Objective—To identify risk factors for rectal tears in horses; assess the effect of initiating cause on tear location, size, and distance from anus; and determine short-term survival rate among horses with various grades of rectal tears.
Design—Retrospective case series.
Procedures—Medical records for horses with a rectal tear were reviewed, and data including age; sex; breed; cause, location, and size of the tear and its distance from the anus; tear grade; treatment; and outcome (short-term survival [ie, survival to discharge from the hospital] vs nonsurvival) were recorded. Data for age, sex, and breed of horses with rectal tears were compared with data for all horses evaluated at the hospital during the same interval to determine risk factors for rectal tears.
Results—Arabians, American Miniature Horses, mares, and horses > 9 years of age were more likely to develop a rectal tear than other breeds, males, or younger horses. Dystocia had a significant influence on rectal tear size. Location of a rectal tear and its distance from the anus were not associated with cause. Applied treatments for grade 1, 2, and 3 rectal tears were effective, unlike treatments for grade 4 rectal tears. Irrespective of treatment, the overall short-term survival rate among horses with grade 1, 2, 3, and 4 rectal tears was 100%, 100%, 38%, and 2%, respectively.
Conclusions and Clinical Relevance—Accurate identification of risk factors could help practitioners and owners implement adequate measures to prevent the development of rectal tears in horses.
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 characterize cytokine messenger RNA
(mRNA) expression in intranasally vaccinated calves
after bovine respiratory syncytial virus (BRSV) challenge.
Animals—Twelve 8- to 12-week-old calves.
Procedures—Calves received modified-live BRSV vaccine
(vaccinated) or spent tissue culture medium
(mock-vaccinated) intranasally, followed by challenge
30 days later with BRSV, or mock challenge with spent
tissue culture medium (mock-challenge controls).
Interleukin-4 (IL-4) and interferon-γ (IFN-γ) mRNA was
measured in lungs, bronchoalveolar lavage (BAL) fluid
cells, pharyngeal tonsils, and tracheobronchial lymph
nodes, and tumor necrosis factor-α (TNF-α) mRNA was
measured in lungs and BAL fluid cells by reverse transcriptase-competitive
polymerase chain reaction assay.
Results—Resistance to clinical signs of disease was
conferred in vaccinated calves. Expression of TNF-α
mRNA in lungs and BAL fluid cells was higher in
mock-vaccinated calves than control or vaccinated
calves. In the lung, IL-4 mRNA expression was higher
in vaccinated calves than control or mock-vaccinated
calves. In pharyngeal tonsils, expression of mRNA for
IL-4 and IFN-γ was higher in mock-vaccinated calves
than control calves. In tracheobronchial lymph nodes,
IFN-γ mRNA expression was higher in mock-vaccinated
calves than vaccinated calves.
Conclusions and Clinical Relevance—Although vaccinated
calves had decreased clinical signs of disease after
BRSV challenge, compared with mock-vaccinated calves,
this difference was not related to a T helper type 1 bias,
as determined by increased expression of interferon-γ
mRNA relative to interleukin-4 mRNA in lungs, BAL fluid
cells, or tracheobronchial lymph nodes of vaccinated
calves. Pulmonary inflammation was decreased in vaccinated
calves as determined by decreased expression of
TNF-α mRNA. (Am J Vet Res 2004;65:725–733)
Objective—To determine whether a single intranasal
dose of modified-live bovine respiratory syncytial
virus (BRSV) vaccine protects calves from BRSV challenge
and characterize cell-mediated immune
response in calves following BRSV challenge.
Animals—13 conventionally reared 4- to 6-week-old
Procedure—Calves received intranasal vaccination
with modified live BRSV vaccine (VC-group calves;
n = 4) or mock vaccine (MC-group calves; 6) 1 month
before BRSV challenge; unvaccinated control-group
calves (n = 3) underwent mock challenge. Serum
virus neutralizing (VN) antibodies were measured on
days –30, -14, 0, and 7 relative to BRSV challenge;
nasal swab specimens were collected for virus isolation
on days 0 to 7. At necropsy examination on day 7,
tissue specimens were collected for measurement of
BRSV-specific interferon gamma (IFN-γ) production.
