Search Results

You are looking at 1 - 10 of 15 items for

  • Author or Editor: Bill Johnson x
  • Refine by Access: All Content x
Clear All Modify Search

Abstract

Objective—To determine the predictive ability of a commercially available lateral-flow immunoassay used for determining passive transfer of immunoglobulins in calves.

Animals—204 male Holstein calves ranging from 4 to 8 days old.

Procedure—Serum samples were obtained from each calf. Results of refractometry, zinc sulfate turbidity technique, and the lateral-flow immunoassay were determined. Sensitivity, specificity, accuracy, and predictive ability were calculated on the basis of IgG concentrations determined by turbidimetric immunoassay (TIA).

Results—Mean IgG concentration in the study was 10.9 mg/ml as determined by TIA. Rate of failure of passive transfer in this study population was 56%. Associations between the values for the refractometry and zinc sulfate turbidity techniques were established by regression analysis. Accuracy for the lateral-flow immunoassay, refractometry, and zinc sulfate turbidity methods was 95, 80, and 73%, respectively.

Conclusions and Clinical Relevance—The lateral-flow immunoassay was better at determining the status of passive transfer of immunoglobulins, compared with the refractometry or zinc sulfate turbidity methods. The ability of the lateral-flow immunoassay to provide accurate results should enable clinicians to make immediate management or intervention decisions. (Am J Vet Res 2002;63:247–250)

Full access
in American Journal of Veterinary Research
in Journal of the American Veterinary Medical Association

Abstract

Objective

To investigate the relation between several racing speed history characteristics and risk of fatal skeletal injury (FSI) in racing Thoroughbreds.

Animals

64 Thoroughbreds euthanatized during a 9-month period in 1991 at a California racemeet because of a catastrophic fracture incurred while racing (cases), identified retrospectively. For each race in which an FSI occurred, 1 control horse was randomly selected from the noncatastrophically injured participants.

Procedure

Racing and officially timed workout histories were obtained for each horse. Several history characteristics were calculated to summarize racing career patterns and high-speed exercise schedules prior to date of injury and included age at first race, proportion of career spent laid up, average duration of laid up periods, average lifetime racing frequency, time from last lay up to date of injury, and total and rate of distance accumulated 1 to 6 months prior to date of injury. History characteristics associated with FSI were screened by paired t-test and studied in detail using conditional logistic regression.

Results

High total and high average daily rates of exercise distance accumulation within a 2-month period were associated with higher risks for FSI during racing, yet career patterns, such as age at first race or total proportion of career spent laid up, were not found to be associated with risk for FSI. A horse that had accumulated a total of 35 furlongs of race and timed-work distance in 2 months, compared with a horse with 25 furlongs accumulated, had an estimated 3.9-fold increase in risk for racing-related FSI (95% confidence interval = 2.1, 7.1). A horse that had accumulated race and timed-work furlongs at an average rate of 0.6 furlong/d within a 2-month period, compared with a horse with an average of 0.5 furlong/d, had an estimated 1.8-fold increase in risk for racing-related FSI (95% confidence interval = 1.4, 2.6).

Conclusions and Clinical Relevance

Thoroughbred racehorses that either accumulate large total highspeed distances or rapidly accumulate high-speed distances within a 2-month period may be at increased risk for FSI during racing. (Am J Vet Res 1996;57:1549–1555)

Free access
in American Journal of Veterinary Research

Summary

During a 3-year period, 4 cases of bovine abortion attributable to Listeria ivanovii were diagnosed from 243 bovine fetuses submitted for diagnostic evaluation. Listeria monocytogenes was isolated only once from a bovine fetus during this same time period. Pathologic findings were similar to those seen in abortions attributable to L monocytogenes. Consistent management factors were not recognized and breed susceptibility was not apparent. Listeria ivanovii is most often associated with abortions from sheep and is rarely reported from cattle. On the basis of findings in this study, L ivanovii must be included as a potential cause of bovine abortions.

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate diagnostic tests used for detection of bovine viral diarrhea virus (BVDV) and determine the prevalence of BVDV subtypes 1a, 1b, and 2a in persistently infected (PI) cattle entering a feedlot.

