Methods and Compositions for Diagnosis and Treatment of Disorders in Pets

Aspects of the invention relate to methods for identifying pets prone to disorders and compositions for preventing, mitigating, delaying the onset and/or reducing the severity of conditions or disorders associated with insufficient nitrogen oxide and/or liver disorder. According to one aspect, provided is a method including determining a genotype of the argininosuccinate synthase gene for a subject being a pet, wherein the genotype is determined to be a minor allele, major allele, or heterozygous allele; and providing instructions to administer arginine based on the genotype of the argininosuccinate synthase gene of the subject.