Current knowledge of vitamin D in dogs

Efficacy of vitamin D2 in maintaining serum total vitamin D concentrations and bone mineralisation in adult dogs fed a plant-based (vegan) diet in a 3-month randomised trial

Dogs are considered omnivores based on their evolution consuming diets including animal tissue. Few feeding trials evaluating the nutritional suitability of exclusively plant-based (vegan) diets in dogs have been published, and the efficacy of vitamin D2 in maintaining canine serum vitamin D levels has not been clearly determined. A blinded dietary trial included sixty-one healthy desexed adult dogs: thirty-one fed an experimental extruded vegan diet (PLANT) and thirty fed a commercial extruded meat-based diet (MEAT) for 3 months. Dogs were screened via veterinary examination and routine laboratory analyses prior to enrolment, at baseline and exit timepoints. Body composition was measured by dual-energy X-ray absorptiometry and blood was collected for vitamin D profiling. All dogs maintained health parameters, body weight and composition throughout the study. Dogs maintained on PLANT demonstrated a significant reduction in platelet count, creatinine, blood urea nitrogen and cholesterol, though values remained within normal reference ranges. Dogs fed PLANT also demonstrated a shift from vitamin D3 to vitamin D2 metabolites, though total vitamin D analogue levels were unchanged, with the exception of 24,25-dihydroxyvitamin D. Bone mineral content and density did not differ from baseline values. Health status was maintained in dogs fed PLANT and vitamin D2 appeared efficacious in maintaining serum total vitamin D concentrations and bone mineralisation. Findings support the hypothesis that PLANT was comparable to MEAT for maintenance of healthy adult dogs for at least 3 months and identified areas where further research is warranted to elucidate the potential risks and benefits of plant-based (vegan) diets.

Comparison of serum 25(OH) vitamin D, parathormone and immunity marker concentrations between dogs with transmissible venereal tumour and healthy dogs

BACKGROUND

1,25-Dihydroxyvitamin D (1,25(OH)2 D) is vital in the homeostasis of calcium and bone health as well as in the prevention of many disorders such as neoplasms. Epidemiological data show that low concentrations of both 1,25(OH)2 D and its precursor 25(OH) vitamin D (25(OH)D) are associated with an increased risk of a variety of human tumours.

OBJECTIVES

To investigate 25(OH)D, parathormone (PTH) and immunity marker concentrations in dogs with transmissible venereal tumour (TVT).

METHODS

25(OH)D, PTH and various biochemical and immunity markers were evaluated in dogs with TVT (n = 26) and in healthy (n = 30) dogs.

RESULTS

25(OH)D concentrations were significantly lower in dogs with TVT in comparison with healthy dogs. In contrast, PTH, immunoglobulin G and interleukin (IL)-9 concentrations were higher in the dogs with TVT. Other variables, including IL-10, interferon γ, calcium and inorganic phosphate, were not statistically different between the two groups.

CONCLUSIONS

Decreased serum 25(OH)D concentration may be a risk factor for the development of canine TVT; however, cause-and-effect remains incompletely understood. Further studies are required to elucidate the exact role of 25(OH)D in canine TVT and whether vitamin D supplementation may be useful prophylactically or as an adjunct to chemotherapy.

Increased dietary vitamin D was associated with increased circulating vitamin D with no observable adverse effects in adult dogs

Introduction

There is no consensus for the optimum concentration of vitamin D, although a minimum concentration of 100 ng/mL (250 nM) of circulating vitamin D, measured as 25(OH) D, has been suggested in order to support optimal health in dogs. Few studies have examined the relationship between dietary vitamin D3 (cholecalciferol) intake and the resulting concentrations of circulating 25(OH) D in adult dogs. Recommendations for dog foods for adult maintenance report a safe upper limit of 3,200 IU vitamin D/kg on a dry matter basis. However, these recommendations were not based on studies of adult maintenance requirements. Understanding the relationship between dietary vitamin D and circulating vitamin D is necessary to utilize dietary vitamin D to influence health in dogs.

