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Abstract

Objective—To describe clinical signs and clinicopathologic findings in donkeys with hypothermia.

Design—Retrospective study.

Animals—10 hypothermic donkeys.

Procedure—Information on signalment, history, physical examination findings, results of diagnostic tests, treatments, and necropsy findings was extracted from medical records of all donkeys with hypothermia between 1988 and 1998 and compared with information from medical records of all normothermic donkeys and hypothermic horses admitted to the hospital during the same period.

Results—Donkeys were more likely to be hypothermic than horses. The mean age of hypothermic donkeys was 6 years (range, 7 months to 11 years), compared with 4.2 years (range, < 1 month to 15 years) for normothermic donkeys; this difference was not significant. Ten of 12 horses with hypothermia were neonates; there were no hypothermic neonatal donkeys. At admission, 7 of 8 hypothermic donkeys were in good body condition and all hypothermic donkeys were weak. Six hypothermic donkeys were able to maintain sternal recumbency, 1 remained in lateral recumbency, and 3 were able to stand. Of the 10 hypothermic donkeys, 2 survived, 1 died, and 7 were euthanatized. Histologically, the thyroid glands from 4 of 5 hypothermic donkeys appeared abnormal and were similar to those of foals with hypothyroidism. During the months that hypothermic donkeys were admitted, there was not a significant difference in environmental temperatures on days of admission between hypothermic and normothermic donkeys.

Conclusions and Clinical Relevance—Hypothermia is a problem in donkeys during cold winter months, and may not be secondary to other diseases or related to diet or management. (J Am Vet Med Assoc 2000;216:725–729)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine whether occlusal angle of the premolar and molar teeth (ie, molar occlusal angle) was associated with feed digestibility, water balance, or fecal particle size in adult horses.

Design—Observational study.

Animals—40 pregnant mares ranging from 3 to 19 years old.

Procedure—The horses were randomly allocated to 1 of 5 feeding groups with 8 horses/group. Horses were sedated, and molar occlusal angle was measured with 2 methods. An oral examination was performed, and total number of dental abnormalities was recorded. Feed digestibility, water balance, and fecal particle size were measured 7 and 16 weeks later.

Results—Molar occlusal angle ranged from 6.3° to 19.3° and was not significantly associated with feed digestibility, water balance, or fecal particle size. The number of dental abnormalities was not associated with feed digestibility. Molar occlusal angle did not vary significantly with horse age.

Conclusions and Clinical Relevance—Results indicate that molar occlusal angles between 6° and 19° do not adversely affect feed digestibility, water balance, or fecal particle size in adult horses. Additionally, there was no association between age and molar occlusal angle. (J Am Vet Med Assoc 2005;227:110–113)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate the effect of dental floating on the position of the mandible relative to the maxilla (a measure of rostrocaudal mobility [RCM] of the mandible) during extension and flexion of the head of horses.

Design—Randomized controlled blinded trial.

Animals—59 horses housed in 1 barn.

Procedure—Horses were formally randomized into a treatment (n = 33) or control (26) group. All horses were sedated, and the distance between rostral portions of the upper and lower incisor arcades were determined with the head fully extended and flexed at the poll (the difference in measurements represented the RCM of the mandible). The oral cavity was examined. For the treatment group, dental floating was performed, and the incisor arcade measurements were repeated.

Results—Dental correction resulted in a significant increase in RCM of the mandible in 31 of 33 horses. The mobility was greater in heavy horses than that detected in other breed classifications. Age and number of dental lesions did not significantly affect mobility before or after dental floating.

Conclusions and Clinical Relevance—Dental floating increased RCM of the mandible, but measurement of this variable was not an indicator of the number or extent of dental lesions, and no specific dental abnormality appeared to significantly affect RCM of the mandible in horses. In horses, measurement of RCM of the mandible can be used as a guide to determine whether dental correction is necessary; after dental floating, it can be used to ensure that irregularities of the occlusal surface have been corrected. (J Am Vet Med Assoc 2003;223:666–669)

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in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE To evaluate the effect of lipopolysaccharide (LPS) on apoptosis of equine neutrophils in vitro.

SAMPLE Venous blood samples from 40 adult horses.

PROCEDURES Neutrophils were isolated from blood samples and cultured with or without LPS from Escherichia coli O55:B5 for 12 or 24 hours. Neutrophil apoptosis was assessed by use of cytologic examination, annexin V and propidium iodide staining quantified with flow cytometry, coincubation with inducers of intrinsic and extrinsic apoptosis or a toll-like receptor (TLR) 4 inhibitor, and measurement of caspase-3, -8, and -9 activities.

