Gastric acid suppression: Wheres the evidence?

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Why they did it

In this recent review of the literature, the authors discuss the role of histamine-2 receptor antagonists (H2-RA) and proton pump inhibitors (PPIs) for acid suppression in dogs and cats and provide guidance for practitioners on the practical use of these agents in the clinical setting.

Overview of the findings

The study authors reviewed the use of H2-RAs and PPIs in human and veterinary medicine. They note that many of the recommendations used in veterinary medicine today are extrapolated primarily from human literature and the handful of veterinary studies that have been done. Further, the endpoints used in veterinary studies to determine effective acid suppression are extrapolated from human studies and have not been validated in dogs and cats. This makes it difficult to truly determine whether current acid suppression protocols are effective in our veterinary patients.

Based on the available literature, the authors propose an evidence-based approach to the use of acid suppression agents in veterinary medicine. They note that of the available H2-RAs, famotidine has demonstrated the greatest efficacy with increasing gastric pH. The recommended dose is 1 mg/kg twice daily-lower for patients with evidence of azotemia.  Dr. Garcia: Should we mention something about this from the study?

Among the PPIs, omeprazole and pantoprazole have demonstrated the greatest efficacy with doses of 1 mg/kg twice daily. The authors note that concurrent use of H2-RAs and PPIs does not appear to increase acid suppressive effects. However, given the delayed onset of action of PPIs (three to four days to reach maximal effect), H2-RAs may be used with a PPI during initial therapy.

The authors also provide guidelines for situations in which acid suppressive therapy would be indicated to prevent and/or treat gastrointestinal ulceration. These include:

> Ultrasonographic, endoscopic, or surgical evidence of gastrointestinal ulceration

> Mast cell disease

> Gastroduodenal or esophageal foreign body

> Gastric dilatation-volvulus

> Gastric neoplasia

> Gastrinoma

> Esophagitis, gastroesophageal reflux

> Mechanical ventilation

> Congenital intra-hepatic portosystemic shunt

> Coagulopathy in the ICU setting

> Acute liver injury, liver failure, or liver disease associated with portal hypertension

> NSAID intoxication

> Concurrent NSAID and corticosteroid use and extreme physical exhaustion

Further, the authors recommend situations in which acid suppression should be considered for patients with a high risk of developing or having an ulcer (two or more of the following conditions are required):

> Hypoadrenocorticism

> Inflammatory bowel disease

> Pancreatitis

> Nonsteroidal anti-inflammatory therapy

> Corticosteroid administration

> Spinal injury

> Acute kidney injury

> Blood urea nitrogen:creatinine ratio > 30

> Packed red cell volume < 20%

> Hypotension < 100 mm Hg

> Outpatient anticoagulant prophylaxis

As a general rule, the authors recommend four to eight weeks of treatment based on the recommendation in human medicine but caution that the optimal duration of acid suppressive therapy is a not clearly defined in veterinary medicine.

Take-home message

The authors acknowledge that further studies are needed and that these recommendations should be considered as preliminary. Even so, they provide a good framework for how we can use acid suppression to help reduce the risk of gastrointestinal ulceration in our patients.

Daure E, Ross L, Webster CR. Gastroduodenal ulceration in small animals: Part 2. Proton pump inhibitors and histamine-2 receptor antagonists. J Am Med Hosp Assoc 2017;53(1):11-23.

Link to abstract: https://www.ncbi.nlm.nih.gov/pubmed/27841679