Lay Abstract:
Urolithiasis (urinary stone disease) is a painful urinary disorder in dogs, and calcium oxalate (CaOx) is one of the most common types of urolith. This stone type is not amenable to dissolution with diet or medications, necessitating costly methods of physical removal, such as surgery. Following stone removal, recurrence rates are as high as 50% in 1-2 years, highlighting an urgent need for improved prevention strategies.

Recent discoveries suggest that the microbiome and small molecules (metabolites) produced by bacteria may influence stone formation. Short chain fatty acids (SCFAs) are metabolites produced in the gut following bacterial interactions with dietary fibers. SCFAs have the potential to lower CaOx stone risk through several mechanisms. However, relationships between SCFAs and CaOx stone risk have been studied primarily in rodent models of urolithiasis, leaving a critical gap in our knowledge of these mechanisms in dogs. In this pilot study, we will compare the abundance of fecal SCFAs and SCFA-producing bacteria in the gut microbiota of dogs with CaOx urolithiasis and stone-free dogs, and we will examine relationships between SCFAs and urine biochemicals that are relevant to stone risk (e.g., urinary calcium and oxalate levels).

Dietary and prebiotic fiber supplementation can enhance SCFA production in dogs and other species. By determining whether canine stone formers exhibit deficiencies in SCFAs, SCFA-producing bacteria, and by examining relationships between SCFAs and urine composition, we will provide practical insight into a novel and readily accessible intervention for CaOx stone prevention.