Objective—To determine the effect of azithromycin chemoprophylaxis on the cumulative incidence of pneumonia caused by Rhodococcus equi, age at onset of pneumonia, and minimum inhibitory concentration (MIC) of azithromycin for R equi isolates cultured from fecal and clinical samples.
Design—Controlled, randomized clinical trial.
Animals—338 foals born and raised at 10 equine breeding farms; each farm had a history of endemic R equi infections.
Procedures—Group 1 foals were control foals, and group 2 foals were treated with azithromycin (10 mg/kg [4.5 mg/lb], PO, q 48 h) during the first 2 weeks after birth. Foals were monitored for development of pneumonia attributable to R equi infection and for adverse effects of azithromycin. Isolates of R equi were tested for susceptibility to azithromycin.
Results—The proportion of R equi–affected foals was significantly higher for control foals (20.8%) than for azithromycin-treated foals (5.3%). Adverse effects of azithromycin treatment were not detected, and there were no significant differences between groups for the MICs of azithromycin for R equi isolates cultured from fecal or clinical samples.
Conclusions and Clinical Relevance—Azithromycin chemoprophylaxis effectively reduced the cumulative incidence of pneumonia attributable to R equi among foals at breeding farms with endemic R equi infections. There was no evidence of resistance to azithromycin. Nonetheless, caution must be used because it is possible that resistance could develop with widespread use of azithromycin as a preventative treatment. Further investigation is needed before azithromycin chemoprophylaxis can be recommended for control of R equi infections.
OBJECTIVE To identify courses in which first-year veterinary students struggled academically and to survey veterinarians as to their opinions on existing prerequisite courses and proposed alternatives.
DESIGN Electronic surveys.
SAMPLE Associate deans for academic affairs at colleges of veterinary medicine and practicing veterinarians in North America and the Caribbean.
PROCEDURES Surveys were sent to associate deans of academic affairs seeking information on courses in which first-year veterinary students most commonly struggled academically. The 6 courses most commonly listed as prerequisites for admission to veterinary college were identified, and practitioners were asked to rank the relative importance of those courses for preparing students for veterinary college and to rank the importance of 7 potential alternative courses.
RESULTS Data were obtained from 21 associate deans and 771 practicing veterinarians. First-year veterinary students most commonly struggled academically in anatomy, physiology, and histology courses, but these courses were rarely included as prerequisites for admission. Practicing veterinarians agreed that anatomy and physiology should be considered as possible alternatives to 1 or more current prerequisite courses, such as organic chemistry and physics.
CONCLUSIONS AND CLINICAL RELEVANCE First-year veterinary students commonly encountered academic difficulties in anatomy, physiology, and histology. Because few surveyed veterinary colleges include these courses as prerequisites for admission, many students were exposed to this material for the first time as veterinary students, potentially adding to their academic difficulties and causing stress and anxiety. To help address this situation, veterinary colleges might consider replacing 1 or more current prerequisite courses (eg, organic chemistry and physics) with anatomy, physiology, and histology.
Objective—To evaluate sensitivity and specificity of a
multiplex polymerase chain reaction (PCR) assay for
simultaneous detection of Rhodococcus equi and differentiation
of strains that contain the virulence-associated
gene (vapA) from strains that do not.
Sample Population—187 isolates of R equi from
equine and nonequine tissue and environmental
specimens and 27 isolates of bacterial species genetically
or morphologically similar to R equi.
Procedure—The multiplex PCR assay included 3
gene targets: a universal 311-bp bacterial 16S ribosomal
RNA amplicon (positive internal control), a 959-bp
R equi-specific target in the cholesterol oxidase gene
( choE ), and a 564-bp amplicon of the vapA gene.
Duplicate multiplex PCR assays for these targets and
confirmatory singleplex PCR assays for vapA and
choE were performed for each R equiisolate. An additional
PCR assay was used to examine isolates for the
Results—Results of duplicate multiplex and singleplex
PCR assays were correlated in all instances, revealing high specificity and reliability (reproducibility)
of the vapA multiplex assay. Of the pulmonary isolates
from horses with suspected R equi pneumonia,
97.4% (76/78) yielded positive results for vapA. Seven
of 50 (14%) human isolates of R equi yielded positive
results for vapA. Six human R equi isolates and 1
porcine isolate yielded positive results for vapB. No
isolates with vapA and vapB genes were detected.
Conclusions and Clinical Relevance—The multiplex
PCR assay is a sensitive and specific method for simultaneous
confirmation of species identity and detection
of the vapA gene. The assay appeared to be a useful
tool for microbiologic and epidemiologic diagnosis and
research. (Am J Vet Res 2005;66:1380–1385)
Objective—To ascertain the frequency of ultrasonographic identification of liver at sites recommended for blind percutaneous liver biopsy in middle-aged horses and to determine whether the liver is obscured by other organs or too thin for safe sample collection at recommended locations.
