Objective: To measure and compare insulin secretion and sensitivity in healthy alpacas and llamas via glucose clamping techniques. Animals: 8 llamas and 8 alpacas. Procedures: Hyperinsulinemic euglycemic clamping (HEC) and hyperglycemic clamping (HGC) were performed on each camelid in a crossover design with a minimum 48-hour washout period between clamping procedures. The HEC technique was performed to measure insulin sensitivity. Insulin was infused IV at 6 mU/min/kg for 4 hours, and an IV infusion of glucose was adjusted to maintain blood glucose concentration at 150 mg/dL. Concentrations of blood glucose and plasma insulin were determined throughout. The HGC technique was performed to assess insulin secretion in response to exogenous glucose infusion. An IV infusion of glucose was administered to maintain blood glucose concentration at 320 mg/dL for 3 hours, and concentrations of blood glucose and plasma insulin were determined throughout. Results: Alpacas and llamas were not significantly different with respect to whole-body insulin sensitivity during HEC or in pancreatic β-cell response during HGC. Alpacas and llamas had markedly lower insulin sensitivity during HEC and markedly lower pancreatic β-cell response during HGC, in comparison with many other species. Conclusions and Clinical Relevance: New World camelids had lower glucose-induced insulin secretion and marked insulin resistance in comparison with other species. This likely contributes to the disorders of fat and glucose metabolism that are common to camelids.

Objective: To determine pharmacokinetic and pharmacodynamic properties of midazolam after IV and IM administration in alpacas. Animals: 6 healthy alpacas. Procedures: Midazolam (0.5 mg/kg) was administered IV or IM in a randomized crossover design. Twelve hours prior to administration, catheters were placed in 1 (IM trial) or both (IV trial) jugular veins for drug administration and blood sample collection for determination of serum midazolam concentrations. Blood samples were obtained at intervals up to 24 hours after IM and IV administration. Midazolam concentrations were determined by use of tandem liquid chromatography–mass spectrometry. Results: Maximum concentrations after IV administration (median, 1,394 ng/mL [range, 1,150 to 1,503 ng/mL]) and IM administration (411 ng/mL [217 to 675 ng/mL]) were measured at 3 minutes and at 5 to 30 minutes, respectively. Distribution half-life was 18.7 minutes (13 to 47 minutes) after IV administration and 41 minutes (30 to 80 minutes) after IM administration. Elimination half-life was 98 minutes (67 to 373 minutes) and 234 minutes (103 to 320 minutes) after IV and IM administration, respectively. Total clearance after IV administration was 11.3 mL/min/kg (6.7 to 13.9 mL/min/kg), and steady-state volume of distribution was 525 mL/kg (446 to 798 mL/kg). Bioavailability of midazolam after IM administration was 92%. Peak onset of sedation occurred at 0.4 minutes (IV) and 15 minutes (IM). Sedation was significantly greater after IV administration. Conclusions and Clinical Relevance: Midazolam was well absorbed after IM administration, had a short duration of action, and induced moderate levels of sedation in alpacas.

Objective-To characterize and quantitatively assess the typical pulmonary anatomy of healthy adult alpacas with multidetector row CT. Animals-10 clinically normal adult female alpacas. Procedures-CT examination of the thorax was performed before and after IV administration of iodinated contrast medium in sedated alpacas in sternal recumbency. Measurements of the trachea, bronchi and related blood vessels, and selected vertebrae as well as the extent and density of lung parenchyma were performed with a Digital Imaging and Communications in Medicine (DICOM) viewer. Morphometric and quantitative data were summarized. Results-Separation of individual lung lobes could not be identified, except for the accessory lung lobe. In all alpacas, both lungs extended farther caudally at the medial aspect than at the lateral aspect. The right lung extended farther in both cranial and caudal directions than did the left lung. The branching pattern of the bronchial tree varied only slightly among alpacas and consisted of 1 cranial bronchus and 3 caudal bronchi bilaterally, with a right accessory bronchus. Luminal diameters of first-generation bronchi ranged from 3 to 9 mm. Mean +/- SD parenchymal lung density was −869 +/- 40 Hounsfield units (HU) before contrast injection and −825 +/- 51 HU after contrast injection. Mean difference in diameter between bronchi and associated arteries or veins was 0.8 +/- 0.9 mm. Conclusions and Clinical Relevance-Knowledge of the typical anatomy of the lungs and bronchial tree in healthy alpacas as determined via CT will aid veterinarians in clinical assessment and bronchoscopic evaluation of alpacas.

