Assessing colostral and serum immunoglobulin G in alpacas using Brix refractometry and total serum protein.

The adequate transfer of passive immunity is a critical factor in neonatal development and survivability. Although well documented in the dairy and equine industries, the recognition of inadequate immunoglobulin transfer on-farm and its impact on the ability of alpaca cria to thrive is largely unknown. Colostrum samples were collected from female alpaca within 24 h of parturition by the owners and whole blood collected from cria by the investigators between 1 and 7 days of age. Direct IgG concentration of milk and serum was determined using radial immunodiffusion assay (RID) and was indirectly estimated using optical and digital Brix refractometry for total solids and clinical refractometry for total serum protein. There was a strong correlation between optical and digital Brix refractometry, and colostral IgG concentration determined by RID. There was a moderate correlation between serum IgG concentration determined by RID and total serum protein in crias. Optical and digital Brix refractometry for colostral IgG estimation and total serum protein for serum IgG estimation are reliable, accurate and easy-to-use tools that can be used on-farm by trained, competent technicians to assess a failure of passive transfer in alpacas. A pilot study at one property only was performed, due to COVID-19 travel restriction interference. Further research is required to determine the reference intervals for these tools to be practical.

ANTIBODY RESPONSE TO EPSILON TOXIN OF CLOSTRIDIUM PERFRINGENS IN CAPTIVE ADULT SPRINGBOK (ANTIDORCAS MARSUPIALIS), IMPALA (AEPYCEROS MELAMPUS), ALPACA (VICUGNA PACOS), AND RED-NECKED WALLABY (MACROPUS RUFOGRISEUS) OVER A YEAR.

Enterotoxemia is an important issue in various zoological taxa. In this study, serologic responses over a 1-yr period after vaccination with a multivalent clostridial vaccine were evaluated in 10 adult springboks (Antidorcas marsupialis), 12 impalas (Aepyceros melampus), seven alpacas (Vicugna pacos), and five red-necked wallabies (Macropus rufogriseus). Antibody production to the Clostridium perfringens type D epsilon toxin component of the vaccine was measured using an indirect enzyme-linked immunosorbent assay and determined as the percentage of inhibition (% inhib). Initial % inhib was (0.01-18.9)%. All animals received initial vaccination with a booster vaccine 4 weeks apart. Serum samples were collected at T0 (nonvaccinated), 15, 30, 60, 180, and 360 days postvaccination (dpv) for analysis. The vaccine induced a high antibody response that peaked at 15, 30, and 60 dpv in springboks, 30 and 60 dpv in impalas (P < 0.01), and 60 dpv in alpacas and wallabies (P < 0.01). The booster vaccine was followed by a high antibody response, which slowly decreased with time. The antibody response was significantly higher at 360 dpv than at T0 in wallabies and alpacas (P < 0.01). In impalas and springboks, it appeared that a booster every 6 mo might be required to maintain an antibody response above baseline (P < 0.01). Because no challenge studies were performed, it is unknown whether the measured humoral immune responses would have been protective. Further research is warranted to investigate protective effects of antibodies to inoculation challenge in nondomestic species.

Pharmacokinetics of subcutaneously administered doramectin in alpacas.

The objective of this research was to evaluate comparative pharmacokinetics of doramectin in alpacas, after subcutaneous administration of 0.2 mg/kg dose. Six healthy adult alpacas, mean age of 5 years ± 1, (three female and three gelded males) of mean bodyweight of 62 kg ± 16 kg with an average body condition scored 2.8 ± 1 out of five, were used in this study. Serial blood samples were collected from the jugular vein before the administration until day 21 afterwards to establish the pharmacokinetics of doramectin after its subcutaneous administration at 0.2 mg/kg dose. The blood samples were analysed using high-performance liquid chromatography (HPLC), fluorescence detection method with precolumn derivatisation, validated for alpacas. The pharmacokinetic parameters were calculated using a noncompartmental model, and results showed Cmax (6.05 ± 5.34 ng/ml), Tmax (3.83 ± 2.48 days), AUC (62.12 ± 18.86 ng/ml × d), terminal half-life (6.2 ± 4.9 days) and MRT (11.56 ± 4.43 days). The results of this study showed that the Cmax and AUC were much lower than in cattle and sheep at the same dosage. Tmax remained similar to cattle and sheep. This study presents valuable information about pharmacokinetics of doramectin in alpacas, which can be utilised in its future efficacy studies.

Deiminated proteins in extracellular vesicles and serum of llama (Lama glama)-Novel insights into camelid immunity.

