An improved radioimmunoassay for measurement of pepsinogen in porcine blood samples

The study was conducted to develop a sensitive and specific radioimmunoassay (RIA) for the measurement of pepsinogen in porcine serum, and to use this test for the determination of pepsinogen concentrations in serum samples from fetuses and pigs of different ages. Compared to a previously described RIA, major improvements were made concerning the use of specific polyclonal antibodies and the use of an appropriate buffer. The assay was able to detect pepsinogen concentrations of >/=0.2 ng/mL. The recovery of pepsinogen was close to 95%. The intra-assay coefficients of variations ranged between 3.9 and 7.5% whereas the interassay ranged between 8.8 and 11.9%. These percentages correspond to a satisfactory accuracy and reproducibility of the assay. No cross-reactions were observed with the main commercially available products of the aspartic proteases family except porcine pepsin cross-reacted over 62.5 microg/mL. Pepsinogen concentrations increased steadily with increasing age of the fetuses and the pigs (P<0.05). Pepsinogen concentrations (+/-SE) in fetuses of 90-100 (n=24) and 100-110 days of pregnancy (n=36) were 0.5+/-0.1 and 5.3+/-1.3 ng/mL, respectively. In pigs of 21, 98, and 213 days of age, the pepsinogen concentrations were 290.6+/-10.8, 343.1+/-17.9 and 383.5+/-15.3 ng/mL, respectively. The results demonstrate that RIA is accurate and can be used easily to assess pepsinogen concentrations in pig sera. The test may constitute a valuable tool in epidemiological surveys and in studies related to gastric diseases in pigs.     

Correlation between a proteolytic method and a radioimmunoassay for porcine serum pepsinogen concentrations

The measurement of serum pepsinogen concentrations by enzymatic method and immunoassay provides diagnostic values and should be helpful in the detection of gastric diseases related to a rise of blood pepsinogen. In the present study, the correlation between a conventional enzymatic method and a recently developed radioimmunoassay (RIA) for serum pepsinogen A was investigated. A total of 123 sera samples of porcine foetuses (n = 28), adult healthy pigs (n = 56), pigs with parakeratosis (n = 25) and pigs with ulceration of the pars oesophagea (n = 14) were tested. Overall, there was a slight correlation between the two methods (r = 0.60). In relation to individual animal groups, the correlations (r) were 0.39 (P>0.05), 0.74 (P<0.001), 0.19 (P>0.05) and 0.34 (P>0.05) in foetuses, healthy pigs, pigs with parakeratosis and pigs with ulcers, respectively. In both methods, pepsinogen concentrations (means+/-SE) were significantly higher (P<0.05) in pigs with parakeratosis (1778 +/- 86.00 mUTyr/L; 690 +/- 53.00 ng/mL) and in pigs with ulcers (2026 +/- 153.00 mUTyr/L; 1747 +/- 94.00 ng/mL) when compared to healthy pigs (935 +/- 58.00 mUTyr/L; 275 +/- 35.00 ng/mL). The proteolytic method gave a significant increased activity (P<0.05) in foetuses (1150 +/- 82.00 mUTyr/L) vs. (935 +/- 58.00 mUTyr/L) in healthy adult pigs, indicating an additional proteolytic activity in the sera of foetuses or neonates.     

Some pharmacokinetic parameters of the trypanocidal drug homidium bromide in Friesian and Boran steers using an enzyme-linked immunosorbent assay (ELISA)

