After almost 10 years with hundreds of alpacas, we had our first bout with Rickets this past fall. I had little idea what Rickets was until we started seeing several of our crias gradually more uncomfortable on their feet, becoming arched in the back and increasingly lethargic. Babies born during the Summer are often found sleeping on their side, stomachs with minimal fleece facing the sun and absorbing Vitamin A & D. Vitamin D is absolutely essential in proper bone development. Without vitamin D, the necessary amounts of phosphorus and calcium may be present in the blood, but will not be incorporated into bone.
Rickets is more common in the fall and winter crias, but is also found in spring and summer crias, especially in warm climates where mothers and crias are in the barn during the day and do not receive adequate UV light. It appears more common in dark, heavily fleece and unshorn crias. Heavily fleeced animals, especially dark fleeced animals have more vitamin D difficulties compared to light-colored or less densely fleeced alpacas – especially in lower altitude. Crias born in the fall are especially susceptible to rickets compared to their spring siblings.
Most clinical signs are common at 4 to 6 months old, especially in the months of January through March which are often cloudy, overcast days. Signs are more apparent in aged alpacas, especially females. It appears as an osteomalacia or osteoporosis. This is call “milk lameness” in dairy cows. Alpacas often show a sway back, weak pasterns and show hypophosphatemia in blood minerals. On one of our crias, where the Vitamin D range should be 250-450 and cria blood work is preferred around 400, our girl came in at 9.
The most common signs we found are and awkward gait, arched back, reluctance to move, in activity due to sore or swollen joints, reduced supplement intake, slow grown and crooked legs. She kept on shifting weight on her back legs and we knew something was not right.
Rickets result in a combination of circumstances where there is a continuous lack of dietary intake of calcium, phosphorus, UV light or supplemented vitamin-D3. This results in depletion and lack of mineral metabolism. Sun-cured hay, which contains Vitamin D2 is not sufficient without UV light. Vitamin D is not stored in alpaca milk but in the alpaca liver, so it is not passed on to the cria.
Diagnosis of deficiency is based on blood chemistry and CBC testing. A key note is that the blood needs to be spun and separated from the clot within 2 hours of pulling or the overall results can be skewed.
Helping to prevent Rickets is relatively easy. Alpacas need UV sunlight to grow. Crias’ digestive systems are not fully developed at 4-8 weeks old and if they are not in the sunlight they may need to be supplemented. Vitamin paste at 1000 IU’s per pound may be necessary every 10 to 14 days. Additionally, injectable Vitamin A & D should be given IM in conjunction with Phos-aid for absorption of the minerals. We have also give our crias bananas to help absorb phosphorus into their system. As mentioned above, Vitamin D is stored in the liver and utilized throughout the year. Early supplemental vitamin therapy can alleviate these symptoms and resolve the initial problem. However, with no intervention, joint and/or long bone dysfunction may become fixed and non-treatable to later vitamin therapy.
It is important to consider the variation of geography (sun exposure), housing and physiology of your alpacas while considering if a member of your herd has rickets.