Peptidylarginine deiminases (PADs) are phylogenetically conserved calcium-dependent enzymes which post-translationally convert arginine into citrulline in target proteins in an irreversible manner, causing functional and structural changes in target proteins. Protein deimination causes generation of neo-epitopes, affects gene regulation and also allows for protein moonlighting. Furthermore, PADs have been found to be a phylogenetically conserved regulator for extracellular vesicle (EVs) release. EVs are found in most body fluids and participate in cellular communication via transfer of cargo proteins and genetic material. In this study, post-translationally deiminated proteins in serum and serum-EVs are described for the first time in camelids, using the llama (Lama glama L. 1758) as a model animal. We report a poly-dispersed population of llama serum EVs, positive for phylogenetically conserved EV-specific markers and characterised by TEM. In serum, 103 deiminated proteins were overall identified, including key immune and metabolic mediators including complement components, immunoglobulin-based nanobodies, adiponectin and heat shock proteins. In serum, 60 deiminated proteins were identified that were not in EVs, and 25 deiminated proteins were found to be unique to EVs, with 43 shared deiminated protein hits between both serum and EVs. Deiminated histone H3, a marker of neutrophil extracellular trap formation, was also detected in llama serum. PAD homologues were identified in llama serum by Western blotting, via cross reaction with human PAD antibodies, and detected at an expected 70 kDa size. This is the first report of deiminated proteins in serum and EVs of a camelid species, highlighting a hitherto unrecognized post-translational modification in key immune and metabolic proteins in camelids, which may be translatable to and inform a range of human metabolic and inflammatory pathologies.

Mycoplasma haemolamae and intestinal parasite relationships with erythrocyte variables in clinically healthy alpacas and llamas.

BACKGROUND: Mycoplasma haemolamae (Mhl) and gastrointestinal nematodes can cause anemia in camelids. Control programs aim to suppress parasitism without promoting anthelminthic resistance, but few evidence-based guidelines define acceptable parasite loads in camelids. HYPOTHESIS/OBJECTIVES: In clinically healthy nonanemic camelids, compare erythrocyte variables to Mhl real-time PCR status and to fecal egg count (FEC). Determine the FEC threshold above which erythrocyte variables are consistently below reference interval medians. ANIMALS: One hundred fourteen client-owned adult alpacas and llamas. METHODS: In a cross-sectional study, whole blood in ethylenediaminetetraacetic acid (EDTA) was assessed for packed cell volume (PCV) by centrifugation, erythrocyte count (RBC), and hemoglobin concentration (HGB) using an ADVIA120 analyzer, and Mhl using real-time PCR. Trichostrongyle eggs per gram (epg) were counted by modified McMaster test on freshly collected feces. Significant differences in erythrocyte variables based on Mhl status and FEC thresholds were assessed by independent t test and one-way ANOVA, respectively. RESULTS: Packed cell volume, RBC, and HGB were not significantly different between Mhl-positive and Mhl-negative animals, but were significantly lower in animals with FEC >1000 epg compared to those with <500 epg. All animals with FEC >600 epg had RBC and HGB below the reference interval median. All animals with FEC >750 epg had PCV below the reference interval median. CONCLUSIONS AND CLINICAL IMPORTANCE: In healthy nonanemic camelids, positive Mhl PCR is not associated with lower erythrocyte variables and such animals may not warrant treatment. Fecal egg count >600-750 epg has a negative effect on erythrocyte variables, and may be a guide for deworming protocols.

Plasma steroid profiles and ovarian response in llamas treated with eCG for superovulation combined with exogenous progesterone during early luteal phase.

The objective of this study was to evaluate the effects of plasma progesterone (P4) concentrations during eCG-ovarian follicular superstimulatory treatment performed in early luteal phase and estradiol concentrations during peri-ovulatory period on ovarian response, number and embryo quality. On Day -2, females (n = 75) having a follicle ≥7 mm were treated with GnRH to induce ovulation. On Day 0, females that had ovulations (n = 54) were treated with 1000 IU eCG and were assigned to one of two treatments: (1) intravaginal device (ID) containing 0.5 g P4 (P4 group) and (2) no ID (Control group). On Day 5, females were administered PGF2α and the ID was removed. On Day 7 and 8, females were mated and embryo recovery was performed 7 or 8 days later. Blood samples were collected from Day 0 to 9. Number (± SD) of follicles ≥7 mm on day of mating was greater (P =  0.04) in the control (9.7 ± 4.2) than P4-treated (6.7 ±â€¯4.9) group; number of corpora lutea did not differ (5.5 ±â€¯3.1 and 5.2 ±â€¯3.4 respectively). Ovulation rate was greater (P <  0.01) in the P4-group (77.4%; 130/168) than control group (53.3%; 135/253). Number of embryos with an excellent grade (grade 1) tended to be greater (P =  0.07) in the P4-group (82.4%; 42/51) than control group (65.4%; 36/55). It was concluded that supplementation with exogenous P4 during eCG treatment in early luteal phase inhibits excessive follicular growth, increases ovulation rate and improves embryo quality.

