Dandrieux J.R.S. and Mans!eld C.S.
In this review, the studies about the prevalence of chronic enteropathy are reviewed as well as the information regarding short- and long-term prognosis for dogs treated with the three most common therapies; these include dietary modification, antibiotics, and immunosuppressants. Although the data available are limited, most studies support a good to excellent long-term response in dogs that have a successful food trial, whereas the response is poor with antibiotics or on-going treatment is required to retain remission. There is a risk of antimicrobial resistance developing with inappropriate use of antimicrobials such as in these situations. The published information highlights the need for alternative strategies to antibiotic treatment to manipulate the GI microbiome; the use of probiotic for the treatment of chronic enteropathy are reviewed.
Chronic enteropathy (CE) is a term used for gastro-intestinal diseases present for a duration of 3 weeks or longer, when extra-intestinal diseases or intestinal disease such as parasitic disease or neoplastic disease are ruled out. Clinically, CE is further classified according to treatment response as food-responsive enteropathy (FRE), antibiotic-responsive enteropathy (ARE), and immunosuppressant-responsive enteropathy (IRE). IRE is the closest entity to the human Crohn’s disease, a variant of inflammatory bowel disease (IBD). The term idiopathic IBD is also used in veterinary medicine interchangeably with IRE in cases not responding to diet or antibiotic trial, and where intestinal inflammation is present on histology. Dogs not responding to treatment are categorized as having non-responsive enteropathy (NRE).
Prevalence
So, how much is CE truly a problem? There are currently insufficient data to fully answer this question. Taking into account the survey results, the authors report that 9.4% of dogs seen will have signs of gastrointestinal disease in general practice. Although gastrointestinal disease is frequently reported in these different studies, it is impossible to determine the true incidence of CE or IBD. In literature, only two studies investigated dogs with signs consistent with CE in referral centres, and reported prevalence values of 2% in UK and 0.09% in Italy, data similar to those reported for dogs of the same breeds (2.1%).
In several studies which assessed the causes of mortality in different type and in purebred dogs, gastrointestinal disease was reported as frequent cause of death, with prevalences varying between different States; the contribution of CE to these is impossible to determine. In summary, further work is required to better understand how prevalent CE truly is both in general and referral practice, but a prevalence of at least 1–2% can be hypothesized.
Response to treatment for Chronic Enteropathy
Although response to treatment has been reported in several studies, the follow-up period is often short and less than 3 months. A total of 17 studies were identified that reported the outcome of dogs treated for CE with a follow up of 3 months or less. Except for one study assessing the effect of natural or synthetic immunomodulators, all the other studies assessed the effects of diet, antibiotics and immunosuppressants. The data suggest there is a good long-term outcome for dogs with CE that initially respond to a dietary trial. However, there are growing concerns that dogs classified as ARE and IRE when first diagnosed, will not respond longer term to the same degree. This finding suggests that strategies that manipulate the microbiome should be evaluated to improve the outcome of dogs diagnosed with CE. Only 5 studies report the outcome of dogs treated for CE with follow up of 3 to 6 months; response to diet trial is reported most frequently (3 studies), with remission rates of over 67%.
Use of probiotics in dogs with CE
The use of probiotics in veterinary practice has been expanding over recent years, due in part to increasing knowledge about the microbiome and in part due to reluctance to use antibiotics long term. Probiotics are defined as live microorganisms that confer a health benefit on the host when administered in adequate amounts.
In addition, probiotics should survive gastric acid and bile to reach and adhere to the intestine, be able to proliferate and colonize the colon, modulate the intestinal immune system, be active against pathogenic micro organisms and have no carcinogenic, toxic, pathogenic or mutagenic effects.
The most common types of bacteria contained in probiotics that are used in veterinary practice include Bifidobacterium, Lactobacillus, Enterococcus faecium, and the yeast Saccharomyces boulardii.
The use of probiotics in veterinary practice has been expanding over recent years, but, a significant issue is the fact that they are not considered veterinary medicines, and therefore products may contain different concentrations of organisms than labelled, and are not obligated to demonstrate efficacy in particular conditions. However several studies were on the use of probiotics in dogs with CE, the variability in other treatments as well as the inclusion of data from dogs that died during the study makes it difficult to attribute benefit entirely to the effects of the probiotic.
Conclusion
In conclusion, although CE is considered as a frequent cause of presentation to the veterinarian, there is currently a lack of studies to determine the true prevalence either at the level of general practice or referral. Although there are many studies reporting short-term response to different treatment trials, there are only a few reporting long-term response and most of the studies included dogs with FRE. Although FRE dogs do have an excellent long-term response, the results are not as clear for ARE or IRE dogs. More studies are required to confirm these results, but this information suggests that other strategies than antibiotic treatment is required.
Based on the literature to date, use of probiotics in dogs with food-responsive enteropathy does not appear to have any benefit. Likewise, the long-term impact on dogs with ARE/IRE is difficult to ascertain. Larger studies are required before any conclusions about the clinical utility of probiotics can be made.