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Vitamin D Metabolism and Hormonal Influences

In many species, the biosynthesis of vitamin D begins with exposure to UV light, wherein 7-dehydrocholesterol is transformed to previtamin D3. Factors that affect synthesis of vitamin D3 include quantity and quality of the UV light, coat, and skin pigmentation. Dogs and cats are unique from humans and many other species in that they lack the ability to synthesize vitamin D3 in the skin, likely because of high activity of 7-dehydrocholesterol-Δ7-reductase.1,2 For this reason, dogs and cats require dietary supplementation with vitamin D to meet nutritional

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in Journal of the American Veterinary Medical Association

Chronic enteropathies are a heterogeneous group of gastrointestinal disorders characterized by gastrointestinal clinical signs that persist for at least 2 weeks. Depending on the study, chronic enteropathies and other diagnoses (eg, IBD) may include a variety of disorders and patient populations, and the inconsistent nomenclature can result in confusing information in the literature. Regardless, achieving a correct diagnosis and classification of chronic enteropathy is essential for proper nutritional management. The most important step in this process is eliminating the possibility of systemic disorders as well as ruling out several primary gastrointestinal diseases, all of which may be less responsive to

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in Journal of the American Veterinary Medical Association

The environment of the GIT is composed of a diverse microbiome. On the basis of environmental, dietary, and genetic factors, the GIT environment develops from a sterile environment to one consisting primarily of anaerobes. 1 During development of the microbiome and after the microbiome is stabilized, commensal and pathogenic microorganisms, along with their interactions, impact the overall microenvironment. The resultant steady-state microenvironment or alternations in steady state attributable to microbial organisms and their products (eg, pH or fatty acid production) interact with the host through the local immune system and enteroendocrine signaling. These local effects, which are influenced by

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in Journal of the American Veterinary Medical Association


Objective—To describe findings in dogs with exogenous thyrotoxicosis attributable to consumption of commercially available dog foods or treats containing high concentrations of thyroid hormone.

Design—Retrospective and prospective case series.

Animals—14 dogs.

Procedures—Medical records were retrospectively searched to identify dogs with exogenous thyrotoxicosis attributable to dietary intake. One case was found, and subsequent cases were identified prospectively. Serum thyroid hormone concentrations were evaluated before and after feeding meat-based products suspected to contain excessive thyroid hormone was discontinued. Scintigraphy was performed to evaluate thyroid tissue in 13 of 14 dogs before and 1 of 13 dogs after discontinuation of suspect foods or treats. Seven samples of 5 commercially available products fed to 6 affected dogs were analyzed for thyroxine concentration; results were subjectively compared with findings for 10 other commercial foods and 6 beef muscle or liver samples.

Results—Total serum thyroxine concentrations were high (median, 8.8 μg/dL; range, 4.65 to 17.4 μg/dL) in all dogs at initial evaluation; scintigraphy revealed subjectively decreased thyroid gland radionuclide in 13 of 13 dogs examined. At ≥ 4 weeks after feeding of suspect food or treats was discontinued, total thyroxine concentrations were within the reference range for all dogs and signs associated with thyrotoxicosis, if present, had resolved. Analysis of tested food or treat samples revealed a median thyroxine concentration for suspect products of 1.52 μg of thyroxine/g, whereas that of unrelated commercial foods was 0.38 μg of thyroxine/g.

Conclusions and Clinical Relevance—Results indicated that thyrotoxicosis can occur secondary to consumption of meat-based products presumably contaminated by thyroid tissue, and can be reversed by identification and elimination of suspect products from the diet.

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in Journal of the American Veterinary Medical Association



To investigate the prevalence of Escherichia coli contamination and E coli virulence gene signatures consistent with known E coli pathotypes in commercially available conventional diets and raw-meat–based diets (RMBDs).


40 diets in total (19 conventionally cooked kibble or canned diets and 21 RMBDs) obtained from retail stores or online distributors.


Each diet was cultured for E coli contamination in 3 separate container locations using standard microbiological techniques. Further characterization of E coli isolates was performed by polymerase chain reaction-based pathotype and virulence gene analysis.


Conventional diets were negative in all culture based testing. In RMBDs, bacterial contamination was similar to previous reports in the veterinary literature, with 66% (14/21) of the RMBDs having positive cultures for E coli. Among the 191 confirmed E coli isolates from these diets, 31.9% (61/191) were positive for virulence genes. Categorized by pathotype, isolates presumptively belonging to the neonatal meningitis E coli pathotype (15.7% [30/191]) were the most common, followed by enterohemorrhagic E coli (10.5% [20/191]), enteropathogenic E coli (5.8% [11/191]), uropathogenic E coli (2.1% [4/191]), and diffusely adherent E coli (1.6% [3/191]).


The results of this study reaffirmed the bacteriologic risks previously associated with RMBDs. Furthermore, potential zoonotic concerns associated with identified pathotypes in these diets may have significant consequences for owners in the animals’ home environment. Potential risk associated with bacterial contamination should be addressed in animals fed RMBDs.

Open access
in American Journal of Veterinary Research