Design—Prospective case series.
Animals—36 healthy middle-aged (between 6 and 18 years old) Quarter Horses or Quarter Horse crosses.
Procedures—Blood samples were collected from each horse and submitted for evaluation of liver function. Horses with any indication of liver dysfunction on serum biochemical analysis were excluded. The region just below a line drawn between the dorsal aspect of the tuber coxae and the point of the elbow joint in the right 11th, 12th, 13th, and 14th intercostal spaces (ICSs) was imaged by ultrasonography for the presence of liver. In each ICS, liver thickness and whether there was partial obstruction in viewing the liver caused by other abdominal or thoracic organs were recorded.
Results—39% (14/36) of horses had liver imaged on ultrasonographic examination in all of the 11th to 14th ICSs. None of the 36 horses had liver of adequate thickness (ie, liver thickness ≥ 3.5 cm) for biopsy in all of the imaged ICSs. For 22 horses in which the liver was not visible on ultrasonographic examination of an ICS, lung was imaged instead in 12 (55%) horses, intestine in 8 (36%), and both intestine and lung in 2 (9%).
Conclusions and Clinical Relevance—On the basis of the results of this study, the practice of blind percutaneous liver biopsy in horses is not recommended because of the risk of serious complications.
Objective—To describe frequency, types, and clinical outcomes of extrapulmonary disorders (EPDs) in foals in which Rhodococcus equi infection was diagnosed, and to identify factors determined at the time of admission that differentiated foals that developed EPDs from foals with R equi infection identified only in the lungs.
Design—Retrospective case series.
Animals—150 foals aged 3 weeks to 6 months with a diagnosis of R equi infection.
Procedures—Medical records were reviewed for information on date of admission, signalment, history, clinical signs, diagnostic testing, treatment, duration of hospitalization, invoice, and outcome. For each EPD identified, further information was collected on the identification, location, treatment, and outcome of the lesion.
Results—Of 150 foals with R equi infections, 111 (74%) had at least 1 of 39 EPDs. Survival was significantly higher among foals without EPDs (32/39 [82%]) than among foals with EPDs (48/111 [43%]), but many EPDs were only recognized after death. Risk factors significantly associated with EPDs included referral status, duration of clinical signs prior to admission, leukocytosis, and neutrophilia. Foals with EPDs also had a higher heart rate and BUN concentration than foals without.
Conclusions and Clinical Relevance—Practitioners should recognize that extrapulmonary manifestations of R equi occur with high prevalence affecting diverse organ systems, that multiple systems are generally affected when EPDs occur, and that suspicion of R equi infection should prompt evaluation and monitoring of extrapulmonary sites. Improved recognition of the presence of these disorders will help practitioners to better advise their clients in the treatment and outcome of foals with R equi infections.
Objective—To assess signalment, history, results of
clinical and laboratory testing, and outcome for beef
cattle with a left displaced abomasum (LDA), right displaced
abomasum (RDA), or abomasal volvulus (AV).
Animals—19 beef cattle with an AV, LDA, or RDA.
Procedure—Signalment; history; results of physical
examination, diagnostic testing, and surgical exploration;
and condition of the animal at discharge were
obtained from medical records.
Results—Fourteen cattle had an AV, 4 had an RDA,
and 1 had an LDA. Duration of clinical signs ranged
from 1 to 21 days. Eighteen cattle had an AV or RDA;
7 were Brahmans, 12 were males, and median age
was 10 months. Abdominal distention was observed
in 11 cattle, heart rate of ≥ 100 beats/minute was
detected in 14, and the abomasum was palpable per
rectum in all cattle in which per rectal examination
was performed. Leukocytosis, neutrophilia, hyperglycemia,
azotemia, hypochloremia, and hypokalemia
were common laboratory findings. At surgery, 3 cattle
with an AV or RDA had a ruptured abomasum. Of the
remaining 15 cattle, 12 survived.
Conclusions—Clinical course in beef cattle with an
AV or RDA was more protracted than that typically
associated with these conditions in dairy cattle, but
survival rate in beef cattle that did not have rupture of
the abomasum was sim ilar to that of dairy cattle.
Clinical Relevance—Abomasal displacement should
be considered for beef cattle with abdominal distention.
Prognostic indicators recommended for use in
dairy cattle may not be useful for beef cattle. (J Am
Vet Med Assoc 2000;216:730–733)
Objective—To identify risk factors for enterolithiasis
Design—Matched case-control study.
Animals—26 horses with enteroliths, 104 horses
with other causes of colic that underwent surgery (52
horses, surgical control group) or were treated medically
(52 horses, nonsurgical control group).
