Characterization of Pathogens in Holstein Calves with and without Bovine
Respiratory Disease
Knie,
B.1,
Williams,
J.E.1,
Neibergs,
H.M.1,
Sieverkropp,
K.D.1,
Scraggs,
E.R.1,
Wang,
This project was supported by National Research
Initiative competitive Grant no 2011-68004-30367
from the USDA National Institute of Food and Agriculture
Z.1,
Bovine Respiratory Disease Consortium2, Neibergs, H.L.1,
*Bovine Respiratory Disease Consortium also includes: J.E. Womack2, S. Aly4, A. Dabney2, S. Dindot2, M. Enns5, L. Falconer2, G. Fredricks1, L .Gershwin4, R.
Hagevoort6, S. Kerr1, S. McGuirk7, J. Neibergs1, L. Skow2, M. Thomas5, C. Tucker4, C. Van Tassell8, A. Zanella9
1Washington
State University, Pullman, WA; 2Texas A&M University, College Station, TX; 3University of Missouri, Columbia, MO; 4University of California, Davis, CA;
5Colorado State University, Forth Collins, CO; 6New Mexico State University, Albuquerque, NM; 7University of Wisconsin, Madison, WI; 8USDA-ARS, Beltsville, MD;
9Scottish Agricultural College, Edinburgh, Scotland
ABSTRACT
Time from Pathogen Sampling to BRD Diagnosis
100.0%
90.0%
80.0%
70.0%
60.0%
50.0%
40.0%
30.0%
20.0%
10.0%
0.0%
1st St. Deviation
4-22d
PM
yc
o
PM plas HS
/M ma
CV yco /MH
BR /M pla s
SV yco ma
/M pla
s
yc
op ma
la
sm
M
yc BR a
op S/
las MN
m
a/
H
PM S
/M
BR
PM H
SV
/M
PM /C
V
yc
op /BR
la
sm SV
a/
M
H
2nd St. Deviation
0-31d
M
M
yc
op
las
m
a
BR
SV
M
H
CV
Prevalence
Millions of dollars and animals are lost each year to Bovine Respiratory Disease (BRD). Bovine respiratory disease
consists of a complex of diseases that results when one or more viral, bacterial or mycoplasma pathogen(s) infect
an animal. Over twenty different pathogens are known to cause BRD. The objective of this study was to
characterize the pathogens present in animals that remained healthy to animals that were healthy when swabbed
but subsequently were diagnosed with BRD. Seventy-four pre-weaned (d1-d74 of age) Holstein calves housed at
a single facility in Hanford, CA were monitored before and after being diagnosed with BRD and compared to 1016
calves that remained healthy. The use of an established BRD calf-health scoring chart (McGuirk 2008) was used to
define animals with (score ≥6) or without (score <6) BRD. Mid-nasal and deep pharyngeal diagnostic swabs were
taken for each calf to characterize the pathogens present. These swabs were tested for bovine corona virus (CV),
bovine respiratory syncytial virus (BRSV), bovine viral diarrhea virus (BVDV), Manheimia haemolytica, Pasturella
multocida, Histophillus somni, and Mycoplasma spp. at the California Health and Food Safety Laboratory in Davis
and Tulare, CA. The prevalence of the pathogens in those animals that remained healthy (controls) compared to
animals that were subsequently diagnosed with BRD (BRD converters) was evaluated by c2. Calves began to
show signs of disease after 30d of age. The prevalence of BRSV with Manheimia haemolytica differed between
controls and BRD converters (p<0.05) suggesting that the presence of these two paired pathogens significantly
increases the likelihood that a pre-weaned Holstein calf will develop BRD.
Pathogen Present
Figure 2. The average time to BRD diagnosis after enrollment as a case
was 13 days (± 9d). Pathogens are represented if an animal had that
pathogen or pathogen pairing. Calves could be present in multiple
categories of pathogens.
INTRODUCTION
Bovine Respiratory Disease (BRD) is the most costly infectious disease in the cattle industry resulting in over one
million cattle deaths each year in the US. In spite of vaccination programs to prevent BRD, morbidity and
mortality from BRD continue to remain prevalent. Bovine corona virus (CV), bovine respiratory syncytial virus
(BRSV), bovine viral diarrhea virus (BVDV), Manheimia haemolytica (MH), Pasturella multocida (PM),
Histophillus somni (HS), and Mycoplasma spp. are among the most prevalent pathogens associated with BRD.
The prevalence of these pathogens were evaluated among healthy calves and calves diagnosed with BRD. This
study was undertaken as part of a larger study to identify BRD susceptibility loci.
OBJECTIVE
The objective of this study was to characterize the pathogens present in healthy and BRD diagnosed pre-weaned
Holstein calves at a common facility.
MATERIALS AND METHODS
Figure 1. Prevalence of pathogens in healthy Holstein calves (red symbols) and
those that were later diagnosed as cases (blue symbol) in days of age
(*p<0.05).
DISCUSSION
Ninety-three percent of calves that were enrolled as healthy pre-weaned calves remained healthy until
weaning. Of the 6.7% of calves that were subsequently diagnosed with BRD, most calves became ill
approximately 13d later. Calves that subsequently became ill differed in that they were more likely to be
infected with BRSV and M. haemolytica. As clinical signs follow 7-10 days post infection with BRSV an
M. haemolytica, it would not have been expected to detect a higher prevalence of a pathogen in animals
destined to become ill in 13 days. A second study has been completed where additional diagnostic
swabs and clinical diagnostic health scores were obtained at diagnosis of a healthy calf that was
subsequently diagnosed with BRD. These data will be compared with the results of the second study to
identify the level of commensal pathogens that are normal for pre-weaned Holstein calves.
Samples
• 2030 (941 BRD calves and 1089 healthy calves) pre-weaned (d1-73) Holstein calves were entered into the
study and categorized as a case or control based on a BRD calf-health scoring chart by evaluating their
rectal temperature, presence of cough, nasal discharge, eye discharge, and head and ear position (McGuirk
2008)
• Approximately 200,000 calves were monitored to obtain the study animals
• 73 of the healthy calves were later diagnosed with BRD
• 2 deep pharyngeal and 1 mid-nasal swab were taken to identify pathogens
• Testing for bacteria and viruses was done at the University of California, Davis in the Davis and Tulare
diagnostic labs
Analysis
• Comparison of pathogens and time to diagnosis were conducted of calves that remained healthy to calves
that were later diagnosed with BRD by Х2 (p<0.05)
• Averaged the days old at sampling and compared it to each pathogen
RESULTS
• Those animals that were later diagnosed with BRD were more likely to be infected with bovine respiratory
syncytial virus (BRSV) and M. haemolytica paired (p<0.05)
• Calves were diagnosed with BRD after 30d of age (Figure 1)
• Healthy calves that were subsequently diagnosed with BRD tended to be more likely to be infected with
mycoplasma than calves that remained healthy (p<0.1); Figure 2
BIBLIOGRAPHY
McGuirk SM. 2008. Disease management of dairy calves and heifers. Vet Clin NA: Food Anim Pract 24:139-153
CONCLUSION
• Diagnostic swabs from calves that were later diagnosed with BRD an average of 13d later were unlikely to
be informative as to the pathogens that were responsible for the BRD infection
• Age did not seem to play a role in the pathogen(s) an animal became infected with
• The pairing of BRSV and M. haemolytica were more prevalent in animals that later became infected with
BRD
• The number of days to BRD diagnosis was independent of the pathogens present when enrolled