Pharmacokinetics and pharmacodynamics of intravenous and transdermal flunixin meglumine in alpacas.

The aim of this study was to determine the pharmacokinetics and prostaglandin E2 (PGE2 ) synthesis inhibiting effects of intravenous (IV) and transdermal (TD) flunixin meglumine in eight, adult, female, Huacaya alpacas. A dose of 2.2 mg/kg administered IV and 3.3 mg/kg administered TD using a cross-over design. Plasma flunixin concentrations were measured by LC-MS/MS. Prostaglandin E2 concentrations were determined using a commercially available ELISA. Pharmacokinetic (PK) analysis was performed using noncompartmental methods. Plasma PGE2 concentrations decreased after IV flunixin meglumine administration but there was minimal change after TD application. Mean t1/2 λz after IV administration was 4.531 hr (range 3.355 to 5.571 hr) resulting from a mean Vz of 570.6 ml/kg (range, 387.3 to 1,142 ml/kg) and plasma clearance of 87.26 ml kg-1  hr-1 (range, 55.45-179.3 ml kg-1  hr-1 ). The mean Cmax, Tmax and t1/2 λz for flunixin following TD administration were 106.4 ng/ml (range, 56.98 to 168.6 ng/ml), 13.57 hr (range, 6.000-34.00 hr) and 24.06 hr (18.63 to 39.5 hr), respectively. The mean bioavailability for TD flunixin was calculated as 25.05%. The mean 80% inhibitory concentration (IC80 ) of PGE2 by flunixin meglumine was 0.23 µg/ml (range, 0.01 to 1.38 µg/ml). Poor bioavailability and poor suppression of PGE2 identified in this study indicate that TD flunixin meglumine administered at 3.3 mg/kg is not recommended for use in alpacas.

Evaluation of automated erythrocyte methodology in new world camelids using the ADVIA 2120 hematology analyzer.

BACKGROUND: Accurate erythrocyte measurements with ADVIA hematology analyzers require isovolumetric cell sphering in one reaction and hemolysis in another. However, camelid erythrocytes are resistant to sphering and osmotic lysis, and no published evaluation of ADVIA methods for camelids exists. OBJECTIVES: The objectives were to demonstrate whether camelid erythrocytes sphere in the ADVIA red blood cell/platelet (RBC/PLT) reagent and lyse in the ADVIA cyanide HGB reagent, and to determine optimal ADVIA settings for camelids. METHODS: Camelid and canine blood were diluted to 1:625 in RBC/PLT reagent and evaluated microscopically for erythrocyte sphering. A camelid sample was incubated with the hemoglobin (HGB) reagent at varying dilutions to evaluate hemolysis. The RBC, hematocrit (HCT), mean cell volume (MCV), and mean corpuscular hemoglobin concentration (MCHC) using three ADVIA species settings (equine, bovine, and caprine) were compared to their respective reference methods: Z2 Coulter impedance counter, packed cell volume, calculated MCV (PCV × 10/Coulter RBC), and calculated MCHC (HGB × 100/PCV). Reference MCV was also compared to MCV calculated using the ADVIA equine RBC count. Comparisons were assessed using Passing-Bablok regression and Bland-Altman difference plots. RESULTS: Camelid erythrocytes did not sphere in the RBC/PLT reagent, but did lyse in the HGB reagent. The ADVIA equine setting RBC count was acceptably close to the Coulter count. Hematocrit, MCV, and MCHC from all settings were significantly different from the reference methods. Mean cell volumes calculated using the equine setting RBC counts were acceptably close to the reference MCV. CONCLUSIONS: Camelid ADVIA erythrogram results should be reported as follows: RBC counts and HGB concentrations using the equine setting, spun PCVs, MCVs calculated using the PCV and equine setting RBC, and MCHCs calculated using the PCV and equine setting HGB.

The effect of elemental Zn boluses on concentrations of Zn in serum and faeces of South American camelids.

