Evaluation of Urinary Carnitine and Taurine Excretion in 5 Cystinuric Dogs with Carnitine and Taurine Deficiency

Abstract

Five client owned dogs with cystinuria were diagnosed with carnitine and taurine deficiency while participating in a clinical trial that used dietary management of their urolithiasis. Stored 24-hour urine samples collected from the cystinuric dogs before enrollment in the clinical diet trial were quantitatively evaluated for carnitine and taurine. These results were compared to those obtained from 18 healthy Beagles. Both groups of dogs were fed the same maintenance diet for a minimum of 2 weeks before 24-hour urine collection. The protocol used for 24-hour urine collections was the same for cystinuric dogs and healthy Beagles except that cystinuric dogs were catheterized at baseline, 8 hours, 12 hours, and at the end of the collection, whereas Beagles were catheterized at baseline, 8 hours, and at the end of the collection. Three of 5 dogs with cystinuria had increased renal excretion of carnitine. None of the cystinuric dogs had increased renal excretion of taurine, but cystinuric dogs excreted significantly less (P < .05) taurine in their urine than the healthy Beagles. Carnitinuria has not been recognized previously in either humans or dogs with cystinuria, and it may be 1 risk factor for developing carnitine deficiency. Cystinuric dogs in this study were not taurinuric; however, cystine is a precursor amino acid for taurine synthesis. Therefore, cystinuria may be 1 risk factor for developing taurine deficiency in dogs. We suggest that dogs with cystinuria be monitored for carnitine and taurine deficiency or supplemented with carnitine and taurine.

ACVIMSmall Animal Consensus Recommendations on the Treatment and Prevention of Uroliths in Dogs and Cats

“…However, the degree of protein restriction that is needed is controversial because protein quality and quantity may affect carnitine content. Carnitine deficiency and associated dilated cardiomyopathy were reported in 5 cystinuric dogs fed low‐protein diets . In 1 study performed on cystinuric dogs, the consumption of a decreased protein, urine‐alkalinizing, canned food resulted in a 20–25% decrease in 24‐hour urine cystine excretion compared with a canned maintenance diet .…”

Assessment of protein and amino acid concentrations and labeling adequacy of commercial vegetarian diets formulated for dogs and cats

“…4 In addition, sulfur-containing AAs (methionine, cystine, and taurine) are found primarily in animal protein. 7 Taurine deficiency has also been identified in dogs fed low-protein diets for extended periods or fed diets limited in sulfur-containing AAs. 5 Taurine is considered conditionally essential for dogs because they have the metabolic capacity to synthesize it when adequate concentrations of sulfur-containing AA precursors (methionine and cysteine) are available, except for specific breeds 6 and diseases associated with decreased taurine synthesis.…”

Etiopatogenia Da Urolitíase Em Cães

“…A cistinúria é uma desordem do transporte transmembrana do aminoácido não essencial cistina e de aminoácidos dibásicos lisina, ornitina e arginina, que ocorre nas células dos túbulos renais e intestinais e leva à eliminação aumentada desses aminoácidos na urina (NATH et al, 1984;SANDERSON et al, 2001;FORTERRE et al, 2006;BANNASCH & HENTHORN, 2008;CHILLARÓN et al, 2010;PUTTICK & SEREDA, 2012;SYME, 2012). Em condições normais, esses aminoácidos seriam reabsorvidos nos túbulos (DANPURE, 2000).…”

“…Muitas vezes, os cães com cistinúria apresentam aumento na excreção urinária de diversos aminoácidos; até mesmo não dibásicos (HOPPE et al, 1993b), como a carnitina (SANDERSON et al, 2001), sendo que 46% desses animais podem apresentar excreção aumentada de cinco ou mais aminoácidos. Cistinúria isolada ou a excreção de aminoácidos dibásicos de maneira isolada são raros (HOPPE et al, 1993b).…”

“…Como a cistina é um aminoácido precursor da síntese de taurina, no entanto, a excreção aumentada de cistina pode afetar a síntese de taurina. Portanto, cães cistinúricos devem ser monitorados quanto à deficiência de carnitina e taurina (SANDERSON et al, 2001). As excreções de treonina, ácido glutâmico, glutamina, cisteína, cistationina, arginina, 1-metil-histidina e 3-metilhistidina também podem estar aumentadas na urina de cães com cistinúria (HOPPE et al, 1993b).…”