Pharmacokinetic studies on the trypanocidal drug homidium bromide using a competitive enzyme immunoassay (detection limit 0.1 ng/mL) are reported for non-infected Friesian and Boran steers following treatment with homidium bromide at a dose of 1.0 mg/kg b.w. Following intravenous (i.v.) treatment of Friesian steers (n = 5), the mean serum drug concentrations were 31.9 +/- 2.1 and 3.9 +/- 0.4 ng/mL at 1 and 24 h, respectively. The decline in serum drug concentration was tri-exponential with half-lives of 0.064 +/- 0.037 h for t1/2 alpha, 7.17 +/- 1.87 h for t1/2 beta and 106.3 +/- 6.6 h for t1/2 gamma for distribution and elimination phases 1 and 2, respectively. Drug was detectable in serum for 17 days following treatment. The mean residence time (MRT) was 63.4 +/- 7.5 h. Following intramuscular (i.m.) treatment of Friesian steers (n = 5), the drug concentration at 1 h after treatment was 72.5 +/- 2.2 ng/mL. This declined to 9.8 +/- 1.8 ng/mL at 24 h. Low concentrations of between 0.1 and 0.3 ng/mL remained in circulation for up to 90 days post-treatment. Following intramuscular treatment of Boran steers (n = 5), the mean serum drug concentration at 1 h after treatment was 112.1 +/- 40.3 ng/mL. By 24 h after treatment, the concentration had fallen to 13.0 +/- 3.3 ng/mL. Thereafter, the serum drug concentration-versus-time profile and the pharmacokinetic parameters obtained following non-compartmental analysis were similar to those obtained following intramuscular treatment of Friesian steers.     

Pharmacokinetics of gallium maltolate after intragastric administration in neonatal foals

OBJECTIVE: To determine the pharmacokinetics of gallium maltolate (GaM) after intragastric administration in healthy foals. ANIMALS: 6 healthy neonatal foals. PROCEDURES: Each foal received GaM (20 mg/kg) by intragastric administration. Blood samples were obtained before (time 0) and at 0.25, 0.5, 1, 2, 4, 8, 12, 24, 36, and 48 hours after GaM administration for determination of serum gallium concentrations by use of inductively coupled plasma mass spectroscopy. RESULTS: Mean +/- SD pharmacokinetic variables were as follows: peak serum gallium concentration, 1,079 +/- 311 ng/mL; time to peak serum concentration, 4.3 +/- 2.0 hours; area under the serum concentration versus time curve, 40,215 +/- 8,420 ng/mL/h; mean residence time, 39.5 +/- 17.2 hours; area under the moment curve, 1,636,554 +/- 931,458 ng([h](2)/mL); and terminal half-life, 26.6 +/- 11.6 hours. The mean serum concentration of gallium at 12 hours was 756 +/- 195 ng/mL. CONCLUSIONS AND CLINICAL RELEVANCE: Gallium maltolate administered via nasogastric tube at a dose of 20 mg/kg to neonatal foals resulted in gallium serum concentrations considered sufficient to suppress growth or kill Rhodococcus equi in macrophages and other infected tissues.     

Serum Levels of Type III Procollagen Peptide in Equidae before and after Intestinal Ischemia

Serum levels of type III procollagen peptide (P-III-P) were measured by radioimmunoassay in clinically normal adult ponies (n = 15) and horses (n = 10). The mean serum levels of P-III-P from the ponies, 10.4 +/- 2.9 (SD) ng/mL, and the horses, 12.2 +/- 2.6 (SD) ng/mL, were not significantly different. Segments of jejunum were made ischemic to induce fibrous peritoneal adhesions in two ponies, and serum P-III-P levels were measured on days 4, 5, 7, 14, and 21. An exploratory celiotomy on day 21 revealed that the ischemic injury had induced fibrosis of the mesentery and bowel, but no adhesions had formed. The fibrotic mesentery contained type III collagen. The highest mean serum level of P-III-P, 23.0 +/- 3.5 (SD) ng/mL on day 7, was more than 4 SD above the mean from the normal ponies. There was a significant difference in the serum P-III-P levels in the ponies on days 0 (7.1 +/- 1.6 ng/mL) and 7 (23.0 +/- 3.5 ng/mL). Serum levels of P-III-P may be useful to study fibrosis associated with intestinal ischemia.     

