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Folate (vitamin B 9 ) and cobalamin (vitamin B 12 ) play an important role in amino acid metabolism, nucleic acid synthesis, and methyl group transfer. Two intracellular enzymes, methionine synthase and methylmalonyl-CoA mutase, are folate and/or cobalamin-dependent, respectively. At the cellular level, a lack of folate and cobalamin leads to accumulation of serum homocysteine (HCY) and a lack of cobalamin leads to increased methylmalonic acid (MMA) concentrations. Altered serum HCY and MMA concentrations can influence amino acid metabolism and nucleic acid synthesis in pigs. Therefore, we aimed to evaluate serum folate, cobalamin, HCY, and MMA concentrations in postweaning pigs between 6 and 26 weeks of age. Serum samples from 12 pigs collected at week 6, 7, 8, 9, 10, 14, 18, 22, and 26 as part of an unrelated study were analyzed. Serum folate (p < .0001), cobalamin (p = .0001), HCY (p < .0001), and MMA (p < .0001) concentrations differed significantly during the postweaning period between 6 and 26 weeks of age; with significantly higher serum HCY (at weeks 6 and 7 compared to weeks 9, 14, 18, 22, and 26) and MMA concentrations (at weeks 6, 7, and 8 compared to weeks 14, 18, 22, and 26) and an overall decrease of serum MMA concentrations from week 6 to week 14 in the pigs studied. This study suggests age-dependent changes in intracellular folate- and cobalamin-dependent metabolites (i.e., HCY and MMA) in pigs between 6 and 26 weeks of age, possibly reflecting decreased availability of intracellular folate and/or cobalamin for amino acid metabolism, nucleic acid synthesis, and methyl group transfer., Competing Interests: Declaration of Competing Interest None of the authors of this paper have a financial or personal relationship with other people or organizations that could inappropriately influence or bias the content of the paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Disorders of cobalamin (vitamin B 12 ) metabolism are increasingly recognized in small animal medicine and have a variety of causes ranging from chronic gastrointestinal disease to hereditary defects in cobalamin metabolism. Measurement of serum cobalamin concentration, often in combination with serum folate concentration, is routinely performed as a diagnostic test in clinical practice. While the detection of hypocobalaminemia has therapeutic implications, interpretation of cobalamin status in dogs can be challenging. The aim of this review is to define hypocobalaminemia and cobalamin deficiency, normocobalaminemia, and hypercobalaminemia in dogs, describe known cobalamin deficiency states, breed predispositions in dogs, discuss the different biomarkers of importance for evaluating cobalamin status in dogs, and discuss the management of dogs with hypocobalaminemia., (© 2019 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.)

Background: Cobalamin (vitamin B12 ) and folate (vitamin B9 ) are important for the amino acid metabolism and nucleic acid synthesis. Immunoassays for the measurement of both vitamins in serum are routinely used in people, cats, and dogs, serving as indicators for clinical disorders including cobalamin and/or folate deficiency, small intestinal dysbiosis, or inadequate dietary supply of these vitamins. The analysis of these analytes may also be clinically useful in pigs., Objective: The purpose of this study was to analytically validate immunoassays for the measurement of cobalamin and folate concentrations in porcine serum, and to determine serum cobalamin and folate concentrations in healthy newborn pigs pre- and postweaning., Methods: Assay validation for both vitamins included the determination of linearity, accuracy, and intra- and inter-assay variability using serum samples from 10 pigs. Also, serum cobalamin and folate concentrations were compared in piglets between pre- and postweaning., Results: For both vitamins, observed-to-expected ratios for linearity and accuracy were 93.2 ± 14.3% and 100.3 ± 8.1% (mean ± standard deviation), respectively. Intra- and inter-assay coefficients of variation for serum were ≤ 8.7% and ≤12.5%, respectively. Significantly higher serum cobalamin and lower folate concentrations were observed in piglets at the time of weaning than at postweaning (P < .0061; P < .0001, respectively)., Conclusions: Both immunoassays are linear, accurate, precise, and reproducible for measurement of porcine serum cobalamin and folate concentrations. Piglets differing in age by only 12 days had significantly different serum cobalamin and folate concentrations. The implications of differing serum cobalamin and folate concentrations in pigs at different stages of life should be further investigated., (© 2016 American Society for Veterinary Clinical Pathology.)

