- Email: [email protected]
Relationships between total body water, ultrasonic measures of fat depots and morphometric measurements in horses
50
Abstracts / Journal of Equine Veterinary Science 52 (2017) 49e63
elicited a 2-fold increase in phosphorylation of Akt in all horses (P < 0.05). Short-term DEX treatment resulted in a significantly greater insulin response to the consumption of a high protein meal. However, despite the elevated insulin concentrations, there was no difference between treatment groups in the magnitude of postprandial Akt activation in the muscle. An exacerbated insulin response to a high protein meal might be a compensatory mechanism, maintaining Akt activation despite DEX induced decrease in tissue insulin sensitivity. Additional research is necessary to determine whether a similar response to protein feeding is seen in horses with naturally occurring insulin dysregulation. Key Words: dexamethasone, insulin, muscle
22 Plasma and muscle amino acid concentrations in insulin resistant compared to normal horses in the fed and fasted state E.L. Macon*1, P.M. Graham-Thiers 2, K.L. Bowen 2 1 Middle Tennessee State University, Murfreesboro, TN, USA; 2 Emory and Henry State College, Bristol, VA, USA The effects of insulin resistance on protein and amino acid metabolism have not been documented in horses, despite knowledge that insulin stimulates the incorporation of amino acids into proteins and decreases the rate of protein degradation in skeletal muscle. The objective of this research was to investigate protein metabolism in insulin resistant (IR) horses compared with Normal controls. Preceding the study, horses were screened for fasting plasma insulin concentrations with insulin concentrations of 10.1 ± 3.5 mU/L ¼ Normal, and 41.2 ± 15.9 mU/L ¼ IR, and then underwent an oral sugar challenge (OST). Blood samples were collected before and at 60, 75, 90, 120, 180 min after administration of Karo Light Syrup (0.15 mL/ kg of BW) for the determination of plasma insulin and glucose. Based on the OST, 8 horses (16 + 3 yrs), 4 IR and 4 Normal, were studied while receiving Purina Strategy and a mixture of Timothy/Bermudagrass hay fed at 2% BW, a diet that met or exceeded NRC recommendations. After a week of dietary adaption, the morning meal (half the daily ration) was fed on d 7. Blood samples were taken at 0, 1, 3, 4, and 6 h post-prandial for determination of plasma amino acids. On d 8, muscle biopsies were taken and immediately frozen in liquid nitrogen for analysis of free amino acids. Glucose was analyzed using an enzymatic assay, and insulin by radioimmunoassay. Plasma free amino acids and semitendinosus muscle free amino acids were determined using reverse-phase HPLC of phenylisothiocyanate derivatives. Data were analyzed using a mixed model with repeated measures analysis of SAS, with time and group as main effects. The OST data confirmed higher insulin (P ¼ 0.020) and a trend for higher glucose (P ¼ 0.055) in IR vs Normal horses. There were no differences between IR and Normal for any plasma free amino acids (P > 0.15) or semitendinosus muscle free amino acids (P > 0.17). Contradictory to this study, hyperinsulinemic clamp procedures in healthy horses and pigs lowered plasma amino acid concentrations, with similar results reported in healthy and diabetic humans. Lack of variation in amino acid concentrations between IR and Normal horses suggests that insulin resistance does not affect amino acid absorption into the plasma pool or incorporation into the muscle in horses. Acknowledgments: This study was conducted at Emory and Henry College with the support of a Virginia Horse Industry Board grant.
