Diarrhoea in dogs. When should antibiotics be used? When should they be avoided?

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Diarrhoea in dogs. When should antibiotics be used? When should they be avoided?

Diarrhoea in dogs is a very common sign in most gastrointestinal diseases. The clinical picture and treatment of diarrhoea in dogs will depend on the aetiology of each case and the use of antibiotics must follow some specific indications. Let’s have a look at each case.

Nutrition and illnesses

Diarrhoea in dogs: chronic inflammatory enteropathies

Chronic inflammatory enteropathies are one of the causes of diarrhoea in dogs. Food intolerances, antibiotic-responsive diarrhoea (ARD) and inflammatory bowel disease (IBD) are included within this group of conditions. The underlying cause is thought to be an imbalance in the immune system and intestinal flora. They are actually considered different manifestations of the same process.

The most frequent cause of chronic diarrhoea in dogs is inflammatory bowel disease. It consists of inflammation of the intestinal mucosa of an undetermined aetiology. Besides diarrhoea in dogs, it also causes vomiting, weight loss and bloody stools.

As it is a disease of unknown origin, it is diagnosed by ruling out other illnesses, both metabolic and infectious, and its definitive diagnosis is based on an intestinal biopsy to confirm the presence of inflammation. A biopsy is also used to classify the disease into subtypes according to which inflammatory cells predominate: lymphocytic–plasmatic enteritis, lymphocytic–plasmatic colitis, eosinophilic gastroenteritis, eosinophilic colitis, eosinophilic granulomas, hypereosinophilic syndrome, histiocytic colitis, granulomatous colitis, transmural granulomatous enterocolitis and suppurative colitis.

Treatment of diarrhoea in dogs

There is a different treatment for each type of inflammatory enteropathy. In the case of food intolerance, an exclusion diet will improve the diarrhoea. The treatment for ARD consists of antibiotics, whereas immunosuppressants are used for IBD. The problem lies with the potential side effects of these drugs.  A special diet is indicated to improve disease management and therefore reduce the dose of these drugs. 

Use of antibiotics for diarrhoea in dogs

Here we focus particularly on ARD. The problem is caused by bacterial overgrowth in the anterior intestine. These bacteria are not pathogenic, but they do cause bowel dysfunction. These bacteria may initiate or perpetuate the intestinal inflammation that results in IBD. Empiric, broad-spectrum antibiotic therapy is used as treatment, since the bacterial population varies from week to week. The aim is to reduce the number of bacteria, as it is impossible to sterilise the digestive tract completely.

The use of aminoglycosides is not recommended because of the presence of anaerobic bacteria. When a rapid response is required in animals with a severe condition, a combination of enrofloxacin and metronidazole can be used. It is important to use a high-quality elimination diet to improve treatment efficacy.

REFERENCE: MICHAEL D. WILLARD. GASTROINTESTINAL INFECTIONS IN CATS AND DOGS. THE USE OF ANTIBIOTICS FOR DIGESTIVE PROCESSES. PRESENTED AT AMVAC 2016, MARCH 3-5, 2016, MADRID, SPAIN. BOOK OF PAPERS AND COMMUNICATIONS - AMVAC 2016, P. 71-76.
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