Serum leptin and ghrelin levels in response to methylprednisolone injection in healthy dogs

The aim of this study was to investigate the effects of methylprednisolone treatment on serum leptin and ghrelin levels in healthy dogs (n=40). After 14 h of fasting, the dogs were injected intramuscularly with saline (control group) or methylprednisolone (1, 5 or 10mg/kg). Blood samples were collected prior to (baseline) and 2, 3, 4, 8, 12 and 24h subsequent to the treatments. Serum leptin and ghrelin were measured by radioimmunoassay. The mean baseline serum leptin and ghrelin were 2.5+/-0.1 ng/mL (n=40) and 35.0+/-2.1 pg/mL (n=40), respectively. In the control dogs, serum leptin, but not ghrelin levels showed a significant fluctuation during the 24h observation period. Serum leptin increased significantly (p<0.05-0.01) between 2 and 12h after 1mg/kg of methylprednisolone. Serum leptin levels showed biphasic response to 5mg/kg of methylprednisolone: its level decreased to 1.9+/-0.1 ng/mL (p<0.01) at 2h and increased at 12h (2.6+/-0.1 ng/mL) (p<0.01). In response to 10mg/kg of methylprednisolone, serum leptin levels decreased significantly (p<0.01) for 24h. Serum ghrelin levels decreased to 19+/-5 pg/mL at 2-3h (p<0.01) or increased to 87+/-18 pg/mL at 3-8h (p<0.05-0.01) after 1mg/kg of methylprednisolone or 10mg/kg of methylprednisolone, respectively. Serum ghrelin levels did not change at any time point during 24h observation period after 5mg/kg of methylprednisolone. There was a significant (p<0.001) inverse correlation (r=-0.635) between serum leptin and ghrelin levels. In conclusion, we found that methylprednisolone increases or decreases serum leptin and ghrelin levels depending upon its dose and there is a negative correlation between serum leptin and ghrelin levels after methylprednisolone administration.     

Effect of light intensity on circadian profiles of melatonin, prolactin, ACTH, and cortisol in pigs.

Eleven crossbred barrows were housed in environmentally controlled rooms with an 8-h photoperiod. Pigs in one room received control illumination of 113 1x (CON; n = 6), and pigs in the other room received intense illumination of 1,783 1x (INT; n = 5) fluorescent light. Pigs were given at least 20 d of exposure to the environment before blood samples were taken every 3 h for 48 h. Data were analyzed by split-plot analysis of variance. Except for prolactin, no treatment x time interactions were noted for the hormone profiles evaluated (P greater than .10). Pigs in INT had greater (P less than .05) concentrations of prolactin in serum than pigs in CON at every sampling time. Concentrations of ACTH and cortisol in plasma were similar for INT (33.9 +/- 3.2 pg/mL of ACTH and 24.4 +/- 3.4 ng/mL of cortisol, respectively) and CON (34.9 +/- 3.0 pg/mL of ACTH and 31.3 +/- 3.1 ng/mL of cortisol, respectively). Within the INT treatment, serum melatonin concentrations were more than doubled (P less than .05) during darkness (66.8 +/- 9.3 pg/mL) compared with during light (30.4 +/- 9.3 pg/mL); however, within the CON treatment, concentrations during light and darkness did not differ (38.4 +/- 9.3 pg/mL and 42.9 +/- 9.3 pg/mL, respectively). Results indicate that light of greater intensity is required to entrain circadian rhythms of melatonin in serum of pigs. Furthermore, pigs may respond to bright light with greater secretion of prolactin, even under constant duration of photoperiod.     

Evaluation of serum cardiac troponin I concentration in Boxers with arrhythmogenic right ventricular cardiomyopathy

OBJECTIVE: To evaluate serum cardiac troponin I (cTnI) concentrations in Boxers with arrhythmogenic right ventricular cardiomyopathy (ARVC), unaffected (control) Boxers, and control non-Boxers. ANIMALS: 10 Boxers with a clinical diagnosis of ARVC defined by > or = 1,000 ventricular premature complexes (VPCs)/24 h on an ambulatory ECG, 10 control Boxers assessed as normal by the presence of < 5 VPCs/24h, and 10 control non-Boxers. PROCEDURES: Serum was extracted from a blood sample from each dog. Analysis of serum cTnI concentrations was performed. RESULTS: Mean +/- SD serum cTnI concentration was 0.142 +/- 0.05 ng/mL for Boxers with ARVC, 0.079 +/- 0.03 ng/mL for control Boxers, and 0.023 +/- 0.01 ng/mL for control non-Boxers. A significant difference in serum cTnI concentrations was observed among the 3 groups. In the combined Boxer population (ie, Boxers with ARVC and control Boxers), a significant correlation was found between serum cTnI concentration and number of VPCs/24 h (r = 0.78) and between serum cTnI concentration and grade of ventricular arrhythmia (r = 0.77). CONCLUSIONS AND CLINICAL RELEVANCE: Compared with clinically normal dogs, Boxers with ARVC had a significant increase in serum cTnI concentration. For Boxers, correlations were found between serum cTnI concentration and number of VPCs/24 h and between concentration and the grade of arrhythmia. Because of the overlap in serum cTnI concentrations in control Boxers and Boxers with ARVC, future studies should evaluate the correlation of serum cTnI concentration with severity of disease in terms of degree of myocardial fibrofatty changes.     