Key Words: insulin resistance, amino acids
23 Comparison of horse body fat composition estimated by D2O dilution, rump fat thickness, and tissue dissection E.N. Ferjak*1, C. Argo 2, C.A. Cavinder 1, D.D. Burnett 1, T.T.N. Dinh 1 1 Mississippi State University, Starkville, MS, USA; 2 University of Liverpool, Liverpool, United Kingdom Research indicates that body condition score (BCS) of horses is positively correlated with reproductive efficiency and indicative of metabolic and lameness issues. However, body fat (BF, %) composition in horses is poorly defined and inaccurately predicted due to procedures that are either subjective or dependent upon one anatomical location to create the whole body prediction. Recently, deuterium oxide (D2O) dilution has been validated as an accurate estimation of BF in ponies. Nonetheless, further studies are warranted to confirm its efficacy in stock-type horses because D2O-prediction in swine was suggested to be only accurate in animals that share physiological resemblances. Therefore, the objective of the current study was to compare 2 methods of predicting BF with whole carcass fat analysis in horses. Twentyone mature, stock-type horses of BCS 2 (n ¼ 1; 415 kg), 3 (n ¼ 1; 376 kg), 4 (n ¼ 5; 469 ± 16 kg), 5 (n ¼ 9; 455 ± 11 kg), and 6 (n ¼ 5; 493 ± 12 kg) were selected based on 3 primary criteria: geriatric, crippled, and/or unsafe. Approximately 20 h before slaughter, horses were weighed and measured via ultrasound for rump fat (RF) thickness. Blood samples were collected immediately before and 4 h after D2O infusion (0.12 g/kg BW). Deuterium oxide concentration of plasma was determined by gas isotope ratio mass spectrometry following filtration and zinc reduction. Horses were housed in a dry lot overnight before being individually sedated (1.1 mg xylazine/kg BW) and anesthetized (2.2 mg ketamine/kg BW); and KCl solution was administered to cease cardiac functions before exsanguination (Mississippi State University IACUC protocol #15093). After euthanasia, horse carcasses were processed and dissected and tissues were collected for nearinfrared spectroscopic (NIR) analysis. Body fat by D2O dilution was correlated with BF by NIR analysis on various weight bases (r ¼ 0.72 to 0.74; P < 0.001), whereas a weaker correlation (r ¼ 0.45 to 0.53; P 0.039) was observed for BF by RF thickness. Paired ttest indicated that BF predicted by D2O dilution was similar to NIR BF on a hot carcass weight basis (P ¼ 0.060); however, it was 3.58 ± 0.68% less than BF by RF thickness. The current study provided evidence that D2O dilution was a more accurate BF prediction method than RF thickness for stock-type horses. Key Words: body fat, deuterium oxide, rump fat thickness
24 Relationships between total body water, ultrasonic measures of fat depots and morphometric measurements in horses A.L. Fowler*1, M.B. Pyles 1, V.T. Bill 1, S.H. Hayes 1, A. Crum 1, J. Parsons 1, L. Walling 1, A. Moffett-Krotky 2, P.A. Harris 3, L.M. Lawrence 1 1 University of Kentucky, Lexington, KY, USA; 2 Mars Horsecare US Inc., Dalton, OH, USA; 3 Waltham Centre for Pet Nutrition, Melton Mowbray, Leicestershire, United Kingdom Body condition score (BCS) is the most commonly used method to monitor changes in equine body composition, however other
Abstracts / Journal of Equine Veterinary Science 52 (2017) 49e63
measures such as ultrasonically determined subcutaneous fat depth and morphometric measurements have also been utilized for body composition assessment. In addition, total body water (TBW), as measured with a deuterium oxide (D2O) dilution technique, has been validated as a method to determine total body fat in ponies with BCS between 3 and 7. The objective of this study was to examine relationships between BCS, total body water, subcutaneous fat depth, and morphometric measurements of horses. Fifteen mature horses (14 Thoroughbreds and 1 Thoroughbred-cross) with BCS between 4 and 6 were used. Two sets of measurements were taken 3 to 4 wk apart on each horse. Morphometric measurements included wither height and circumferences of the neck, heart girth and belly girth. Ultrasound was used to measure subcutaneous fat depths at the mid-neck, shoulder, ribs, rump, and tail head. Total body water was measured using the D2O dilution technique. Briefly, horses were weighed and 0.12 g D2O/kg was quantitatively administered via IV catheter after an initial blood sample was obtained. A second blood sample was obtained at 4 h post-administration and TBW was calculated from the change in D2O concentration. Regression was used to examine relationships among measurements. Total