Serum homocysteine and methylmalonic acid concentrations in Chinese Shar-Pei dogs with cobalamin deficiency

Vet J. 2013 Aug;197(2):420-6. doi: 10.1016/j.tvjl.2013.02.002. Epub 2013 Mar 15.


Cobalamin deficiency is suspected to be hereditary in Chinese Shar-Pei dogs (Shar-Peis), and inherited causes of cobalamin deficiency may affect the cellular processing of cobalamin. In humans, a defect of the two main cobalamin-dependent intracellular enzymes (i.e., methionine synthase and methylmalonyl-CoA mutase) may lead to hyperhomocysteinemia and hypermethylmalonic acidemia. The aim of this retrospective study was to evaluate serum homocysteine (HCY) and methylmalonic acid (MMA) concentrations in cobalamin-deficient Shar-Peis and dogs of six other breeds. Serum samples (n=297) from cobalamin-deficient dogs (Shar-Peis, German Shepherd dogs, Labrador Retrievers, Yorkshire Terriers, Boxers, Cocker Spaniels, and Beagles) were analyzed for serum HCY and MMA concentrations. A Fisher's exact test was used to evaluate if cobalamin deficiency in Shar-Peis is associated with hyperhomocysteinemia. Serum HCY and MMA concentrations were higher in cobalamin-deficient Shar-Peis compared to cobalamin-deficient dogs of the six other breeds (P<0.0001). Hyperhomocysteinemia was associated with cobalamin deficiency in Shar-Peis (P=0.009). In addition, serum HCY and MMA concentrations did not differ between cobalamin-deficient German Shepherd dogs with and without exocrine pancreatic insufficiency (EPI), a potential cause of secondary cobalamin deficiency. These findings suggest that the function of the two intracellular cobalamin-dependent enzymes is impaired in Shar-Peis with cobalamin deficiency.

Keywords: Cobalamin; Deficiency; Homocysteine; Methylmalonic acid; Shar-Pei dog.

MeSH terms

  • Animals
  • Dog Diseases / blood*
  • Dog Diseases / genetics
  • Dog Diseases / metabolism
  • Dogs
  • Genetic Predisposition to Disease*
  • Homocysteine / blood*
  • Homocysteine / metabolism
  • Methylmalonic Acid / blood*
  • Methylmalonic Acid / metabolism
  • Retrospective Studies
  • Vitamin B 12 Deficiency / blood
  • Vitamin B 12 Deficiency / genetics
  • Vitamin B 12 Deficiency / veterinary*


  • Homocysteine
  • Methylmalonic Acid