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Abstract

Objective—To determine the associations between serum IgG concentration and serum activities of γ-glutamyltransferase (GGT), alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, and pseudocholinesterase for the potential use of these serum enzymes as predictors of passive transfer status in neonatal lambs.

Design—Prospective observational study.

Animals—47 Sardinian lambs from birth to 2 days old.

Procedure—Serum enzyme activities were measured by use of commercially available kits and a clinical biochemical analyzer. Serum IgG concentration was determined by single radial immunodiffusion. Associations between serum IgG concentration and the activity of each serum enzyme were established by use of regression analysis.

Results—A significant correlation was detected between serum IgG concentration and serum GGT activity in 1- and 2-day-old lambs. Minimal correlations were detected between serum IgG concentration and serum alkaline phosphatase activity in 1-dayold lambs and serum pseudocholinesterase activity in 1- and 2-day-old lambs. No significant associations were detected between serum IgG concentration and serum activities of aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase. A multiple linear regression model was accurate for the estimation of the natural logarithm of serum IgG concentration as a function of the natural logarithm of serum GGT activity and of the age of lambs at the time of sampling (adjusted R 2 = 0.89). This model was then used to calculate the serum GGT activity equivalent to various serum IgG concentrations for 1- and 2-day-old lambs.

Conclusions and Clinical Relevance—Results suggested that passive transfer status in neonatal lambs can be successfully predicted by measurement of serum GGT activity but not by measurement of the other enzymes tested. (J Am Vet Med Assoc 2005; 226:951–955)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine whether serum IgG concentrations in neonatal calves are adversely affected by short-term frozen storage of colostrum.

Design—Prospective study.

Sample Population—Experiment 1 consisted of 10 pairs of Holstein calves (n = 20) fed matched aliquots of either fresh (n = 10) or frozen and thawed (10) colostrum. In experiment 2, 26 Holstein calves were fed either fresh (n = 13) or frozen and thawed (n = 13) colostrum.

Procedure—Experiment 1 consisted of calves resulting from observed parturitions; calves were randomly assigned to treatment groups (fresh or frozen and thawed colostrum) in pairs. Calves were fed 4 L aliquots of colostrum via oroesophageal intubation at 3 hours of age. Serum IgG concentrations at 2 days of age were compared between the 2 groups by use of a paired t-test. Experiment 2 consisted of calves resulting from observed parturitions; calves were randomly assigned to treatment groups (fresh or frozen and thawed colostrum). Calves were fed 4 L aliquots of colostrum via oroesophageal intubation at 3 hours of age. Regression analysis was used to determine whether calf serum IgG concentration was a function of colostral IgG concentration and colostrum storage group.

Results—Significant differences were not observed between the 2 groups in experiment 1. No significant relationship was observed between colostrum storage group and serum IgG concentration in experiment 2. The model that best predicted serum IgG concentrations accounted for 20% of the variability in serum IgG concentration.

Conclusion and Clinical Relevance—Frozen colostrum is an adequate source of IgG for calves. (J Am Vet Med Assoc 2001;219:357–359)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective

To examine systemic immunity in kittens, including transfer of maternal immunoglobulins from the queen to kittens, and subsequent decay of passively obtained immunoglobulins.

Animals

6 healthy queens and their 46 kittens.

Procedure

Immunoglobulin concentrations were measured in serum, colostrum, and milk of queens and in their kittens' sera. Decay rate constants and half-lives of maternally derived immunoglobulins were determined. To determine intestinal absorption, foreign IgG was given to kittens at 6- to 8-hour intervals after birth, and bovine IgM was given to kittens at birth.

Results

Immunoglobulin concentrations of milk and colostrum did not differ significantly after removal of milk fat. Mean IgG concentration was higher in colostrum/milk, whereas mean IgA and IgM concentrations were lower than those in the queens' serum. No IgG or IgA was detected in any of the precolostral serum samples obtained from kittens. Small amounts of IgM were present in the sera from 5 kittens at birth. Transferred IgG and IgA decreased rapidly with half-lives of 4.4 ± 3.57 and 1.93 ± 1.94 days, respectively. Serum IgM concentration increased irregularly during the first week of life, followed by a steady increase. Foreign IgG given up to 12 hours after birth was detected in kittens' serum, whereas IgG given at or after 16 hours was not found in any kitten's serum.

Conclusions

Milk and colostral immunoglobulin concentrations did not differ significantly. The half-lives of maternally derived IgG and IgA in kittens were shorter than those reported in dogs. IgG given at or after 16 hours of life was not absorbed by neonatal kittens.

Clinical Relevance

Queen's milk obtained anytime during lactation may be used as a replacement for colostrum as a source of antibodies for neonatal kittens. Kittens at risk for neonatal isoerythrolysis must only be removed from the queens during the first day of life. (Am J Vet Res 1996;57:1653–1658)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To develop a flow cytometric assay for detection of platelet-bound IgG in dogs.