Effect of exercise, training, circadian rhythm, age, and sex on insulin-like growth factor-1 in the horse

Insulin-like growth factor-1 could be a useful marker in the horse for diagnostic, selection, or forensic purposes, provided its physiological regulation is well understood. The objective of this study was to investigate factors, such as acute exercise, fitness training, time of day, sex, and age, that may influence serum IGF-1 in normal, healthy horses. Throughout a 9-wk training program, 6 geldings maintained a mean (+/- SEM) IGF-1 concentration of 302 +/- 29 ng/mL. Moderate or high intensity exercise had no effect on IGF-1 concentrations, when pre- and postexercise values were compared. Over a 24-h period, there was some variation in IGF-1 concentrations but no clear diurnal rhythm. Concentrations of IGF-1 were measured in a large population of thoroughbred horses (1,880) on 3 continents. The population deviated slightly from a normal distribution (P < 0.001) because of large IGF-1 concentrations in 10 horses. The global mean IGF-1 concentration was 310 +/- 2.2 ng/mL, with a greater mean value (P < 0.001) in gonad-intact males (336 +/- 5.6 ng/mL) than in females (303 +/- 3.2 ng/mL) or geldings (302 +/- 3.2 ng/mL). However, the greatest IGF-1 concentrations observed for all stallions, mares, and geldings were 627, 676, and 709 ng/mL, respectively. In mares and geldings, IGF-1 concentrations showed a gradual decrease with advancing age (P < 0.001), but the effect was much less marked in stallions. This study confirms that IGF-1 concentrations are stable, compared with GH concentrations, in the horse and that a meaningful measure of IGF-1 status can be obtained from a daily serum sample.     

Survey of Gastric Lesions and Blood Pepsinogen Levels in Pigs in Burkina Faso

The purpose of the study was to investigate the prevalence of gastric lesions and to provide diagnostic values for serum pepsinogen in non-infected pigs and in pigs with gastric disease. In an abattoir survey, the pepsinogen concentrations were measured in the serum from 62 non-infected pigs, 33 pigs with gastric lesions and 17 pigs infected with Hyostrongylus rubidus, using a specific radioimmunoassay (RIA). The mean (±SE) pepsinogen concentrations in the serum of non-infected pigs, in pigs with gastric ulcers, and in pigs with a heavy H. rubidus infection were 630.8±39.2 ng/ml, 1084.5±166.2 ng/ml and 1095.2±102.3 ng/ml, respectively (p<0.05). Because of the higher concentrations of pepsinogen in the blood of pigs with gastric ulcers or parasitic infections, it is suggested that the measurement of serum pepsinogen by RIA may be an effective biochemical approach to the diagnosis of chronic gastric disorders in pigs.     

Endostatin concentrations in healthy dogs and dogs with selected neoplasms

Endostatin prevents angiogenesis and tumor growth by inhibiting endothelial cell proliferation and migration. The purpose of this study was to determine serum endostatin concentrations in 53 healthy dogs and in 38 dogs with confirmed malignant neoplasms. Endostatin concentration was determined with a competitive enzymatic immunoassay (EIA) with rabbit polyclonal antibody generated against a recombinant canine endostatin protein. Both the presence of cancer and increasing age were associated with increased serum concentration of endostatin. Endostatin concentration in healthy dogs was 87.7 +/- 3.5 ng/mL. Upper and lower limits of the reference range for serum endostatin concentration in healthy dogs were 60 and 113 ng/mL. Dogs with lymphoma (LSA) and hemangiosarcoma (HSA) had endostatin concentrations of 107 +/- 9.3 ng/mL. In conclusion, this study demonstrates that endostatin can be quantified in dogs and that endostatin concentrations are high in dogs with HSA and LSA.     