RESULTS Treatment with LPS resulted in a significant delay in apoptosis after incubation for 12 and 24 hours (neutrophils from blood samples of 40 horses). There was a significant correlation between increases in LPS dose and decreases in apoptosis after incubation for 24 hours (3 experiments, each of which involved neutrophils obtained from the same 3 horses at 3 separate times). Caspase-9 activity, but not caspase-3 or -8 activity, was significantly reduced in LPS-treated neutrophils after incubation for 12 hours (neutrophils from blood samples of 17 horses). Treatment with a TLR4 inhibitor or intrinsic and extrinsic inducers of apoptosis prevented LPS-delayed apoptosis.

CONCLUSIONS AND CLINICAL RELEVANCE LPS treatment delayed apoptosis of equine neutrophils in vitro for up to 24 hours in a dose-dependent manner by alteration of the intrinsic pathway of apoptosis and was dependent on TLR4 signaling. Increased neutrophil life span may contribute to the development of a systemic inflammatory response syndrome in endotoxemic horses.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To investigate the effect of routine dental floating on weight gain, body condition score, feed digestibility, and fecal particle size in pregnant mares fed various diets.

Design—Randomized controlled clinical trial.

Animals—56 pregnant mares.

Procedure—Mares were randomly allocated to 1 of 4 feed groups (n = 14 mares/group). All horses were sedated and an oral examination was performed, after which dental floating was performed on 7 horses in each group. Body weight was measured, and a body condition score was assigned before and at various times for 24 weeks after dental floating. Feed digestibility and fecal particle size were analyzed 7 and 19 weeks after dental floating.

Results—Weight gain, change in body condition score, feed digestibility, and fecal particle size were not significantly different between horses that underwent dental floating and untreated control horses. In contrast, weight gain was significantly associated with feed group. In the control horses, neither the number of dental lesions nor the presence of any particular type of lesion at the time of the initial oral examination was significantly associated with subsequent feed digestibility.

Conclusions and Clinical Relevance—Results suggest that dental floating does not result in significant short-term changes in body weight, body condition score, feed digestibility, or fecal particle size in healthy pregnant mares. Further studies are necessary to determine the clinical utility of regular dental floating in apparently healthy horses. (J Am Vet Med Assoc 2004;225:1889–1893)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To describe 3 epidemics of respiratory tract disease caused by influenza virus infections in a large population of horses.

Design—Cross-sectional and prospective longitudinal observational studies.

Animals—All horses stabled at a Thoroughbred racetrack.

Procedure—During a 3-year period, descriptive information was collected as horses arrived at the racetrack and throughout race meetings. Routine observations and physical examinations were used to classify horses' disease status. Cause of epidemics was established by use of serologic testing and identification of influenza virus in nasal secretions.

Results—An epidemic of respiratory tract disease caused by influenza virus infections was identified during each year of the study. Attack rates of infectious upper respiratory tract disease (IURD) ranged from 16 to 28%. Incidence of disease caused by influenza virus infections during racing seasons in the second and third years was 27 and 37 cases/1,000 horses/mo, respectively. Physical distributions of stall locations revealed that affected horses were stabled throughout the population; horses affected later in epidemics were often clustered around horses affected earlier. Mucopurulent nasal discharge and coughing were observed in 83 and 62% of horses with IURD, respectively. Median duration of clinical disease was 11 days. Serologic testing was the most sensitive method used to detect influenza virus infections; 76% of affected horses seroconverted to influenza virus.

Conclusion and Clinical Relevance—Epidemics of IURD were observed annually in association with influenza virus infections. Few precautions were taken to limit spread of infection. Preventing or decreasing the likelihood of exposure and improving immunity in the population could substantially decrease risk of disease in similar populations. (J Am Vet Med Assoc 2000;216:535–544)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To identify risk factors associated with respiratory tract disease in horses during 3 epidemics caused by influenza virus infections.

Design—Cross-sectional and prospective longitudinal observational studies.

Animals—1,163 horses stabled at a Thoroughbred racetrack.

Procedure—Investigations were conducted during a 3-year period. An epidemic of respiratory tract disease caused by influenza virus infections was identified in each year. Routine observations and physical examinations were used to classify horses' disease status. Data were analyzed to identify factors associated with development of disease.

Results—Results were quite similar among the epidemics. Concentrations of serum antibodies against influenza virus and age were strongly associated with risk of disease; young horses and those with low antibody concentrations had the highest risk of disease. Calculation of population attributable fractions suggested that respiratory tract disease would have been prevented in 25% of affected horses if all horses had high serum antibody concentrations prior to exposure. However, recent history of vaccination was not associated with reduction in disease risk. Exercise ponies had greater risk of disease than racehorses, which was likely attributable to frequent horse-to-horse contact.