Tissue distribution of CD3+ T and BLA.36+ B cells
was evaluated by use of immunohistochemistry.
Results—The MC-group calves had significantly higher
rectal temperatures, respiratory rates, and clinical
scores on days 5 to 7 after BRSV challenge than VCgroup
calves. No difference was seen between distributions
of BRSV in lung tissue of VC- and MC-group
calves. Production of BRSV-specific IFN-γ was
increased in tissue specimens from VC-group calves,
compared with MC- and control-group calves. Virusspecific
IFN-γ production was highest in the mediastinal
lymph node of VC-group calves. Increased numbers
of T cells were found in expanded bronchialassociated
lymphoid tissue and airway epithelium of
Conclusions and Clinical Relevance—An intranasal
dose of modified-live BRSV vaccine can protect calves
against virulent BRSV challenge 1 month later. ( Am J Vet Res 2004;65:363–372)
Objective—To compare the results of regulatory
screening and confirmation assays with those of highperformance
liquid chromatography (HPLC) in the
detection of ceftiofur metabolites in the tissues of
culled dairy cattle.
Animals—17 lactating Holstein dairy cows.
Procedure—Daily IM injections of ceftiofur sodium
were administered at a dose of 2.2 mg of ceftiofur
equivalents/kg (n = 6) or 1.0 mg of ceftiofur equivalents/kg (10) for 5 days. Following withdrawal times of
12 hours (high-dose ceftiofur) and either 5 or 10 days
(low-dose ceftiofur), cows were slaughtered and liver,
kidney, and diaphragmatic muscle specimens were
harvested and analyzed by HPLC and standard regulatory
methods that included the following assays:
the swab test on premises, the fast antimicrobial
screen test, the calf antibiotic and sulfa test, and the
7-plate bioassay confirmation test.
Results—In all tissue specimens, residues of ceftiofur
and desfuroylceftiofur-related metabolites, as
measured by HPLC, were less than regulatory tolerance,
as defined by the FDA. False-positive screening
assay results were more likely for tissue specimens
that had been frozen for shipment to a federal laboratory,
compared with fresh tissue specimens that
were assayed at the slaughter establishment (23% vs
3% false-positive results, respectively).
Conclusions and Clinical Relevance—The observation
that fresh tissues had negative results on screening
assays, whereas subsets of the same tissue specimens
had false-positive results on screening assays
following freezing, suggests that freezing and thawing
interferes with microbial inhibition-based regulatory
screening assays. (Am J Vet Res 2004;65:1730–1733)
Objective—To estimate spatial risks associated with
mare reproductive loss syndrome (MRLS) during
2001 among horses in a specific study population and
partition the herd effects into those attributable to
herd location and those that were spatially random
and likely attributable to herd management.
Animals—Pregnant broodmares from 62 farms in 7
counties in central Kentucky.
Procedure—Veterinarians provided the 2001 abortion
incidence proportions for each farm included in the
study. Farms were georeferenced and data were analyzed
by use of a fully Bayesian risk-mapping technique.
Results—Large farm-to-farm variation in MRLS incidence
proportions was identified. The farm-to-farm
variation was largely attributed to spatial location
rather than to spatially random herd effects
Conclusions and Clinical Relevance—Results indicate
that there are considerable data to support an
ecologic cause and potential ecologic risk factors for
MRLS. Veterinary practitioners with more detailed
knowledge of the ecology in the 7 counties in
Kentucky that were investigated may provide additional
data that would assist in the deduction of the
causal factor of MRLS via informal geographic information
systems analyses and suggest factors for
inclusion in further investigations. (Am J Vet Res 2005;66:17–20)
To determine whether muscle-sparing laryngoplasty results in fewer changes in swallowing function compared to standard surgical treatment for laryngeal paralysis.
12 clinically normal sexually intact male Beagles.