body water averaged 69 ± 0.4% (mean ± SE) of body weight and ranged from 65 to 75%. Total body water and body weight were related (P < 0.05, R2 ¼ 0.81), with an increase in body weight (kg) correlating to an increase in TBW (kg). However, TBW increased as BCS decreased (P < 0.05, R2 ¼ 0.45), indicating that TBW is related to palpable fatness. In horses with BCS 5, TBW% decreased as subcutaneous tail head fat depth increased (P < 0.05, R2 ¼ 0.55) and BCS increased as subcutaneous tail head fat depth increased (P < 0.05, R2 ¼ 0.30). Body condition score of these horses was related to body weight, belly girth:height, heart girth:height, heart girth:body weight, and belly girth:body weight (P < 0.05). These findings suggest that using TBW, morphometric measures or subcutaneous fat depth measures may augment the determination of equine body fatness typically assessed using BCS. Key Words: body condition, deuterium, ultrasound
25 Immunological changes in horses occur early during road transportation J.M. Bobel*, T.L. Hansen, J.W. Callaham, J.R. Abbott, L.K. Warren University of Florida, Gainesville, FL, USA Alterations in physiological and immune status and heightened risk for respiratory disease in response to transportation are well documented in horses. However, information on mucosal immune responses and how quickly immunological changes occur is lacking. The aim of this preliminary study was to determine the onset of physiological changes and the mucosal immune response to long distance road transportation. Three cecally cannulated geldings (mean ± SEM, 589 ± 10 kg; 17.7 ± 1.8 y) were tethered with their heads elevated and transported for 24 consecutive hours. Nasopharyngeal flush (NPF), whole blood, cecal fluid, saliva and fecal samples were obtained before (n ¼ 3 baseline samples), during (at 6-h intervals), immediately after (0 h post), and up to 120 h after transportation. Leukocyte (WBC) populations in whole blood and NPF were quantified by an automated cell counter and IgA concentrations were determined by ELISA in blood, NPF, cecal fluid and feces. Dry matter (DM) and pH in feces and cecal fluid were also measured. Data were log-transformed and compared using mixed model ANOVA. Transportation resulted in body weight loss of 35 ± 2 kg (P ¼ 0.0001) despite access to hay and water while in transit, and was not regained by 120 h post transport (P ¼ 0.009). Systemic neutrophils (as % of WBC) were
51
elevated from h 6 of transit through 24 h after transport (P < 0.05) and had returned to baseline by 72 h post transport. A decline in the number (P < 0.05) and percentage (P < 0.05) of systemic lymphocytes occurred from h 6 of transit to 0 h post and from h 18 of transit to 24 h post transport, respectively. Interestingly, systemic lymphocytes continued to increase in number and were greater than baseline at 120 h post transport (P ¼ 0.02). Leukocytes in NPF were elevated from 0 to 24 h post transport (P < 0.05) but had returned to baseline by 72 h post. Salivary IgA was greater at h 18 of transit (P ¼ 0.007), returned to baseline at 0 h post, but was elevated again at 24 h post transport (P ¼ 0.07). NPF IgA was elevated from 0 to 24 h post transport (P < 0.05). Both salivary and NPF IgA had recovered to pre-transit values 72 h after arrival. Fecal IgA was variable and lacked a clear pattern in response to transport. Fecal DM (14e24%) and pH (5.8e7.6) and cecal DM (2e11%) and pH (7.0e8.2) were not consistently affected by transport. Systemic immunological changes occurred within 6 h of the onset of transportation while mucosal IgA responses were delayed. Together these data indicate that even short bouts of transport can cause immunological changes. The consequences of these cellular changes may be a predisposing factor for respiratory disease. Key Words: nasopharyngeal flush, cecal fluid, mucosal immunity
26 Evaluation of intradermal skin testing in five horses E.K. Moyer*, A.J. Tucker, G.M. Juli, J.E. Bowser, C.A. Jim, S.E. Cyprianna Mississippi State University, Mississippi State, MS, USA Allergen panels developed and refined for human allergy have been successfully adapted for intradermal skin testing (IDT) in dogs, which cohabitate with man. Inconsistent testing outcomes have lead to criticisms of IDT in horses. Environmental allergens relevant to horses differ from those of humans and dogs. Insect hypersensitivity is an IgE-mediated skin disease of horses, substantiating the presence IgE sensitizing skin antibodies. Challenges to IDT in horses may reflect bias toward human antigens in allergy panels, and absence of replicate antigen injections