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- Author or Editor: Robert J. Van Saun x
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Abstract
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, ≥ 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 ≥ 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. (Am J Vet Res 2001;62:1187–1193)
Objective
To evaluate vitamin D concentrations in juvenile llamas and alpacas with hypophosphatemic rickets.
Design
Prospective cohort study.
Animals
21 llamas (14 with rickets, 7 clinically normal) and 9 alpacas (6 with rickets, 3 clinically normal).
Procedures
Blood samples were collected at the time of diagnosis and prior to the initiation of treatment. Serum concentrations of calcium, inorganic phosphorus, and 25-hydroxycholecalciferol ({vitamin Dy were determined on all samples. Comparisons were completed for disease status, age, sex, species, month of birth, and all interactions.
Results
Serum concentrations of phosphorus and vitamin D were lower in affected llamas and alpacas than in clinically normal llamas and alpacas, even when mean concentrations were adjusted for age differences. Species (Ilama or alpaca), sex, and age did not affect any of the metabolite concentrations within this study population. Month of birth influenced vitamin D concentrations and number of affected llamas and alpacas per month. The greatest number of affected llamas and alpacas was identified between January through March, suggesting a seasonal pattern to this syndrome. Treatment of affected llamas and alpacas with vitamin D resulted in increased concentrations of phosphorus and vitamin D. Serum phosphorus concentration was best predicted by 2 independent variables (serum vitamin D concentration and month of birth).
Clinical Implications
We believe vitamin D deficiency is the primary cause of hypophosphatemic-rickets of growing camelids, and the observed hypophosphatemia is secopdary to a primary deficiency of vitamin D. Appropriate treatment with vitamin D supplements can correct hypophosphatemia and vitamin D deficiency in camelids. (J Am Vet Med Assoc 1996; 209:1128-1133)
Abstract
Objective—To determine blood glucose clearance in 2 species of New World camelids after IV challenge and to examine mechanisms of this clearance.
Animals—5 adult female llamas and 5 adult gelded alpacas.
Procedure—After food was withheld for 12 hours, camelids received 0.5 g of glucose/kg of body weight by rapid IV infusion. Serum concentrations of glucose, nonesterified fatty acids, cortisol, and insulin, and plasma concentrations of lactate were determined before and 0, 1, 2, 3, 4, 5, 15, 30, 60, 90, 120, 180, and 240 minutes after infusion. Ratios of insulin to glucose and insulin to cortisol were calculated for each time point.
Results—Postinfusion glucose concentrations were significantly higher in llamas than alpacas for the first 15 minutes and remained significantly higher than baseline values in both species for 180 minutes. Lactate and cortisol concentrations did not change significantly; nonesterified fatty acid concentrations decreased in both species 30 minutes after infusion. Baseline insulin concentrations were < 6 μU/ml in both species and increased only to 10.1 ± 0.7 μU/ml in llamas. Insulin concentrations did not change significantly in alpacas.
Conclusions and Clinical Relevance—Llamas and alpacas clear glucose more slowly than other domestic species after challenge, mainly because of a weak insulin response and slow cellular uptake. This response may impair the assimilation of exogenous glucose as well as make llamas and alpacas prone to diabetes-like disorders when an abundance of endogenous or exogenous glucogenic agents are present. (Am J Vet Res2001;62:682–686)
Abstract
Objectives—To determine whether feed restriction induces hepatic lipidosis (HL) in llamas and to evaluate the metabolic changes that develop during feed restriction.
Animals—8 healthy adult female llamas.
Procedure—Llamas were fed grass hay at a rate of 0.25% of their body weight per day for 13 to 28 days. Llamas were monitored by use of clinical observation, serum biochemical analyses, and ultrasound-guided liver biopsies.
Results—All 8 llamas lost weight and mobilized fat. Five llamas developed HL, including 4 that were nursing crias. During the period of feed restriction, mean serum concentration of bile acids and activities of aspartate aminotransferase (AST), sorbitol dehydrogenase (SDH), and γ-glutamyl transferase (GGT) were significantly higher in llamas that developed HL, compared with llamas that did not. Mean insulin-to-cortisol concentration ratios were lower in llamas with HL before and up to 7 days of feed restriction, compared with those that did not develop HL.
Conclusions and Clinical Relevance—HL in llamas may be induced by severe feed restriction, particularly in the face of increased energy demand. Llamas with weight loss attributable to inadequate dietary intake may develop biochemical evidence of hepatopathy and HL. Increases in serum concentration of bile acids and activities of GGT, AST, and SDH may indicate the development of HL in llamas and identify affected animals for aggressive therapeutic intervention. (Am J Vet Res 2001;62:1081–1087)
Objective
To identify factors associated with hepatic lipidosis (HL) in llamas and alpacas.