Methods

Five groups of adult dogs (each n = 8) were fed food of approximately 4,000 kcal/kg containing one of the following dry matter concentrations of vitamin D for 6 months: 795.7, 3087.3, 5510.9, 7314.0, and 9992.5 IU/kg. Body weight was recorded at baseline and measured weekly, and daily food intake was recorded. Blood samples were taken at baseline and at the end of the 26-week study period.

Results

There were no clinical signs of vitamin D deficiency or excess. Serum concentrations of creatinine, blood urea nitrogen, albumin, hematocrit, hemoglobin, alkaline phosphatase, phosphorus, total calcium, ionized calcium, and parathyroid hormone were maintained within reference values in all groups. Circulating 25(OH) D increased in all groups except those that consumed food with 795.7 IU/kg vitamin D, and increased in a linear and quadratic fashion in response to dietary vitamin D concentration. All of the dogs fed food with 5510.9 IU/kg vitamin D or above met or exceeded 100 ng/mL (250 nM) circulating 25(OH) D.

Discussion

Dietary vitamin D was positively associated with increased circulating concentrations in concentrations up to 9992.5 IU/kg dry matter, with no observable adverse effects. Consumption of ≥5510.9 IU/kg vitamin D resulted in all dogs with at least the 100 ng/mL (250 nM) circulating concentration.

The effects of age, sex, breed, diet, reproductive status and housing condition on the amounts of 25(OH) vitamin D in the serum of healthy dogs: Reference values

BACKGROUND

Optimal amount of vitamin D for the proper functioning of the immune system is different from the required vitamin D amount for bones to prevent rickets. However, reports on vitamin D reference values in dogs are minimal, and there is still not enough information regarding the relationship between vitamin D and various variables such as disease, age, breed, diet type, and so on, as well as its relationship with haematological and serum biochemical parameters.

OBGECTIVES

The present study aimed to determine reference values of 25(OH) Vit D in dogs and its concentration in different groups, categorized based on age, sex, breed, housing conditions, and diet, as well as 25(OH) Vit D relationship with hematology and serum biochemistry parameters.

METHODS

In this study, 90 healthy dogs were selected to determine the reference value of 25 (OH) Vit D of serum after evaluating of their haematological and biochemical parameters to assess their general health. Dogs were divided into different groups according to above-mentioned variables. Serum 25 (OH) Vit D was subsequently measured by the ELISA method.

RESULTS

The median concentration of 25 (OH) Vit D was 52.50 ng/ml with minimum and maximum amounts of 14.00 and 155.57 ng/ml, respectively. No significant difference was observed between 25 (OH) Vit D levels in the studied dogs regarding their different age, sex, breed, diet, housing condition, and reproductive status. Serum 25 (OH) Vit D concentration is directly correlated with the number of band neutrophils (p < 0.05). We also witnessed indirect correlations between serum 25 (OH) Vit D levels and the number of blood eosinophils and serum glucose (p < 0.05).

CONCLUSION

In the present study age, sex, breed, housing condition and age had no significant effects on the amounts of 25(OH) vitamin D. According to correlations of vitamin D with MCH, band and eosinophil numbers and glucose, vitamin D may have a role in erythropoiesis and leukocytes response and also in energy metabolism in dog.

Persistent hypercobalaminemia three months after successful gradual attenuation of extrahepatic shunts in dogs: a prospective cohort study

Background

Deficiencies in vitamin A and D and disorders in the vitamin B complex are often present in people with chronic liver diseases. So far, the serum concentrations of these vitamins have not yet been studied in dogs with congenital extrahepatic portosystemic shunts (EHPSS), who also have some degree of liver dysfunction. The objective was to assess serum vitamin concentrations in dogs with EHPSS from diagnosis to complete closure. A prospective cohort study was performed using ten client-owned dogs with EHPSS, closed after gradual surgical attenuation. Serum concentrations of vitamin A, 25-hydroxyvitamin D, folic acid, cobalamin and methylmalonic acid (MMA) were measured at diagnosis prior to institution of medical therapy, prior to surgery, and three months after gradual attenuation and complete closure of the EHPSS.

