Relationship between serum cobalamin concentration and endoscopic ileal appearance and histology in dogs with chronic inflammatory enteropathy

Background

It has not been determined whether ileal appearance differs among dogs with chronic inflammatory enteropathy (CIE) and different serum concentrations of cobalamin.

Objective

To compare endoscopic and histologic ileal findings in dogs with CIE and different serum cobalamin concentrations and then evaluate the correlation of ileal changes to cobalamin serum concentration using updated scoring systems to assess the ileum.

Animals

Sixty‐eight dogs with CIE.

Methods

Retrospective study. Frequency of ileal features and ileal histologic and endoscopic scores (IHS and IES) were obtained and compared among CIE dogs with severe hypocobalaminemia (SHC; <200 ng/L), hypocobalaminemia (HC; 200‐350 ng/L), or normocobalaminemia (NC; >350 ng/L). The correlation of IHS and IES with cobalamin was evaluated.

Results

Friability, villus atrophy, crypt dilatation, epithelial injury, and intraepithelial lymphocytes were more frequent in SHC than in NC dogs (all P ≤ .01). Median SHC‐IES (2; range, 0‐4) was higher than NC‐IES (1; range, 0‐5; P = .004). Median SHC‐IHS (6; range, 3‐9) was higher than HC‐IHS (4; range, 1‐7; P < .001) and NC‐IHS (3; range, 1‐8; P < .001). Cobalamin concentration correlated negatively with IES (ρ = −.34, P = .005) and IHS (ρ = −.58, P < .001).

Conclusions and Clinical Importance

Ileal features and involvement degree markedly differed when cobalamin was <200 or >350 ng/L in CIE dogs. With updated scales to assess the mucosa, greater ileal damage was associated with lower serum cobalamin concentration.

Serum cobalamin concentrations in dogs with leishmaniosis before and during treatment

Hypocobalaminemia in dogs is most commonly associated with gastrointestinal disorders leading to impaired absorption and utilization of cobalamin. The objectives of this study were to compare serum cobalamin concentrations between dogs with leishmaniosis and clinically healthy dogs, and to assess possible alterations of serum cobalamin concentrations in dogs with leishmaniosis at different timepoints during treatment. Fifty-five dogs with leishmaniosis and 129 clinically healthy dogs were prospectively enrolled. Diagnosis of leishmaniosis was based on clinical presentation, positive serology and microscopic detection of Leishmania amastigotes in lymph node aspiration smears. Twenty of the dogs with leishmaniosis were treated with a combination of meglumine antimonate and allopurinol for 28 days and serum cobalamin concentrations were measured in blood samples that were collected before initiation of treatment (timepoint 0) and on days 14 and 28. In order to estimate alterations of serum cobalamin concentrations during treatment, cobalamin concentrations were measured in blood samples from 20 out of 55 dogs with leishmaniosis at all timepoints. Serum cobalamin concentrations were significantly lower in dogs with leishmaniosis before treatment (median: 362 ng/L; IQR: 277-477 ng/L) compared to clinically healthy dogs (median: 470 ng/L; IQR: 367-632 ng/L; P = 0.0035). Serum cobalamin concentrations increased significantly in dogs with leishmaniosis on day 14 of treatment compared to timepoint 0 (P = 0.02). In the present study, serum cobalamin concentrations were significantly lower in dogs with leishmaniosis compared to clinically healthy dogs. In addition, there was an increase in serum cobalamin concentrations during treatment. The clinical significance of hypocobalaminemia in dogs with leishmaniosis remains to be determined.

Review of cobalamin status and disorders of cobalamin metabolism in dogs

Disorders of cobalamin (vitamin B₁₂) 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.

SERUM COBALAMIN AND FOLATE CONCENTRATIONS AS INDICATORS OF GASTROINTESTINAL DISEASE IN KILLER WHALES ( ORCINUS ORCA)

Cobalamin and folate are water-soluble vitamins that are useful indicators of chronic gastrointestinal (GI) function in humans and some animal species. Serum cobalamin and folate concentrations in an ex situ population of killer whales ( Orcinus orca) were measured and factors that may affect their serum concentrations were identified. Serum samples ( n = 104) were analyzed from killer whales ( n = 10) both while clinically healthy and during periods of clinical GI disease as defined by clinical signs and fecal cytology. To characterize serum cobalamin and folate concentrations in clinically healthy animals, a mixed-model regression was used, with cobalamin and folate both significantly affected by weight (cobalamin: P < 0.0001, folate: P = 0.006) and season (cobalamin: P < 0.0001, folate: P < 0.0001). The marginal mean concentrations for cobalamin and folate across weight and season were 742 ± 53.6 ng/L and 30.2 ± 2.6 μg/L, respectively. The predicted 95% confidence intervals (CI) for these analytes were then compared with samples collected during periods of GI disease. Across individuals, 22% (2/9) of the folate and 80% (8/10) of the cobalamin samples from the animals with GI disease fell outside the 95% CI for the population. When comparing samples within an individual, a similar pattern presented, with 100% of cobalamin of the observed abnormal samples reduced compared to healthy animal concentration variability. The same was not true for folate. These results suggest that serum concentrations of cobalamin and folate may be useful minimally invasive markers to identify GI disease in killer whales, especially when values are compared within an individual.

