A lady called into Sirius when I was on Mario’s show in the afternoon and said her 5 year old cat has gingivitis and had four extractions and her dental vet said that too much vitamin D in the diet causes (worsens??) osteoporosis in cats and therefore she shouldn’t feed wet food!? He wanted to feed only the Royal Canin dry food he was selling (surprise!) What made no sense to me was how a young cat could have osteoporosis — and how they would even know? So I got in touch with Dr. Elizabeth Hodgkins, the Official Vet of Cat Chat. She told me:
Vitamin D toxicity is largely a problem for pet consuming commercial diets that are oversupplemented with Vit D. The signs of this toxicity do not include osteopososis but are more acute signs like vomiting, diarrhea, lethargy and even death in severe cases. I think this lady either misunderstood her vet or the vet misunderstood someone else. Ironically, Royal Canin is one of the brands (esp in Canada) that has had recalls due to known oversupplementation of their foods with vitamin D. It is all over the internet. But we don’t look for it the way we do in humans so I can’t say we really know, but spontaneous fractures in cats are very rare so we can assume it is not a common problem. Oseodystrophy is the closest thing we have to osteoporosis in animals and that is caused by hyperparathyroidism secondary to kidney failure (the renal variety) OR the feeding (long-term) of calcium deficient diets (the nutritional variety).