Results

At diagnosis, median serum concentrations of vitamin A, 25-hydroxyvitamin D and folic acid were 18.2 μg/dL (8.8 - 79.5 μg/dL), 51.8 ng/mL (19.4 - 109.0 ng/mL), and 8.1 μg/L (5.2 - 14.5 μg/L), respectively, which increased significantly postoperatively (88.3 μg/dL (51.6 - 182.2 μg/dL, P=0.005), 89.6 ng/mL (49.3 - >150.0 ng/mL, P =0.005), and 14.8 μg/L (11.5 - 17.7 μg/L, P <0.001), respectively). Median serum cobalamin concentrations were 735.5 ng/L (470 - 1388 ng/L) at diagnosis and did not significantly decrease postoperatively (P =0.122). Both at diagnosis and three months postoperatively 7/10 dogs had hypercobalaminemia.

Conclusions

Serum concentrations of vitamin A, 25-hydroxyvitamin D and folic acid significantly increase after surgical attenuation. Nevertheless, persistent hypercobalaminemia is suggestive of ongoing liver dysfunction, despite successful surgery.

A Comparison of Key Essential Nutrients in Commercial Plant-Based Pet Foods Sold in Canada to American and European Canine and Feline Dietary Recommendations

Simple Summary

Plant-based pet foods appear to be growing in popularity, but it is unclear how suitable these products are for dogs and cats, considering both species naturally consume diets rich in, or exclusively comprised of, animal tissues. Laboratory analyses of essential nutrients were performed on 26 plant-based diets available in Ontario, Canada in 2018, including 18 canine products (13 products labelled for adult maintenance, four for all life stages, one for puppy growth), 5 feline products (two for adult maintenance and three for all life stages), and 3 products labelled for both dogs and cats (one for adult maintenance and two for all life stages). The nutrient measurements were compared to industry standard nutrient profiles. Four products met the recommendations of the Association of American Feed Control Officials and one product the nutrient recommendations of the European Pet Food Industry Federation for adult dogs. No diets met recommended nutrient content for adult cats or growing puppies or kittens. Nutrients most commonly found to be insufficient were: sulfur amino acids, taurine, arachidonic acid, EPA and DHA, calcium phosphorus and vitamin D. These nutrients are all typically found in animal tissues, though non-animal sources are available, and require careful formulation or supplementation in products made without animal-derived ingredients. Compliance with Canadian labelling regulation and guidelines was poor. These problems do not appear to be exclusive to plant-based foods and have been demonstrated previously in commercially available animal-based products as well. This study demonstrates areas where manufacturers of plant-based pet foods must improve formulation and/or manufacturing practices to produce products appropriate for feeding cats and dogs.

Abstract

Plant-based foods intended for feeding dogs and cats are available in Canada, though few studies have examined the suitability of plant-based foods for dogs and cats. All commercial plant-based extruded and wet pet food products available in Ontario, Canada, in 2018 (n = 26) were acquired and analysed for energy, crude protein, crude fat, crude fibre, ash, amino acids, fatty acids, minerals and vitamins A, B₁₂, D₂ and D₃. Results were compared with recommendations of the Association of American Feed Control Officials (AAFCO) and the European Pet Food Industry Federation (FEDIAF). Thirteen products were labelled for adult canine maintenance, four for canine all life stages, one for puppy growth, two for adult feline maintenance, three for feline all life stages, one for adult maintenance of dogs and cats and two for all life stages of dogs and cats. Four products met AAFCO and one product met FEDIAF nutrient recommendations for canine maintenance. No diets met AAFCO or FEDIAF recommendations for feline maintenance or growth for either species. Nutrients most commonly found insufficient were: sulfur amino acids, taurine, arachidonic acid, EPA and DHA, calcium phosphorus and vitamin D. There were no nutrients unable to be provided from non-animal sources. Compliance with labelling guidelines was also poor, similar to other findings with commercial animal-based pet products. The results from this study indicate areas where producers of plant-based pet foods must improve to meet the industry recommended nutrient profiles and labelling requirements.