for valid assessments. Therefore, we performed IDT on 5 horses, 3 with equine pasture asthma, and 2 nondiseased horses, employing 5 grass and 7 mold antigens of relevance to horse environments in the southeastern US. We performed quadruplicate injections for each antigen. Wheal size (mm) and induration (0e4) were evaluated at 20 min and 6 h. Positive test was defined by wheal size exceeding saline control by 2 mm and induration at all replicates. Sensitivity to 3 grass and 3 mold antigens was identified by positive tests at 6 h. A positive test at 20 min was highly specific (100%) with strong diagnostic value (positive predictive value ¼ 100%, negative predictive value 75%) for a positive test at 6 h. Few reactions at 20 min made this criteria insensitive (10%). Reaction to a single antigen in the Helminthosporia group was unique to diseased horses. Key Words: allergy, intradermal skin testing, equine asthma
27 Cross-sectional analysis of salivary cortisol and strongyle-type egg shedding levels in horses D.L. Keating*, J.S. Lehman, S.V. Burk Otterbein University, Westerville, OH, USA
Abstracts / Journal of Equine Veterinary Science 52 (2017) 49e63
elicited a 2-fold increase in phosphorylation of Akt in all horses (P < 0.05). Short-term DEX treatment resulted in a significantly greater insulin response to the consumption of a high protein meal. However, despite the elevated insulin concentrations, there was no difference between treatment groups in the magnitude of postprandial Akt activation in the muscle. An exacerbated insulin response to a high protein meal might be a compensatory mechanism, maintaining Akt activation despite DEX induced decrease in tissue insulin sensitivity. Additional research is necessary to determine whether a similar response to protein feeding is seen in horses with naturally occurring insulin dysregulation. Key Words: dexamethasone, insulin, muscle
22 Plasma and muscle amino acid concentrations in insulin resistant compared to normal horses in the fed and fasted state E.L. Macon*1, P.M. Graham-Thiers 2, K.L. Bowen 2 1 Middle Tennessee State University, Murfreesboro, TN, USA; 2 Emory and Henry State College, Bristol, VA, USA The effects of insulin resistance on protein and amino acid metabolism have not been documented in horses, despite knowledge that insulin stimulates the incorporation of amino acids into proteins and decreases the rate of protein degradation in skeletal muscle. The objective of this research was to investigate protein metabolism in insulin resistant (IR) horses compared with Normal controls. Preceding the study, horses were screened for fasting plasma insulin concentrations with insulin concentrations of 10.1 ± 3.5 mU/L ¼ Normal, and 41.2 ± 15.9 mU/L ¼ IR, and then underwent an oral sugar challenge (OST). Blood samples were collected before and at 60, 75, 90, 120, 180 min after administration of Karo Light Syrup (0.15 mL/ kg of BW) for the determination of plasma insulin and glucose. Based on the OST, 8 horses (16 + 3 yrs), 4 IR and 4 Normal, were studied while receiving Purina Strategy and a mixture of Timothy/Bermudagrass hay fed at 2% BW, a diet that met or exceeded NRC recommendations. After a week of dietary adaption, the morning meal (half the daily ration) was fed on d 7. Blood samples were taken at 0, 1, 3, 4, and 6 h post-prandial for determination of plasma amino acids. On d 8, muscle biopsies were taken and immediately frozen in liquid nitrogen for analysis of free amino acids. Glucose was analyzed using an enzymatic assay, and insulin by radioimmunoassay. Plasma free amino acids and semitendinosus muscle free amino acids were determined using reverse-phase HPLC of phenylisothiocyanate derivatives. Data were analyzed using a mixed model with repeated measures analysis of SAS, with time and group as main effects. The OST data confirmed higher insulin (P ¼ 0.020) and a trend for higher glucose (P ¼ 0.055) in IR vs Normal horses. There were no differences between IR and Normal for any plasma free amino acids (P > 0.15) or semitendinosus muscle free amino acids (P > 0.17). Contradictory to this study, hyperinsulinemic clamp procedures in healthy horses and pigs lowered plasma amino acid concentrations, with similar results reported in healthy and diabetic humans. Lack of variation in amino acid concentrations between IR and Normal horses suggests that insulin resistance does not affect amino acid absorption into the plasma pool or incorporation into the muscle in horses. Acknowledgments: This study was conducted at Emory and Henry College with the support of a Virginia Horse Industry Board grant.