Group A dogs (n = 4) had a standard approach to the larynx, with left arytenoid cartilage lateralization. Group B dogs (n = 4) had a muscle-sparing laryngoplasty performed with the thyropharyngeus muscle fibers bluntly separated, and the cricoarytenoideus dorsalis muscle spared. Pre- and 24-hour postoperative fluoroscopic swallowing studies were performed and graded. Larynges were harvested after humane euthanasia, and glottic area was measured. Group C dogs (n = 4) acted as controls, with surgical dissection ending lateral to the thyropharyngeus muscle, arytenoid lateralization not performed, and the dogs not euthanized. The study was performed between October 15, 2011 and May 15, 2021.
Changes in pharyngeal and upper esophageal sphincter function were not detected in any group. There was no difference in glottic area between treatment groups. Aspiration of liquid was not a consistent finding. Two dogs in each treatment group developed moderate to severe cervical esophageal paresis. This did not occur in control dogs.
We found no evidence to support our hypothesis that muscle-sparing laryngoplasty results in less severe changes in swallowing function compared to a standard technique. The cervical esophageal paresis identified in both treatment groups could increase the risk of postoperative aspiration pneumonia in dogs treated for laryngeal paralysis via a lateral approach to the larynx. Further study to determine the frequency, cause, and duration of esophageal dysfunction is warranted.
Objective—To determine the safety and short-term efficacy of intrabursal administration of botulinum toxin type B (BTXB) to alleviate lameness in horses with degenerative injury to the podotrochlear apparatus (PA).
Animals—10 Quarter Horses with degenerative injury to the PA.
Procedures—Degenerative injury to the PA was confirmed with diagnostic analgesia and imaging. Then, BTXB (3.8 to 4.5 U/kg) was injected into the podotrochlear (navicular) bursa of each horse. Three horses were used in a safety evaluation. Subsequently, video recordings of lameness evaluations were obtained for 7 client-owned horses 5 days before (baseline) and 7 and 14 days after BTXB treatment and used to determine the effect of BTXB injection on lameness; 1 horse was removed from the study 8 days after BTXB treatment. Three investigators who were unaware of the treated forelimbs or time points separately reviewed the recordings and graded the lameness of both forelimbs of the horses.
Results—Improvement in lameness of the treated forelimbs was detected at 1 or both time points after BTXB administration in all horses. However, all horses had some degree of lameness at the end of the study. Two horses developed transient increases in lameness 48 to 72 hours after treatment; lameness resolved uneventfully.
Conclusions and Clinical Relevance—Intrabursal injection of BTXB temporarily alleviated chronic lameness in horses with degenerative injury to the PA, without causing serious short-term adverse effects. Further investigation into the potential use of BTXB in horses affected by degenerative injury to the PA is warranted.
Objective—To determine the incidence of equine herpesvirus-1 (EHV-1) infection among Thoroughbreds residing on a farm on which the virus was known to be endemic.
Design—Prospective cohort study.
Animals—10 nonpregnant mares, 8 stallions, 16 weanlings, 11 racehorses, and 30 pregnant mares and their foals born during the 2006 foaling season.
Procedures—Blood and nasopharygeal swab samples were collected every 3 to 5 weeks for 9 months, and placenta and colostrum samples were collected at foaling. All samples were submitted for testing for EHV-1 DNA with a PCR assay. A type-specific EHV-1 ELISA was used to determine antibody titers in mares and foals at birth, 12 to 24 hours after birth, and every 3 to 5 weeks thereafter.
Results—Results of the PCR assay were positive for only 4 of the 1,330 samples collected (590 blood samples, 590 nasopharyngeal swab samples, 30 placentas, and 30 colostrum samples), with EHV-1 DNA detected in nasal secretions from 3 horses (pregnant mare, stallion, and racehorse) and in the placenta from 1 mare. Seroconversion was detected in 3 of 27 foals during the first month of life.
Conclusions and Clinical Relevance—Results suggested that there was a low prevalence of EHV-1 infection among this population of Thoroughbreds even though the virus was known to be endemic on the farm and that pregnant mares could become infected without aborting. Analysis of nasopharyngeal swab samples appeared to be more sensitive than analysis of blood samples for detection of EHV-1 DNA.