Aims: To monitor the effect of using long-acting Zn boluses on the Zn status of a group of South American camelids, using measurements of concentrations of Zn in faeces and serum. Methods: As part of a facial eczema (FE) prevention programme, 15 camelids were treated with long-acting Zn boluses designed for preventing FE in sheep. Based on bodyweight, 13 alpacas (Vicugna pacos) received two boluses (26.4 g Zn/bolus) and two llamas (Lama glama) received three boluses. In order to monitor Zn status, measurements were made of concentrations of Zn in serum and faeces immediately prior to bolus treatment (Week 0) and 4, 6, 8 and 10 weeks later. Gamma glutamyl transferase (GGT) activity in serum was measured at Weeks 0 and 8. Results: Two alpacas regurgitated the boluses; in one case the animal was quickly re-treated but this was not possible in the second animal. Mean concentrations of Zn in faeces were higher at all time points compared to Week 0 (p < 0.001). Peak concentrations were measured at Week 8, and concentrations >120 mg/kg fresh weight (FW), suggested as being protective in calves, were only measured in all (13/13) treated camelids at Week 6. Mean concentrations of Zn in serum differed between weeks of sampling but changes were not consistent, and concentrations did not exceed 18 µmol/L following treatment. There was no evidence of a natural sporidesmin challenge during the study period and activity of GGT in serum of all animals was <45 IU/L. Conclusions: Treatment with Zn boluses significantly increased concentrations of Zn in faeces but not in serum, but peak concentrations in faeces were only detected 8 weeks after treatment. Clinical Relevance: The delay in achieving concentrations of Zn in faeces which were associated with protection against FE in calves, combined with the difficulties of administering boluses to camelids, means that we do not believe that Zn boluses should be used as the primary method for preventing FE in camelids. We recommend that FE prevention in camelids should focus on minimising spore production in pasture through the use of fungicides, grazing management and alternative forages, with boluses only used when it is thought that these methods are unlikely to provide sufficient protection against FE. Such use should always be under the guidance of a veterinarian and monitoring of serum GGT activity should be used to ensure that FE control is being achieved.

Evaluation of controlled-release devices for providing chromium sesquioxide and zinc in Huacaya alpacas at pasture.

OBJECTIVE: To assess the effectiveness of controlled-release devices (CRDs) for providing zinc and for estimating faecal output in alpacas and sheep at pasture. METHODS: The study groups of 10 alpacas and 10 sheep at pasture were paired within species and allocated at random to receive by mouth either one CRD containing chromium sesquioxide designed to function for at least 21 days or two CRDs, one containing chromium sesquioxide and the other zinc oxide designed to release over a nominal 60-day period. Faecal concentrations of chromium, zinc and ash, blood and plasma concentrations of zinc and plasma activity of alkaline phosphatase (ALP) were measured over a period of 117 days after treatment. RESULTS: The mean faecal chromium excretion profiles suggested that the CRDs performed in a similar manner in both species, releasing chromium for nearly 30 days in alpacas and for slightly more than 30 days in sheep. Using a common predetermined release rate of chromium from the CRDs, the daily faecal outputs of alpacas and sheep were estimated to be 0.54 kg dry matter and 0.33 kg dry matter, respectively. The CRD containing zinc oxide provided after 1 week an estimated daily release rate of 40 mg zinc with a lifetime of between 60 and 70 days in both species. The additional zinc did not elicit a response in blood zinc concentrations or in plasma ALP activity. CONCLUSION: The CRDs were retained in the gastrointestinal tracts of the alpacas and sheep and both types functioned as expected. The CRD delivering chromium sesquioxide at a known release rate provided an estimate of faecal dry matter output over a period of almost 3 weeks and the CRD formulated to deliver supplementary zinc did so at the nominal release rate over a period of approximately 60 days in both species. These data indicated that the standard sheep CRD is applicable for use in alpacas.

Pharmacokinetic evaluation of marbofloxacin after intravenous administration at different ages in llama crias, and pharmacokinetic/pharmacodynamic analysis by Monte Carlo simulation.

In llama crias (tekes), Escherichia coli and Staphylococcus aureus are major pathogens, and marbofloxacin could be a suitable choice. The objectives of this study were (a) to evaluate the serum pharmacokinetics of marbofloxacin (5 mg/kg) after intravenous administration in tekes and simulate a multidose regimen; (b) to emulate pharmacokinetic profiles after single dose and steady-state conditions by Monte Carlo simulation (c) to determine the MIC of regional strains of Escherichia coli and Staphylococcus aureus; (d) to perform a PK/PD analysis by Monte Carlo simulation. Pharmacokinetics of marbofloxacin was evaluated in six animals at 3, 10, 24, 50, and 80 days after birth. Marbofloxacin were determined by HPLC. A steady-state multi-dose simulation was carried out, and concentration-time profiles were generated by Monte Carlo simulation. MIC of marbofloxacin against regional E. coli and S. aureus strains were also determined. Finally, a PK/PD analysis was conducted by Monte Carlo simulation. After pharmacokinetic analysis, clearance showed a trend to increase (0.14 and 0.18 L kg-1  hr-1 ), and AUC (36.74 and 15.21 µg hr-1  ml-1 ) and Vss (3.06 and 3.37 L/kg) trended to decrease at 3 and 80 days-old, respectively, showing accumulation ~50% in animals with 3 days. All strains tested of E. coli (MIC90  = 0.06 µg/ml) and S. aureus (MIC90  = 0.25 µg/ml) were susceptible to marbofloxacin. PK/PD analysis suggests that the therapeutic regimen of marbofloxacin could be effective for infections caused by E. coli strains in animals between 3 and 80 days, with a CFR for Cmax /MIC > 10 of 100% and for AUC24 /MIC > 125 of 99.99%; and for infections produced by S. aureus in animals between 3 and 24 days old, with a CFR for Cmax /MIC > 10 of 93.08% and for AUC24 /MIC > 60 of 97.01%, but a higher dose should be used in older animals, because PK/PD endpoints were not met.