Key Words: insulin resistance, amino acids
23 Comparison of horse body fat composition estimated by D2O dilution, rump fat thickness, and tissue dissection E.N. Ferjak*1, C. Argo 2, C.A. Cavinder 1, D.D. Burnett 1, T.T.N. Dinh 1 1 Mississippi State University, Starkville, MS, USA; 2 University of Liverpool, Liverpool, United Kingdom Research indicates that body condition score (BCS) of horses is positively correlated with reproductive efficiency and indicative of metabolic and lameness issues. However, body fat (BF, %) composition in horses is poorly defined and inaccurately predicted due to procedures that are either subjective or dependent upon one anatomical location to create the whole body prediction. Recently, deuterium oxide (D2O) dilution has been validated as an accurate estimation of BF in ponies. Nonetheless, further studies are warranted to confirm its efficacy in stock-type horses because D2O-prediction in swine was suggested to be only accurate in animals that share physiological resemblances. Therefore, the objective of the current study was to compare 2 methods of predicting BF with whole carcass fat analysis in horses. Twentyone mature, stock-type horses of BCS 2 (n ¼ 1; 415 kg), 3 (n ¼ 1; 376 kg), 4 (n ¼ 5; 469 ± 16 kg), 5 (n ¼ 9; 455 ± 11 kg), and 6 (n ¼ 5; 493 ± 12 kg) were selected based on 3 primary criteria: geriatric, crippled, and/or unsafe. Approximately 20 h before slaughter, horses were weighed and measured via ultrasound for rump fat (RF) thickness. Blood samples were collected immediately before and 4 h after D2O infusion (0.12 g/kg BW). Deuterium oxide concentration of plasma was determined by gas isotope ratio mass spectrometry following filtration and zinc reduction. Horses were housed in a dry lot overnight before being individually sedated (1.1 mg xylazine/kg BW) and anesthetized (2.2 mg ketamine/kg BW); and KCl solution was administered to cease cardiac functions before exsanguination (Mississippi State University IACUC protocol #15093). After euthanasia, horse carcasses were processed and dissected and tissues were collected for nearinfrared spectroscopic (NIR) analysis. Body fat by D2O dilution was correlated with BF by NIR analysis on various weight bases (r ¼ 0.72 to 0.74; P < 0.001), whereas a weaker correlation (r ¼ 0.45 to 0.53; P 0.039) was observed for BF by RF thickness. Paired ttest indicated that BF predicted by D2O dilution was similar to NIR BF on a hot carcass weight basis (P ¼ 0.060); however, it was 3.58 ± 0.68% less than BF by RF thickness. The current study provided evidence that D2O dilution was a more accurate BF prediction method than RF thickness for stock-type horses. Key Words: body fat, deuterium oxide, rump fat thickness
24 Relationships between total body water, ultrasonic measures of fat depots and morphometric measurements in horses A.L. Fowler*1, M.B. Pyles 1, V.T. Bill 1, S.H. Hayes 1, A. Crum 1, J. Parsons 1, L. Walling 1, A. Moffett-Krotky 2, P.A. Harris 3, L.M. Lawrence 1 1 University of Kentucky, Lexington, KY, USA; 2 Mars Horsecare US Inc., Dalton, OH, USA; 3 Waltham Centre for Pet Nutrition, Melton Mowbray, Leicestershire, United Kingdom Body condition score (BCS) is the most commonly used method to monitor changes in equine body composition, however other
Abstracts / Journal of Equine Veterinary Science 52 (2017) 49e63
measures such as ultrasonically determined subcutaneous fat depth and morphometric measurements have also been utilized for body composition assessment. In addition, total body water (TBW), as measured with a deuterium oxide (D2O) dilution technique, has been validated as a method to determine total body fat in ponies with BCS between 3 and 7. The objective of this study was to examine relationships between BCS, total body water, subcutaneous fat depth, and morphometric measurements of horses. Fifteen mature horses (14 Thoroughbreds and 1 Thoroughbred-cross) with BCS between 4 and 6 were used. Two sets of measurements were taken 3 to 4 wk apart on each horse. Morphometric measurements included wither height and circumferences of the neck, heart girth and belly girth. Ultrasound was used to measure subcutaneous fat depths at the mid-neck, shoulder, ribs, rump, and tail head. Total body water was measured using the D2O dilution technique. Briefly, horses were weighed and 0.12 g D2O/kg was quantitatively administered via IV catheter after an initial blood sample was obtained. A second blood sample was obtained at 4 h post-administration and TBW was calculated from the change in D2O concentration. Regression was used to examine relationships among measurements. Total body water averaged 69 ± 0.4% (mean ± SE) of body weight and ranged from 65 to 75%. Total body water and body weight were related (P < 0.05, R2 ¼ 0.81), with an increase in body weight (kg) correlating to an increase in TBW (kg). However, TBW increased as BCS decreased (P < 0.05, R2 ¼ 0.45), indicating that TBW is related to palpable fatness. In horses with BCS 5, TBW% decreased as subcutaneous tail head fat depth increased (P < 0.05, R2 ¼ 0.55) and BCS increased as subcutaneous tail head fat depth increased (P < 0.05, R2 ¼ 0.30). Body condition score of these horses was related to body weight, belly girth:height, heart girth:height, heart girth:body weight, and belly girth:body weight (P < 0.05). These findings suggest that using TBW, morphometric measures or subcutaneous fat depth measures may augment the determination of equine body fatness typically assessed using BCS. Key Words: body condition, deuterium, ultrasound