Design
Retrospective case series.
Animals
30 llamas and 1 alpaca.
Procedures
Medical records were searched to identify llamas or alpacas in which a histologic diagnosis of HL was made. Information was retrieved on signalment, history, clinical and laboratory findings, and results of necropsy or examination of biopsy specimens. Data were analyzed using descriptive statistics and χ2 analyses.
Results
Females were affected more often than males; however, the sex distribution was not different from that of the camelid population in the diagnostic laboratory's database. Fifty-four percent of the females were pregnant, and 46% were lactating. Most affected camelids were 6 to 10 years old. Anorexia and recent weight loss were common (51.6% of camelids). An infective agent was found in only one llama, and toxins and mineral deficiencies were not identified. The most common abnormalities on serum biochemical analysis were a high concentration of bile acids, high activities of γ-glutamyltrans-ferase (GGT) and aspartate aminotransferase (AST), and hypoproteinemia. Concentrations of nonesterified fatty acids (NEFA) and β-hydroxybutyrate (β-HB) were high in those camelids in which these compounds were assayed. Twenty-nine camelids did not survive.
Clinical Implications
Sick camelids should be considered at risk for developing HL, especially those with anorexia or the metabolic demands of pregnancy and lactation. Other stresses also appear to contribute. High concentrations of NEFA, γ-HB, and bile acids; high activities of GGT and AST; and hypoproteinemia may indicate that HL has developed. (J Am Vet Med Assoc 1999;214:1368–1372)
Abstract
Objective
To establish reference values for blood concentrations of total calcium (Ca), inorganic phosphorus (P), iron (Fe), copper (Cu), zinc (Zn), selenium (Se), and vitamin E (Vit E) in clinically normal llamas.
Animals
270 llamas ranging in age from < 1 month to > 15 years and grouped by age, sex, pregnancy status, and stage of gestation. Selected llamas were from 21 farms in Oregon, did not have previous health problems, and met specific health criteria on examination.
Procedure
Serum and blood samples were obtained and analyzed for concentrations of Ca, P, Fe, Cu, Se, Zn, and Vit E, and total iron binding capacity (TIBC) and percentage of transferrin saturation (% Sat). Mean differences by age, sex, pregnancy status, and stage of gestation, as well as all interactions, were compared to establish reference values.
Results
Mean values and reference ranges for most of the minerals and vitamins were similar to previously reported values. Male versus female differences were not identified for any measurements. Age was a significant variable for Ca, P, Fe, and Se concentrations, as well as Ca-to-P ratio and TIBC. Identified age-based effects were modeled by use of linear regression. Copper and Zn concentrations and % Sat did not differ as a function of age. Serum Vit E concentration was influenced by an age by sex interaction and stage of gestation.
Conclusions
Age was found to be an important variable influencing many blood nutrient concentrations in healthy llamas.
Clinical Relevance
Clinical diagnosis of metabolic disease may be improved with use of age-based reference values, especially for neonates. (Am J Vet Res 1998;59:1063–1070)
Abstract
Objective—To evaluate temporal changes in bone mineral density associated with seasonal variation in serum vitamin D, calcium, and phosphorus concentrations in alpacas.
Animals—5 healthy mature neutered male alpacas.
Procedure—Metacarpal bone mineral density was measured at 4 times during a year. Each time alpacas were weighed, blood was collected for determination of serum calcium, phosphorus, and vitamin D concentrations, and samples of feed were analyzed for nutrient content. Vitamin D status was determined by use of an assay that measured serum 25-hydroxycalciferol concentration. Effects of changes in serum vitamin D, calcium, and phosphorus concentration and body weight with season on bone mineral density were determined.
Results—Bone mineral density, body weight, and serum vitamin D and phosphorus concentrations varied with season. Bone mineral density, serum vitamin D concentration, and body weight also varied among individual alpacas. Serum vitamin D concentration was lower in January than the previous October and increased from May to the following September. The decrease in bone mineral density lagged behind the decrease in serum vitamin D concentration and was lower in May, compared with the previous October. Body weight was lower in May than the previous October or following September. Solar radiation was highest in July and lowest in December.
Conclusions and Clinical Relevance—Seasonal changes in bone mineral density are associated with changes in serum vitamin D concentrations in alpacas. Changes in bone mineral density associated with a decline in serum vitamin D concentration may predispose some alpacas to developing fractures minimal trauma. (Am J Vet Res 2002; 63:948–953)
