Vitamin D in Dogs – are we missing the boat? – Arthritis and Itching

Dogs cannot make vitamin D – not even from sun and hence are totally dependent on diet. Osteoarthrtis in humans is only  protected in humans with HIGH vitamin D levels. Might this apply to my dog as well?

Below article discusses the potential need for Vitamin D. Deficiencies were common:

Thirty-three dogs (71·7 %) had 25(OH)D values below the previously reported minimum concentration indicating sufficient vitamin D status of 100 ng/ml”

Young, Lauren R., and Robert C. Backus. “Oral vitamin D supplementation at five times the recommended allowance marginally affects serum 25-hydroxyvitamin D concentrations in dogs.” Journal of nutritional science 5 (2016).

Importance of Vitamin D in dogs so far:

In veterinary medicine, many investigators have reported associations between low serum 25(OH)D concentrations and canine mast cell tumour(16) , chronic kidney disease (17), congestive heart failure(18) , inflammatory bowel disease (19) and cancer (10)

16 Wakshlag JJ, Rassnick KM, Malone EK, et al. (2011)
Cross-sectional study to investigate the association between vitamin D status and cutaneous mast cell tumours in Labrador retrievers. Br J Nutr 106, S60–S63

17 Gerber B, Hassig M & Reusch CE (2003) Serum concentrations of 1,25-dihydroxycholecalciferol and 25-hydroxycholecalciferol in clinically normal dogs and dogs with acute and chronic renal failure. Am J Vet Res 64, 1161–1166

18 Kraus MS, Rassnick KM, Wakshlag JJ, et al. (2014) Relation of vitamin D status to congestive heart failure and cardiovascular events in dogs. J Vet Intern Med 28, 109–115

19 Gow AG, Else R, Evans H, et al. (2011) Hypovitaminosis D in dogs with inflammatory bowel disease and hypoalbuminaemia. J Small Anim Pract 52, 411–418.

10 Selting KA, Sharp CR, Ringold R, et al. (2014) Serum 25-hydroxyvitamin D concentrations in dogs – correlation with health and cancer risk. Vet Comp Oncol (epublication ahead of print version 8 July 2014).



What is little known in human studies is only high levels fully protect people

only HIGH levels fully protect mono sufferers from getting MS:
Munger, Kassandra L., et al. “Serum 25-hydroxyvitamin D levels and risk of multiple sclerosis.” Jama 296.23 (2006): 2832-2838.

“HIGH circulating levels of vitamin D are associated with a lower risk of multiple sclerosis.”

HIGH levels fully help protect subjects from heart disease:

J Prev Med Public Health. 2017 Jul; 50(4): 278–281.
The Big Vitamin D Mistake
Dimitrios T. Papadimitriou

HIGH  levels are helpful in lupus:

Pakchotanon, Rattapol, et al. “Randomized Double-Blind Controlled Trial To Evaluate Efficacy Of Vitamin D Supplementation Among Patients With Systemic Lupus Erythematosus.” Journal of Southeast Asian Medical Research 4.1 (2020): 24-32.


AND Most importantly, only HIGH levels gave best protection against Osteoarthritis.

In a Framingham study of osteoarthritis only subjects in the Upper 1/3 blood levels of vitamin D were protected from osteoarthritis progression: Relation of Dietary Intake and Serum Levels of Vitamin D to Progression of Osteoarthritis of the Knee among Participants in the Framingham Study Timothy E. McAlindon et al Ann Intern Med. 1996;125(5):353-359.

“Risk for progression increased threefold in participants in the middle and lower tertiles for both vitamin D intake (odds ratio for the lower compared with the upper tertile, 4.0 [95% CI, 1.4 to 11.6]) and serum levels of vitamin D (odds ratio for the lower compared with the upper tertile, 2.9 [CI, 1.0 to 8.2]).”

This is huge with “normal” and low levels getting THREE times the osteoarthritis rates. However, where I live vitamin D deficiency is rampant and there seems to be no understanding that knee replacement might be in part related to low vitamin D levels.

 Suspect same seems to go with canines.

Dogs carry huge risk of osteoarthritis yet there is little research into need for vitamin d.

Initial article used:

2·3 μg vitamin D 3 /kg BW exp 0·75

Exponenting the weight comes from studies:
Sidhu KS. Basis for body weight exponent (0.75) as a scaling factor in energy metabolism and risk assessment. J Appl Toxicol. 1992 Oct;12(5):309-10

1 mcg vitamin D is equal to 40 IU

10 kg exp 0.75 comes to 5.6 kg

Results work out to 560 u/day for a 10 kg dog (400 u = one drop pediatric – so one drop for 3 days and 2 drops on forth day)


Gave my 10 k cocker spaniel his first drop today….  More heavy set dogs are going to need it more…

addendum – vit d supplementation might help itch in dogs:

Klinger, Christoph J., et al.
Vitamin D shows in vivo efficacy in a placebo‐controlled, double‐blinded, randomised clinical trial on canine atopic dermatitis.
Veterinary Record 182.14 (2018): 406-406.

“After eight weeks of treatment, patients who received cholecalciferol showed significantly less pruritus than patients from the placebo group (P<0.0001)” – actually cut it in half! I’m hoping my dog will scratch less…


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