Objective—To determine sex, breed, and age distributions in a population of horses with cervical vertebral compressive myelopathy (CVCM), compared with contemporaneous control horses.
Design—Retrospective case-control study.
Animals—811 horses with CVCM and 805 control horses.
Procedures—The Veterinary Medical Database was searched to identify horses with CVCM and contemporaneous control horses registered between July 1974 and August 2007. Admission date, admitting institution, sex, breed, age at the time of registration in the database, weight, and discharge status (alive, died, or euthanized) were recorded for each case and control horse.
Results—On the basis of results of multivariable logistic regression analysis, geldings and sexually intact males had a significantly higher likelihood of having CVCM than females (odds ratio [OR], 2.0 [95% confidence interval, 1.5 to 2.6]; and OR, 2.4 [95% confidence interval, 1.8 to 3.2], respectively). Thoroughbreds, Tennessee Walking Horses, and Warm-bloods were overrepresented in the CVCM group, compared with Quarter Horses. Horses that ranged from < 6 months to < 7 years of age had significantly higher odds of having CVCM, compared with horses ≥ 10 years of age.
Conclusions and Clinical Relevance—Sex, breed, and age predilections were detected in horses with CVCM. Improved understanding of these factors will aid clinical recognition of the disease in groups that may have a high prevalence of CVCM or were previously not recognized to be commonly affected. The results may also stimulate future investigations to further delineate etiopathogenesis, such as breed-related genetic causality.
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 evaluate the effect of an indwelling
nasogastric tube on gastric emptying of liquids in
Animals—9 healthy adult horses.
Procedure—A randomized block crossover design
was used. For treatment group horses, a nasogastric
tube was placed and 18 hours later, acetaminophen
was administered; the nasogastric tube remained in
place until the experiment was complete. For control
group horses, a nasogastric tube was passed into the
stomach, acetaminophen was administered, and the
nasogastric tube was removed immediately. Serial
blood samples were collected 15 minutes before and
after administration of acetaminophen. Serum concentration
of acetaminophen was determined by use
of fluorescence polarization immunoassay. The variables,
time to maximum acetaminophen concentration
(Tmax) and the appearance constant for acetaminophen
(Kapp), were determined. The values for
Kapp and Tmax in horses with and without prolonged
nasogastric tube placement were compared.
Results—No significant difference was found in Kapp
between horses with and without prolonged nasogastric
tube placement; the median difference in Kapp
was 0.01 min–1 (range, –0.48 to 0.80 min–1). No significant
difference was found in Tmax between horses
with and without prolonged nasogastric tube placement;
the median difference in Tmax was 5 minutes
(range, –30 to 50 minutes). Reanalysis of data following
the removal of possible outlier values from 1
horse resulted in a significant difference in Tmax
between horses with and without prolonged nasogastric
Conclusions and Clinical Relevance—Although no
clinically important impact of 18 hours of nasogastric
intubation was found on gastric emptying in healthy
horses, considerable variability in Kapp and Tmax was
found among horses. (Am J Vet Res 2005;66:642–645)
Objective—To characterize changes in lymphocyte
subsets over time in foals from birth to 18 weeks of
age, accounting for differences among individuals, and
to determine the effect of overnight storage of blood
samples on foal lymphocyte subset concentrations.
Animals—8 healthy Quarter Horse foals from birth to
18 weeks of age.
Procedure—Blood samples were collected longitudinally
from birth to 18 weeks of age and a CBC performed
on each sample. The samples were stained
for lymphocyte markers, either immediately or after
overnight storage and analyzed by flow cytometry.
Results—Total leukocytes, total lymphocytes, and
the absolute concentrations of all lymphocyte subsets
increased significantly with age. The proportions
of B29A+, CD21+, and equine major histocompatability
complex class-II molecule+ lymphocytes
increased significantly with age. The proportion of
equine (Eq) CD5+, EqCD8+, and EqWC4+ lymphocytes
decreased significantly with age. Significant differences
among foals were found with respect to initial
concentrations with respect to initial concentrations,
but not with respect to the rate of increase of the various
subsets tested. Significant differences were not
found in subset values when comparing blood samples
stained on the day of collection or after
overnight storage at room temperature (approx 21 C)
or under refrigeration.
Conclusions and Clinical Relevance—These results
are consistent with an increase in subset numbers
and proportions over time, but with individual differences
among foals. The observation of individual differences
in subsets among foals suggests that there
may be individual differences in susceptibility to infectious
disease during the perinatal period. The absence
of an effect of overnight storage makes field studies
of lymphocyte subset concentrations more feasible.