Objective—To compare numbers of L cells in intestinal samples and blood concentrations of glucagon-like peptide (GLP)-1 between neonatal and mature alpacas. Sample—Intestinal samples from carcasses of 4 suckling crias and 4 postweaning alpacas for immunohistochemical analysis and blood samples from 32 suckling crias and 19 healthy adult alpacas for an ELISA. Procedures—Immunohistochemical staining was conducted in accordance with Oregon State University Veterinary Diagnostic Laboratory standard procedures with a rabbit polyclonal anti–GLP-1 primary antibody. Stained cells with staining results in ileal tissue were counted in 20 fields by 2 investigators, and the mean value was calculated. For quantification of GLP-1 concentrations, blood samples were collected into tubes containing a dipeptidyl peptidase-4 inhibitor. Plasma samples were tested in duplicate with a commercial GLP-1 ELISA validated for use in alpacas. Results—Counts of stained cells (mean ± SD, 50 ± 18 cells) and plasma GLP-1 concentrations (median, 0.086 ng/mL; interquartile range, 0.061 to 0.144 ng/mL) were higher for suckling alpacas than for postsuckling alpacas (stained cells, 26 ± 4 cells; plasma GLP-1 concentration, median, 0.034 ng/mL; interquartile range, 0.015 to 0.048 ng/mL). Conclusions and Clinical Relevance—Older alpacas had lower numbers of L cells in intestinal tissues and lower blood concentrations of GLP-1 than those in neonates. These findings suggested that there may be a decrease in the contribution of GLP-1 to insulin production in adult alpacas, compared with the contribution in neonates.

A small population of resident T-lymphocytes is present in the normal epidermis of skin from humans, mice, sheep, and cattle. The objective of this study was to determine the prevalence of lymphocytes, CD3+ cells (T-lymphocytes) and CD79a+ cells (B-lymphocytes and plasma cells), in the epidermis and adnexal epithelia of alpacas. Skin-biopsy specimens from the normal skin of the dorsolateral thorax of 31 alpacas were examined histologically and immunohistochemically for the presence of CD3+ cells and CD79a+ cells in the epidermis and adnexal epithelia. CD3+ T-lymphocytes, but not CD79a+ cells, were present in the epidermis and adnexal epithelia. Therefore, in the absence of other signs of inflammation, the presence of lymphocytes in these structures in skin-biopsy specimens should be considered normal.

Objective: To characterize serum trace mineral, sex steroid hormone, and vitamin D concentrations and identify factors associated with metacarpophalangeal and metatarsophalangeal hyperextension in llamas and alpacas. Samples: Serum samples from 79 llamas and 15 alpacas and owner survey data for 573 llamas and 399 alpacas. Procedures: Serum samples were stored at −20°C until analysis and were evaluated for trace mineral, vitamin D, estradiol, progesterone, and testosterone concentrations. Information regarding age of onset, number of affected animals in herd, feed and supplements given, type of housing, and management practices was obtained in an owner survey. Results: Higher serum zinc and iron concentrations were associated with metacarpophalangeal and metatarsophalangeal hyperextension in camelids, compared with controls. In summer and fall months, vitamin D concentrations were significantly higher in affected camelids than controls. Overall prevalence was 13.3% in llamas, compared with 0.7% in alpacas. No management factors were found to be predictive of this condition. No other factors examined were associated with metacarpophalangeal and metatarsophalangeal hyperextension. Conclusions and Clinical Relevance: Despite similar supplementation practices and environmental conditions between affected and unaffected animals, an association of high serum zinc, iron, and vitamin D concentrations in affected camelids, compared with controls, may indicate differences of intake or absorption of dietary supplements.