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.
A 3-year-old approximately 450-kg (990-lb) Quarter Horse gelding was referred to the University of Georgia's Large Animal Teaching Hospital because of fever, signs of depression, inappetence, extensive alopecia, and crusting of the skin of 1 month's duration. One month prior to referral, crusts and marked edema of the lower portions of the horse's limbs were evident. Cytologic examination of the moist underside of crusts taken from the skin of the lower aspects of the limbs performed at that time revealed infection with Dermatophilus congolensis. Appropriate systemic and topical treatments with antimicrobials, along with administration of NSAIDs, did
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)
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 study the local immune response of
calves to bovine respiratory syncytial virus (BRSV)
infection with emphasis on IgE production and
cytokine gene expression in pulmonary lymph.
Animals—Twelve 6- to 8-week-old Holstein bull
calves. Six similar control calves were mock infected
to obtain control data.
Procedure—Lymphatic cannulation surgery was performed
on 12 calves to create a long-term thoracic
lymph fistula draining to the exterior. Cannulated
calves were exposed to virulent BRSV by aerosol.
Lymph fluid collected daily was assayed for BRSV and
isotype-specific IgE antibody, total IgG, IgA, IgM, and
protein concentrations. Interleukin-4 (IL-4), interleukin-
2 (IL-2), and interferon-γ were semi-quantitated
by reverse transcription-polymerase chain reaction
(RT-PCR). Cell counts and fluorescence-activated cell
scanner (FACSCAN) analysis of T-cell subsets were
performed on lymph cells.
Results—Calves had clinical signs of respiratory tract
disease during days 5 to 10 after infection and shed
virus. Bovine respiratory syncytial virus-specific IgE in
infected calves was significantly increased over baseline
on day 9 after infection. Mean virus-specific IgE
concentrations strongly correlated with increases in
severity of clinical disease (r = 0.903). Expression of
IL-2, IL-4, and interferon-γ was variably present in
infected and control calves, with IL-4 expression
most consistent during early infection.
Conclusions and Clinical Relevance—Infection with
BRSV was associated with production of BRSV-specific
IgE, and IL-4 message was commonly found in
lymph cells of infected calves. This finding supports
the concept that BRSV-induced pathophysiology
involves a T helper cell type-2 response. Effective
therapeutic and prophylactic strategies could, therefore,
be developed using immunomodulation to shift
the immune response more toward a T helper cell
type-1 response. (Am J Vet Res 2000;61:291–298)
Objective—To identify herd-level risk factors for bovine respiratory disease (BRD) in nursing beef calves.
Design—Population-based cross-sectional survey.
Sample—2,600 US cow-calf producers in 3 Eastern and 3 Plains states.
Procedures—The associations of herd characteristics with BRD detection in calves and cumulative BRD treatment incidence were determined.
Results—459 (177%) surveys were returned and met the inclusion criteria; 48% and 52% of these surveys were completed by producers in Plains and Eastern states, respectively. Mean (95% confidence interval) number of animals in herds in Plains and Eastern states were 102 (77 to 126) and 48 (40 to 56), respectively. Bovine respiratory disease had been detected in ≥ 1 calf in 21% of operations; ≥ 1 calf was treated for BRD and ≥ 1 calf died because of BRD in 89.2% and 46.4% of operations in which calf BRD was detected, respectively. Detection of BRD in calves was significantly associated with large herd size, detection of BRD in cows, and diarrhea in calves. Calving season length was associated with BRD in calves in Plains states but not Eastern states. Cumulative incidence of BRD treatment was negatively associated with large herd size and examination of cows to detect pregnancy and positively associated with calving during the winter, introduction of calves from an outside source, offering supplemental feed to calves, and use of an estrous cycle synchronization program for cows.
Conclusions and Clinical Relevance—Results of this study indicated factors associated with calf BRD risk; modification of these factors could potentially decrease the incidence of BRD in nursing calves.
OBJECTIVE To determine herd-level risk factors for bovine respiratory disease (BRD) in nursing beef calves.
DESIGN Matched case-control study.
SAMPLE 84 cow-calf operations in Nebraska, North Dakota, and South Dakota.
PROCEDURES Case herds were herds that treated at least 5% of the calf crop for BRD prior to weaning. Control herds were herds that treated < 0.5% of the calf crop for BRD prior to weaning. Each case herd was matched with 2 control herds on the basis of veterinary practice and enrollment year. Herd owners or managers were interviewed by telephone, and characteristics and practices associated with case status were determined by multivariable conditional logistic regression.
