The world is full of bacteria; many kinds are harmful and can cause illness, but there are also beneficial bacteria. The gastrointestinal (GI) tract uses bacteria to digest food and to make certain vitamins. Most of these helpful bacteria live in the large intestine (colon). Stress, illness, medication, or change in diet can upset the balance of bacteria in the large intestine, which can lead to minor problems such as gas, or more major problems such as diarrhea. Having the right balance of bacteria helps your dog to make better use of food and can help prevent some GI illnesses.
Probiotic is the general term applied to a group of live bacteria that are normally found in the gastrointestinal tract of healthy dogs and are thought to have a beneficial effect on GI health. The two main beneficial bacteria for dogs are Lactobacillus acidophilus and Enterococcus faecium (previously known as Streptococcus faecium). These beneficial bacteria can out-compete some of the bad bacteria such as Escherichia coli (E. coli) and prevent them from colonizing in the GI tract. In addition, L. Acidophilus and E. Faecium produce lactic acid. Lactic acid, in turn, stimulates the development of L. Acidophilus and E. Faecium and increases acidity in the large intestine, which is unfavourable for some pathogenic bacteria and good for increased enzyme activity.
Probiotics are believed to be useful in improving digestion and are reputed to help improve immune function. Adding probiotics to your dog’s diet may be most useful if your dog:
• has had antibiotic treatment
• has changed to a new food
• has a food allergy
• has inflammatory bowel disease
• is a senior or a puppy.
Probiotic bacteria are host specific. Just as dogs have a variety of breeds within the species, L. Acidophilus and E. Faecium have a variety of different strains. This means that the L. Acidophilus strain that is beneficial to humans may not be beneficial to dogs and vice versa. One of the most common sources of probiotics is live culture yogurt, but not all yogurt contains live bacterial strains and these probiotics are designed for humans and may not be fully beneficial to dogs. When looking to purchase a probiotic you want to make sure that you are purchasing a dog probiotic.
Probiotics live and function in the large intestine. For a probiotic to be effective, it needs to survive the very acidic environment of the stomach and small intestine so it can reach and colonize the large intestine. One of the ways to ensure enough probiotic reaches the large intestine is to start with a very high concentration of live probiotic bacteria. As the high quantity of bacteria passes through the GI tract, some will die but the majority will survive. In order to ensure that the probiotic is effective, the dog needs to consume millions or billions of viable bacteria. The number of live bacteria is measured as the number of colony-forming units (CFU) per gram of probiotic. When looking to purchase a probiotic, look for a product that has millions or billions of CFU per gram. You may see this reported in scientific notation. For example, one million probiotic bacteria may be reported as 1 x 106 CFU and 1 billion may be reported as 1 x 109 CFU.
Canine probiotics are not drugs and, as a result, they are not currently regulated in Canada. Unfortunately, this means that there is no assurance as to the accuracy of the manufacturer’s label. A study done in 2003 tested 19 commercial pet foods claiming to contain probiotics and found that none of the products tested contained all the strains claimed on the label. Some labels will claim the presence of a bacterial fermentation product (i.e., Lactobacillus acidophilus fermentation product). These fermentation products are not probiotics because they do not contain live bacterial cells. Instead, they are a source of enzyme activity that may not survive the acidic environment of the stomach and may not, therefore, be beneficial.
For a variety of reasons, scientific research has had some difficulty proving the proposed benefits of feeding probiotics to dogs, however, they are unlikely to cause harm to your dog. There are some conditions in which you should consult your veterinarian before feeding probiotics. If your dog is immune compromised or undergoing GI surgery, or is suffering a severe bout of gastroenteritis, you should not feed probiotics until you have discussed it with your veterinarian.
While there is an increasing awareness in society about bacteria and viruses, most of the media focus has been on pathogenic bacteria. It is important to remember that there are many beneficial bacteria. Not all bugs are bad.