Computer-aided ration calculation (Diet Check Munich© ) versus blood profile in raw fed privately owned dogs

Many dog owners create nutritionally imbalanced raw meat-based diets (RMBD) with information from the Internet and pseudo-scientific books, some even use pre-prepared frozen raw feed from online shops, local butchers or other providers. The risk of nutritional imbalances is therefore present. Blood profiles for dogs fed RMBD are promoted by laboratories as a simple tool for the owner to check the nutritional supply situation. Veterinarian nutrition specialists seem to be consulted less frequently and, in most cases, when blood analyses show deviations from reference ranges. The aim of the present study was to evaluate whether a RMBD blood profile reflects possible malnutrition according to a computer-aided ration check and to assess its clinical relevance. Using standardized questionnaires, the average daily rations of 104 dogs, 83 of which were fed raw diets versus 21 commercially fed dogs, were analysed using Diet Check Munich©, based on the National Research Council values. Afterwards, the SYNLAB.vet GmbH 'Barfer-Profil' test including calcium, phosphate, calcium/phosphate ratio, vitamin A, vitamin D, copper, zinc and iodine with additional parameters taurine, urea, uric acid and creatinine was carried out. No significant correlation between nutrient supply and associated blood parameters could be detected. Diet calculation revealed significantly more nutritional imbalances in the RMBD group than in the control group. Low plasma taurine could be detected only in the RMBD group. After participating, 30% of the dog owners (RMBD group) decided to adjust their dogs' diets at the nutrition consultation of the Clinic for Small Animal Internal Medicine of the LMU Munich. Based on these results, for most parameters a RMBD blood profile is not an appropriate tool to monitor a dog's nutrition and computer-aided ration calculation remains the gold standard for detecting nutritional imbalances.

Effects of silybin supplementation on nutrient digestibility, hematological parameters, liver function indices, and liver-specific mi-RNA concentration in dogs

Background

Hepatopathies are an important group of disorders in dogs where proper nutritional care is crucial. Supplementation with a hepatoprotectant like silybin can improve liver function and should not interfere with nutrient digestibility. The purpose of this study was to investigate the effect of both pure silybin and commercial hepatoprotectant on nutrients digestibility, liver function indices and health status in healthy dogs (EXP1). Moreover, the second experiment (EXP2) investigated the effect of commercial hepatoprotectant on liver function tests and liver-associated miRNAs concentration in dogs with idiopathic liver disorder.

Results

Nutrient digestibility was not affected by treatment in EXP1. Supplementation did alter the serum fatty acid profile, with no clinical relevance. The levels of liver markers such as ALT, AST and GGT significantly decreased. In EXP2, supplementation with commercial hepatoprotectant containing silybin improved liver function tests. A decrease was observed in liver serum markers such as ALT, AST and miR122 concentration.

Conclusions

EXP1 confirmed that silybin (whether pure or as a commercial hepatoprotectant) does not interfere with digestion which subsequently exerts no detrimental effect on dogs’ health and metabolism. In EXP2, dietary supplementation with commercial hepatoprotectant containing silybin resulted in a decreased activity of serum liver markers, accompanied by a decrease in the concentration of liver-specific miRNA molecules. Liver function indices were consequently improved. Silybin supplementation can thus serve as an effective therapeutical tool in dogs with hepatopathies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-021-02929-3.

Calcium, Phosphorus, and Vitamin D in Dogs and Cats: Beyond the Bones

Calcium, phosphorus, and vitamin D are nutrients that play a key role in maintaining normal organ, cell, and tissue function. Much is known about their role in bone metabolism, but these nutrients are also important in renal health, urinary tract disease, and multiple other organ systems. It is nutritionally important to meet the physiologic requirements for each of these nutrients, but the interplay between them should also be considered.

Serum 25-hydroxyvitamin D concentration in Japanese Akita dogs: A survey

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Low serum 25-hydroxyvitamin D levels are detected in Japanese Akita dogs.

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Healthy Akitas show a higher level of vitamin D than pathological ones.

