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  • Author or Editor: Eleanor M. Green x
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SUMMARY

Loline and ergot alkaloids found in endophyte-infected (Acremonium coenophialum) tall fescue (eitf) cause vasoconstriction of equine vessels in vitro. An aggregate risk study was used to evaluate the association between horses exposed to eitf and development of laminitis. Veterinary teaching hospitals participating in the Veterinary Medical Data Base were grouped by whether equine accessions were likely to have been at high, moderate, or low risk for exposure to eitf. From 1980-1990, there were 185,781 accessions, of which 5,536 had diagnosis of laminitis. Proportion of equine accessions with laminitis reported by veterinary teaching hospitals for high, moderate, and low risks, were 3.41, 3.04, and 2.00 cases/100 accessions, respectively (P < 0.0001). Comparison of the proportion of accessions with laminitis in the high- and moderate-risk groups with that in the low-risk group revealed significant differences between risk groups over all months (P = 0.063) and differences from month to month within risk groups (P = 0.0001). If the difference among risk groups is attributed entirely to exposure to eitf, the population-attributable risk is 7 cases/1,000 admissions, or 15% of all admissions for laminitis at veterinary teaching hospitals in our data base. Preliminary data support an association between horses exposed to eitf and increased risk of laminitis; however, studies at the individual animal level are indicated to confirm this hypothesis.

Free access
in American Journal of Veterinary Research

Summary

Total protein (tp), albumin, and IgG concentrations were measured in csf from the atlanto-occipital (ao) and lumbosacral (ls) sites and in serum of 15 clinically normal neonatal foals ≤ 10 days old (mean, 7.0 days). The albumin quotient (aq; csf albumin/serum albumin × 100) and IgG index ([csf IgG/serum IgG] × [serum albumin/csf albumin]), indicators of blood-brain barrier permeability and intrathecal IgG production, respectively, were then calculated.

Mean ± sd values obtained from the foals of this study were: serum albumin, 2,900 ± 240 mg/dl; serum IgG, 1,325 ± 686 mg/dl; ao csf total protein (tp), 82.8 ± 19.2 mg/dl; ls csf tp, 83.6 ± 16.1 mg/dl; ao csf albumin, 52.0 ± 8.6 mg/dl; ls csf albumin, 53.8 ± 15.7 mg/dl; ao csf IgG, 10.2 ± 5.5 mg/dl; ls csf IgG, 9.9 ± 5.7 mg/dl; ao aq, 1.86 ± 0.29; ls aq, 1.85 ± 0.51, ao IgG index, 0.52 ± 0.28; and ls IgG index, 0.48 ± 0.27. Significant difference between values for the ao and ls sites was not found. A csf albumin concentration > 85.2 mg/dl or aq > 2.4, as determined by mean ± 2 sd, may indicate increased blood-brain barrier permeability. An IgG index value >1.0 may indicate intrathecal IgG production.

Values obtained for foals of this study should serve as baseline for comparison in the evaluation of blood-brain barrier permeability and intrathecal IgG production in neonatal foals with neurologic disease.

Free access
in American Journal of Veterinary Research

Objective—

To evaluate results of a combined dexa-methasone suppression/thyrotropin-releasing hormone (TRH) stimulation test in horses suspected clinically to have a pars intermedia pituitary adenoma (PIPA).

Design—

Case-control study.

Animals—

7 healthy adult horses and 5 horses suspected to have a PIPA.

Procedure—

A baseline blood sample was collected, and dexamethasone (40 μg/kg [18 μg/lb] of body weight, IV) was administered; a second blood sample was collected 3 hours later, and TRH (1.1 mg, IV) was administered; serial blood samples were collected 15, 30, 45, 60, and 90 minutes and 21 hours after TRH administration (24 hours after dexamethasone injection). Cortisol concentration was determined for all blood samples.

Results—

Baseline Cortisol concentration was significantly lower in horses suspected to have a PIPA than in healthy horses. Cortisol concentration was suppressed by dexamethasone in both groups; however, after TRH administration, Cortisol concentration returned to baseline values in horses suspected to have a PIPA, but not in healthy horses. Concentration was still less than the baseline value 24 hours after dexamethasone administration in healthy horses.

