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  • Author or Editor: Jeff L. Caswell x
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Abstract

OBJECTIVE To describe the ultrasonographic changes in the cricoarytenoideus dorsalis (CAD) and cricoarytenoideus lateralis (CAL) muscles of horses before and at various times during the 32 weeks after unilateral neurectomy of the right recurrent laryngeal nerve.

ANIMALS 28 healthy Standardbreds.

PROCEDURES For each horse, the appearance of the CAD and CAL muscles on the right (neurectomized) and left (control) sides was serially monitored ultrasonographically by percutaneous (CAD and CAL) and transesophageal (CAD) approaches. The ultrasonographic images were assessed to determine the mean pixel intensity, muscle thickness, and appearance grade, and comparisons were made between the muscles of the neurectomized and control sides.

RESULTS The muscle appearance grade and mean pixel intensity for the CAL and CAD muscles on the neurectomized side were significantly increased by 2 and 4 weeks, respectively, after the neurectomy. The transesophageal approach enhanced the ultrasonographic visibility of the CAD muscle and allowed us to detect a significant decrease in the thickness of the CAD muscle on the neurectomized side over time, compared with thickness of the CAD muscle on the control side.

CONCLUSIONS AND CLINICAL RELEVANCE Results suggested ultrasonography can be used to successfully assess the CAL and CAD muscles of horses. A qualitative grading scheme was sufficient for successful detection and monitoring of muscle atrophy and reduced the need for image standardization. The transesophageal approach described for assessment of the CAD muscle warrants further investigation.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To describe histologic findings in the small airways during postmortem examination of actively racing horses and to quantify the degree of airway inflammation by use of a semiquantitative scoring system.

SAMPLE Lung tissues obtained from 95 horses (Thoroughbreds, Standardbreds, and Quarter Horses) that had been actively racing or training.

PROCEDURES 10 standardized lung sections were obtained during postmortem examination of 37 horses that had been actively racing or training, and 2 histologic sections of the caudodorsal lung lobes previously collected from each of 58 horses that died or were euthanized during racing or training were also obtained. Sections were evaluated by use of a validated histologic small airway scoring system.

RESULTS Scores for inflammatory cells, smooth muscle, and hemosiderin typically were high. Signalment and cause of death were not significant predictors of lung scores. Lung sample location was a significant predictor, with the highest scores in the caudal and dorsal sections. Inflammatory cell infiltration in peribronchiolar tissues, smooth muscle hyperplasia, and hemosiderin (prevalence of 86%, 98%, and 80%, respectively) were common findings in lungs of these horses, with the caudodorsal regions more severely affected. Correlation was moderate between smooth muscle hyperplasia and inflammatory cell infltration, with minimal correlation between hemosiderin and inflammatory cell infiltration.

CONCLUSIONS AND CLINICAL RELEVANCE Inflammatory airway disease has been identified by use of bronchoalveolar lavage in young athletic horses throughout the world. In the study reported here, pathological changes were detected in the wall of small airways of horses that were actively training or racing.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To compare laparoscopic dissection withlaparoscopic dissection combined with abdominal instillation of ferric hyaluronate gel for the treatment of experimentally induced adhesions in pony foals.

Animals—12 healthy pony foals.

Procedure—A serosal abrasion method was used to create adhesions at 4 sites on the jejunum (day 0). At day 7, laparoscopy was performed and the adhesions observed in each foal were recorded. In group-1 foals (n = 6), the adhesions were separated laparoscopically (treatment 1). In group-2 foals (n = 6), 300 mL of 0.5% ferric hyaluronate gel was infused into the abdomen after the adhesions were separated laparoscopically (treatment 2). At day 24, terminal laparoscopy was performed and the adhesions observed were recorded. Total number of adhesions within each group was compared between day 7 and 24. Data were analyzed to determine whether an association existed between the number of adhesions on day 24 and treatment type.

Results—At day 24, the number of adhesions was significantly decreased within each group, compared with the number of adhesions at day 7 (group-1 foals, 10 vs 22 adhesions; group-2 foals, 3 vs 20 adhesions). Treatment 1 was associated with a significantly higher number of adhesions at day 24, compared with treatment 2 (odds ratio, 4.54; 95% confidence interval, 1.03 to 23.02).

Conclusions and Clinical Relevance—Abdominal instillation of 0.5% ferric hyaluronate gel after laparoscopic dissection was a more effective technique than laparoscopic dissection alone to treat experimentally induced adhesions in pony foals. Laparoscopic adhesiolysis following abdominal surgery in foals is a safe and effective technique. ( Am J Vet Res 2004;65:681–686)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To characterize the impact of Mannheimia haemolytica infection on feed intake and weight gain in feedlot heifers and to evaluate the clinical efficacy of isoflupredone acetate administered in combination with oxytetracycline.

Animals—96 weanling heifers in a research feedlot facility.

Procedures—Bronchopneumonia was induced by intrabronchial infusion of M haemolytica. Control heifers underwent a sham procedure. Infected heifers were treated with oxytetracycline alone or in combination with isoflupredone acetate (OXY-ISO) or with nothing. Clinical variables were recorded daily for 7 days following disease induction, and feedlot performance indices were measured over a 12-week period.