Chinese Shar-Pei dogs have a high prevalence of hypocobalaminemia and are commonly presented with clinical signs suggestive of severe and long-standing gastrointestinal disease such as diarrhea, vomiting, and/or weight loss. The aim of the current study was to evaluate serum concentrations of inflammatory markers, markers for intestinal disease, and immunological markers in Shar-Peis with hypocobalaminemia or normocobalaminemia (serum cobalamin concentrations within the reference interval). Serum samples from Shar-Peis were collected from various parts of the United States. Serum concentrations of inflammatory markers (i.e., C-reactive protein [CRP], calprotectin [CP], and S100A12), hyaluronic acid (HA, a marker for cutaneous mucinosis), and analytes commonly altered in chronic intestinal diseases (i.e., albumin, zinc, alpha1-proteinease inhibitor [α1PI], immunoglobulin [Ig]A, and IgM) were compared between Shar-Peis with hypocobalaminemia and Shar-Peis with normocobalaminemia. Serum concentrations of CRP, CP, S100A12, HA, zinc, and cα1-PI concentrations did not differ between hypocobalaminemic and normocobalaminemic Shar-Peis (P > 0.05). Serum concentrations of albumin were significantly lower in hypocobalaminemic Shar-Peis (median: 2.5 g/dl) than in normocobalaminemic Shar-Peis (median: 2.9 g/dl; P < 0.0001). Higher serum IgA concentrations and lower serum IgM concentrations were observed in hypocobalaminemic Shar-Peis (median: 1.7 g/l and 0.8 g/l, respectively) than in normocobalaminemic Shar-Peis (median: 0.7 g/l and 1.9 g/l, respectively; both P < 0.0001). In conclusion, no difference was found in serum concentrations of CRP, CP, S100A12, and HA between hypocobalaminemic and normocobalaminemic Shar-Peis whereas some differences were observed in analytes (e.g., albumin, IgA, and IgM) that may be altered in patients with chronic enteropathies., (© 2014 The Author(s).)

Fecal canine alpha1-proteinase inhibitor (cα1-PI) concentration has been reported to be increased in dogs with protein-losing enteropathy due to the loss of cα1-PI into the gastrointestinal tract. A chronic loss of cα1-PI may theoretically deplete serum cα1-PI, potentially altering the proteinase-to-proteinase inhibitor balance. Protein-losing enteropathy has been reported to occur frequently in certain dog breeds such as Yorkshire Terriers and to be associated with hypocobalaminemia. The objective was to compare serum cα1-PI concentrations in Yorkshire Terriers with and without cobalamin (COB) deficiency. Serum samples from 52 COB-deficient and 69 normocobalaminemic Yorkshire Terriers, which had been submitted to the Gastrointestinal Laboratory (2008-2011; College Station, TX), were included retrospectively. Serum cα1-PI concentrations were measured using an in-house radioimmunoassay and compared between Yorkshire Terriers with and without COB deficiency using a Mann-Whitney U test. A Fisher exact test was used to evaluate whether a decreased serum cα1-PI concentration is associated with COB deficiency in Yorkshire Terriers. Serum cα1-PI concentrations were significantly lower in COB-deficient Yorkshire Terriers (median: 1,016 mg/l, range: 315-3,945 mg/l) than in normocobalaminemic Yorkshire Terriers (median: 1,665 mg/l, range: 900-2,970 mg/l; P < 0.0001). One-fourth (n = 13) of the COB-deficient Yorkshire Terriers had a serum cα1-PI concentration below the lower limit of the reference interval (<732 mg/l), and COB deficiency was associated with decreased serum cα1-PI concentrations (P < 0.0001). In the current study, serum cα1-PI concentrations are significantly lower in COB-deficient Yorkshire Terriers when compared to normocobalaminemic Yorkshire Terriers. Further studies are needed to determine the functional and potential prognostic implications of serum cα1-PI concentrations in dogs with gastrointestinal disease.

Altered serum cobalamin concentrations have been observed in dogs with gastrointestinal disorders such as exocrine pancreatic insufficiency (EPI) or gastrointestinal inflammation. The aims of the current study were 1) to identify breeds with a higher proportion of dogs with a decreased serum cobalamin concentration, 2) to determine whether dogs with such decreased concentrations tend to have serum canine trypsin-like immunoreactivity (cTLI) concentrations diagnostic for EPI, and 3) to compare the number of submissions for serum cobalamin analysis by breed to the American Kennel Club (AKC) breed ranking list of 2009. In this retrospective study, results of 28,675 cobalamin tests were reviewed. Akitas, Chinese Shar-Peis, German Shepherd Dogs, Greyhounds, and Labrador Retrievers had increased proportions of serum cobalamin concentrations below the lower limit of the reference interval (<251 ng/l; all P < 0.0001). Akitas, Chinese Shar-Peis, German Shepherd Dogs, and Border Collies had increased proportions of serum cobalamin concentrations below the detection limit of the assay (<150 ng/l; all P < 0.0001). Akitas, Border Collies, and German Shepherd Dogs with serum cobalamin concentrations <150 ng/l were more likely to have a serum cTLI concentration considered diagnostic for EPI (≤2.5 µg/l; all P ≤ 0.001). The breed with the highest proportion of samples submitted for serum cobalamin analysis in comparison with the AKC ranking list was the Greyhound (odds ratio: 84.6; P < 0.0001). In Akitas and Border Collies, further investigations are warranted to clarify if a potentially breed-specific gastrointestinal disorder is responsible for the increased frequency of decreased serum cobalamin and cTLI concentrations.