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Abstract

Objective—To estimate prevalence of and identify factors associated with anhidrosis in horses in Florida.

Design—Cross-sectional study and case-control study.

Animals—4,620 horses on 500 farms.

Procedures—A questionnaire was structured and mailed to farm owners or managers to obtain information related to diagnosis of anhidrosis in horses and exposure factors associated with this condition. The frequency of investigated farm- and animal-level factors was compared between farms and horses affected and not affected with anhidrosis, respectively.

Results—The prevalence of anhidrosis was 11% at the farm level and 2% at the animal level. The odds of anhidrosis were 2.13 and 4.40 times as high in farms located in central and southern Florida, respectively, compared with odds for farms in northern Florida. The odds of anhidrosis were 5.26 and 15.40 times as high in show and riding instruction operations, respectively, compared with odds for ranch operations. At the animal level, breed (Thoroughbreds and warmblood horses), foaling place (western or midwestern region of the United States), and family history of anhidrosis were significantly associated with anhidrosis.

Conclusions and Clinical Relevance—This study provides new information on the prevalence of and factors for anhidrosis in horses in Florida. Horses with a family history of anhidrosis should be examined by a veterinarian for diagnosis of this condition before they are exposed to exercise in a hot and humid climate.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Case Description—A 6-year-old Appaloosa mare was examined because of inappetance, difficulty eating, and swelling and mucopurulent discharge in the right eye.

Clinical Findings—Results of a CBC and serum bio-chemical analysis revealed no important findings. Ophthalmologic examination revealed scarring and ulcer-ation of the superficial layers of the cornea. Endoscopic examination of the upper portion of the respiratory tract and auditory tube diverticula (guttural pouches) revealed abnormal thickness of the right stylohyoid bone and a plaque suggestive of mycotic growth on the left internal carotid artery. Radiographic examination revealed right-sided otitis media. Temporohyoid osteoarthropathy in the right guttural pouch and mycosis in the left guttural pouch were diagnosed.

Treatment and Outcome—Ceratohyoidectomy of the right stylohyoid bone was performed, and the left internal carotid artery was occluded via placement of stainless steel spring embolization coils. The mare regained the ability to eat without difficulty and improved clinically for approximately 4 weeks. However, the mare returned to the medical center 53 days after surgery with left-sided Horner syndrome, atrophy of the right side of the tongue, and a 3-week history of dysphagia and weight loss. Endoscopic evaluation revealed progression of mycotic growth in the left guttural pouch. The mare was euthanatized.

Clinical Relevance—Although the mycotic lesion in the left guttural pouch was an incidental finding at the time of initial examination, the lesion progressed to cause dysphagia and Horner syndrome after occlusion of the left internal carotid artery, a treatment that is typically associated with resolution of guttural pouch mycosis. Arterial occlusion is not necessarily a reliable method of resolving guttural pouch mycosis.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective

To determine the efficacy of polymyxin B-dextran 70 (PBD) for treatment of endotoxemic horses.

Animals

15 horses during study 1 and 6 horses during study 2.

Procedures

3 groups were used in study 1. Horses in groups 1 and 2 were given 30 ng of lipopolysaccharide (LPS)/kg of body weight, IV, over 60 minutes. Horses in group 3 were given saline (0.9% NaCI) solution. Beginning 15 minutes before LPS infusion and continuing for 75 minutes, horses in groups 1 and 3 were given PBD, IV. Horses in group 2 were given dextran 70. Blood samples were obtained for hemograms and determination of cytokine, lactate, and prostanoid concentrations. In study 2, horses were given ketoprofen (2.2 mg/kg) or saline solution 15 minutes before infusion of PBD. Fourteen days later, treatments were reversed, using a crossover design. Blood samples were obtained for measurement of thromboxane B2 (TXB2) concentration.

Results

For study 1, prior treatment with PBD completely blocked endotoxin-induced changes for heart and respiratory rates, rectal temperature, WBC count, and plasma tumor necrosis factor, interleukin 6, TXB2, and prostaglandin F1 concentrations. There was transient tachypnea, sweating, and increased plasma TXB2 concentration in horses given PBD (with or without LPS). Prior treatment with ketoprofen eliminated all PBD-induced signs and prevented the increase in plasma TXB2 concentration.

Conclusions

Signs of endotoxemia were prevented in horses by treatment with PBD, although its use was associated with mild adverse effects.

Clinical Relevance

When used in combination with a cyclooxygenase-inhibiting drug, PBD has potential for treatment of horses with endotoxemia. (Am J Vet Res 1999;60:68–75)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To evaluate the humoral response of horses to vaccination, using a murine monoclonal anti-idiotypic antibody (A4) that shares an epitope with lipid A.