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Depigmented skin areas appearance is associated with low levels of vitamin D.

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Sebaceous adenitis is the prevalent disease recorded among investigated Akitas.

Low serum level of vitamin D has been linked to numerous diseases. The Akita breed of dog shows a high incidence of immune-mediated diseases such as uveodermatologic (UVD) syndrome and sebaceous adenitis (SA). Furthermore, in Japanese Akita dogs, skin depigmentation often appears after birth at different ages, in healthy dogs, and without any other symptoms. In humans poliosis is associated to low vitamin D level. The aim of this survey was to evaluate serum 25-hydroxyvitamin D (25(OH)D) levels in Japanese Akita dogs. One hundred and three Akita blood samples were collected for the 25(OH)D evaluation. Age, sex, current disease, presence and location of skin depigmentation, and diet were reported on a medical record. Based on history and clinical examination, dogs were classified according their health status as healthy (HE) or pathological (PA). The overall mean of 25(OH)D concentration was 82.42 ± 26.14 ng/mL, whereas the concentrations in the healthy dogs were significantly higher (84.90 ± 3.36 ng/mL) in comparison with the dogs with diseases (72.13 ± 4.09 ng/mL) (P < 0.01). In this study, the depigmented healthy dogs showed low level of 25(OH)D and very similar to the sick group. The appearance of depigmented areas associated with low levels of vitamin D could be considered as an alert sign in Akitas as well as in humans. However, clinical trials should also be carried out to establish whether vitamin D supplementation could be an effective preventive treatment to limit the onset of immune-mediated diseases in Japanese Akita dogs.

Vitamin D status is seasonally stable in northern European dogs

BACKGROUND

Numerous studies in veterinary species have recently linked vitamin D status with nonskeletal health disorders. Previous studies have indicated that dogs cannot produce endogenous vitamin D via cutaneous production and rely solely on dietary intake of vitamin D. The seasonal variation of vitamin D seen in humans due to changes in ultraviolet (UV) exposure, therefore, is unlikely to be replicated in these animals.

OBJECTIVES

The objective of this study was to investigate the natural variation in 25-hydroxyvitamin-D concentrations in dogs subject to seasonal UV exposure.

METHODS

This longitudinal study followed 18 healthy dogs fed a standardized diet over 1 year, with blood samples obtained monthly. Two key vitamin D metabolites, 25-hydroxyvitamin-D₂ and 25-hydroxyvitamin-D₃ , were assessed by liquid chromatography-tandem mass spectrometry in serum samples. Various other biochemical parameters were also measured. Seasonality was assessed using cosinor statistical analysis.

RESULTS

Although the dogs were subject to seasonally varying UV radiation, 25-hydroxyvitamin-D and related biomarkers (including calcium and parathyroid hormone) remained stable over time and did not follow a seasonal pattern. 25-hydroxyvitamin-D was not positively correlated with exposure to UV radiation. Nonetheless, variation in 25-hydroxyvitamin-D concentrations between individual dogs was detected.

CONCLUSIONS

Given the standardization of diet, we concluded that the seasonal stability of 25-hydroxyvitamin-D concentration (vitamin D status) was likely a direct result of lack of cutaneous vitamin D production in this species and highlights the importance of dietary intake. The variation in 25-hydroxyvitamin-D concentration between animals warrants further investigation.

Development and application of a LC-MS/MS assay for simultaneous analysis of 25-hydroxyvitamin-D and 3-epi-25-hydroxyvitamin-D metabolites in canine serum