Ovarian cyclicity in thyroid-suppressed ewes treated with propylthiouracil immediately before onset of seasonal anestrus

Two experiments were conducted to determine if propylthiouracil (PTU)-induced thyroid suppression immediately before onset of anestrus would extend the breeding season in mature ewes. In Exp. 1, twice-weekly serum concentrations of progesterone indicated that all ewes were cyclic before initiation of treatment. Beginning on d 0 (January 17), ewes received 0 (n = 4), 20 (n = 5), or 40 (n = 5) mg of PTU x kg(-1) of body weight (BW) x (-1) for 35 d. Blood samples were collected regularly throughout the trial and serum thyroxine and progesterone were quantified. Ewe BW were similar (P > 0.90) among treatments before the experiment began (mean = 78.2 +/- 4.5 kg). Likewise, serum concentrations of thyroxine averaged 86.5 +/- 8.0 ng/mL on d 0. After 11 d of PTU treatment, serum thyroxine was 90.2,75.2, and 44.2 +/- 14.0 ng/mL in ewes receiving 0, 20, and 40 mg of PTU/kg BW, respectively (linear effect, P = 0.04). On d 20, thyroxine values in the three respective groups were 73.0, 51.1, and 16.1 +/- 12.9 ng/mL (linear effect, P < 0.01). Fourteen days after PTU treatment ended, serum thyroxine did not differ (P = 0.53) among the three respective groups (71.4,73.3, and 57.5 +/- 11.8 ng/mL). Ewes receiving PTU tended to weigh less on d 42 (84.2, 78.2, and 71.8 +/- 5.1 kg for ewes treated with 0, 20, and 40 mg PTU/kg, respectively; linear effect, P = 0.10). Day of onset of anestrus was designated as the day on which serum progesterone decreased and remained below 1 ng/mL. Ewes treated with 0, 20, or 40 mg of PTU/kg BW became anestrous on d 16,40, and 81 (+/- 12) of the experiment, respectively (linear effect, P < 0.01). At the time the 35-d treatment period ended, 25, 60, and 100% of ewes receiving 0, 20, or 40 mg of PTU/kg exhibited normal estrous cycles. In Exp. 2, ewes received 0, 20, or 40 mg of PTU/kg BW for 14 d. The dose was then decreased to 0, 10, and 20 mg of PTU/kg BW for the remaining 21 d. Serum thyroxine decreased to concentrations below 20 ng/mL by d 9 after initiation of PTU treatment. Ewe weights did not differ throughout the trial and no BW loss was observed. The average day that each group entered anestrus was similar to those in Exp 1. Large doses of PTU dramatically lower serum thyroxine and this effect appears to inhibit onset of anestrus in ewes.     

Bioavailability of a silybin-phosphatidylcholine complex in dogs

Liver dysfunction often is associated with an imbalance in the production and removal of free radicals derived from oxygen and nitrogen and has been managed clinically with antioxidant supplements, including silymarin extract derived from milk thistle. The potential for enhanced bioavailability of a phytosome complex containing phosphatidylcholine and silybin, the primary active flavonolignan in silymarin extract, was tested in dogs. A group of eight beagles (four males, four females) were dosed orally with a silybin-phosphatidylcholine complex (SPC) and a commercially available standardized silymarin extract containing equivalent levels of silybin. Dosing with the SPC resulted in Cmax, Tmax, and AUC0-24 h values (mean+/-SD) for total silybin of 1310+/-880 ng/mL, 2.87+/-2.23 h, and 11,200+/-6520 ng.h/mL, respectively; corresponding values for a standardized silymarin extract were 472+/-383 ng/mL, 4.75+/-2.82 h, and 3720+/-4970 ng.h/mL. A second, separate group of beagles were also dosed with the extract alone, yielding values of 449+/-402 ng/mL, 6.87+/-7.43 h, and 2520+/-2976 ng.h/mL. These data show that a phytosome complex of phosphatidylcholine and silybin markedly enhances bioavailability in dogs.     