Design

Serum concentrations of antilipid A antibody and 1C9 (epitope on murine monoclonal antihpid A antibody) were measured serially during the period of vaccination with A4.

Animals

6 clinically normal adult ponies.

Procedure

Ponies were inoculated IM 3 times at monthly intervals with A4. Two weeks after each inoculation, serum was obtained and was assayed by ELISA for antilipid A and 1C9 concentrations. Additional vaccinations were given to 2 of the ponies after a several-month rest period.

Results

There was significant increase in 1C9 concentration (P<0.0001) during the period of vaccination and a trend toward increased antilipid A concentration. The latter effect was not significant (P= 0.055). Additional vaccinations produced further increase in serum 1C9 concentration; antihpid A concentration increased in one of these ponies but not the other. Maximal antihpid A concentration recorded in these ponies was approximately 6 times preimmune concentration and was comparable to that found in a commercial antiendotoxin antiserum. 1C9 also was detected in the commercial antiserum.

Conclusions

A4 anti-idiotype vaccination of horses is safe and may be effective in eliciting an antibody response against endotoxin. The finding of 1C9 in a commercial antiendotoxin antiserum indicates that this idiotype may be part of the normal polyclonal antibody response of horses to endotoxin.

Clinical Relevance

It may be possible to use anti-idiotypic antibody vaccination in horses to induce protection against the effects of endotoxin. (Am J Vet Res 1996; 57:655–658)

Free access
in American Journal of Veterinary Research

SUMMARY

Tumor necrosis factor-α (tnf) is an important mediator of endotoxin-induced pathologic changes. To help define the role of tnf in equids with endotoxemia, the effects of pretreatment with a murine monoclonal antibody (mab) against equine tnf were evaluated in Miniature Horses given endotoxin. Five horses were given tnf mab at a dosage of 1.86 mg/kg of body weight, iv, and 5 were given control mab. Five minutes later, lipopolysaccharide (lps; Escherichia coli O55:B5), 0.25 µg/kg, was given to all horses by bolus iv infusion. Clinical signs of disease were monitored at intervals up to 24 hours after lps infusion, and blood was taken for determination of hematologic and clinical responses of horses given wbc count, pcv, plasma total protein concentration, plasma tnf activity, and serum mab concentration. Reduction of plasma tnf activity in anti-tnf-treated horses was highly significant (P < 0.001), compared with that in control horses. Horses given tnf mab had significantly improved clinical abnormality score (P < 0.010), lower heart rate (P < 0.001), and higher wbc count (P < 0.001), compared with horses given control mab. Rectal temperature, respiratory rate, pcv, and plasma total protein concentration were not significantly different between groups. Serum mab concentration peaked at 68 µg/ml 30 minutes after the end of antibody infusion in both groups. Neutralization of lps-induced tnf activity reduced the hematologic and clinical responses of horses given lps iv.

Free access
in American Journal of Veterinary Research

SUMMARY

A monoclonal antibody (mab) against equine tumor necrosis factor-α (Eq tnf) was used to investigate the role of tnf in cytokine, eicosanoid, and metabolic responses of Miniature Horses given endotoxin. Plasma concentrations of interleukin 6 (il-6), lactate, thromboxane A2 metabolite, and prostacyclin metabolite (6-keto-pgf ) were measured in 10 Miniature Horses given 0.25 µg of lipopolysaccharide (lps; Escherichia coli O55:B5)/kg of body weight. Five horses were given Eq tnf mab and 5 were given isotype-matched mab as control. All horses were given 1.86 mg of antibody/kg by iv infusion, 5 minutes before lps was given iv. Blood samples were taken 20 minutes before and at multiple intervals for 24 hours after lps was given. Interleukin 6 bioactivity in plasma was measured, using il-6-dependent cell line (B9). Eicosanoid activities were assessed by enzyme immunoassay, and plasma lactate concentration was determined enzymatically. Data were analyzed by anova and Tuke's honest significant difference test for significant (P < 0.05) effect of treatment. Horses given Eq tn mab had significantly (P < 0.050) lower peak mean ± sem il-6 (59 ± 29 U/ml), lactate (16 ± 2.00 mg/dl), and 6-keto-pgf (254 ± 79 pg/ml) values then did horses given control mab (880 ± 375 U/ml for il-6; 26 ± 0.04 mg/dl for lactate; and 985 ± 290 pg/ml for 6-keto-pgf ). There was no effect of anti-tnf treatment on lps-induced thromboxane A2 metabolite production. Tumor necrosis factor mediated il-6, lactate, and prostacyclin responses, without affecting thromboxane production in horses given lps.