Verification of the Heska Element Point-of-Care blood gas instrument for use with venous blood from alpacas and llamas, with determination of reference intervals.

BACKGROUND: The Heska Element POC ("EPOC") is a blood gas instrument intended for use with canine, feline, and equine whole blood; no verification for use with camelid specimens has been reported. OBJECTIVES: Using camelid specimens and commercial quality control materials (QCM), we investigatee EPOC analytical performance and establish EPOC camelid reference intervals (RIs). METHODS: Camelid blood (n = 124) was analyzed using the EPOC (pH, pCO2 , pO2 , HCO3 , base excess, SO2 , sodium, potassium, chloride, ionized calcium, TCO2 , anion gap, HCT, HGB, glucose, lactate, and creatinine); plasma was analyzed using a Roche Cobas c501 (sodium, potassium, chloride, TCO2 , anion gap, glucose, and creatinine). Method comparison data were assessed using Pearson's correlation, Passing-Bablok regression, and Bland-Altman plots. EPOC precision was evaluated using QCM and camelid blood. RESULTS: For all measurands except anion gap, the EPOC vs Cobas instrument correlation was r > .85. Except for pO2 and pCO2 , EPOC precision (QCM and blood) ranged from a repeatability CV <1%-6.3%. Mild constant bias for chloride, glucose, TCO2 , anion gap, and creatinine, and mild proportional bias for chloride, glucose, and anion gap were present. The total error (QCM data) for the EPOC instrument was below the ASVCP-recommended allowable total error. Alpacas had higher potassium and lactate, while llamas had higher creatinine, sodium, chloride, ionized calcium, pO2 , and SO2 . Statistical RIs based on alpaca (n = 74-96) and llama data (n = 12-17) are reported descriptively. CONCLUSIONS: The EPOC analyzer shows good performance with camelid blood. A lack of complete agreement with automated chemistry analyzers highlights the importance of interpreting patient data using instrument-specific RIs.

Pharmacokinetics of intravenous gentamicin in healthy young-adult compared to aged alpacas.

The study objective was to evaluate the effects of age on aminoglycoside pharmacokinetics in eight young-adult (<4 years) and eight aged (≥14 years) healthy alpacas, receiving a single 6.6 mg/kg intravenous gentamicin injection. Heparinized plasma samples were obtained at designated time points following drug administration and frozen at -80°C until assayed by a validated immunoassay (QMS® ). Compartmental and noncompartmental analyses of gentamicin plasma concentrations versus time were performed using WinNonlin (v6.4) software. Baseline physical and hematological parameters were not significantly different between young and old animals with the exception of sex. Data were best fitted to a two-compartment pharmacokinetic model. The peak drug concentration at 30 min after dosing (23.8 ± 2.1 vs. 26.1 ± 2 µg/ml, p = .043) and area under the curve (70.4 ± 10.5 vs. 90.4 ± 17.6 µg hr/ml, p = .015) were significantly lower in young-adult compared to aged alpacas. Accordingly, young alpacas had a significantly greater systemic clearance than older animals (95.5 ± 14.4 and 75.6 ± 16.1 ml hr-1 kg-1 ; p = .018), respectively). In conclusion, a single 6.6 mg/kg intravenous gentamicin injection achieves target blood concentrations of >10 times the MIC of gentamicin-susceptible pathogens with MIC levels ≤2 µg/ml, in both young-adult and geriatric alpacas. However, the observed reduction in gentamicin clearance in aged alpacas may increase their risk for gentamicin-related adverse drug reactions.

Prevalence of Candidatus Mycoplasma haemolamae, bovine viral diarrhoea virus, and gastrointestinal parasitism in a sample of adult New Zealand alpaca (Vicugna pacos).

