably agree with this.

The day has come to identify the cause of IBS and not to merely just treat the effects!


1. Barczyk, M., Debek, W., and Chyczewski, L. (1995) Mast cells in the gastrointestinal tract. Rocz. Akad. Med.Bialymst., 40, 36.

2. Kleinschmidt, S. and Meneses, F., et al. (2007) Characterization of mast cell numbers and subtypes in biopsies from the gastrointestinal tract of dogs with lymphocytic-plasmacytic or eosinophillic gastroenterocolitis. Vet. Immunol. Immunopathol., 120, 80.

3. Lecoindre, P. and Gaschen, F.P. (2011) Chronic idiopathic large bowel diarrhea in the dog. Vet. Clin. North Am. Small Anim. Pract., 41, 447