Urinary liver-type fatty acid-binding protein in two dogs with acquired Fanconi syndrome: A case report

BACKGROUND: Fanconi syndrome (FS) is defined as multiple defects of the proximal tubules and is diagnosed by clinical symptoms. However, in dogs with FS, the damage in the proximal tubules that is responsible for the clinical symptoms has not been evaluated. Among FS cases, tubular damage in acquired FS is reversible following the elimination of a causative factor. Liver-type fatty acid-binding protein (L-FABP) is a biomarker of tubular damage in various animals including dogs. Urinary L-FABP measurement may be useful for the diagnosis and follow-up evaluation in canine FS. CASE DESCRIPTION: At the first visit, two Toy Poodles that had no remarkable findings on physical examination presented with glycosuria without hyperglycemia, hypokalemia, hyperchloremia, increased levels of plasma alkaline phosphatase, and metabolic acidosis. Considering all the factors involved, the dogs were clinically diagnosed with acquired FS. The owner reported that they routinely fed the dog with chicken jerky, a recently considered cause of acquired FS. Following the withdrawal of the jerky, abnormalities including glycosuria improved in both dogs. Moreover, urinary L-FABP levels, which were high at diagnosis, presented a decreasing trend during the follow-up. However, in one dog, the elevated urinary L-FABP level did not return to normal. CONCLUSION: Although the clinical symptoms of acquired FS in dogs could be improved by the elimination of a causative factor, the severity of tubular damage described by urinary L-FABP may not be necessarily linked to the degree of functional deterioration. Therefore, the evaluation of proximal tubular damage by L-FABP may be of clinical value during the follow-up of acquired FS in canines.