Clinical Implications—

The combined dexamethasone suppression/TRH stimulation test may be a useful diagnostic test in horses suspected to have a PIPA. For clinical application, collection of a blood sample 30 minutes after TRH administration is recommended. (J Am Vet Med Assoc 1997;211:79–81)

Free access
in Journal of the American Veterinary Medical Association

Summary

Serum interleukin-6 (il-6) concentration was measured in 11 colostrum-fed (cf) and 8 colostrum-deprived (cd) 2- to 3-day-old foals after foals were infused with lipopolysaccharide (lps; Escherichia coli O55:B5 endotoxin, 0.5 µ.g/kg of body weight in sterile saline [0.9% NaCl] solution). Four cf and 2 cd foals were given saline solution alone. Serum il-6 concentration was estimated by use of an in vitro proliferative bioassay, using the IL-6 dependent B.13.29 clone 9 cells. Interleukin-6 concentration increased in all lps-infused foals, and geometric mean serum il- 6 concentration was significantly higher in cf than cd foals 30 and 90 minutes after infusion. Both lps- infused groups had multiple spikes of mean il-6 concentration that peaked at 120 minutes in cf foals and 150 minutes in cd foals. Results indicated that il-6 is produced in neonatal foals in response to lps infusion. Furthermore, colostrum deprivation resulted in longer times to peak mean serum il-6 concentration and tended to reduce serum il-6 concentration in neonatal foals.

Free access
in American Journal of Veterinary Research

Summary

We examined the effect of infusion of lipopolysaccharide (lps) on serum tumor necrosis factor alpha (tnfα) concentration and clinical attitude in 2- to 3-day-old colostrum-fed (cf) and colostrum-deprived (cd) foals. Eleven cf and 8 cd neonatal foals were given a bolus IV infusion of Escherichia coli O55:B5 lipopolysaccharide (0.5 µg kg of body weight) in sterile saline (0.9% NaCl) solution. Four cf and 2 cd foals were given saline solution alone. Serum IgG concentration and serum anti-lps IgG(T) antibody titer were determined for each foal prior to infusion. A depression index was used to score clinical abnormalities. Serum tnfα concentration was estimated by use of an in vitro cytotoxicity bioassay that used WEHI 164 clone 13 cells as targets. The cytotoxic serum factor was identified as tnfα by immunoprecipitation with caprine antisera raised against the 15 NH2- terminal amino acids of human tnfα. Tumor necrosis factor alpha was not detected in any preiniusion serum samples nor in any samples from foals given saline solution alone. Serum tnfα concentration increased in all lps-infused foals and peaked between 60 and 90 minutes after infusion. Serum tnfα concentrations, expressed as mean percentage of peak serum tnfα concentration, persisted longer in cd foals given lps than in cf foals given lps. All lps-infused foals displayed clinical signs of endotoxemia, but mean depression index scores of the cf and cd foals given lps were not significantly different at any time. Serum tnfα concentrations were correlated with depression index scores in both lps-infused groups. Mean rectal temperature increased by 1 hour and remained high for 4 hours after infusion in cf foals given lps . Mean rectal temperature in cd foals given lps was significantly less than that for cf foals given lps 1 and 2 hours after infusion and was higher than mean rectal temperature prior to infusion 3 and 4 hours after infusion. Neither preinfusion total serum IgG concentration nor serum anti-lps IgG(T) antibody titer correlated with peak serum tnfα concentration in the 19 lps-infused foals.

Free access
in American Journal of Veterinary Research

Summary

Body weight of 48 horses competing in a 3-day event was measured the day before the event (baseline), following the dressage phase of the event (day 1), after the endurance phases of the event (day 2), and 18 to 24 hours after the endurance phases (day 3). Plasma sodium and potassium concentrations were measured the evening before, immediately after, and 10 minutes after the endurance phases. Total body water, water loss, and net exchangeable cation loss were then calculated.

Body weight and total body water were significantly decreased, compared with baseline values, at all times during the event, and significant water loss was detected. The largest changes were recorded after the endurance phases of the event. Water deficits were still detected 18 to 24 hours after the endurance phases of the event.

Mean plasma sodium concentration was significantly increased immediately after the endurance phases of the event, compared with concentration measured the evening before, and remained increased after the 10-minute recovery period, presumably because of dehydration. Mean plasma potassium concentration was significantly increased immediately after the endurance phases of the event, compared with concentration measured the evening before, but was not increased after the 10-minute recovery period.

Free access
in Journal of the American Veterinary Medical Association