Objective—To determine the effects of florfenicol
injection on the meat characteristics of the cervical
muscles in cattle.
Animals—100 steers (mean weight, 380 kg).
Procedure—In 50 calves, florfenicol (25 ml, twice)
was injected into the cervical muscles of 1 side of the
neck, and saline (0.9% NaCl) solution (25 ml, twice)
was injected into the cervical muscles of the other
side of the neck. In the remaining 50 calves, florfenicol
was injected into the cervical muscles of 1 side of
the neck, and nothing was injected into the cervical
muscles of the other side of the neck. Animals were
slaughtered 132 days later, and samples of the cervical
muscles were submitted for histologic evaluation
and measurement of shear forces.
Results—2 injection sites used in the present study
had extensive lesions, and both of these were sites
where florfenicol had been injected. However, histologic
scores for the florfenicol injection sites were not
significantly different from scores for the contralateral
saline solution injection sites and uninjected control
sites. In addition, shear force values were not significantly
different between sites in which florfenicol had
been injected and the contralateral sites.
Conclusion and Clinical Relevance—Results suggest
that few reactions should be expected with
injection of florfenicol into the cervical muscles in
steers and that reactions that do occur will consist
mainly of fibrosis and infiltration of adipose tissue.
However, shear force values, a measure of tenderness
of the meat, should not be affected. (Am J Vet
Objective—To identify factors associated with renal insufficiency in colic- or colitis-affected horses with high serum creatinine (SCr) concentrations evaluated at a referral hospital.
Design—Retrospective case series.
Animals—167 colic- or colitis-affected horses (88 represented a random sample [hospital population], and 79 had high SCr concentration at initial evaluation [study population]).
Procedure—Medical records were reviewed. Data collected included signalment; physical examination, clinicopathologic, and diagnostic findings; and outcome. The study population was categorized on the basis of whether SCr concentration did (AR group; n = 53) or did not (PA group; 26) normalize within 72 hours of fluid therapy. Characteristics of the study and hospital populations were compared.
Results—Males and Quarter Horses were significantly overrepresented in the study population. Compared with the hospital population, study-population horses were significantly more likely to have colitis, gastric reflux, and diarrhea at initial evaluation. Initial mean SCr concentration in the PA group was significantly higher than the AR group; identification of gastric reflux, abnormal rectal examination findings, and hypochloremia were significantly associated with persistent azotemia after 72 hours of fluid therapy. Compared with the AR group, PA group horses were 3 times as likely to die or be euthanized.
Conclusions and Clinical Relevance—In colic- or colitis-affected horses, factors associated with renal insufficiency included gastric reflux, abnormal rectal examination findings, or hypochloremia initially; prognosis for horses in which azotemia resolves within 72 hours of treatment appears to be better than for horses with persistent azotemia.
Objective—To characterize the prevalence of Mycoplasma bovis infection in backgrounding and stocker cattle operations and compare bacteriologic culture with PCR assay for detection of M bovis.
Design—Prospective descriptive study.
Animals—432 calves, 3 to 9 months old, from 9 operations.
Procedures—2 nasal swab specimens were collected from each calf. Swab specimens were evaluated via bacteriologic culture and PCR assay for organisms of the class Mollicutes and M bovis. Culture results were considered negative if no growth occurred within 21 days. Positive results were indicated by characteristic colony formation with PCR assay confirmation. Deoxyribonucleic acid was extracted from 1 swab specimen for direct PCR assay for Mollicutes and M bovis.
Results—Of 432 calves, 374 (87%) had positive results for Mollicutes via PCR assay and 63 (15%) via culture. Seven (2%) calves had positive results for M bovis via PCR assay and 10 (2%) via culture. Prevalence of Mollicutes at the farm level ranged from 54% to 100% via PCR assay and from 0% to 59% via culture. Prevalence of M bovis at the farm level ranged from 0% to 4% via PCR assay and from 0% to 6% via culture. Calves that shed M bovis were significantly more likely to have a fever than were calves that did not shed M bovis.
Conclusions and Clinical Relevance—M bovis was detected at a low level in recently purchased backgrounded and stocker calves in Georgia. Although slightly more infected calves were detected via culture and PCR assay together, PCR assay appeared to accurately identify M bovis at the farm level.
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)