Sample Population

Negative-control platelets were obtained from 5 clinically normal Greyhounds. Positive-control platelets were platelets from 1 clinically normal dog, sensitized with dog anti-canine platelet alloantibodies.

Procedure

Washed platelets were incubated with mouse anti-canine IgG conjugated to fluorescein isothiocyanate and analyzed by flow cytometry. Optimal dilution of antibody reagent and dose-response were determined, as were effects on platelet-bound IgG detection of storage time and temperature of K3EDTA-anticoagulated blood samples, variable platelet numbers, and variable filling of K3EDTA evacuated tubes.

Results

A 1:128 dilution of antibody reagent was optimal. There was a linear increase in platelet-bound IgG when normal canine platelets were incubated with increasing concentrations of positive-control serum. Variable numbers of positive-control platelets tested and variable filling of K3EDTA evacuated tubes had no significant effect on platelet-bound IgG concentration. Platelet-bound IgG concentration increased with storage time at room temperature (P = 0.0003), but not when blood was kept cool. Sufficient platelets for assay were able to be isolated from 3 ml of blood from 5 dogs with < 10,000 platelets/μl.

Conclusions

This assay for platelet-bound IgG in dogs is simple, repeatable, and practical. The assay is not affected by platelet count or variable filling of evacuated tubes, and requires only 3 ml of K3EDTA-anticoagulated blood. Blood samples for testing require packaging on ice and overnight delivery but, after arrival at the laboratory, can be refrigerated and analyzed within 72 hours of collection.

Clinical Relevance

Assays for platelet-bound IgG may help in assessing causes and treatment of thrombocytopenia.

Free access
in American Journal of Veterinary Research

SUMMARY

Four virgin heifers were experimentally inoculated intravaginally with 7 × 106 Tritrichomonas foetus, and 2 heifers served as uninfected controls. The durations of infection were 13, 20, 21, and 28 weeks, respectively. An ELISA that used whole T foetus antigen was used to detect anti-T foetus immunoglobulins (IgA, IgG1, IgG2, and IgM) in vaginal, cervical, and uterine secretions, and sera during the course of infection. The vaginal and cervical antibody responses were characterized by significantly increased T foetus-specific IgA and IgG1 at 7 to 9 weeks of infection, whereas uterine IgA and IgG1 responses peaked at 10 to 12 weeks. The antibody response in serum was predominantly of the IgG1 and IgG2 subclasses. In all reproductive tract regions, IgA persisted at least until the time of T foetus clearance, and usually longer. The next most persistent isotype was IgG1, lasting longest in the vagina, then cervix, and for the shortest time in the uterus. In local secretions, IgG2 was seen only transiently, increasing at weeks 13 to 15 in the vagina, and at weeks 10 to 12 in the cervix. Little IgM, relative to that present before infection, was detected in any secretion or serum, although cervical secretions had the greatest amount. Eight to 12 weeks after clearance, the 4 experimental heifers were inoculated intravaginally with 1 × 105 T foetus; transient infections (2 to 3 weeks' duration) were established in only 2 of 4 heifers, as determind by culturing of reproductive tract secretions. The lag times of antibody responses during this reinfection were shorter than in the initial infection, and elisa optical densities were at least as high as during the primary infection, suggesting an anamnestic response.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine the effects of dexamethasone on development of IgG subclass responses following vaccination of healthy horses.

Animals—11 mature Thoroughbreds.

Procedure—Horses received 2 IM injections at 2- week intervals of a vaccine containing inactivated infectious bovine rhinotracheitis, bovine viral diarrhea, and parainfluenza-3 viral antigens and were then randomly assigned to 2 groups. Six horses received dexamethasone (0.2 mg/kg of body weight, IM) twice weekly for 8 weeks starting the day of the first vaccination. Five control horses received an equivalent volume of saline (0.9% NaCl) solution. Antigen-specific serum IgG subclass titers were determined weekly after vaccination by use of an ELISA.

Results—Vaccination resulted in similar antigen-specific serum IgG(T) titers in dexamethasone-treated and control horses. In contrast, although control horses developed IgGa and IgGb responses after vaccination, corticosteroid administration completely inhibited these responses in treated horses.

Conclusions and Clinical Relevance—Cortico steroids can have profound effects on primary immune responses in horses and can significantly affect IgG responses to inactivated vaccines. Corticosteroid treatment regimens commonly used to treat diseases in horses may result induction of a nonprotective IgG subclass response, leaving treated horses susceptible to disease. Additionally, mechanisms regulating IgGa and IgGb responses appear to differ from those regulating IgG(T) responses. Further defining these mechanisms is a critical step in designing effective vaccines, and corticosteroid-induced immunomodulation may be a valuable tool for studying immune responses in horses. (Am J Vet Res 2000;61:1530–1533)

Full access
in American Journal of Veterinary Research

SUMMARY

Objective

To develop an automated turbidimetric immunoassay (TIA) for measurement of bovine IgG.

Sample Population

24 bovine serum samples.