Design—Prospective study.

Animals—21,743 calves.

Procedures—Samples were obtained from calves initially testing positive via antigen capture ELISA (ACE) performed on fresh skin (ear notch) specimens, and ACE was repeated. Additionally, immunohistochemistry (IHC) was performed on skin specimens fixed in neutral-buffered 10% formalin, and reverse transcriptase PCR (RT-PCR) assay and virus isolation were performed on serum samples. Virus was subtyped via sequencing of the 5′ untranslated region of the viral genome.

Results—Initial ACE results were positive for BVDV in 88 calves. After subsequent testing, results of ACE, IHC, RT-PCR assay, and viral isolation were positive in 86 of 88 calves; results of all subsequent tests were negative in 2 calves. Those 2 calves had false-positive test results. On the basis of IHC results, 86 of 21,743 calves were PI with BVDV, resulting in a prevalence of 0.4%. Distribution of BVDV subtypes was BVDV1b (77.9%), BVDV1a (11.6%), and BVDV2a (10.5%).

Conclusions and Clinical Relevance—Rapid tests such as ACE permit identification and segregation of PI cattle pending results of further tests, thus reducing their contact with the rest of the feedlot population. Although vaccines with BVDV1a and 2a components are given to cattle entering feedlots, these vaccines may not provide adequate protection against BVDV1b.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate with CT the efficacy of various combinations of firearms and ammunitions to penetrate and disrupt the brain tissue of cadaveric heads of feedlot steers.

Sample—42 fresh cadaveric heads of 12- to 18-month-old Bos taurus steers.

Procedures—For each of 7 combinations of firearms and ammunitions (.22-caliber rifle firing a long rifle 30-grain plated lead solid- or hollow-point round, .223-caliber carbine firing a 50-grain ballistic-tip round, 9-mm pistol firing a 124-grain total metal jacket round, .45-caliber automatic Colt pistol [ACP] firing a 230-grain full metal jacket round, and 12-gauge shotgun firing a 2.75-inch 1.25-ounce No. 4 birdshot shell or a 1-ounce rifled slug), 6 cadaveric heads were shot at an identical distance (3 m), angle, and anatomic location. Heads were scanned with third-generation CT, and images were evaluated to determine extent of penetration, projectile fragmentation, cranial fracture, and likelihood of instantaneous death (≥ 30% destruction of brain tissue or a brainstem lesion).

Results—41 of 42 skulls were penetrated by the projectile. Instantaneous death was considered a likely consequence for 83% (25/30) of heads shot with a rifle-fired .22-caliber solid-point round, pistol-fired .45-caliber ACP round, carbine-fired .223-caliber round, and shotgun-fired birdshot and slug. Of the 18 heads shot with pistol-fired 9-mm and .45-caliber ACP rounds and rifle-fired .22-caliber hollow-point rounds, only 6 had brainstem lesions.

Conclusions and Clinical Relevance—Results suggested that gunshots delivered by all firearm-ammunition combinations except rifle-fired .22-caliber hollow-point rounds and pistol-fired 9-mm rounds were viable options for euthanasia of feedlot cattle.

Full access
in American Journal of Veterinary Research

Abstract

In collaboration with the American College of Veterinary Radiology

Open access
in Journal of the American Veterinary Medical Association

Objective

To determine whether a two-month or longer period without official high-speed workouts (lay-up) is associated with humeral or pelvic fracture in Thoroughbred racehorses.

Design

Retrospective study.

Animals

Thoroughbred racehorses in California that were euthanatized because of a complete humeral or pelvic fracture.

Procedure

Age, sex, activity, number of lay-ups, number of days from a race or official timed workout to fracture, number of days from end of last lay-up to fracture, mean duration of lay-ups, and total number of days in race training were compared between horses with humeral fractures and horses with pelvic fractures. A case-crossover study was used to estimate relative risk for fracture of the humerus or pelvis occurring within hazard periods of 10 and 21 days following lay-up, compared with periods following more regular participation in official racing or timed workout events.