Effects of supplemental lactoferrin on serum lactoferrin and IgG concentrations and neutrophil oxidative metabolism in Holstein calves

Lactoferrin (LF) is an iron-binding protein present in both colostrum and secondary granules of polymorphonuclear neutrophils (PMNs). We hypothesized that supplemental LF enhances neutrophil function in neonatal calves. Newborn calves were assigned to receive colostrum (C), colostrum + LF (CLF, 1 g/kg), or milk replacer + LF (MRLF, 1 g/kg). Serum (LF and IgG) and whole blood (neutrophil isolation) samples were obtained prior to treatment (day 0) and at 24 hours and 9 days of age. Serum IgG concentrations (mean +/- SD) in C, CLF, and MRLF calves at 24 hours were 1,911 +/- 994 mg/dL, 2,181 +/- 625 mg/dL, and 0 mg/ dL, respectively. Serum LF concentrations in C, CLF, and MRLF calves on day 0 were 324 +/- 334 ng/mL (range 0-863 ng/mL), 135 +/- 158 ng/mL (range 0-429 ng/mL), and 318 +/- 337 ng/mL (range 0-964 ng/mL), respectively. LF concentrations in C, CLF, and MRLF calves at 24 hours were significantly higher (P < .05), at 1,564 +/- 1,114 ng/mL (range 335-3,628 ng/mL, 2,237 +/- 936 ng/mL (range 31-3,287 ng/mL), and 3,189 +/- 926 ng/mL (range 1,736-4,120 ng/mL), respectively. Cytochrome c reduction in opsonized zymosan-treated or phorbol ester-treated cells was not significantly affected by supplemental LF provided at birth. Oral LF is absorbed in calves but does not alter PMN superoxide production and does not alter IgG absorption.     

Relationship between serum insulin-like growth factor-I and genotype during the postpartum interval in beef cows

The objective of this study was to determine the effect of genotype and week postpartum on serum concentrations of IGF-I, body condition score (BCS), BW, and ovarian function in beef cows. Cows from the following genotypes were utilized in two consecutive years: Angus (A x A; n = 9), Brahman (B x B; n = 10), Charolais (C x C; n = 12), Angus x Brahman (A x B; n = 22), Brahman x Charolais (B x C; n = 19) and Angus x Charolais (A x C; n = 24). Serum concentrations of IGF-I, BCS, and BW were determined between wk 2 and 9 postpartum. Rectal ultrasound was used to determine days postpartum to first medium (6 to 9 mm) and first large (> or = 10 mm) follicle. Averaged across genotype, BCS decreased (P < 0.05) from 5.0 +/- 0.1 on wk 3 to 4.8 +/- 0.1 on wk 6 postpartum, and BW decreased (P < 0.05) between wk 2 and 3 and again between wk 4 and 9 postpartum. Averaged over year and week postpartum, serum IGF-I concentrations were greatest (P < 0.05) in B x B cows (46 +/- 5 ng/mL) compared with all other genotypes; lowest in A x A (12 +/- 4 ng/mL), C x C (13 +/- 4 ng/mL), and A x C cows (18 +/- 3 ng/mL); and intermediate (P < 0.05) in A x B (28 +/- 3 ng/mL) and B x C (26 +/- 3 ng/mL) cows compared with all other genotypes. Serum IGF-I concentrations did not change (P > 0.10) with week postpartum in C x C, A x A, and A x C cows, but increased (P < 0.05) between wk 2 and 7 postpartum in B x C, A x B, and B x B cows. Average interval to first medium (16 +/- 2 d) and first large (35 +/- 2 d) follicle did not differ (P > 0.10) among genotypes. Serum IGF-I concentrations correlated with BCS (r = 0.53 to 0.72, P < 0.001) but not with days to first large follicle (r = -0.19 to -0.22, P > 0.10). Averaged across genotypes, cows that lost BCS postpartum had lower (P < 0.01) serum IGF-I concentrations. Cows that calved with adequate BCS (i.e., > or = 5) had greater (P < 0.01) serum IGF-I concentrations postpartum than cows that calved with inadequate BCS (i.e., < 5) but days to first large and medium follicle did not differ (P > 0.10). In conclusion, concentrations of IGF-I in serum differed among genotypes and were associated with BCS but not days to first large or medium follicle in postpartum beef cows.     