Procedure

IgG concentration was determined by use of the TIA, and results were compared with those of the radial immunodiffusion (RID) method. Variables were determined, using commercially available reagents and a clinical biochemical analyzer. For the TIA, polyclonal goat anti-bovine IgG (Fc specific) serum, bovine IgG calibrator serum, and polyethylene glycol reaction buffer were used. Sample concentrations were determined by the instrument, using the linear regression method of least squares. The accuracy of this assay was validated by referencing to a purified bovine IgG standard and by recovery of control standards. Parallelism was documented by assay linearity and serial sample dilution linearity. Interference resulting from hemolyzed samples was examined.

Results

The TIA method correlated positively (r = 0.9957) and significantly (P < 0.05) with the RID method, yielding a regression equation with slope of 0.78708 and y-intercept of 1.02102. Bias attributable to hemolysis was not observed.

Conclusions

The TIA method is automated, accurate, and precise for bovine serum IgG quantification.

Clinical Relevance

This assay provides sample results in approximately 10 minutes and may be used as an alternative to the manual RID method. (Am J Vet Res 1997;58:1201–1205)

Free access
in American Journal of Veterinary Research

Summary

The effect of postnatal acid-base status on the absorption of colostral immunoglobulins by calves was examined in 2 field studies. In study 1, blood pH at 2 and 4 hours after birth was related to serum IgG1 concentration 12 hours after colostrum feeding (P < 0.05). Decreased IgG1 absorption from colostrum was associated with respiratory, rather than metabolic, acidosis, because blood PCO2 at 2 and 4 hours after birth was negatively related to IgG1 absorption (P < 0.05), whereas serum bicarbonate concentration was not significantly related to IgG1 absorption.

Acidosis was frequently observed in the 30 calves of study 1. At birth, all calves had venous PCO2 value ≥ 60 mm of Hg, 20 of the calves had blood pH < 7.20, and 8 of the calves had blood bicarbonate concentration < 24 mEq/L. Blood pH values were considerably improved by 4 hours after birth; only 7 calves had blood pH values < 7.20.

Calves lacking risk factors for acidosis were examined in study 2, and blood pH values at 4 hours after birth ranged from 7.25 to 7.39. Blood pH was unrelated to IgG1 absorption in the calves of study 2. However, blood PCO2 was again found to be negatively related to colostral IgG1 absorption (P < 0.005).

Results indicate that postnatal respiratory acidosis in calves can adversely affect colostral immunoglobulin absorption, despite adequate colostrum intake early in the absorptive period.

Free access
in Journal of the American Veterinary Medical Association

SUMMARY

Immunoglobulin values were determined in fetal and kitten sera. In the fetal and precolostral kitten sera, only IgG was detected, except in 1 case in which IgM was detected. The IgG, IgA, and IgM were transferred to the kittens through colostrum ingestion with some selectivity. Concentration of the transferred IgG, IgA, and IgM decreased significantly with half-lives of 4.15 ± 1.29 days, 2.03 ± 0.33 days, and 2.2 ± 1.2 days, respectively. As a result of this decrease and increase of de novo immunoglobulin synthesis, IgG, IgA, and IgM were at their lowest values when kittens were 20 to 25 days, 14 to 20 days, and 8 to 10 days old, respectively. After their nadir was reached, IgG values increased gradually, IgA slowly, and IgM rapidly, as a result of de novo immunoglobulin synthesis. When the kittens were 90 days old, their immunoglobulin values were 80% (IgG), 7% (IgA), and 100% (IgM), compared with those of adult cats. These findings suggest that kittens that receive inadequate colostrum from their mothers will be particularly susceptible to infection after they are 5 weeks old.

Free access
in American Journal of Veterinary Research

SUMMARY

Immunoglobulin reactions to Salmonella dublin in serum and milk from 4 groups of lactating cows were measured by an indirect elisa. The groups consisted of (1) cows that were natural carriers of S dublin in the mammary gland, (2) experimentally infected cows that did not become carriers, (3) cows inoculated with a commercial S dublin bacterin, and (4) cows used as S dublin-negative controls. Milk and serum samples were obtained at monthly intervals. Models for predicting carrier status were developed by use of stepwise logistic regression. Independent variables consisted of serum and milk IgG and IgM titers to S dublin lipopolysaccharide and a ratio of IgG to IgM. The utility of a single sample vs multiple samples obtained at 1-month or 2-month intervals was tested by comparison of goodness-of-fit χ2 P values for 8 models predicting carrier status.

Immunoglobulin reactions specific to S dublin were a significant predictor of carrier status (P < 0.001). Serum IgG titers specific for S dublin were the most important variable for predicting carrier status. Two serum IgG titers to S dublin obtained 2 months apart was a better predictor of carrier status than measurement of the IgG:IgM ratio from a single serum sample. Immunoglobulin recognizing S dublin epitopes also were detected in milk samples. In milk, performing 2 ELISA 60 days apart to determine IgG and IgM reactions to S dublin appeared to be useful for the prediction of carrier status, but was not as accurate as models for serum immunoglobulin reactions.

Free access
in American Journal of Veterinary Research