AIM: To determine the prevalence of infection with Candidatus Mycoplasma haemolamae (Mhl), antibodies to bovine viral diarrhoea virus (BVDV), and BVDV antigen, and the prevalence of animals with elevated faecal nematode egg counts (FEC) in a sample of adult New Zealand alpaca (Vicugna pacos). METHODS: Blood samples were obtained from 175 alpaca, collected from 15 farms around New Zealand, and from 31 samples sent to a diagnostic laboratory for routine haematology. Blood smears (n=170) were examined microscopically for the presence of haemoplasma, and DNA was extracted from whole blood (n=206) for real-time PCR testing for Mhl. Packed cell volume (PCV) was determined for 193 samples. Serum samples (n=195) were tested for BVDV antibody using ELISA, and for BVDV antigen using a real-time PCR assay. Faecal samples were collected from 143 animals; FEC were measured, and samples pooled for larval culture. RESULTS: No haemoplasma organisms were present on blood smear examination. Of the 206 blood samples, two (from the same farm) were positive for Mhl by real-time PCR testing, giving a prevalence of infection with Mhl of 0.97%. Of the 195 serum samples tested, four (2.1%) were positive for antibodies to BVDV; animals with BVDV antibodies were from 3/15 (20%) farms, none of which farmed cattle. None of the serum samples were positive by PCR for BVDV antigen. The median FEC was 50 epg (min 0, max 4,700), with 55/143 (38.5%) samples having 0 epg, and 33/143 (23.1%) having ≥250 epg. Haemonchus spp. were the most common nematodes present in faecal larval cultures from the North Island. Log10 FEC was negatively associated with PCV (p=0.02), and was higher in males than females (p<0.001), and in animals that were positive compared with negative for Mhl (p=0.022). CONCLUSIONS AND CLINICAL RELEVANCE: The number of alpaca infected with Mhl was low, as was the seroprevalence of BVDV. Gastrointestinal parasitism was, however, a common finding in this sample of New Zealand alpaca.

Effect of age and castration on serum anti-Müllerian hormone concentration in male alpacas.

The synthesis of anti-Müllerian Hormone (AMH) by the Sertoli cells in males is crucial for sexual differentiation. There are no studies on AMH in Camelids. The objectives of this research were to 1) compare AMH serum concentrations in prepubertal and adult male alpacas and 2) determine the effect of castration on these concentrations in adult males to provide a validation of a commercial AMH test in alpacas. Serum samples were obtained from 15 prepubertal animals (5 for each age groups of 6, 7 and 8 months) and from 5 adult males (age 5-9 years), pre- and 24 h post-castration. AMH was determined with a quantitative ELISA according to the manufacture's instructions. There was not significant difference (P < 0.05) in AMH level (pg/ml) between pre-pubertal (549.9 ± 120.8, 789.4 ± 172.3, 597.5 ± 177.3 for ages 4, 7, and 8 months, respectively) and adult alpacas (938.7 ± 175.9). In adult males, AMH concentration decreased significantly following castration (P < 0.05) (938.7 ± 383.5 pg/ml) pre-castration, and 222.1 ± 116.5 pg/ml) after castration). There was a positive correlation between testosterone levels and AMH. In conclusion, the quantitative assay used is a reliable test to determine AMH in alpacas. The AMH level in prepubertal and adult alpacas appear to not differ, contrarily from other mammals, this requires further investigation. The decrease in serum AMH concentrations after castration suggests that measurement of this hormone can be used to diagnose bilateral cryptorchid or hemicastrated unilateral cryptorchid animals in this species.

Uterine endometrial vascularization during ovarian follicular growth in llamas: The effect of estradiol plasma concentration.

The aim of this study was to evaluated changes in endometrial vascularization area (EVA) between the left and right uterine horn: a) during the ovarian follicular growth in intact llamas, and b) after exogenous estradiol administration of estradiol benzoate in ovariectomized (OVX) llamas. In experiment 1 follicle wave emergence was synchronized (n = 5 llamas) by follicle ablation (Day 0). Females were examined every other day from Day 1 to Day 27, using B mode ultrasonography to evaluate dominant follicle growth profile. Also, EVA was evaluated in each horn using Color-Power Doppler. Blood samples were taken every other day from Day 1 to Day 27 to measure estradiol (E2) plasma concentration by RIA. In experiment 2 OVX llamas (n = 4 llamas/group) were given a single im administration of: a) 1 mg of estradiol benzoate (EB) or b) 1 mL of saline. Females were subjected to ultrasound examinations every 48 h from Day -4 until treatment (Day 0), every 12 h from Day 0 to Day 4, and again every 48 h from Day 5 to Day 11. Evaluation of EVA in both uterine horns was performed as described for experiment 1. Blood sampling for the measurement of E2 was carried out at the same time points indicated for the ultrasound examinations. Serial data were analyzed by one way ANOVA for repeated measures using the MIXED Procedure in SAS. Also, Pearson's correlation was used to determine the relationship between variables. In intact llamas there was an effect of day on the dominant follicle growing profile (P < 0.01) and estradiol plasma concentration (P < 0.05). Dominant follicle diameter positively correlated (r = 0.4; P < 0.017) with estradiol plasma concentration. Also, EVA of right and left uterine horn did not differ (P = 0.89) during the evaluation period; however, it was affected by time (P < 0.05). In ovariectomized llamas estradiol concentration was significantly (P < 0.001) affected by treatment, time and their interaction. Accordingly, treatment with EB (P < 0.0001), time (P < 0.05) and their interaction (P < 0.01) affected EVA of both uterine horns; however, this variable did not differ between horns (P = 0.98). In conclusion, circulating concentrations of estradiol determined an increase in uterine vascularization, during the phase of follicular growth in intact llamas and after the exogenous administration of EB to ovariectomized females; however, no differential effect in endometrial vascularization area between right and left uterine horn was observed.

