Question
I know that too much vitamin D (fat soluble) can cause toxicity in cats, but how much is too much?
The reason I asked this is - When I open my vitamin D bottle, because I take it, my kitty goes "can I get one of those" - every time. She's convinced that they must taste great.
My cat is crazy, I've caught her eating dust bunnies which I sometimes pull from her mouth, sometimes I'm not successful.
I've seen her eat feathers from my pillow, biting the plastic ends off things and swallowing the plastic.
I've tried to cat-proof my house, but she's just one of those "if I can chew on it, I'll eat it" types.
Fortunately she's gotten better. When she was a kitten she was just crazy. She likes ear wax and more than once has pulled an used Q-tip out of the garbage and chewed on the used end.
I feed her well. Expensive canned food and some dry food.
She wants my vitamin D. On googling I find that, some cats can be vitamin D deficient, but dosing should be done properly.
My cat is 10 lb (4.5 kg). Is once in a while (or maybe just once), vitamin D supplement, a safe dose? It might be that she just wants the gelatin, in which case, maybe I'll squeeze the vitamin D oil out of the pill and give her the gel capsule.
Note added 11 months later: While not part of the question exactly, my little kitty, now nearly 2 years old and 11 lbs (5 kg), she no longer begs when I open my (Dr. prescribed) vitamin D pill container. I think it may have been a kitten thing, kittens having an urge to try stuff, but that's just a guess.
Answer
Just like in most terrestrial animals, humans included, sunlight is needed to produce vitamin D.
It is not the vitamin D that is the most dangerous, but the content of vitamin A is. But your question is about vitamin D so I will focus on this here.
In the summer your cat will get the vitamin D it needs from the Sun and it only need about 20 minutes of sunlight daily to synthesise the required amount.
It is hard to find reliable sources on what dosage is safe for cats. Please take a look at this article on provet.co.uk about the subject of cod liver oil and the potential toxicity of vitamin A.
So in essence, a cat does not need any type of additional vitamin D supplementation during the summer, unless it is an strictly indoor cat and is exposed to very little sunlight. But that is just an extreme example, please never expose any animals to this type of environment of living in the dark.
If one lives in the far north/south, in the winter your cat might get too little sunlight to produce the needed vitamin D and the same goes for yourself.
If you give your cat fat fish or give your cat fish oil (fish oil is often given in the winter to avoid dry skin) your cat will not need extra vitamin D.
Please note that FISH OIL IS NOT THE SAME AS CODLIVER OIL.
So if your cat is not given fat fish AND lives in the dark, you might give your cat one small drop of codliver oil once a week, but not any more and not if your cat gets the sunlight it needs. Please note that the dosage I mention here is what i see as safe for most cats, but i am not a vet.
Codliver oil and the vitamin D are types of fat so it will acumulate in your cat's liver, any excess of vitamin D will acumulate and slowly poison your cat.
In short, be very careful if you give your cat vitamin D.
Edit: it is mentioned in a comment that cats do not produce vitamin D from the sunlight. This might be right or wrong and is of little importance for the conclusion in this answer: cats in general do not need extra vitamin D supplementation.
Regardless, sunlight or simulated sunlight is important for the well-being of most pets.
Answered By - trond hansen