Sunlight, Cats and Vitamin D
Cats always prefer the sunshine. Well, not always. If you are a black cat in hot sun, you’ll go into the shade. Humans need sunshine because we synthesise vitamin D in the skin through exposure to sunlight. In the northwest of America and in Britain, people do not get enough sunshine. This can have a negative impact on health.
Cat napping in the sun inside the home – Photo by Pak Gwei (Flickr) creative commons.
So what about cats? Cats do like to lie in the sun. We all know that. Why do they like it so much? Is it because they instinctively wish to soak up sunlight to convert it into Vitamin D?
One website says that cats convert sunlight to vitamin D, as we do. The problem that I have with this is that a cat is covered with fur. The process of sunlight shining on skin and being synthesised in the skin is not going to work unless the hair can absorb sunlight and transmit it to the skin which is far too fanciful to be believed.
The answer is that, although vitamin D (calcitriol) is an essential dietary ingredient for cats, they cannot synthesise it from sunlight. Cats obtain vitamin D from food. Caution: people should not provide vitamin D supplements if providing their cat with high quality cat food as it is possible to overdose a cat with vitamin D. At high levels it is toxic to a cat. A vet should be involved before providing vitamin D supplements.
Vitamin D is important for strong bones. A deficiency can cause rickets. However, only small amounts are required on a daily basis: 50 to 100 I.U. – International Unit).
Cats lie in the sun for warmth. This preserves energy for other activities. When napping cats often pick out a spot in the sun. The body does not have to work as hard to maintain the correct body temperature if it is being warmed up from an external source. A radiator is just as good.
Associated post: Vitamin supplement senior cat.
Source: Drs Eldredge, Carlson, Carlson (DVMs) and Giffin MD.