New Evidence Supports the Importance of Vitamin D for Cats

Published: June 12, 2015
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A recent study published in the online journal PLoS ONE shows how important vitamin D is, especially to sick cats. As the authors explain: “vitamin D metabolism is altered in dogs and cats with a wide range of infectious, inflammatory and neoplastic conditions,” and “low serum 25(OH)D [a metabolite of vitamin D] concentrations have also been linked to all-cause mortality in the general human population.”

Investigating the role of serum 25(OH)D concentrations and all-cause mortality in cats would be of interest to veterinarians since it is presently difficult to accurately predict mortality in hospitalised, ill cats. The identification of clinical measures which were predictive of mortality would be extremely helpful in providing much needed prognostic information to owners of ill cats. 

Ninety-nine cats were included in the study. The researchers were able to gather a lot of data from the cats’ medical records, residual blood samples, and follow-up conversations with the cats’ owners and referring veterinarians, including the cats’ 25(OH)D concentrations and whether or not the cats were alive 30 days after their initial presentation. They found that cats with 25(OH)D concentrations in the lowest third of the observed range had an increased risk of dying. Blood potassium levels and a reduced appetite were the only other indicators that could be used to predict a cat’s chance of surviving.

While measuring 25(OH)D concentrations could help inform veterinarians and owners about the potential benefit of treating extremely sick cats, it is important to note that this study says nothing about the usefulness of vitamin D supplements. Commercially available foods and home-cooked diets prepared according to a veterinary nutritionist’s recipe should all contain the right amount of vitamin D for healthy cats.

Vitamin D is one of those nutrients that can actually be dangerous when a cat takes in too much. It is a fat soluble vitamin, which means that it can build up to toxic levels in the body and lead to potentially fatal kidney and lung damage.

If I had to guess, I would say that giving extra vitamin D to sick cats who have normal 25(OH)D levels will also have little beneficial effect. This study found no significant difference in the mortality rate of cats who had 25(OH)D concentrations in the upper third in comparison to the middle third of the observed range. Therefore, it doesn’t seem like “a lot” of vitamin D is any better than “enough” vitamin D.

But I would very much like to see a future study that looked into whether giving vitamin D supplements to sick cats with low 25(OH)D concentrations improved their outcomes.

The authors of this paper note that a previous study “investigating the effects of vitamin D on cardiovascular morbidity and mortality” in people showed that vitamin D supplementation improved overall survival… but only in vitamin D deficient patients.

Dr. Jennifer Coates


Vitamin d status predicts 30 day mortality in hospitalised cats. Titmarsh H, Kilpatrick S, Sinclair J, Boag A, Bode EF, Lalor SM, Gaylor D, Berry J, Bommer NX, Gunn-Moore D, Reed N, Handel I, Mellanby RJ. PLoS One. 2015 May 13;10(5):e0125997. 

Image: maudanros / Shutterstock