Assessment of the Zinc and Copper Status in Alpaca.

This study was performed with the aim of investigating the concentration of zinc and copper in the blood of healthy alpacas (Vicugna pacos) kept in central Europe and to compare the concentration of Zn and Cu in plasma and in whole blood. A further objective was to evaluate blood Zn and Cu in relation to different micromineral supplementation, age and sex groups of alpacas. A total of 299 alpacas (224 adults and 75 crias) from 18 farms were included in this study. The concentrations of copper and zinc in plasma/whole blood were measured by flame atomic absorption spectrometry. The results of this study show high individual variability in plasma Zn (median 3.54, range 1.56-8.01 µmol/l), whole blood Zn (median 10.01, range 6.23-75.0 µmol/l), plasma Cu (median 7.53, range 2.93-16.41 µmol/l) and whole blood Cu (median 6.33, range 3.02-13.95 µmol/l). Plasma Zn was not significantly influenced by sex, age or feeding group. Whole blood Zn was only significantly higher in females than in males. The intake of Zn in all groups was equal to or higher than the nutritional recommendation. During excessive supplementation, Zn absorption decreased and thus blood Zn did not reflect the higher intake. Only a weak correlation was found (Spearman correlation coefficient r = 0.384; p > 0.01; n = 204) between plasma and whole blood Zn concentrations. Plasma copper concentration was significantly influenced by age, sex and feeding; whole blood Cu by age and feeding. However, neither plasma Cu nor whole blood Cu reflected the intake of the element. We found a close correlation between plasma and blood copper concentrations (Spearman correlation coefficient r = 0.9043; p ≤ 0.01; n = 99). According to our results, copper in plasma or blood is not a good indicator of copper intake.

Prediction of Packed Cell Volume after Whole Blood Transfusion in Small Ruminants and South American Camelids: 80 Cases (2006-2016).

BACKGROUND: Calculation of desired whole blood transfusion volume relies on an estimate of an animal's circulating blood volume, generally accepted to be 0.08 L/kg or 8% of the animal's body weight in kilograms. OBJECTIVE: To use packed cell volume before and after whole blood transfusion to evaluate the accuracy of a commonly used equation to predict packed cell volume after transfusion in small ruminants and South American camelids; to determine the nature and frequency of adverse transfusion reactions in small ruminants and camelids after whole blood transfusion. ANIMALS: Fifty-eight small ruminants and 22 alpacas that received whole blood transfusions for anemia. METHODS: Retrospective case series; medical record review for small ruminants and camelids that received whole blood transfusions during hospitalization. RESULTS: Mean volume of distribution of blood as a fraction of body weight in sheep (0.075 L/kg, 7.5% BW) and goats (0.076 L/kg, 7.6% BW) differed significantly (P < 0.01) from alpacas (0.103 L/kg, 10.3% BW). Mild transfusion reactions were noted in 16% of transfusions. CONCLUSIONS AND CLINICAL RELEVANCE: The generally accepted value of 8% for circulating blood volume (volume of distribution of blood) is adequate for calculation of transfusion volumes; however, use of the species-specific circulating blood volume can improve calculation of transfusion volume to predict and achieve desired packed cell volume. The incidence of transfusion reactions in small ruminants and camelids is low.

Evaluation of transmission infrared spectroscopy and digital and optical refractometers to identify low immunoglobulin G concentrations in alpaca serum.

This study aimed to evaluate the digital Brix and optical serum total protein (STP) refractometers for measuring concentrations of serum immunoglobulin G (IgG) in alpacas and compare them to IgG concentrations measured by the reference method of radial immunodiffusion (RID) assay. The appropriate cutoff point for Brix and STP refractometers and the transmission infrared (TIR) spectroscopy method was determined for low IgG concentrations (< 10 g/L). Serum samples were collected from alpacas (N = 169) and tested by both refractometers. The correlation between Brix % and STP was high [correlation coefficient (r) = 0.99]. However, the correlation coefficients between Brix % and STP with serum RID-IgG concentrations were only 0.56 and 0.55, respectively. Twenty-one (12.4%) of 169 alpaca serum samples had IgG concentrations of < 10 g/L. Using receiver operator characteristic curve (ROC) analysis, the optimal cutoff points for the TIR assay, digital Brix, and optical STP refractometers for assessing low IgG (RID < 10 g/L) were 13 g/L, 8.8%, and 50 g/L, respectively. The TIR assay showed higher sensitivity (Se = 95.2%) and specificity (Sp = 96.8%) than either the digital Brix (Se = 90.5% and Sp = 65.5%) or optical STP (Se = 81% and Sp = 73.7%) refractometers for assessing alpacas with low IgG. In conclusion, the Brix and STP refractometers lack accuracy in measuring alpaca IgG concentrations, but may be useful for screening animals for low serum IgG. However, the TIR assay with a cutoff point of 13 g/L was more appropriate for identifying low IgG than either refractometer. Another study that focuses on neonatal crias is recommended in order to evaluate the usefulness of these assays for field diagnosing of failure of transfer of passive immunity (FTPI).