25 Immunological changes in horses occur early during road transportation J.M. Bobel*, T.L. Hansen, J.W. Callaham, J.R. Abbott, L.K. Warren University of Florida, Gainesville, FL, USA Alterations in physiological and immune status and heightened risk for respiratory disease in response to transportation are well documented in horses. However, information on mucosal immune responses and how quickly immunological changes occur is lacking. The aim of this preliminary study was to determine the onset of physiological changes and the mucosal immune response to long distance road transportation. Three cecally cannulated geldings (mean ± SEM, 589 ± 10 kg; 17.7 ± 1.8 y) were tethered with their heads elevated and transported for 24 consecutive hours. Nasopharyngeal flush (NPF), whole blood, cecal fluid, saliva and fecal samples were obtained before (n ¼ 3 baseline samples), during (at 6-h intervals), immediately after (0 h post), and up to 120 h after transportation. Leukocyte (WBC) populations in whole blood and NPF were quantified by an automated cell counter and IgA concentrations were determined by ELISA in blood, NPF, cecal fluid and feces. Dry matter (DM) and pH in feces and cecal fluid were also measured. Data were log-transformed and compared using mixed model ANOVA. Transportation resulted in body weight loss of 35 ± 2 kg (P ¼ 0.0001) despite access to hay and water while in transit, and was not regained by 120 h post transport (P ¼ 0.009). Systemic neutrophils (as % of WBC) were
51
elevated from h 6 of transit through 24 h after transport (P < 0.05) and had returned to baseline by 72 h post transport. A decline in the number (P < 0.05) and percentage (P < 0.05) of systemic lymphocytes occurred from h 6 of transit to 0 h post and from h 18 of transit to 24 h post transport, respectively. Interestingly, systemic lymphocytes continued to increase in number and were greater than baseline at 120 h post transport (P ¼ 0.02). Leukocytes in NPF were elevated from 0 to 24 h post transport (P < 0.05) but had returned to baseline by 72 h post. Salivary IgA was greater at h 18 of transit (P ¼ 0.007), returned to baseline at 0 h post, but was elevated again at 24 h post transport (P ¼ 0.07). NPF IgA was elevated from 0 to 24 h post transport (P < 0.05). Both salivary and NPF IgA had recovered to pre-transit values 72 h after arrival. Fecal IgA was variable and lacked a clear pattern in response to transport. Fecal DM (14e24%) and pH (5.8e7.6) and cecal DM (2e11%) and pH (7.0e8.2) were not consistently affected by transport. Systemic immunological changes occurred within 6 h of the onset of transportation while mucosal IgA responses were delayed. Together these data indicate that even short bouts of transport can cause immunological changes. The consequences of these cellular changes may be a predisposing factor for respiratory disease. Key Words: nasopharyngeal flush, cecal fluid, mucosal immunity
26 Evaluation of intradermal skin testing in five horses E.K. Moyer*, A.J. Tucker, G.M. Juli, J.E. Bowser, C.A. Jim, S.E. Cyprianna Mississippi State University, Mississippi State, MS, USA Allergen panels developed and refined for human allergy have been successfully adapted for intradermal skin testing (IDT) in dogs, which cohabitate with man. Inconsistent testing outcomes have lead to criticisms of IDT in horses. Environmental allergens relevant to horses differ from those of humans and dogs. Insect hypersensitivity is an IgE-mediated skin disease of horses, substantiating the presence IgE sensitizing skin antibodies. Challenges to IDT in horses may reflect bias toward human antigens in allergy panels, and absence of replicate antigen injections for valid assessments. Therefore, we performed IDT on 5 horses, 3 with equine pasture asthma, and 2 nondiseased horses, employing 5 grass and 7 mold antigens of relevance to horse environments in the southeastern US. We performed quadruplicate injections for each antigen. Wheal size (mm) and induration (0e4) were evaluated at 20 min and 6 h. Positive test was defined by wheal size exceeding saline control by 2 mm and induration at all replicates. Sensitivity to 3 grass and 3 mold antigens was identified by positive tests at 6 h. A positive test at 20 min was highly specific (100%) with strong diagnostic value (positive predictive value ¼ 100%, negative predictive value 75%) for a positive test at 6 h. Few reactions at 20 min made this criteria insensitive (10%). Reaction to a single antigen in the Helminthosporia group was unique to diseased horses. Key Words: allergy, intradermal skin testing, equine asthma
27 Cross-sectional analysis of salivary cortisol and strongyle-type egg shedding levels in horses D.L. Keating*, J.S. Lehman, S.V. Burk Otterbein University, Westerville, OH, USA