Decreased Serum Folate
To our knowledge the benefit of supplementing folic acid to dogs and cats with gastrointestinal disease and serum folate concentrations below the lower limit of the reference interval has not been clearly demonstrated. However, because experimentally-induced folate deficiency can lead to clinical consequences and folic acid is cheap and safe we consider supplementation in animals with a decreased serum concentrations. The difficulty in administering pills to the patient and the severity of their hypofolatemia also influence our decision whether to treat individual patients or not.
Folic acid supplements sold for use in humans are readily available. We recommend a dose of 200 mcg for cats and smaller dogs (<20 kg BW) and 400 mcg for larger dogs (20 kg BW) PO once daily for 4 weeks. It is very important to also address the proximal small intestinal disease that is suspected as the underlying cause of the decreased serum folate concentration. If the animal’s clinical signs have resolved, we do not usually recheck serum folate concentrations. If the clinical signs are persistent, rechecking serum folate concentration 1 week after supplementation is stopped may be helpful
Increased Serum Folate
Small intestinal bacterial dysbiosis may result in an increased ability of the intestinal microbiota to synthesize folate, which may lead to increased serum concentrations of this vitamin. However, hyperfolatemia has not be shown to predict a positive response to antimicrobial treatment. Small intestinal dysbiosis often occurs secondary to chronic enteropathy or other gastrointestinal disorders (such as exocrine pancreatic insufficiency) but can also be primary (idiopathic). Treatment recommendations vary depending on the patient’s clinical presentation and past treatments. For appetent non-critically ill dogs and cats with chronic enteropathy a diet trial(s) is usually recommended at an early stage in their diagnostic work up. Often this means feeding an elimination diet in case of suspected dietary intolerance/allergy. A feeding trial with an easily digestible diet (these diets are often referred to “intestinal” diets and are often supplemented with fermentable fiber that act as a prebiotic, are moderately fat restricted, and contain an optimized ratio of omega-3 to omega-6 fatty acids) can also be tried. Especially in dogs, therapies aimed to modulate the gastrointestinal microbiota are often tried next. These include certain antimicrobials (e.g., tylosin: 25 mg/kg PO q12 hours for 6-8 weeks), probiotics, and/or prebiotics (fermentable fibers). Some animals require a combination of the treatments described above possibly in conjunction with immunomodulatory therapy.