Rickets associated with vitamin D deficiency in young sheep

Determination of the fate of Cholecalciferol injected by the basis of 25D3 plasma concentration

Sun exposure in bovines is believed to be the most important route of 25D₃ synthesis in suitable latitudes. In some situations, e.g. breeding systems, solar radiation cannot reach or penetrate into the skin and thus causes the 25D₃ deficiency. Because of the critical effect of vitamin D on the immune and endocrine systems, the plasma must be enriched with 25D₃ in a short period of time. In such a condition, injection of Cholecalciferol has been recommended. However, to our knowledge, the certain dose of Cholecalciferol injection for rapid 25D₃ plasma enrichment has not been verified. On the other hand, it seems that the basis 25D₃ concentration can influence or shift the 25D₃ metabolism at the injection time. In the same line, the present study, designed to induce the different basis 25D₃ concentration in treatment groups, aimed at investigating the effect of Cholecalciferol intramuscularly injection with the intermediate dose (11,000 IU/kg) on the calves' plasma 25D₃ with different basis 25D₃. Besides, an attempt was made to clarify the time that 25D₃ reaches the sufficient concentration after injection in different treatment groups. To do this, twenty calves of 3 to 4 months old were chosen for the farm with semi-industrial elements. Furthermore, the effect of optional sun exposure/deprivation and Cholecalciferol injection on the 25D₃ concentration variations was assayed. To do this, the calves were divided into four groups. Groups A and B were unconstrained to choose sun to expose or shadow in a semi-roofed place, but groups C and D were restricted to the completely dark barn. The interference of the digestive system in supplying vitamin D was minimized through dietary. All groups had a different basic concentration (25D₃) on the day 21 of the experiment. At this time, groups A and C received the intermediate dose of (11,000 IU/kg) Cholecalciferol intramuscularly (IM). After Cholecalciferol injection, the effects of basis 25D₃ concentration on the details of variation and fate of plasma concentration of 25D₃ were investigated. The data collected from the two groups C and D showed that sun deprivation without any vitamin D supplementation, could rapidly and severely deplete the plasma from 25D₃. Cholecalciferol injection could not immediately increase the 25D₃ in the groups C and A. However, this injection enriches the 25D₃ to sufficient value after two weeks if the basis 25D₃ of plasma is insufficient, i.e. less than 30 ng/mL. Moreover, the injection of Cholecalciferol could not significantly increase the 25D₃ concentration in the group A that had a sufficient basis 25D₃ concentration. Therefore, it is concluded that the variation of 25D₃ in plasma, after injection of Cholecalciferol, depends on its basic level at the time of injection.

Investigation of relationship between vitamin D status and reproductive fitness in Scottish hill sheep

There is a growing interest in the influence of vitamin D on ovine non-skeletal health. The aim of this study was to explore the relationship between pre-mating vitamin D status, as assessed by serum concentrations of 25-Hydroxyvitamin D [25(OH)D; comprising D2 and D3] and subsequent reproductive performance of genetically unimproved Scottish Blackface (UBF), genetically improved Scottish Blackface (IBF) and Lleyn ewes kept under Scottish hill conditions. 25-Hydroxyvitamin D2 (25(OH)D2) and 25-Hydroxyvitamin D3 (25(OH)D3) concentrations were determined in serum samples harvested in November from ewes grazed outdoors. There were no significant differences in 25(OH)D2concentrations amongst the 3 genotypes. Lleyn ewes had significantly higher 25(OH)D3 and 25(OH)D concentrations than both Scottish Blackface ewe genotypes, whereas these vitamin D parameters did not differ significantly between the UBF and IBF ewes. Concentrations of 25(OH)D3 and 25(OH)D were positively associated with subsequent birth weights of singleton and of twin lamb litters. No significant associations between vitamin D status and number of lambs born or weaned per ewe were found. This study demonstrates that concentrations of cutaneously-derived 25(OH)D3, but not of orally consumed 25(OH)D2, differed between breeds. The positive association between ewe vitamin D status and offspring birth weight highlights the need for further investigations.

