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An Outbreak of Viral Respiratory Disease in an Ontario Dairy Herd. Jenna Donaldson OVC 2013. http://www.sciencedaily.com/releases/2010/06/100607065902.htm. Case History. Signalment Holstein herd milking 53 cows Presenting Complaint Whole herd off feed. Herd Management. Barn design
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An Outbreak of Viral Respiratory Disease in an Ontario Dairy Herd Jenna Donaldson OVC 2013 http://www.sciencedaily.com/releases/2010/06/100607065902.htm
Case History • Signalment • Holstein herd milking 53 cows • Presenting Complaint • Whole herd off feed
Herd Management • Barn design • Nutrition • Total mixed ration • Vaccine protocol • MLV • Biosecurity • No showing animals, heifers raised on farm Schematic of Barn Layout
Background • Above-average maximum daily temperature and relative humidity prior to initial farm visit June 2012 Initial farm visit http://kitchenerwaterloo.weatherstats.ca/charts/relative_humidity-1year.html http://climate.weatheroffice.gc.ca/climateData/generate_chart_e.html?timeframe=2&Prov=ONT&StationID=48569&dlyRange=2010-04-18|2012-11-13&Year=2012&Month=6&type=line&MeasTypeID=maxtemp&Day=13
Initial Investigation • Water • No changes • Feed • New 1st cut haylage fed for 4 days • Gradual decrease in feed intake over 3 days • Mold contamination of high-moisture corn http://www.kosvi.com/courses/vpat5215_1/vpat5310/
Herd Exam Milking cows slightly dull Mild tachypnea w/ normal respiratory effort Increased mucoid nasal discharge 40% of herd scouring Many cows pyrexic Rumen motility normal to decreased Not interested in TMR No mucosal lesions noted
Viral Respiratory Disease Differentials • Bovine coronavirus • Parainfluenza-3 • Infectious bovine rhinotracheitis • Bovine respiratory syncytial virus • Bovine viral diarrhea
Bovine Coronavirus • Pneumoenteric virus • Fecal-oral and aerosol transmission • Subclinical infection • 3 common clinical syndromes • Respiratory disease typically mild
Initial Management • Vaccinated all animals with intranasal IBR/BRSV/PI-3 modified-live vaccine
Lab Diagnostics for Respiratory Disease • Polymerase chain reaction (PCR) and/or virus isolation • Nasal swabs from live animals • Fecal samples (useful for bovine coronavirus) • Postmortem: URT tissue, lung, lymph nodes, liver • Virus neutralization (serum) • Histology on postmortem tissues
Laboratory Diagnostics • Bovine coronavirus titres • Acute and convalescent samples (14 days apart) • Virus neutralization at AHL • Four cows tested • No clear demonstration of seroconversion
Prevention and Management Nutrition and silo management Ventilation and barn design Vaccination program Biosecurity
Herd Outcome Initial farm visit Milk production returned to normal in ~14 days One abortion at 60 days gestation
Cost to Producer • Veterinary costs: ~$1600 • Professional time and products (intranasal vaccine, anti-inflammatory, antimicrobials) • Estimated lost milk: ~$4100 • Laboratory diagnostics • Coronavirus titres x 4 cows: $150 • Full respiratory serology panel: $120 /cow
Acknowledgements • Dr. Ray Reynen • Heartland Veterinary Services • Dr. Jessica Gordon http://rocksolidnutrition.wordpress.com/category/dairy/