Hypovitaminosis D and hypervitaminosis D are well recognised disorders in dogs. Hypovitaminosis D can occur following consumption of a diet inadequately supplemented with vitamin D or as a sequelae of severe intestinal disease. Hypervitaminosis D may occur as a result of consuming proprietary dog foods over-supplemented with vitamin D or through ingestion of vitamin D containing medicinal products or rodenticides. Consequently, there is a clear need to establish a methodology that can accurately quantify vitamin D metabolites across a broad dynamic range in dogs. The existence of C3-epimers of vitamin D metabolites has yet to be elucidated in dogs, yet are known to interfere with the analysis of vitamin D and have unknown biological activity in other species. Here, we describe the development and validation of a sensitive, specific and robust analytical liquid chromatography tandem mass spectrometry (LC-MS/MS) assay capable of separating and accurately measuring 25-hydroxyvitamin-D_2/3 (25(OH)D_2/3) and 3-epi-25-hydroxyvitamin-D_2/3 (3-epi-25(OH)D_2/3). We describe a simplified workflow utilising supported liquid extraction (SLE) without derivatization that provides good linearity (mean r > 0.996) and accuracy across a broad dynamic range of 4-500 nmol/L for D₃ metabolites and 7.8-500 nmol/L for D₂ metabolites. Upon application of this assay to 117 canine serum samples, 25(OH)D₃ was detectable in all samples with a median concentration of 82.1 nmol/L (inter-quartile range (IQR) 59.7-101.8 nmol/L). 3-epi-25(OH)D₃ could be detected in 87.2 % of the study population, with a median concentration of 5.2 nmol/L (2.4-8.1 nmol/L). However, 3-epi-25(OH)D₃ was quantified below the LLOQ in 40.2 % of these samples. 3-epi-25(OH)D₃ contributed on average 6.3 % to 25(OH)D₃ status (contribution ranges from 0 to 23.8%) and a positive correlation was detected between 25(OH)D₃ and 3-epi-25(OH)D₃ concentrations. Free 25(OH)D was also measured using an immunoassay with a median concentration of 15.2 pmol/L (12.5-23.2 pmol/L), and this metabolite was also positively correlated to both 3-epi-25(OH)D₃ and 25(OH)D₃ concentrations. D₂ metabolites were not detected in canine serum as expected. Vitamin D metabolite concentrations were variable between individuals, and research into the causes of this variation should include factors such as breed, age, sex and neuter status to determine the impact of genetic and hormonal factors. Given the clinical importance of vitamin D in dogs, and the immense potential for utilising this species as a model for human disease, further elucidation of the vitamin D pathway in this species would provide immense clinical and research benefit.

Nutrition consultation for an overweight growing Bernese Mountain Dog-A case report

In growing dogs, overweight is assimilated and attributed to a fast growth rate. Proper nutrition plays a very important role during growth as mistakes in feeding may lead to severe disease. This case report is an example for excessive weight gain during growth that, particularly in large breed dogs, may lead to skeletal disorders such as improper alignments of the limbs. If body weight gain exceeds the ideal range of the individual growth curve (by initially 4 kg in this case), fast growth may lead to growth disturbances and associated chronic diseases. These cases require a dietary adaption. However, the success in the nutritional management of the body weight relies largely on the owner's compliance.

Comparison of clinical, clinicopathologic, and histologic variables in dogs with chronic inflammatory enteropathy and low or normal serum 25-hydroxycholecalciferol concentrations

Background

The cause of low serum vitamin D concentrations in dogs with chronic inflammatory enteropathy (CIE) is not well understood.

Objective

Improve understanding of pathogenesis of low serum vitamin D concentrations in dogs with CIE by comparing several clinical, clinicopathologic, and histologic variables between CIE dogs with low and normal serum 25‐hydroxyvitamin D concentrations (25[OH]D).

Animals

Fifteen dogs with CIE and low serum 25[OH]D concentrations; 15 dogs with CIE and normal serum 25(OH)D concentrations.

Methods

Prospective cohort study. Clinical and clinicopathologic variables were compared between groups. Correlations between serum 25(OH)D concentration and histopathologic variables were assessed.

Results

Dogs with CIE and low serum 25(OH)D concentrations had higher canine chronic enteropathy clinical activity index scores (P = .003), lower serum α‐tocopherol (P < .001), cholesterol (P < .001), and albumin (P < .001) concentrations and higher serum C‐reactive protein (P = .004) concentrations compared to CIE dogs with normal serum 25(OH)D concentrations. Serum concentrations of vitamin D‐binding protein (VDBP) were not different between groups (P = .91). Duodenal morphologic and inflammatory histopathological scores (P = .002 and P = .004, respectively) and total histopathological scores in duodenum and combined duodenum and ileum negatively correlated with serum 25(OH)D concentration.

