Search Results
You are looking at 1 - 6 of 6 items for
- Author or Editor: Bradford B. Smith x
- Refine by Access: All Content x
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)
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)
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 test whether generalized Streptococcus zooepidemicus infection could be induced by intratracheal inoculation in llamas and to characterize this infection.
Animals—6 test and 3 control llamas.
Procedure—Test llamas received 1 of 3 dosages of S zooepidemicus by intratracheal injection, whereas control llamas received sterile culture medium. Physical examination variables and results of clinicopathologic analyses of blood, peritoneal fluid, and tracheal wash fluid were compared in test llamas between, before, and during the development of bacteremia and with control llamas. Bacteriologic culture was performed on all collected body fluids and tissue specimens that were collected at necropsy. Tissue specimens that were collected at necropsy were examined histologically.
Results—Infection induced fever, anorexia, and signs of depression. Five of 6 infected llamas developed specific signs of inflammation in the thorax or abdomen, bacteremia, neutrophilic leukocytosis with toxic changes and high band neutrophil cell counts, hyperfibrinogenemia, and high peritoneal fluid WBC counts and protein concentrations. On development of bacteremia, llamas had significant decreases in serum iron (from 118 ± 25 to 6 ± 4 µg/ml) and increases in serum glucose (from 131 ± 5 to 253 ± 48 mg/dl) concentrations.
Conclusions and Clinical Relevance—Streptococcus zooepidemicus spreads rapidly to other body compartments after intratracheal inoculation in llamas. Fever, anorexia, and signs of depression are the most consistent clinical signs, although other signs are possible. Clinicopathologic analysis of body fluids yields evidence of inflammation. Infection by S zooepidemicus can be proven by bacteriologic culture of body fluids before death or of tissue specimens after death. (Am J Vet Res 2000:61;1525–1529)
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)
Abstract
Objective—To compare the efficacy of a Salmonella bacterin and a modified live Salmonella ser. Choleraesuis vaccine on a commercial dairy.
Animals—450 cows in late gestation and 80 calves.
Procedure—Group-1 cows (n = 150) were vaccinated once with a modified live S Choleraesuis (serogroup C1) strain 54 (SC54) vaccine, group-2 cows (150) were vaccinated on enrollment and 30 days later with a Salmonella ser. Montevideo (serogroup C1) bacterin, and group-3 cows (150) served as unvaccinated controls. One gallon of colostrum harvested from the first 80 cows to calve was fed to each calf. Outcome assessments included fecal shedding of Salmonella spp for the first 10 days after parturition (cows) or birth (calves), milk production, involuntary culling rate, mastitis incidence, antimicrobial use, and mortality rate.
Results—Salmonellae were isolated from 306 of 309 (99%) cows and 64 of 74 (86.5%) calves. Shedding frequency was less in SC54-vaccinated cows and calves that received colostrum from those cows, compared with the other groups, and vaccination was specifically associated with less shedding of serogroup C1 salmonellae. Production data were similar among groups.
Conclusions and Clinical Relevance—Vaccination of pregnant cows with an autogenous Salmonella bacterin had no effect on fecal shedding of salmonellae, whereas vaccination with a modified live S Choleraesuis vaccine reduced the frequency of fecal shedding of serogroup C1 salmonellae during the peripartum period. A commercial S Choleraesuis vaccine licensed for use in swine may be more efficacious than autogenous Salmonella bacterins on dairies infected with serogroup C1 salmonellae. (Am J Vet Res 2001;62:1897–1902)
