My dog produces so much gas!  Why is this happening? Is she sick?
It is appropriate first to define terms. Flatulence is the formation of excess gas in the stomach or intestines. Excessive flatulence may result in belching (burping) or the expulsion of gas through the anus, called flatus. Most flatus is composed of odorless gases. The odor comes from sulfur-containing gases like hydrogen sulfide.
Flatulence can also cause grumbling sounds in the gastrointetinal (GI) system that can sometimes be heard across the room. These sounds are called borborygmus. Belching, borborygmus, and flatus can occur normally in dogs, but if they become excessive, there may be an underlying issue requiring medical attention. If these signs develop along with weight loss or diarrhea, it is quite likely that something serious is happening in the GI system, and this warrants a visit with your veterinarian.
My dog does not have diarrhea and is acting perfectly normal. What could be causing her excessive gas?
Some gastrointestinal gas is normal. The three sources of GI gas are:            
- Swallowed air            
- Gas production inside the GI tract            
- Diffusion of gas from the bloodstream into the GI tract
The first two sources will be closely considered by your veterinarian.
The amount of flatus varies greatly among individuals – both among dogs and humans. Swallowed air most likely makes the largest contribution to flatulence and flatus. Exercise and eating too fast can increase air swallowing. Swallowed air can exit the body as flatus within two hours.
In terms of gas produced inside the GI tract, colon bacteria break down (or ferment) carbohydrates and certain fibers. Both soluble and insoluble fiber in dog food is fermented by colonic bacteria, contributing to flatus. Soybean meal, or peas, are often used as a protein source in dog food and may contribute to flatulence depending on the amount in the food on a dry matter (DM) basis.
Is there any way for me to reduce the amount of gas my dog passes?
There are several effective ways to reduce excessive flatulence and subsequent flatus. A highly digestible/low residue (low in fiber and non-digestible components) food – specifically the carbohydrate and protein components – reduces the residues available for fermentation by colonic bacteria.
Changing the carbohydrate source in your dog’s food may modify flatus production. Foods that use rice as the carbohydrate source may generate less flatulence than foods that rely on wheat or corn.
Changing your dog's dietary protein source may also help. Dry matter protein content should not exceed 30%, and soy protein should be avoided by dogs with offensive flatus.
Fiber may play a significant role in producing excessive flatulence and flatus in some dogs. Soluble fibers like fruit pectins are easily broken down by GI bacteria and can significantly contribute to excessive flatulence and flatus. Mixed soluble and insoluble fibers can also contribute to the problem. It may be best to limit fiber to 5% DM or less.
One option to reduce excess gas is to switch from a food containing corn, chicken and soybean meal to one with lamb, rice and barley. It is also important to remember that vegetarian dog foods may be problematic because of the likelihood that they contain sulfur-containing vegetables and legumes which promote gas production.
What steps should I take to change my dog’s food in order to reduce her flatus?
It is always appropriate to work with your veterinarian to determine the best nutritional steps to take with your individual dog. Step one is to gather the labels of all the foods and treats you are using, and look for any ingredients that may contribute to the problem. Specific ingredients that may be a problem include:
- Soy fiber
- Soybean hulls
- Pea fiber
- Psyllium
- Pectin
- Bran
- Beet pulp
- Fruits
- High fructose corn syrup
If the major ingredients are potential contributors, look for a nutrient profile that avoids these particular items. There are several therapeutic nutritional formulations currently available to support optimal GI health and to address adverse food reactions. One of these nutrient profiles may be the best one to eliminate excessive GI gas in your dog. It may be necessary to try a couple of different things in order to find the “best fit” for a specific dog with objectionable flatus.
The way your dog eats is also important. Multiple small feedings instead of one or two feedings per day may reduce flatulence by improving digestibility and reducing the food residue available for fermentation by colonic bacteria. Decreasing the speed of eating will decrease the amount of swallowed air. Interactive food toys, raised food dishes, a “food puzzle” dish, and decreasing perceived food competition by feeding household dogs in separate areas may all help decrease a dog’s flatulence and flatus. Walking a dog outside within 30 minutes of feeding encourages defecation and may help dispel excess intestinal gas.
Finally, it is important to remember that intestinal gas production is a normal body process. Excessive flatulence and subsequent flatus, if accompanied by weight loss or diarrhea, may indicate an underlying metabolic disease and should be investigated. If there is no evidence of a disease condition, it is reasonable to presume that excessive canine flatus can be controlled nutritionally.