Effect of hypothyroidism on the blood lipid response to higher dietary fat intake in mares

Blood lipid and lipoprotein concentrations were measured and compared between euthyroid and thyroidectomized mares on low-fat or high-fat diets to test the hypothesis that hypothyroidism alters the blood lipid response to higher dietary fat intake. Four healthy adult mares and four adult mares that had been thyroidectomized 3 to 6 mo earlier were placed on low-fat or high-fat diets according to a replicated 2 x 2 Latin square design consisting of two 5-wk feeding periods separated by a 2-wk washout interval. Plasma lipid concentrations were measured at 0, 3, 4, and 5 wk, and plasma lipase activities were measured at the end of each 5-wk feeding period. Compared with euthyroid mares (0.46 ng/mL [range 0.34 to 0.68 ng/mL T3], and 21.5 ng/mL [range 18.1 to 25.1 ng/mL T4], respectively), median serum concentrations of T3 and T4 were lower (P = 0.029 and P = 0.021, respectively) in thyroid-ectomized mares (0.26 ng/mL [range 0.23 to 0.26 ng/ mL T3], and undetectable T4). Serum T4 concentrations were below the limits of detection in thyroidectomized horses. Alterations in body weight over 5 wk did not differ between groups. Mean plasma very low density lipoprotein (VLDL) and triglyceride (TG) concentrations were higher (P = 0.045 and 0.034, respectively) in hypothyroid mares (55.42 +/- 35.05 mg/dL and 52.83 +/- 34.46 mg/dL, respectively) compared with euthyroid mares (28.28 +/- 13.76 mg/dL and 23.53 +/- 9.84 mg/dL, respectively). Mean plasma total cholesterol (TC) concentrations increased from 88.73 +/- 25.49 mg/dL at baseline to 103.93 +/- 24.42 mg/dL after 5 wk on the low-fat diet, but increased by a greater magnitude (P = 0.006 diet +/- time interaction) in mares that were on the high-fat diet (81.05 +/- 17.24 mg/dL and 123.84 +/- 32.27 mg/ dL, respectively). Mean plasma TC concentrations were higher (P = 0.099) in hypothyroid mares (116.16 +/- 32.89 mg/dL) than in euthyroid mares (89.56 +/- 14.45 mg/ dL). Higher post-heparin plasma lipoprotein lipase and hepatic lipase activities (P = 0.012 andP = 0.017, respectively) were detected in mares that were on the high-fat diet (2.66 +/- 0.91 micromol FA x mL(-1) x h(-1) and 2.95 +/- 0.49 micromol FA x mL(-1) x h(-1), respectively) vs. a low-fat diet (1.75 +/- 0.55 micromol FA x mL(-1) x h(-1) and 2.27 +/- 0.59 micromol FA x mL(-1) x h(-1), respectively). We conclude that plasma VLDL and TG concentrations are elevated in hypothyroid mares, but the blood lipid response to higher dietary fat intake is not influenced by hypothyroidism.     

Nocturnal melatonin and prolactin plasma concentrations in sheep selected for fertility in autumn lambing'.

