Association between hypocobalaminaemia and hyperhomocysteinaemia in dogs

Coagulation status, fibrinolysis, and platelet dynamics in dogs with chronic inflammatory enteropathy

Background

Coagulation status is poorly understood in dogs with chronic inflammatory enteropathy (CIE). Fibrinolytic activity and platelet dynamics have not been evaluated in CIE dogs.

Objectives

To assess coagulation status and fibrinolysis in normoalbuminemic CIE dogs (CIE‐N) and CIE dogs with protein‐losing enteropathy (CIE‐PLE) compared to healthy controls (HC). To evaluate thromboelastography (TEG) variable differences between groups and for correlations with clinicopathologic data. To report platelet dynamics in CIE dogs.

Animals

Twenty‐five client‐owned dogs with CIE (n = 16 CIE‐N; n = 9 CIE‐PLE); 14 HC beagle dogs.

Methods

All dogs had tissue factor + tissue plasminogen activator TEG. Nine of 25 CIE dogs had whole blood impedance platelet aggregometry. The TEG variables and coagulation data were compared between all CIE vs HC dogs, CIE‐N dogs vs HC, and CIE‐PLE dogs vs HC. Clinicopathologic and coagulation data were available for CIE dogs and assessed for correlation to TEG variables.

Results

Dogs with CIE had higher maximum amplitude (MA; P < .001), longer clot lysis times (CLTs; P < .001), lower % lysis after 30 minutes (LY30; P < .001), and % lysis after 60 minutes (LY60; P < .001) compared to HC, suggesting hypercoagulability and hypofibrinolysis. When separated out, both CIE‐N and CIE‐PLE dogs had higher MA, longer CLT, and lower LY30 and LY60 compared to HC. Serum albumin and 25‐hydroxyvitamin D (25[OH]D) concentrations, and plasma antithrombin and fibrinogen concentrations moderately correlated with MA.

Conclusions and Clinical Importance

Normoalbuminemic and hypoalbuminemic CIE dogs were considered hypercoagulable based on TEG compared to HC. Some CIE dogs displayed hypofibrinolytic phenotypes on TEG.

Serum homocysteine concentration in dogs with immunosuppressant-responsive enteropathy

Background

Homocysteine (HCY) was evaluated in healthy and chronic enteropathic dogs, however no studies on dogs with immunosuppressant-responsive enteropathy are available.

Objectives

The aim was to evaluate serum HCY concentrations and its prognostic role in dogs with immunosuppressant-responsive enteropathy compared to healthy dogs.

Methods

Serum HCY concentration was statistically compared between 24 healthy dogs and 29 dogs with immunosuppressant-responsive enteropathy. Correlation analyses between serum total protein, albumin (ALB), C-reactive protein (CRP), folate and cobalamin, and serum HCY concentration were performed in immunosuppressant-responsive enteropathic dogs.

Results

The associations between serum HCY concentration and clinical, histological, endoscopic scores and follow-up were evaluated. Mean serum HCY concentration was higher in immunosuppressant-responsive enteropathic dogs compared to control dogs (30.22 ± 8.67 µmol/L vs. 5.26 ± 2.78 µmol/L; p < 0.0001). No association between serum HCY concentration and total protein, ALB, CRP, folate concentration as well as, clinical score, histological and endoscopic scores was found. A negative correlation between serum HCY concentration and cobalamin was noted (p = 0.0025, r = −0.54). No significant difference in HCY was found between responsive and non-responsive dogs or between survivors and non-survivors.

Conclusions

Although, serum HCY concentration was higher in immunosuppressant-responsive enteropathy, its prognostic value remains unclear. However, further prospective, large-scale studies are warranted to better investigate the possible prognostic role of HCY in immunosuppressant-responsive enteropathic dogs.

Assessment of folate and cobalamin concentrations in relation to their dependent intracellular metabolites in serum of pigs between 6 and 26 weeks of age

Folate (vitamin B₉) and cobalamin (vitamin B₁₂) 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.

Serum concentration of homocysteine in spontaneous feline chronic kidney disease

Serum homocysteine (Hcy) increases in people and dogs with chronic kidney disease (CKD). Hyperhomocysteinemia (HHcy) has also been associated with CKD-related hypertension and proteinuria. The aims of this study were to: (1) validate an enzymatic method for quantification of Hcy in feline serum; (2) evaluate whether HHcy was associated with the presence and severity of CKD, proteinuria or hypertension; and (3) determine whether HHcy could predict disease progression. The intra- and inter-assay coefficients of variation (CVs) and the recovery rates of linearity under dilution and spiking recovery tests of the enzymatic method were 3.1-6.7%, 11.6-12.5%, 96.9±5.4% and 96.9±5.4%, respectively. Healthy cats at risk of CKD (n=17) and cats with CKD (n=19) were sampled over a 6-month period (63 samples in total). Cats with CKD had significantly higher Hcy concentrations (P=0.005) than cats at risk. The concentration of Hcy was higher (P=0.002) in moderate-severe CKD than in mild CKD and correlated moderately with serum creatinine (P<0.0001; r=0.51). The concentration of Hcy increased with the magnitude of proteinuria and correlated weakly with urinary protein to creatinine ratio (P=0.045; r=0.26). HHcy was not associated with hypertension. At the time of enrollment, Hcy concentration was significantly higher (P=0.046) in cats that developed CKD compared to cats that remained stable. The enzymatic method for Hcy measurement in feline serum was precise and accurate. HHcy was relatively common in cats with advanced CKD and seemed to predict disease progression, but further studies are warranted.