RESULTS 30 case herds and 54 control herds were evaluated. Increasing herd size, frequent pasture movement for intensive grass management (intensive grazing), and use of estrus-synchronization programs were significantly associated with herd status. The odds of being a case herd for herds with 150 to 499 cows was 7.9 times and that for herds with ≥ 500 cows was 12 times, compared with the odds of being a case herd for herds with < 150 cows. The odds of being a case herd for herds that used intensive grazing was 3.3 times that for herds that did not use intensive grazing. The odds of being a case herd for herds that used an estrus-synchronization program was 4.5 times that for herds that did not use an estrus-synchronization program.
CONCLUSIONS AND CLINICAL RELEVANCE Management practices can be associated with an increase in the BRD incidence in nursing beef calves. Modification of management practices may decrease BRD incidence in nursing calves for herds in which it is a problem.
Objective—To test the hypothesis that feedlot cattle
with acute interstitial pneumonia (AIP) have bacterial
infection of the lung or liver and concurrent bovine
respiratory syncytial virus (BRSV) infection significantly
more often than pen mates without AIP.
Animals—39 feedlot cattle with signs consistent
with AIP and no history of treatment with antimicrobials
and 32 healthy control cattle from the same
Procedure—Lung and liver specimens were
obtained postmortem for bacterial or mycoplasmal
culture and histologic examination; lung tissue was
assessed for BRSV infection immunohistochemically.
Results—Among affected cattle, 26 had AIP confirmed
histologically. Lung tissue from 11 cattle with
AIP yielded microbial respiratory tract pathogens on
culture; tissues from control animals yielded no
microbial growth. In 4 cattle with AIP and 2 control
animals, liver abscesses were detected; bacteria
were isolated from abscessed tissue in 3 and 1 of
those animals, respectively. Immunohistochemically,
9 cattle with AIP and no control animals were BRSV-positive.
Histologically, 9 AIP-affected cattle had only
acute alveolar damage with exudation, and the other
17 had acute exudation with type II pneumocyte
hyperplasia. No lesions of AIP were detected in control
animals. Only 4 AIP-affected cattle had bacterial
infection of the lung with concurrent BRSV infection.
Conclusions and Clinical Relevance—Results indicated
that microbial respiratory tract pathogens are
more common in cattle with AIP than in healthy pen
mates. Control of bacterial pneumonia late in the
feeding period may reduce the incidence of AIP at
feedlots where AIP is a problem. (Am J Vet Res 2004;65:1525–1532)
Objective—To compare immune responses following modified-live virus (MLV) vaccination at weaning after intranasal or SC administration of an MLV vaccine to beef calves at 2 or 70 days of age.
Procedures—Calves were allocated to 1 of 5 groups. The IN2 (n = 37) and IN70 (37) groups received an MLV vaccine containing bovine herpesvirus 1 (BHV1), bovine viral diarrhea virus (BVDV) types 1 and 2, bovine respiratory syncytial virus (BRSV), and parainfluenza 3 virus intranasally and a Mannheimia haemolytica and Pasteurella multocida bacterin SC at median ages of 2 and 70 days, respectively. The SC2 (n = 36) and SC70 (37) groups received a 7-way MLV vaccine containing BHV1, BVDV1, BVDV2, BRSV, parainfluenza 3 virus, M haemolytica, and P multocida SC at median ages of 2 and 70 days, respectively; the control group (37) remained unvaccinated until weaning. All calves received the 7-way MLV vaccine SC at median ages of 217 (weaning) and 231 days. Serum neutralizing antibody (SNA) titers against BHV1, BVDV1, and BRSV and intranasal IgA concentrations were determined at median ages of 2, 70, 140, 217, and 262 days. Cell-mediated immunity (CMI) against BHV1, BRSV, BVDV1, and P multocida was determined for 16 calves/group.
Results—At median ages of 140 and 217 days, BVDV1 SNA titers were significantly higher for the SC70 group than those for the other groups. Intranasal IgA concentrations and CMI increased over time for all groups. Vaccination at weaning increased SNA titers and CMI in all groups.
Conclusions and Clinical Relevance—SC administration of an MLV vaccine to 70-day-old calves significantly increased BVDV1 antibody titers before weaning.