Alpacas have a very dense fleece and at high altitude (above 3500 metres), UV radiation is intense enough to penetrate the fleece and reach the skin. This level of radation induces the production of vitamin D. At low altitude (like the conditions in New Zealand), UV light does not penetrate to skin level and the cycle is not completed - vitamin D deficiency can occur and rickets manifests.
Rickets is a disease of young, growing alpacas, characterised by defective calcium deposition within the bone. This usually occurs at growth plates in the bones that have not yet fused or calcified shut; the poorly calcified bones are then subject to stress and distortions. Calcification and closure of these growth plates are complete in most alpacas by the age of 18 months.
Rickets is caused by a lack of vitamin D, calcium and phosphorus or a combination of all three. In the presence of adequate dietary calcium and phosphorus (through good nutrition) but in the absence of vitamin D, (through lack of sunlight-derived UV radiation), calcium metabolism in bones is affected and rickets will occur. This is especially so in the case of fast growing young animals.
Clinical signs of rickets in alpacas include
- Depression
- Sore limbs/lameness
- Hunched back
- Weight loss
- Reluctance to move
Diagnosis of rickets is done on the basis of clinical signs but the definitive diagnosis is made based on blood phosphorus levels.
Prevention is achieved by ensuring good nutrition and Vitamin D supplementation. A standard vitamin D3 supplementation for an alpaca begins at about 8 weeks of age. At this time most crias are also given their first clostridial (5-in-1) vaccination. Injectable vitamin D is the easiest way of supplementing vitamin D3 in young alpaca.
The supplementation regimen after this first shot varies depending on the time of the year/season. A standard programme would give three shots of vitamin D3 over the winter/spring period with one shot over the summer months if the alpaca was in full fleece. This programme is then repeated into the following year until the alpaca is 2 years old.
The only other time after two years of age that an alpaca is likely to need vitamin D3 supplementation is prior to giving birth (unpacking). To ensure that the lactating alpaca's milk is rich in vitamin D3 for early bone development in the newborn cria, most owners are recommended to give pregnant females vitamin D3, four to eight weeks prior to unpacking.
Please feel free to contact your vet at either of the Totally Vets clinics if you have questions about this disease and its prevention.