Conclusions and Clinical Importance

The pathogenesis of low serum vitamin D concentrations in dogs with CIE is likely multifactorial. Fat malabsorption deserves further study in dogs with low serum vitamin D concentration and CIE. Loss of VDBP does not appear to be an important cause of low serum vitamin D concentration in dogs with CIE.

Serum concentrations of lipid-soluble vitamins in dogs with exocrine pancreatic insufficiency treated with pancreatic enzymes

Background

In humans, exocrine pancreatic insufficiency (EPI) is associated with deficiencies in lipid‐soluble vitamins. Little is reported regarding lipid‐soluble vitamin status in dogs with EPI.

Hypothesis/Objectives

Compare serum concentrations of retinol, 25‐hydrocholecalciferol (25OHD), and α‐tocopherol among dogs with EPI, those with subclinical EPI (sEPI), and healthy dogs. Detect associations between serum concentrations of lipid‐soluble vitamins and residual clinical signs in treated dogs with EPI and sEPI.

Animals

Twenty dogs with EPI and five dogs with sEPI receiving pancreatic enzyme replacement therapy. Ten healthy dogs sampled before and after 10 days of pancreatic enzyme supplementation.

Methods

Case‐control study. Serum retinol and α‐tocopherol concentrations were measured by high‐performance liquid chromatography. Serum 25OHD concentrations were measured by radioimmunoassay.

Results

Serum retinol concentration was significantly lower in dogs with EPI (median, 490 ng/mL; range, 322‐990 ng/mL) and serum α‐tocopherol concentration was significantly lower in dogs with EPI (median, 11.51 μg/L; range, 4.8‐27.1 μg/L) and sEPI (median, 12.66 μg/L; range, 10.21‐21.03 μg/L) compared with healthy dogs (median, 1203 ng/mL; range, 637‐1768 ng/mL and median, 43.54 μg/L; range, 34.26‐53.97 μg/L, respectively). Dogs with weight loss had significantly lower 25OHD (mean, 243.50 nmol/L; standard deviation [SD], 3.54 nmol/L) than dogs with stable weight (314.0 nmol/L; SD, 138.38 nmol/L).

Conclusions and Clinical Importance

Altered homeostasis of lipid‐soluble vitamins is present in dogs with EPI and sEPI, despite enzyme replacement therapy. Additional studies are needed to determine the clinical relevance of these findings and the therapeutic potential of lipid‐soluble vitamin supplementation in dogs with EPI and sEPI.

Maternal omega-3 polyunsaturated fatty acid supplementation on offspring hip joint conformation

Unsaturated omega-3 fatty acids, especially docosahexaenoic acid (DHA), when fed to dogs improves cognitive and neurological development. Supplementation with omega-3 fatty acids such as DHA and eicosapentaenoic acid (EPA) has also been associated with lipid peroxidation, which in turn has been implicated in reduced body weight and altered bone formation. To assess the impact of omega-3 fatty acid supplementation on skeletal growth, diets containing three levels of DHA and EPA (0.01 and 0.01%, 0.14 and 0.12%, and 0.21 and 0.18%, respectively) were fed to bitches during gestation and lactation with puppies also supplemented through weaning. Thus, the subjects studied were the puppies supplemented with DHA and EPA through gestation and early postnatal life. The hip joint conformation of the puppies (n = 676) was recorded at adulthood using two radiographic, non-invasive evaluations. In this population, females had higher hip distraction indices (DI) than males. Males from the lower two levels of DHA and EPA supplementation had significantly smaller hip DI than all females and males from the highest DHA and EPA supplementation. In contrast, there were no diet effects on anatomical indicators of hip joint conformation and no visible arthritic changes. These data suggest that dietary supplementation of DHA and EPA during gestation and the perinatal period to weaning does not adversely influence hip joint formation of dogs.