(Am J Vet Res 2002;63:531–537)
Objective—To quantify and compare geochemical
factors in surface soils from horse-breeding farms
with horses with pneumonia caused by Rhodococcus
equi (affected farms) and horse-breeding farms with
no history of pneumonia caused by R equi (unaffected
Sample Population—Soil from 24 R equi-affected
farms and 21 unaffected farms.
Procedure—Equine veterinary practitioners
throughout Texas submitted surface soil samples
from areas most frequented by foals, on R equi affected
and unaffected horse-breeding farms in
their practice. Soil samples were assayed for the
following factors: pH, salinity, nitrate, phosphorus,
potassium, calcium, magnesium, sodium, sulfur,
zinc, iron, manganese, and copper. Median values
for all factors were recorded, and differences
between affected and unaffected farms were compared.
Results—Significant differences in soil factors were
not detected between affected and unaffected
farms; hence, there was no association between
those factors and R equi disease status of the
Conclusion and Clinical Relevance—The surface
soil factors monitored in this study were not significant
risk factors for pneumonia caused by R equi. As
such, it is not possible to determine whether foals on
a given farm are at increased risk of developing disease
caused by R equi on the basis of these factors.
Data do not support altering surface soil for factors
examined, such as alkalinization by applying lime, as
viable control strategies for R equi. (Am J Vet Res
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 evaluate fecal concentrations of
selected genera of colonic bacteria in healthy dogs,
and to investigate effects of dietary fructooligosaccharides
(FOS) on those bacterial populations.
Animals—6 healthy adult Beagles.
Procedure—Dogs were randomly assigned to 2
groups of 3 and fed an unsupplemented diet for 370
days. After 88 days, fecal samples were collected.
Another fecal sample was collected from each dog
282 days later. Group A then received a diet supplemented
with FOS, and group B continued to receive
the unsupplemented diet. Twenty-eight to 29 days
later, fecal samples were collected. Diets were
switched between groups, and fecal samples were
collected 31 and 87 days later. Concentrations of
Bifidobacterium spp, Lactobacillus spp, Clostridium
spp, Bacteroides spp, and Escherichia coli in freshly
collected feces were determined. Effects of diet and
time on bacterial concentrations were compared
Results—Bifidobacterium spp and Lactobacillus spp
were inconsistently isolated from feces of dogs fed
either diet. Sequence of diet significantly affected
number of Bacteroides spp subsequently isolated
from feces, but diet had no effect on numbers of
Clostridium spp or E coli.
Conclusions and Clinical Relevance—Some genera
of bacteria (eg, Bifidobacterium) believed to be common
components of colonic microflora may be only
sporadically isolated from feces of healthy dogs. This
deviation from expected fecal flora may have implications
for the effectiveness of supplementing diets
with prebiotics. (Am J Vet Res 2000;61:
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 determine the types of musculoskeletal
problems that result in lameness or poor performance
in horses used for team roping and determine
whether these problems are different in horses used
for heading versus heeling.
Procedure—Medical records of team roping horses
that were evaluated because of lameness or poor performance
were reviewed to obtain information
regarding signalment, primary use (ie, head horse or
heel horse), history, results of physical and lameness
examinations, diagnostic tests performed, final diagnosis,
Results—Among horses evaluated by lameness clinicians,
the proportion with lameness or poor performance
was significantly greater in horses used for
heading (74/118) and lower in horses used for heeling
(44/118) than would be expected under the null
hypothesis. Most horses examined for poor performance
were lame. A significantly greater proportion
of horses used for heading had right forelimb lameness
(26/74 [35%]), compared with horses used for
heeling (7/44 [16%]). Horses used for heading had
more bilateral forelimb lameness (18/74 [24%]), compared
with horses used for heeling (4/44 [9%]).
Horses used for heeling had more bilateral hind limb
lameness (3/44 [7%]), compared with horses used for
heading (0%). The most common musculoskeletal
problems in horses used for heading were signs of
pain limited to the distal sesamoid (navicular) area,
signs of pain in the navicular area plus osteoarthritis
of the distal tarsal joints, and soft tissue injury in the
forelimb proximal phalangeal (pastern) region. Heeling
horses most commonly had signs of pain in the navicular
area, osteoarthritis of the metatarsophalangeal
joints, and osteoarthritis of the distal tarsal joints.
Conclusions and Clinical Relevance—Horses used
for heading were most commonly affected by lameness
in the right forelimb. Horses used for heeling had
more bilateral hind limb lameness than horses used for
heading. (J Am Vet Med Assoc 2005;226:1694–1699)