Free access
in American Journal of Veterinary Research

Summary

Polymyxin B and an antiserum against an Re mutant Salmonella typhimurium were evaluated for protective effect in an equine model of endotoxemia. Six 3- to 5-month-old foals were given endotoxin (0.25 μg/kg of body weight) iv after no pretreatment, or pretreatment with polymyxin B (6,000 U/kg, iv) or S typhimurium antiserum (1.5 ml/kg, iv). When given without pretreatment, endotoxin caused transient recumbency and increases in rectal temperature, and heart and respiratory rates. In addition, leukopenia and increases in circulating tumor necrosis factor (tnf) and interleukin 6 (il-6) activities were detected. Compared with results obtained when endotoxin was given alone, pretreatment with polymyxin B resulted in significantly (P < 0.05) lower maximal plasma tnf and il-6 activities, and significantly lower rectal temperature and respiratory rate. In contrast, compared with effects of endotoxin given without pretreatment, use of antiserum was associated with significantly (P < 0.05) higher respiratory rate, maximal plasma il-6 activity, and total tnf response (as determined by areas under curves of plasma tnf vs time). These results indicate that polymyxin B may have potential as a treatment for equine endotoxemia. Salmonella typhimurium antiserum had no positive effect in this model, and, under certain conditions, may exacerbate the actions of endotoxin.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the effect of intermittent oral administration of ponazuril on immunoconversion against Sarcocystis neurona in horses inoculated intragastrically with S neurona sporocysts.

Animals—20 healthy horses that were seronegative for S neurona–specific IgG.

Procedures—5 control horses were neither inoculated with sporocysts nor treated. Other horses (5 horses/group) each received 612,500 S neurona sporocysts via nasogastric tube (day 0) and were not treated or were administered ponazuril (20 mg/kg, PO) every 7 days (beginning on day 5) or every 14 days (beginning on day 12) for 12 weeks. Blood and CSF samples were collected on day – 1 and then every 14 days after challenge for western blot assessment of immunoconversion. Clinical signs of equine protozoal myeloencephalitis (EPM) were monitored, and tissues were examined histologically after euthanasia.

Results—Sera from all challenged horses yielded positive western blot results within 56 days. Immunoconversion in CSF was detected in only 2 of 5 horses that were treated weekly; all other challenged horses immunoconverted within 84 days. Weekly administration of ponazuril significantly reduced the antibody response against the S neurona 17-kd antigen in CSF. Neurologic signs consistent with EPM did not develop in any group; likewise, histologic examination of CNS tissue did not reveal protozoa or consistent degenerative or inflammatory changes.

Conclusions and Clinical Relevance—Administration of ponazuril every 7 days, but not every 14 days, significantly decreased intrathecal anti–S neurona antibody responses in horses inoculated with S neurona sporocysts. Protocols involving intermittent administration of ponazuril may have application in prevention of EPM.

Full access
in American Journal of Veterinary Research

Abstract

Case Description—Two geldings, aged 11 and 17 years, were examined for treatment of ureteroliths located approximately 10 cm proximal to the bladder.

Clinical Findings—Ureteral obstruction was an incidental finding in 1 horse that was referred because of urinary tract obstruction and a cystic calculus. This horse did not have clinical or laboratory evidence of renal failure, although severe hydronephrosis was evident on transabdominal ultrasonography. The second patient had a serum creatinine concentration of 6.3 mg/dL (reference range, 0.8 to 2.2 mg/dL) and mild hydronephrosis of the affected left kidney.

Treatment and Outcome—In both patients, the obstructed ureter was exteriorized through a flank incision as a standing procedure, and the calculus was crushed and removed with a uterine biopsy forceps introduced through a ureterotomy approximately 25 cm proximal to the calculus. The cystic calculus was removed through a perineal urethrostomy by lithotripsy, piecemeal extraction, and lavage. The horse without azotemia developed pyelonephritis in the affected kidney and was euthanatized because of complications of a nephrectomy 13 months later. In the horse with azotemia, the serum creatinine concentration decreased after surgery, and the horse returned to its intended use. However, it was euthanatized approximately 2 years after surgery because of progressive renal failure, and a large nephrolith was found in the previously unobstructed right kidney.

Clinical Relevance—The technique used for ureterolith removal was successful in both horses in this report, did not require sophisticated equipment, and could be effective in the early stages of ureteral obstruction as a means of restoring urine flow and renal function. The outcome in the horse with advanced unilateral renal disease without azotemia would suggest that nephrectomy should be considered as a treatment in such patients.

Full access
in Journal of the American Veterinary Medical Association