Results

Horses with pelvic fractures were more often female, older, and had 0 or ≥ 2 lay-ups. Horses with humeral fractures were typically 3-year-old males that had 1 lay-up. Horses with pelvic fractures had more total days in race training, fewer days from last exercise event to fracture, and a greater number of days from end of last lay-up to fracture than horses with humeral fractures. Return from lay-up was strongly associated with risk for humeral fracture during hazard periods of 10 and 21 days (relative risk = 71 and 45, respectively).

Clinical Implications

Risk of humeral fracture may be reduced if horses are cautiously reintroduced into race training after lay-up. (J Am Vet Med Assoc 1998;212: 1582–1587)

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective

To evaluate selected shoe characteristics as risk factors for fatal musculoskeletal injury (FMI) and specifically for suspensory apparatus failure (SAF) and cannon bone condylar fracture (CDY) of Thoroughbred racehorses in California.

Design

Case-control study.

Animals

Thoroughbred racehorses (n = 201) that died or were euthanatized at California racetracks between August 1992 and July 1994.

Procedure

Shoe characteristics were compared between case horses affected by FMI (155), SAF (79), and CDY (41) and control horses that died for reasons unrelated to the appendicular musculoskeletal system (non-FMI; 46). Multivariable logistic regression was used to estimate odds ratios for FMI, SAF, and CDY.

Results

Toe grabs were identified as possible risk factors for FMI, SAF, and CDY. The odds of FMI, SAF, and CDY were 1.8, 6.5, and 7.0, respectively, times greater for horses shod with low toe grabs than for horses shod without toe grabs on front shoes. Horses shod with regular toe grabs on front shoes had odds 3.5, 15.6, and 17.1 times greater (P < 0.05) for FMI, SAF, and CDY, respectively, compared with horses shod without toe grabs. The odds of horses shod with rim shoes were a third (P < 0.05) of those shod without rim shoes for either FMI or SAF. The apparent association between toe grab type and CDY may, in part, be attributable to concurrent SAF and CDY injuries in many horses.

Clinical Relevance

Avoiding the use of toe grabs should decrease the incidence of FMI, especially SAF, in Thoroughbred racehorses. The use of rim shoes that are more consistent with natural hoof shape may decrease injury risk. (Am J Vet Res 1996;57:1147-1152)

Free access
in American Journal of Veterinary Research

Abstract

Objectives

To develop a standard technique for evaluation of racehorse shoes, to assess homotypic variation (interlimb variation) in shoe characteristics, and to determine whether shoe characteristics varied with age and sex.

Design

Cross-sectional study.

Animals

Thoroughbred racehorses (n = 201) that died or were euthanatized at California racetracks between August 1992 and July 1994.

Procedure

Shoe characteristics were measured on horses examined after death. Percentage of agreement was used to compare shoe characteristics between limbs (homotypic variation). Using χ2analysis, shoe characteristics were compared between horses grouped by age and sex.

Results

Toe grabs were present on 90.5% of horses, and rim shoes were present on 15.9% of horses. Heel traction devices were less frequent on front (2.5%) than rear (6%) hooves. Pads were present on 24.9% of horses, with bonded rim pads most common. Special types of shoes were present on 5% of horses. Percentage of agreement between left and right front hooves and between left and right rear hooves was high (20/25 variables; % agreement ≥ 99). In contrast, percentage of agreement between left front and left rear hooves and between right front and right rear hooves was low (2/25 variables; % agreement ≥ 99). Presence of a pad was significantly (P < 0.05) associated with age, and several shoe variables (size, presence of a special shoe, overall wear matched) were significantly (P < 0.05) associated with sex.

Clinical Relevance

Except for variables related to special shoes, wear, and weight, 1 shoe for the respective fore- or hind limbs could be used as an indicator for the contralateral shoe worn by Thoroughbred racehorses without substantial loss of information. However, 1 shoe could not be used as an indicator for shoe characteristics of all 4 limbs. Some shoe characteristics are associated with age and sex, and these variables should be considered possible confounders in studies of shoe characteristics. (Am J Vet Res 1996;57:1141-1146)

Free access
in American Journal of Veterinary Research