Results—Infection caused a reduction in dry-matter intake and average daily gain (ADG) in heifers that received no treatment. Oxytetracycline treatment alone did not prevent reductions in feed intake and ADG during the first week after infection was induced, whereas OXY-ISO treatment did prevent these reductions. Treatment with OXY-ISO also resulted in faster clinical improvement. No significant differences were evident between the oxytetracycline and OXY-ISO groups with respect to dry-matter intake or ADG throughout the study period.

Conclusions and Clinical Relevance—Isoflupredone acetate appeared to be a useful clinical adjunct to treatment with oxytetracycline in cattle with acute M haemolytica bronchopneumonia.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To assess the efficacy of laparoscopic adhesiolysis in the treatment of experimentally induced adhesions in foals.

Animals—8 healthy pony foals.

Procedure—Celiotomy was performed and adhesions created at the jejunoileal junction and at sites 0.5 and 1 m proximal to this junction, using a serosal abrasion method. Ten days after celiotomy, exploratory laparoscopy was performed. Laparoscopic adhesiolysis was performed in the treatment group only (4 foals, randomly selected). Thirty days after the exploratory laparoscopy, a final laparoscopic examination was performed, and the foals were euthanatized. The number and characteristics of abdominal adhesions were recorded during laparoscopy 10 and 30 days after celiotomy and during necropsy.

Results—At 30 days after celiotomy, the number of adhesions in the control group was significantly higher than the number in the treatment group. In the control group, all adhesions observed during the exploratory laparoscopy were still evident at the final laparoscopy and necropsy. In the treatment group, adhesions did not form again after separation. During final laparoscopy and necropsy, a focal adhesion between the omentum and site of the initial laparoscope portal was observed in 5 of 8 foals.

Conclusions and Clinical Relevance—The serosal abrasion model is useful for studying abdominal adhesions in foals. Laparoscopic adhesiolysis was an effective technique to break down experimentally induced adhesions in the early maturation stage of formation in pony foals. Studies are required to investigate prevention of de novo adhesions at the laparoscope portal sites. (Am J Vet Res 2002;63:289–294)

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To investigate the effects of meloxicam administration before long-distance transport on inflammatory mediators and leukocyte function of cattle at feedlot arrival.

ANIMALS 60 healthy yearling beef steers.

PROCEDURES Single-source steers were assigned to a transported (n = 40) or nontransported (20) group. Then, half of the steers within each group were assigned to receive meloxicam (1 mg/kg, PO) or a lactose placebo (1 bolus/steer, PO). All steers were transported approximately 1,300 km overnight to a feedlot; however, the nontransported group was moved before treatment (meloxicam or placebo) administration and allowed a 17-day acclimation period, whereas the transported group was moved immediately after treatment administration on day −1. Blood samples for measurement of inflammatory mediators and leukocyte function were collected from all steers on days −1, 0, and 3.

RESULTS For steers that received meloxicam, mean plasma meloxicam concentration for the transported group was significantly greater than that for the nontransported group on day 0. For steers that received the placebo, mean haptoglobin-matrix metalloproteinase-9 complex for the transported group was significantly greater than that for the nontransported group on day 0. Mean haptoglobin concentration, neutrophil L-selectin intensity, and polymorphonuclear leukocyte count for the transported group were significantly greater than those for the nontransported group. Mean substance P concentration for nontransported steers that received meloxicam was significantly lower than that for the other 3 treatment groups.

CONCLUSIONS AND CLINICAL RELEVANCE Results indicated meloxicam administration to healthy steers immediately before long-distance transport did not significantly mitigate the effects of transport-induced stress on leukocyte function or inflammatory markers.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine the prevalence of Mycoplasma bovis infection in the lungs of cattle at various times after arrival at a feedlot, to measure the relationship between clinical disease status and the concentration and genotype of M bovis within the lungs, and to investigate changes in the genotype of M bovis over time.

Sample—Bronchoalveolar lavage fluid (BALF) from 328 healthy or pneumonic beef cattle and 20 M bovis isolates obtained from postmortem samples.

Procedures—The concentration of M bovis in BALF was determined via real-time PCR assays, and M bovis isolates from BALF were genotyped via amplified fragment length polymorphism (AFLP) analysis.

Results—Prevalence of M bovis in BALF was 1 of 60 (1.7%) at arrival to a feedlot and 26 of 36 (72.2%) and 36 of 42 (85.7%) at ≤ 15 days and 55 days after arrival, respectively. Neither the concentration nor the AFLP type of M bovis in BALF was correlated with clinical disease status. The M bovis AFLP type differed between early and later sampling periods in 14 of 17 cattle.

Conclusions and Clinical Relevance—The findings implied spread of M bovis among calves and suggested that host factors and copathogens may determine disease outcomes in infected calves. Chronic pulmonary infection with M bovis may represent a dynamic situation of bacterial clearance and reinfection with strains of different AFLP type, rather than continuous infection with a single clone. These findings impact our understanding of why cattle with chronic pneumonia and polyarthritis syndrome inadequately respond to antimicrobial treatment.

Full access
in American Journal of Veterinary Research