Conclusion and Clinical Relevance—Particular attention should be paid to young horses, those with low serum antibody concentrations, and horses that have frequent contact with other horses when designing and implementing control programs for respiratory tract disease caused by influenza virus infections. It appears that control programs should not rely on the efficacy of commercial vaccines to substantially reduce the risk of disease caused by influenza virus infections. (J Am Vet Med Assoc 2000;216:545–550)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine whether maternally derived antibodies interfere with the mucosal immune response following intranasal (IN) vaccination of newborn calves with a multivalent modified-live virus vaccine.

Design—Randomized controlled clinical trial.

Animals—23 newborn Holstein bull calves.

Procedures—Calves received colostrum and were assigned to group A (unvaccinated control calves), group B (IN vaccination on day 0), or group C (IN vaccination on days 0 and 35). Serum and nasal secretion sample (NSS) titers of antibodies specific for bovine herpesvirus 1, bovine viral diarrhea virus 1, and bovine viral diarrhea virus 2; WBC counts; and NSS interferon concentrations were determined up to day 77.

Results—Calves had high serum titers of maternally derived antibodies specific for vaccine virus antigens on day 0. High IgA and low IgG titers were detected in NSSs on day 0; NSS titers of IgA decreased by day 5. Group B and C NSS IgA titers were significantly higher than those of group A on days 10 through 35; group C IgA titers increased after the second vaccination. Serum antibody titers decreased at a similar rate among groups of calves. Interferons were not detected in NSSs, and calves did not develop leukopenia.

Conclusions and Clinical Relevance—IN vaccination of newborn calves with high concentrations of virus-neutralizing antibodies increased NSS IgA titers but did not change serum antibody titers. Revaccination of group C calves on day 35 induced IgA production. Intranasal vaccination with a modified-live virus vaccine was effective in calves that had maternally derived antibodies.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate the effect of hemi-circumferential periosteal transection and elevation (HCPTE) in foals with experimentally induced angular limb deformities.

Design—Prospective study.

Animals—10 healthy foals.

Procedure—When foals were 30 days old, transphyseal bridge implants were placed on the lateral aspects of both distal radial physes. At 90 days of age (or when 15 degrees of angulation had developed), implants were removed, and HCPTE was performed on 1 limb. Foals were confined in small pens after surgery; the front feet of the foals were rasped weekly to maintain medial-to-lateral hoof wall balance. Dorsopalmar radiographic projections of the carpi were obtained before HCPTE and 2, 4, 6, 8, and 48 weeks later.

Results—At the time of transphyseal bridge removal and HCPTE, both treated and control limbs were observed to have a significantly greater carpal valgus, compared with the initial degree of angulation at 30 days of age. Following HCPTE or sham surgery, all limbs straightened over the subsequent 2 months of the study. Median angulation was not significantly different between treated and control limbs at any time during the study.

Conclusions and Clinical Relevance—Results suggest that in foals with experimentally induced limb deformities, HCPTE was no more effective than stall confinement and hoof trimming alone for correction of the deformity. (J Am Vet Med Assoc 2002;221:536–540)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine comparative efficacy of vaccines administered IM and intranasally, used alone or sequentially, to protect puppies from infection with Bordetella bronchiseptica and determine whether systemic or mucosal antibody response correlated with protection.

Design—Randomized controlled trial.

Animals—50 specific-pathogen-free Beagle puppies.

Procedure—In 2 replicates of 25 dogs each, 14-weekold puppies that were vaccinated against canine distemper virus and parvovirus were vaccinated against B bronchiseptica via intranasal, IM, intranasal-IM, or IMintranasal administration or were unvaccinated controls. Puppies were challenge exposed via aerosol administration of B bronchiseptica 2 weeks after final vaccination. Clinical variables and systemic and mucosal antibody responses were monitored for 10 days after challenge exposure. Puppies in replicate 1 were necropsied for histologic and immunohistochemical studies.

Results—Control puppies that were seronegative before challenge exposure developed paroxysmal coughing, signs of depression, anorexia, and fever. Vaccinated puppies (either vaccine) that were seronegative before challenge exposure had fewer clinical signs. Puppies that received both vaccines had the least severe clinical signs and fewest lesions in the respiratory tract. Vaccinated dogs had significantly higher concentrations of B bronchiseptica-reactive antibodies in serum saliva before and after challenge. Antibody concentrations were negatively correlated with bacterial growth in nasal cavity and pharyngeal samples after challenge exposure.

Conclusions and Clinical Relevance—Parenterally and intranasally administered vaccines containing B bronchiseptica may provide substantial protection from clinical signs of respiratory tract disease associated with infection by this bacterium. Administration of both types of vaccines in sequence afforded the greatest degree of protection against disease. (J Am Vet Med Assoc 2001;218:367–375)

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in Journal of the American Veterinary Medical Association