Vitamin D Overdose Warning

I have just read an article in the latest edition of Alpaca World (a UK alpaca magazine) regarding vitamin D dosing to prevent rickets. It is written by an Australian alpaca breeder. In the article she advocates doses of up to 18,000 IU/kg using pure vitamin D3. She does not justify the use of these very high doses except to say that if they're fine for a cow to be given just before calving then they must be fine for alpacas.... She is apparently aware of the concern for vitamin D toxicity but states that she has "not heard of, or seen any ill effects" - although she does not include any mention of the clinical signs or pathology so I'm not sure that she would recognise them if they occurred. 
 
I am very concerned that alpaca breeders reading this article, potentially your clients, may think that this is a good idea. I am aware of some breeders already recommending this protocol, mostly those with Australian connections. Please be advised that, for prevention or treatment of hypovitaminosis D in camelids (obviously including rickets in growing animals), the recommended doses are 1000-2000 IU/kg - parenterally (SQ) this can be given every 2 months during the winter, or orally every 4-6 weeks. These recommendations are made on the basis of known and published pharmacokinetics - there is no justification for higher doses which may in fact depress normal function via feedback mechanisms. 
 
Please can you ensure that your clients are using the appropriate doses of vitamin D supplementation (follow the link below) and are not following the unsubstantiated recommendations of other alpaca owners. Fortunately I don't believe Vitamin D3 is available in the UK any more (unless anyone else knows differently!) but owners have been known to import (and sell) their own drugs from outside the UK without knowing this is illegal. 
 
Claire E Whitehead BVM&S MS MRCVS 
Diplomate ACVIM (Large Animal) 
Camelid Veterinary Services 
www.ukalpacavet.com 
 
Vitamin D, used for prevention or treatment of rickets in camelids, is no longer easy to source in the UK.

UPDATE June 2020
We wanted to alert you about a new large animal licensed injectable vitamin D product that has recently come onto the market in the UK. As you know, it has been a few years since we have had a licensed product and we have been reliant on completing an SIC online with the VMD before buying through our veterinary wholesalers - not a big deal, just an extra hoop to jump through. It is called Belavit AD3E. From the point of view of veterinary medicines legislation, this means that this should be the product of preference from now on since we are supposed to use products licensed in the UK before using products that need to be imported. 
 
This is the comparison of the two products:
 

 

Belavit AD3E (per ml)

Hipravit ADE (per ml)

Vitamin D (cholecalciferol)

100,000 IU

75,000 IU

Vitamin A (retinol palmitate)

300,000 IU

500,000 IU

Vitamin E (a tocopherol acetate)

50.00mg

50.00mg

Recommended prophylactic dose for camelids: at 1000 IU/kg 

[repeat every 2 months Oct-April]

0.1ml per 10kg BW

0.13ml per 10kg BW

Recommended treatment dose, at 2000 IU/kg

[repeat after one month]

0.2ml per 10kg BW

0.26ml per 10kg BW

One advantage of the new product of course is the vitamin D content resulting in easier numbers for dosing, but it is important to stress that the new dosing regimen is based on using a higher concentration product. DON'T USE PREVIOUSLY USED DOSES!
Vitamin D overdose is to be taken seriously. There is one publication in the literature discussing the case of a female alpaca that died from a ruptured renal artery due to calcification in the wall of the vessel - this female had been dosed at around 6300 IU/kg.