Vertebral fractures in two alpaca crias with rickets syndrome

CASE REPORT

Two dark-coloured alpaca crias aged 5 and 5.5 months, respectively, born in September in the Pacific Northwest, USA, were presented for evaluation of acute recumbency. Both crias had cervical spine fractures and one had additional fractures in other locations within the spine. Both crias had valgus deformities of the forelimbs and one had similar deformities of the hindlimbs. Both crias showed characteristic radiological signs of rickets syndrome, including wide, irregular physes, cupping of the metaphyses, bowing of long bones, pathological fractures and enlarged costochondral junctions. One cria responded clinically to treatment with parenteral administration of vitamin D. The other cria was euthanased because of the multiple spinal fractures and postmortem examination supported the diagnosis of rickets syndrome.

CONCLUSIONS

Hypovitaminosis D is associated with abnormal bone formation in young growing animals. The clinical and laboratory findings of rickets syndrome in camelids in the Pacific Northwest, and other regions with low annual sunlight exposure, have been described, although there are only few reports of the radiological signs associated with this condition in camelids and other animals. Additionally, vertebral fractures have not been previously reported in animals with rickets syndrome. Because vertebral fractures were identified in both crias in this report, it suggests that this is a common and clinically important manifestation of the disease in alpaca crias. Hence, in geographic regions with low sunlight exposure, rickets syndrome should be considered as a differential diagnosis in crias presenting with clinical signs consistent with vertebral fracture.

Vitamin D metabolism and rickets in domestic animals: a review

Rickets and osteomalacia are increasing in prevalence in people because of cultural practices, breast-feeding, decreased sun exposure, and increased sunscreen usage. Several hereditary forms of rickets owing to either renal phosphate wasting or defects in vitamin D metabolism are also reported in people. Rickets is well recognized in domestic animals, but published reports are not always supported by microscopic findings, and diagnoses based on clinical signs and radiology are unreliable. Most cases in domestic animals are caused by dietary deficiency of either vitamin D or phosphorus, but occasional inherited forms are reported in pigs, sheep, cats, and dogs. There is variation between species in susceptibility to dietary vitamin D and phosphorus deficiency and in the ability to manufacture vitamin D in their skin. A number of mouse models have been discovered or created to study human skeletal diseases and skeletal homeostasis. With the discovery that vitamin D is involved in not only calcium and phosphorus homeostasis but also in the immune system and cancer, there is great potential for new and existing animal models to generate valuable information about vitamin D and its many functions. This review presents an overview of vitamin D metabolism and rickets in domestic and laboratory animals and makes comparisons where appropriate with the disease in humans.

Seasonal changes in serum calcium, phosphorus, and vitamin D concentrations in llamas and alpacas

OBJECTIVE

To evaluate the interaction of season and age on serum calcium, phosphorus, and vitamin D3 concentrations in llamas and alpacas.

ANIMALS

23 clinically normal llamas and 7 alpacas.

PROCEDURES

Animals were assigned to 1 of the 3 following groups on the basis of age at the start of the study: adult (age, > or = 24 months; n = 8), yearling (> 12 but < 20 months; 5), and neonate (< 6 months; 17). Twelve serum samples were obtained at monthly intervals. Calcium, phosphorus, and vitamin D3 concentrations were measured, and the calcium-to-phosphorus concentration (Ca:P) ratio calculated. Effect of season and age on each of these variables was determined.

RESULTS

Vitamin D3 concentrations varied significantly as a function of season; the highest and lowest concentrations were detected September through October and February through March, respectively. The seasonal decrease in vitamin D3 concentration was significantly greater in neonates and yearlings, compared with adults. Serum phosphorus concentration decreased as a function of age, with the most significant seasonal change detected in the neonate group. The Ca:P ratio in neonates varied between 1.1 and 1.3 except during winter months when it increased to > or = 2.0.

CONCLUSIONS AND CLINICAL RELEVANCE

Mean vitamin D3 concentration varied by > 6 fold in neonatal and yearling llamas and alpacas and > 3 fold in adult animals as a function of season. These results support the hypothesis that seasonal alterations in vitamin D3 concentrations are a key factor in the development of hypophosphatemic rickets in llamas and alpacas.