Cette étude visait à évaluer un réfractomètre Brix digital et un réfractomètre optique pour protéines sériques totales (PST) pour mesurer les concentrations sériques d'immunoglobulines G (IgG) chez les alpagas et de les comparer aux concentrations d'IgG mesurées par la méthode de référence d'immunodiffusion radiale (IDR). La valeur seuil appropriée pour les réfractomètres Brix et PST ainsi que pour la méthode de spectroscopie infrarouge à transmission (SIT) fut déterminée pour des faibles concentrations d'IgG (< 10 g/L). Des échantillons de sérum ont été prélevés d'alpagas (N = 169) et testés avec les deux réfractomètres. La corrélation entre le % Brix et PST était élevée [coefficient de corrélation (r) = 0,99]. Toutefois, les coefficients de corrélation entre % Brix et le PST et les concentrations d'IgG déterminées par IDR étaient seulement de 0,56 et 0,55, respectivement. Vingt-et-un (12,4 %) des 169 échantillons de sérum d'alpaga avaient des concentrations d'IgG < 10 g/L. En utilisant l'analyse de la courbe de la fonction d'efficacité du récepteur, les valeurs seuils optimales pour l'épreuve SIT, et les réfractomètres Brix digital, et PST optique pour évaluer un faible niveau d'IgG (IDR < 10 g/L) étaient de 13 g/L, 8,8 % et 50 g/L, respectivement. L'épreuve SIT a montré une sensibilité (Se = 95,2 %) et une spécificité (Sp = 96,8 %) plus élevée que le réfractomètre Brix digital (Se = 90,5 % et Sp = 65,5 %) ou le réfractomètre PST optique (Se = 81 % et Sp = 73,7) pour évaluer les alpagas avec de faibles concentrations d'IgG. En conclusion, les réfractomètres Brix et PST manquent de précision pour mesurer les concentrations d'IgG d'alpagas, mais peuvent être utiles pour vérifier les animaux pour des faibles concentrations d'IgG sériques. Toutefois, l'épreuve SIT avec une valeur seul de 13 g/L était plus appropriée que les deux réfractomètres pour identifier des valeurs faibles d'IgG. Une autre étude qui s'attardait aux crias nouveau-nés est recommandée afin d'évaluer l'utilité de ces épreuves pour le diagnostic des déficiences de transfert d'immunité passive.(Traduit par Docteur Serge Messier).

Application of laboratory and portable attenuated total reflectance infrared spectroscopic approaches for rapid quantification of alpaca serum immunoglobulin G.

The objective of this study was to develop and compare the performance of laboratory grade and portable attenuated total reflectance infrared (ATR-IR) spectroscopic approaches in combination with partial least squares regression (PLSR) for the rapid quantification of alpaca serum IgG concentration, and the identification of low IgG (<1000 mg/dL), which is consistent with the diagnosis of failure of transfer of passive immunity (FTPI) in neonates. Serum samples (n = 175) collected from privately owned, healthy alpacas were tested by the reference method of radial immunodiffusion (RID) assay, and laboratory grade and portable ATR-IR spectrometers. Various pre-processing strategies were applied to the ATR-IR spectra that were linked to corresponding RID-IgG concentrations, and then randomly split into two sets: calibration (training) and test sets. PLSR was applied to the calibration set and calibration models were developed, and the test set was used to assess the accuracy of the analytical method. For the test set, the Pearson correlation coefficients between the IgG measured by RID and predicted by both laboratory grade and portable ATR-IR spectrometers was 0.91. The average differences between reference serum IgG concentrations and the two IR-based methods were 120.5 mg/dL and 71 mg/dL for the laboratory and portable ATR-IR-based assays, respectively. Adopting an IgG concentration <1000 mg/dL as the cut-point for FTPI cases, the sensitivity, specificity, and accuracy for identifying serum samples below this cut point by laboratory ATR-IR assay were 86, 100 and 98%, respectively (within the entire data set). Corresponding values for the portable ATR-IR assay were 95, 99 and 99%, respectively. These results suggest that the two different ATR-IR assays performed similarly for rapid qualitative evaluation of alpaca serum IgG and for diagnosis of IgG <1000 mg/dL, the portable ATR-IR spectrometer performed slightly better, and provides more flexibility for potential application in the field.