Objective—To compare relative sensitivity and overall yields of various methods of fecal examination for gastrointestinal parasites in llamas and alpacas.
Sample Population—Fecal samples from 42 alpacas and 62 llamas.
Procedures—Fecal samples were analyzed via direct smear, a modified McMaster technique with sucrose solution or saturated saline (approx 36% NaCl) solution, and a centrifugation-flotation procedure. McMaster flotation chambers were examined 15 and 60 minutes after loading. Centrifugation-flotation samples were examined after 10 and 60 minutes of flotation. The proportions of samples with positive results and concentrations of parasites were compared among methods.
Results—The centrifugation-flotation technique yielded more positive results than other methods for all parasites except small coccidia. Longer flotation time increased the proportion of positive results and parasite concentrations for all parasites except Nematodirus spp. Longer time in the McMaster chamber made little difference. By use of the modified McMaster technique, sucrose solution yielded more positive results for Trichuris spp, Eimeria macusaniensis, and strongyles, whereas saline solution yielded more positive results for Nematodirus spp and small coccidia. The saline solution McMaster test yielded more positive results for small coccidia than did most other methods, and the sucrose McMaster technique yielded more positive results for Trichuris spp.
Conclusions and Clinical Relevance—The centrifugation-flotation technique appeared to offer clear advantages in detecting infection with E macusaniensis, Trichuris spp, Nematodirus spp, and capillarids. The saline McMaster technique appeared to offer an advantage in detecting small coccidia.
Objective—To test the ability of a nested PCR assay to detect Eimeria macusaniensis at various stages of infection in alpacas.
Animals—4 healthy adult alpacas with no detectable E macusaniensis.
Procedures—Alpacas were inoculated with 2 × 104 sporulated oocysts. Serial fecal samples collected during the next 38 days were tested via sucrose flotation and PCR assay.
Results—Oocyst passage was detected via fecal flotation in all 4 alpacas 31 to 35 days after inoculation. Three had positive results for PCR assays on samples obtained 7 to 14 days after inoculation. One alpaca subsequently was removed from the study because of weight loss and inappetence. Two remaining alpacas had positive PCR reactions 28 and 31 days after inoculation, up to 7 days before oocysts appeared in the feces. All fecal samples with positive results for flotation also had positive results for PCR assay.
Conclusions and Clinical Relevance—The PCR assay was able to detect early (7 to 14 days) and late (28 to 31 days) prepatent infection. These positive results suggested that the assay could have been detecting DNA unassociated with oocysts or detecting shedding earlier than has been previously recognized. The gap between the early and late detection periods may not be evident in alpacas receiving a larger or continuous inoculum, as might occur with natural infection. Use of a PCR assay for analysis of fecal samples may be valuable for detection of E macusaniensis during the prepatent period, thus aiding in the identification and control of infected animals.
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.