Hyperhomocysteinemia in Greyhounds and its Association with Hypofolatemia and Other Clinicopathologic Variables

Background

Folate and cobalamin are essential cofactors for homocysteine (HCY) metabolism. Hyperhomocysteinemia, a multifactorial condition, may reflect B vitamin deficiency and is associated with increased risk of cardiovascular disease, thrombosis, and neurodegenerative and chronic gastrointestinal diseases in humans. Hyperhomocysteinemia has been reported in Greyhounds with suspected chronic enteropathy.

Objectives

To evaluate the frequencies of and the association between hypofolatemia and hyperhomocysteinemia in Greyhounds.

Animals

Data and serum samples from 559 Greyhounds.

Methods

Nested case‐control study. The frequency of hypofolatemia in Greyhounds was determined by a laboratory database search. The relationship between hyperhomocysteinemia (measured by gas chromatography‐mass spectrometry) and hypocobalaminemia and hypofolatemia was evaluated, and its frequency compared between healthy Greyhounds and Greyhounds with thrombosis or chronic diarrhea.

Results

Hypofolatemia was identified in 172 of 423 (41%) Greyhounds and was more common in hypo‐ than in normocobalaminemic dogs (49% vs. 35%; P = .0064). Hyperhomocysteinemia was detected in 53 of 78 (68%) of Greyhounds, being more common in hypo‐ than in normofolatemic dogs (88% vs. 59%; P = .0175). All healthy Greyhounds, 21 of 30 (70%) of dogs with chronic diarrhea and 6 of 8 (75%) of those with thrombosis, were hyperhomocysteinemic. Serum HCY concentrations were inversely correlated with serum folate concentration (ρ = −0.28; P = .0386) and were positively associated with serum albumin concentration (ρ = 0.66; P = .0022).

Conclusions and Clinical Relevance

Hyperhomocysteinemia occurs frequently in the Greyhound population. Its association with hypofolatemia suggests decreased intracellular availability of B vitamins, but the functional implications warrant further investigation. Hyperhomocysteinemia in Greyhounds potentially may serve as a spontaneous canine model to further investigate hyperhomocysteinemia in humans.

Methylmalonic Aciduria Secondary to Selective Cobalamin Malabsorption in a Yorkshire Terrier

An 8 wk old male Yorkshire terrier was presented with a 2 wk history of recurrent hypoglycemia, lethargy, and seizures. Investigations revealed a marked increase in blood ammonia, low serum cobalamin, and increased levels of urinary methylmalonic acid (MMA) excretion. No liver vascular abnormality was detected. The patient was diagnosed with methylmalonic aciduria due to cobalamin malabsorption. The patient responded well to parenteral cobalamin administration, and the urinary MMA levels normalized rapidly following instigation of treatment. Due to the suspected hereditary nature of selective cobalamin deficiency, one sibling of this dog was screened and found to be normal. This is the first reported case of MMA secondary to hypocobalaminemia in Yorkshire terriers, and the second report of this disease in a dog in the United Kingdom. Given the fact that clinical signs of MMA are similar to those seen in dogs with portosystemic shunts and that Yorkshire terriers are predisposed to liver vascular abnormalities, this case report adds important clinical information to the current available literature.

Nonregenerative anemia: mechanisms of decreased or ineffective erythropoiesis

In veterinary medicine, anemia without an appropriate compensatory hematopoietic response is termed nonregenerative. Nonregenerative anemia is a common clinical entity, occurring as a result of diminished or ineffective erythropoiesis in association with many types of pathology. This article reviews nonregenerative anemia in domestic animals, emphasizing mechanisms of disease, and also covers other conditions associated with nonregenerative anemia in people. Many aspects of nonregenerative anemia in animals are worthy of further investigation, from molecular mechanisms of disease to epidemiologic impacts.

Canine breed predispositions for marked hypocobalaminaemia or decreased folate concentration assessed by a laboratory survey

OBJECTIVE

The aim of this study was to determine canine breed predispositions for decreased serum folate or markedly decreased cobalamin concentrations.

METHODS

Retrospective analysis of samples from dogs that had serum folate and cobalamin concentrations measured, from 1990 to 2002 at the Comparative Gastroenterology Laboratory of Liverpool, were enrolled. A total of 13,069 samples were analysed. Those with trypsin-like immunoreactivity < 5·0 lg/L were excluded, and only breeds with at least 30 individuals tested were further analyzed. Breed predisposition was determined by calculating odds ratios and 95% confidence intervals for hypocobalaminaemia or decreased folate concentration. Significance was tested with a two-sided Fisher's exact test, and the level of statistical significance was set at P<0·05.

RESULTS

A total of 9960 dogs fulfilled the inclusion criteria. Forty breeds contained at least 30 individuals. Predispositions for hypocobalaminaemia were identified in shar peis, Staffordshire bull terriers, German shepherd dogs and mixed breeds. Predispositions for decreased folate concentration were found in golden retrievers and boxers.

CLINICAL SIGNIFICANCE

Predisposition for marked hypocobalaminaemia and decreased folate concentration differed between breeds. The shar peis had a markedly increased odds ratio for hypocobalaminaemia, as previously reported in North America, but other at-risk breeds were also identified.

Serum concentrations of canine alpha1-proteinase inhibitor in cobalamin-deficient Yorkshire Terrier dogs

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.