Ewes selected for fertility in autumn lambing were used to evaluate correlated responses in nocturnal hormone levels. Four jugular blood samples were obtained during nighttime in August from each of 113 selected and 69 control ewes. Melatonin levels were lower for selected ewes (143 +/- 14 pg/mL) than for control ewes (184 +/- 13 pg/mL), and melatonin levels decreased with increases in estimated breeding values (EBV) for fertility (-2.23 +/- 0.79 pg mL(-1) x %(-1)). Prolactin levels were higher for selected ewes (90 +/- 7 ng/mL) than for control ewes (52 +/- 7 ng/mL), but significant line x ewe age interaction was also observed, with smaller differences in prolactin levels in 2-yr-old and older ewes (74 +/- 7 vs. 56 +/- 9 ng/mL for select and control ewes, respectively; P < 0.20 before and P = 0.05 after logarithmic transformation). Prolactin levels increased with both fertility EBV (1.23 +/- 0.53 ng mL(-1) x %(-1)) and maternal birth weight EBV (9.0 +/- 4.0 ng x ml(-1) kg(-1)). Heritability estimates were 0.43 (P < 0.02) for melatonin levels and 0.11 (P > 0.25) for prolactin levels. Thus, we conclude that selection for fertility in autumn lambing has affected patterns of melatonin and prolactin secretion during the dark phase.     

Cardiac troponin I in pastured and race-training Thoroughbred horses

Cardiac troponin I (cTnI), a myocardial polypeptide, is a highly sensitive and specific biomarker of myocardial injury in people and dogs. The structure of cTnI is highly conserved across species, and equine myocardium has high reactivity with human immunoassays. The purpose of this study was to describe cTnI concentrations in normal pastured and race-training Thoroughbred horses. Ten horses on pasture and 10 horses in race training were studied. Horses were considered normal on the basis of physical examination, training performance, electrocardiography (ECG), and echocardiography. Serum cTnI concentrations were determined with a colorimetric immunoassay. The assay has an analytical sensitivity of 0.04 ng/mL. Serum cTnI concentrations in race-training horses were not significantly different from those of pastured horses. When groups were combined, mean cTnI concentration (+/- SD) was 0.047 +/- 0.085 ng/mL. and the median was 0 (range, 0-0.35 ng/mL). The 90th percentile for both groups combined was 0.11 ng/mL. This study establishes a preliminary reference range for serum cTnI in normal Thoroughbred horses.     

Subnormal concentrations of serum cobalamin (vitamin B12) in cats with gastrointestinal disease

The present study sought to determine the spectrum of diseases associated with subnormal concentrations of serum cobalamin in cats undergoing investigation of suspected gastrointestinal problems. The solid-phase boil radioassay (RA) for cobalamin employed in the present study was immunologically specific, precise, and accurate, with a sensitivity of 15 pg/mL. The RA yielded results that strongly correlated with those obtained by bioassay (Spearmann rho = .805; P < .0001), although the absolute values were lower for the RA. Forty-nine of 80 serum samples submitted during the period of January 1996-January 1998 had cobalamin concentrations below the reference range for healthy cats (range 900-2,800 pg/mL; mean +/- SD, 1,775 +/- 535 pg/mL; n = 33). Cats with subnormal cobalamin concentrations (mean +/- SD; 384 +/- 272 pg/mL, range 3-883 pg/mL) were middle-aged or older and were presented for weight loss. diarrhea, vomiting, anorexia, and thickened intestines. Definitive diagnoses in 22 cats included inflammatory bowel disease (IBD), intestinal lymphoma, cholangiohepatitis or cholangits, and pancreatic inflammation. Serum concentrations of cobalamin were particularly low in cats with intestinal lymphoma, three-fifths of whom also had subnormal serum concentrations of folate (< 9 ng/mL). The simultaneous presence of disease in the intestines, pancreas, or hepatobiliary system in many cats made it difficult to determine the cause of subnormal cobalamin concentrations. The circulating half-life of parenteral cyanocobalamin was shorter in 2 cats with IBD (5 days) than in 4 healthy cats (12.75 days). The presence of subnormal serum concentrations of cobalamin in 49 of 80 cats evaluated suggests that the measurement of serum cobalamin may be a useful indirect indicator of enteric or pancreatic disease in cats. The rapid depletion of circulating cobalamin in cats suggests that cats may be highly susceptible to cobalamin deficiency. However, the relationship of subnormal serum cobalamin concentrations to cobalamin deficiency and the effect of cobalamin deficiency on cats remain to be determined.