Peer-reviewed veterinary case report
How age and sex affect vitamin B12 and related blood tests in healthy
By Proksch, Anna-Lena et al.·Published in Journal of veterinary internal medicine·2025·Clinic for Small Animals, Germany·View original on PubMed →
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Original publication title: The effects of age and sex on reference intervals for cobalamin, homocysteine, and serum and urinary methylmalonic acid in healthy adult dogs.
- Species:
- dog
Plain-English summary
A study looked at healthy adult dogs to understand how age and sex affect certain blood and urine markers related to metabolism. They found that intact male dogs had higher urinary methylmalonic acid-to-creatinine ratios compared to females and neutered males, which could indicate different health considerations for these dogs. The researchers established reference ranges for cobalamin and other markers, noting that age significantly influenced cobalamin levels. This information can help veterinarians interpret test results more accurately, especially for intact male dogs.
People also search for: dog blood test results explained · high methylmalonic acid in dogs · cobalamin levels in male dogs
Abstract
BACKGROUND: In dogs, data on reference intervals (RIs) for cobalamin, markers of metabolism (markersBmet), age and sex effects are limited. HYPOTHESIS/OBJECTIVES: Establish RI for serum cobalamin, homocysteine, and methylmalonic acid (sMMA) concentrations, urinary methylmalonic acid-to-creatinine ratio (uMMA:crea), and determine effects of sex and age. METHODS: Prospective study using healthy dogs (1-10 years). Cobalamin and markersBmet were determined using chemiluminescence immunoassay (cobalamin) and liquid chromatography/tandem mass spectrometry (homocysteine, sMMA, uMMA:crea). In dogs with outlying data, changes in health, markersBmet, and onset of gastrointestinal signs were reevaluated after 9-15 months. RESULTS: Twelve of 120 healthy dogs had abnormal uMMA:crea ratios. No other cobalamin analyte outliers were found. Outlying data re-examination (odRE) was performed in 10/12 dogs. Chronic gastrointestinal signs occurred in 64% of odRE-dogs, whereas 36% remained healthy. In total, 112 dogs (67 females, 45 males; median ages, 3.5 and 3.75 years, respectively) were included in RI analyses. Reference intervals were 178.5-851 pmol/L (cobalamin), 5.8-29.0 μmol/L (homocysteine), 45.3-159.5 μg/L (sMMA), and ≤22.4 mg/g (uMMA:crea). Only age affected cobalamin concentrations (significant decrease). Compared by sex and neuter status, intact male dogs had significantly higher uMMA:crea ratios (median, 13.5; range, 1.9-83.6 mg/g) than the other groups (median, 2.5; range, 0.7-9.7 mg/g; P < .0001). Sex-specific RI were ≤58.9 mg/g (intact male) vs ≤5.2 mg/g (females and neutered males). CONCLUSION AND CLINICAL IMPORTANCE: Intact male dogs had significantly higher uMMA:crea ratios than the other groups. Thus, sex-specific RI are recommended for uMMA:crea. Because of the wide distribution of uMMA:crea ratios, careful interpretation in intact male dogs is advised.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/39676668/