It is becoming more and more common to hear people talk about their dogs having ‘allergies’, ‘food sensitivities’ and ‘sensitive stomachs’, and how these ailments are oftentimes accompanied by odd sores, redness and itching, poor coat and skin, with occasional diarrhea and defy diagnosis!
Although I have addressed these issues before, I will state again that allergies, especially food allergies, are rare in dogs. Environmental allergies are more common, but oftentimes it is really yeast (Malassezia) overgrowth. Food allergies are much rarer. A dog needs to be at least 2 years of age or older to have a true food allergy. Food allergies in dogs develop when they are exposed to the same food over and over for long periods of time (i.e., fixed commercial diet or feeding predominately one meat source in a raw or cooked diet).
Yeast and Fungi are found in the environment (most often malassezia) and can cause skin issues when a dog has been itching, been bit by a tick or flea, or has become run down. Yeast can bounce back and forth with bacteria on the skin which can cause face rubbing, runny eyes, ear issues accompanied by a brown discharge, and thickening of the skin.

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Allergies most often occur with hives, or a reddening and thickening of the skin that itches. You can find yeast AND bacteria in the affected areas.
http://www.ncbi.nlm.nih.gov/pubmed/7848179
http://www.peteducation.com/article.cfm?c=2+2102&aid=321
When a dog is having skin and coat issues, my first advice is to have your veterinarian do a skin scraping and culture to determine if yeast and/or bacteria are present. The skin scraping is sent to a lab to be cultured for at least 3 days. The results not only tell if these are present, but also WHAT strain of bacteria is there AND what medication is needed to treat it. The right diagnosis is always the best way to begin treatment.
IF your dog has loose stools, with or without vomiting, it can be inflammation of the digestive tract lining. When the digestive tract lining becomes inflamed, food cannot process and digest well, and FATS and CARBOHYDRATES are the hardest foods to digest. Fats tend to just rush through the digestive system oftentimes causing diarrhea with mucus. Carbohydrates (fiber) continue to create irritation and stop any healing process. This in turn, can affect the dog’s whole digestive system resulting in poor coat, red or itchy skin, and reduced immune system response. Bacteria and yeast seem to just flock to these dogs and set up shop on their skin.
How is this treated? After a skin scraping and culture are done to determine if bacteria and/or yeast is present and then treated, a diet change can be very helpful. If the dog is eating a commercial pet food, a good change would be to a raw or home cooked diet that contains low or no carbohydrates and reduced fat (at least reduced fat for a few weeks). It is also helpful to feed smaller, more frequent meals for the first few weeks. Less food in the system at one time means less stress on the digestive tract. If you are already feeding a raw diet, remove some of the fat. Remove the skin from chicken parts (NO leg quarters as these are fatty), remove fat from meat and feed protein sources that are lower in fat for a few weeks. Chicken necks without skin (turkey necks too!) are ideal as the raw meaty bone part of the diet.
To enhance healing, add l-glutamine at 1,000 mg per 20 pounds of body weight daily. L-glutamine is an amino acid used in premature babies and people who have suffered starvation to assist with healing of the digestive tract lining. Also, add animal-based digestive enzymes (pancreatin and pancrealipase) as these help predigest fats in the stomach before they hit the small intestine. Lastly, add probiotics (beneficial bacteria) to enhance immunity and put the good flora and fauna back into the gut which is often lost when dogs have diarrhea. The Berte’s Digestion Blend contains all of these supplements, however, you may need to add more l-glutamine in some cases.
How long do these changes take to heal the digestive tract?
Most people get impatient when they don’t see changes right away. You should see improvement in a few days, but it does take a few weeks for the intestinal lining to heal. Usually things go up and down over these weeks, with the good improvements (firmer stools, having ‘to go’ less often, reduced vomiting, and improved skin and coat) slowly getting better and better over time.
Once the digestive tract lining is no longer inflamed, you can go back to feeding two meals a day and slowly increase the fat content. I had a dog with this issue 20 years ago and used this method. He healed in about 6-8 weeks and never had another incident. It takes persistence, patience and determination, but the outcome is well worth it! Taking the stress off the digestive tract by feeding smaller, more frequent meals, reducing the fat and removing or reducing the carbohydrates in the diet, all contribute to the healing of the digestive tract lining. When healing occurs, the immune system starts returning to normal and the dog’s coat and skin improve, along with returned energy and more normal stools.
To help topically, bathing weekly to cleanse the skin will assist the healing process. Rinse with a solution of ¾ water and ¼ WHITE vinegar. This removes any excess soap AND kills yeast on contact. I use a solution of ¾ witch hazel and ¼ aloe vera or Thayers Witch Hazel with Aloe topically as needed. This helps temporarily stop the itching, cools the area, and helps with healing. I have also used the Halo Derma Dream Salve on affected areas twice daily. This promotes hair growth and also assists in healing.