Procedure—Medical records were reviewed for horses
with enteroliths and control horses. Information
collected included signalment, anamnesis, and findings
on physical examination and clinicopathologic
testing at admission. Horses with enteroliths and control
horses were compared by means of conditional
logistic regression to identify factors associated with
Results—Horses that were fed alfalfa hay, spent ≤
50% of time outdoors, or were Arabian or miniature
breeds had an increased risk of developing
enteroliths. Horses with enteroliths were more likely
to have been hyperbilirubinemic and to have had clinical
signs > 12 hours prior to admission.
Conclusions and Clinical Relevance—Breed and
diet appear to influence the risk of enterolithiasis;
other management factors also may influence development
of enteroliths. Duration of clinical signs may
be longer and signs may be less severe among horses
with enteroliths, compared with horses with
other causes of colic. (J Am Vet Med Assoc
Objective—To identify farm characteristics as risk
factors for the development of Rhodococcus equi
pneumonia in foals.
Design—Prospective matched case-control study.
Animals—2,764 foals on 64 equine breeding farms
with 9,991 horses.
Procedure—During 1997, participating veterinarians
completed paired data collection forms, 1 for a
farm with ≥ 1 foal with R equi pneumonia and 1 for
an unaffected control farm. Matched data were
compared by use of conditional logistic regression
Results—Farm characteristics found in bivariate
analyses to be associated with increased risk for
pneumonia caused by R equi in foals included >
200 farm acres, ≥ 60 acres used in the husbandry
of horses, > 160 horses, ≥ 10 mares housed permanently
on the farm (resident mares), > 17 foals,
> 0.25 foals/acre, and the presence of transient
mares (mares brought temporarily to the farm for
breeding or foaling) and their foals. Affected farms
were significantly more likely to be > 200 acres in
size and have ≥ 10 resident dam-foal pairs, whereas
control farms were significantly more likely to
have ≥ 75% of their dam-foal pairs housed permanently
on the farm.
Conclusions and Clinical Relevance—Breeding
farms with large acreage, a large number of mares and
foals, high foal density, and a population of transient
mares and foals are at high risk for foals developing
pneumonia caused by R equi. (J Am Vet Med Assoc
Objective—To determine whether foal management
practices, environmental management, and preventative
health practices are risk factors for development
of Rhodococcus equi pneumonia in foals.
Design—Prospective matched case-control study.
Animals—2,764 foals on 64 equine breeding farms
with 9,991 horses.
Procedure—During 1997, participating veterinarians
completed paired data collection forms for comparison;
1 for an affected farm (containing ≥ 1 foal with
pneumonia caused by R equi)and 1 for a control farm.
Information collected pertained to stabling facilities,
environmental management, foal husbandry, and preventative
equine health practices.
Results—Matched farm data compared by use of conditional
logistic regression indicated that personnel on
affected farms were more likely to attend foal births,
test foals for adequacy of passive immunity, administer
plasma or other treatments to foals to supplement
serum immunoglobulin concentrations, administer
hyperimmune plasma prophylactically to foals, vaccinate
mares and foals against Streptococcus equi
infection, and use multiple anthelmintics in deworming
programs. Affected farms were also more likely to
have foals that developed other respiratory tract disorders
and were approximately 4 times as likely to have
dirt floors in stalls used for housing foals as were control
Conclusions and Clinical Relevance—Rhodococcus
equi pneumonia does not appear to be associated
with poor farm management or a lack of attention to
preventative health practices. Housing foals in stalls
with dirt floors may increase the risk for development
of R equi pneumonia. (J Am Vet Med Assoc 2003;
Objective—To evaluate the correlation between the
half-time of liquid-phase gastric emptying (T50) determined
by use of nuclear scintigraphy, using technetium
Tc 99m pentetate, and absorption variables of
orally administered acetaminophen in horses with
experimentally delayed gastric emptying.
Animals—6 mature horses.
Procedure—Delayed gastric emptying was induced
by IV injection of atropine sulfate. Twenty minutes
later, acetaminophen and technetium Tc 99m pentetate
were administered simultaneously via nasogastric
tube. Serial lateral images of the stomach region
were obtained, using a gamma camera. Power exponential
curves were used for estimation of T50 and
modified R2 values for estimation of goodness-of-fit of
the data. Serial serum samples were obtained, and
acetaminophen concentration was determined, using
fluorescence polarization immunoassay. Maximum
serum concentration (Cmax), time to reach maximum
serum concentration (Tmax), area under the curve for
480 minutes, and the appearance rate constant were
determined, using a parameter estimation program.
Correlations were calculated, using a Spearman rank
Results—A significant correlation was detected
between T50 determined by use of scintigraphy and
Tmax determined by use of acetaminophen absorption.
Correlation between T50 and other absorption
variables of acetaminophen was not significant.
Conclusions and Clinical Relevance—The acetaminophen
absorption method was a valid technique in
this model of delayed gastric emptying in horses. The
method may be a valuable tool for use in research as
well as in clinical evaluation of gastric emptying in
horses. (Am J Vet Res 2002;63:170–174)