Influence of Various Factors on Circulating 25(OH) Vitamin D Concentrations in Dogs with Cancer and Healthy Dogs

Background

Low blood 25‐hydroxyvitamin D (25(OH)D) concentrations have been associated with cancer in dogs. Little research has examined what other factors may affect 25(OH)D concentrations.

Objectives

(1) To determine whether the presence of cancer (lymphoma, osteosarcoma, or mast cell tumor [MCT]) in dogs is associated with plasma 25(OH)D concentrations and (2) identify other factors related to plasma 25(OH)D concentrations in dogs.

Animals

Dogs newly diagnosed with osteosarcoma (n = 21), lymphoma (n = 27), and MCT (n = 21) presented to a tertiary referral oncology center, and healthy, client‐owned dogs (n = 23).

Methods

An observational study design was used. Dietary vitamin D intake, sex, age, body condition score (BCS), muscle condition score (MCS), and plasma concentrations of 25(OH)D, 24,25‐dihydroxyvitamin D (24,25(OH)₂D) (a marker of CYP24A1 activity), as well as ionized calcium (ICa), parathyroid hormone, and parathyroid hormone‐related protein concentrations were measured. An analysis of covariance was used to model plasma 25(OH)D concentrations.

Results

Cancer type (P = 0.004), plasma 24,25(OH)₂D concentrations (P < 0.001), and plasma ICa concentrations (P = 0.047) had significant effects on plasma 25(OH)D concentrations. Effects of age, sex, body weight, BCS, MCS, and plasma PTH concentrations were not identified. A significant interaction between ICa and cancer was found (P = 0.005). Plasma 25(OH)D concentrations increased as ICa concentrations increased in dogs with cancer, whereas plasma 25(OH)D concentrations decreased as ICa concentrations increased in healthy dogs.

Conclusions and Clinical Importance

Results support a relationship between cancer and altered vitamin D metabolism in dogs, mediated by plasma ICa concentrations. The CYP24A1 activity and plasma ICa should be measured in studies examining plasma 25(OH)D concentrations in dogs.

Association of Vitamin D Metabolites with Parathyroid Hormone, Fibroblast Growth Factor-23, Calcium, and Phosphorus in Dogs with Various Stages of Chronic Kidney Disease

BACKGROUND

Hypovitaminosis D is associated with progression of renal disease, development of renal secondary hyperparathyroidism (RHPT), chronic kidney disease-mineral bone disorder (CKD-MBD), and increased mortality in people with CKD. Despite what is known regarding vitamin D dysregulation in humans with CKD, little is known about vitamin D metabolism in dogs with CKD.

OBJECTIVES

The purpose of our study was to further elucidate vitamin D status in dogs with different stages of CKD and to relate it to factors that affect the development of CKD-MBD, including parathyroid hormone (PTH), fibroblast growth factor-23 (FGF-23), calcium, and phosphorus concentrations.

METHODS

Thirty-seven dogs with naturally occurring CKD were compared to 10 healthy dogs. Serum 25-hydroxyvitamin D [25(OH)D], 1,25-dihydroxyvitamin D [1,25(OH)₂ D], and 24,25-dihydroxyvitamin D [24,25(OH)₂ D], and PTH and FGF-23 concentrations were measured. Their association with serum calcium and phosphorus concentrations and IRIS stage was determined.

RESULTS

Compared to healthy dogs, all vitamin D metabolite concentrations were significantly lower in dogs with International Renal Interest Society (IRIS) stages 3 and 4 CKD (r [creatinine]: -0.49 to -0.60; P < .05) but not different in dogs with stages 1 and 2 CKD. All vitamin D metabolites were negatively correlated with PTH, FGF-23, and phosphorus concentrations (r: -0.39 to -0.64; P < .01).

CONCLUSIONS AND CLINICAL IMPORTANCE

CKD in dogs is associated with decreases in all vitamin D metabolites evaluated suggesting that multiple mechanisms, in addition to decreased renal mass, affect their metabolism. This information could have prognostic and therapeutic implications.