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.

Thromboembolism in Dogs with Protein-Losing Enteropathy with Non-Neoplastic Chronic Small Intestinal Disease

Dogs with protein-losing enteropathy (PLE) are suggested to be at increased risk of developing thromboembolic events. However, with some exceptions, there are very few reports of thromboembolism in such dogs. This multicentre retrospective observational study describes a case series of thromboembolism (TE) in eight dogs with PLE secondary to non-neoplastic, chronic small intestinal disease. Seven dogs had poorly controlled PLE when the thromboembolic event occurred. Pulmonary thromboembolism (PTE) occurred in six dogs, while one dog developed splenic vein thrombosis and another had concurrent splenic vein and aortic TE. Six dogs died, all with PTE. Antithrombin activity was decreased in one of two dogs in which it was measured. Serum cobalamin and folate concentrations were measured in three dogs and cobalamin was subnormal in all three. Serum magnesium, measured in two dogs, was low in both. Dogs with uncontrolled chronic small intestinal disease and PLE are at risk for developing serious life-threatening TE, mostly PTE.

Relationship between cobalamin-dependent metabolites and both serum albumin and alpha1 -proteinase inhibitor concentrations in hypocobalaminemic dogs of 7 different breeds

BACKGROUND

Increased serum concentrations of homocysteine (HCY) and methylmalonic acid (MMA), the 2 main cobalamin-dependent metabolites, as well as decreased serum albumin and canine alpha1 -proteinase inhibitor (cα1 -PI) concentrations have previously been described in hypocobalaminemic dogs with gastrointestinal disease. However, no studies have been conducted to evaluate potential relationships between these serum biomarkers.

OBJECTIVE

The aim of this study was to evaluate the relationship between HCY and MMA, 2 cobalamin-dependent metabolites, and both serum albumin and cα1 -PI concentrations in hypocobalaminemic dogs.

METHODS

Serum samples from 285 dogs including 7 different breeds (Beagle, Boxer, Cocker Spaniel, German Shepherd, Labrador Retriever, Chinese Shar-Pei, and Yorkshire Terrier) with hypocobalaminemia were used. Serum HCY, MMA, albumin, and cα1 -PI concentrations were determined.

RESULTS

There was a significant correlation between serum HCY and albumin concentrations, as well as serum HCY and cα1 -PI concentrations (ρ = 0.62 and ρ = 0.37, respectively; P < .0001). No correlations were observed between serum MMA and albumin concentrations, or cα1 -PI concentrations (ρ = 0.01 and ρ = 0.08, respectively; P > .05). In addition, significant breed-specific correlations were observed between serum MMA and albumin concentrations in German Shepherds, and serum HCY and MMA concentrations in Chinese Shar-Peis with hypocobalaminemia.

CONCLUSIONS

This study shows a correlation between serum albumin and cα1 -PI and HCY concentrations, but not with serum MMA concentration in dogs with hypocobalaminemia. In addition, significant breed-specific correlations were observed between serum MMA and albumin concentrations in German Shepherds, as well as serum HCY and MMA concentrations in Chinese Shar-Peis, emphasizing the unique metabolic interactions in those dog breeds affected by hypocobalaminemia.

Big-endothelin 1 (big ET-1) and homocysteine in the serum of dogs with chronic kidney disease

This study was aimed at determining the serum concentration of homocysteine (Hcy) and big endothelin-1 (big ET-1, the precursor of endothelin) in dogs with chronic kidney disease (CKD) with and without hypertension, proteinuria and inflammation, in order to explore their role as biomarkers of hypertension associated with CKD. Hcy and big ET-1 were measured using an enzyme-linked immunosorbent assay and an enzymatic cyclic reaction, respectively, in dogs with CKD staged, as proposed by the International Renal Interest Society (IRIS), using serum creatinine, urinary protein to creatinine (UPC) ratio and systolic blood pressure, and classified as affected or not by inflammation based on the serum concentration of C-reactive protein (CRP). Serum Hcy was significantly higher in dogs of IRIS stages II, III and IV compared with controls and in proteinuric compared with non-proteinuric dogs. No differences relating to the degree of hypertension or to the CRP concentration were found. Serum big ET-1 significantly increased in dogs of IRIS stage IV compared with controls, in proteinuric compared with non-proteinuric dogs, in dogs with severe hypertension compared with those without hypertension, and in dogs with increased CRP compared to those with normal CRP concentrations. Hcy only correlated with serum creatinine but big ET-1 significantly correlated with serum creatinine, UPC ratio, systolic blood pressure, and increased CRP. In conclusion, both Hcy and big ET-1 increase in dogs with CKD. Although further research is needed, big ET-1, but not Hcy, may also be considered as a biomarker of hypertension.