Infectious Disease and Cow Removal

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Lecture Slides/Handout
The Handout for the slide set can be retrieved
by pulling up (or printing) the note page in
Power Point program .
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Infectious Disease and Cow Removal
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Infectious Disease and Cow Removal

• If a cow dies.
• Do we know if an infectious disease was involved?
• If so, which one(s)?
• Was it the primary or secondary cause?
• Carriers and Chronic Disease
• Contagious vs infectious
• Do we cull?

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If a cow dies and an infectious disease is
suspected

• Time and money will be invested (perhaps
  indefinitely) to
• Prevent (vaccinations, housing changes)
• Treat (feed additives)
• Monitor (routine tests)
• A diagnosis helps to make sure this time and
  money are well spent

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How to get a Diagnosis

• Herd Picture---panoramic view
• Housing
• Nutrition
• History of cow removal
• History of sick cows
• History of herd additions

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How to get a Diagnosis

• Physical exam
• Live animal diagnostic tests
• Serology BVD, IBR, BRSV, PI3, Johnes
• Fecal cultures Salmonella, E. coli, Johnes
• Milk culture Mycoplasma
• Fecal flotation Cryptosporidia, coccidia

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How to get a Diagnosis

• Post-mortem (Necropsy)
• Often can be the definitive answer
• Can be done on-farm
• Tissue samples collected by vet
• Fresh is critical
• Especially if trying to identify causative
  bacteria
• No diagnosis results occur

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Primary or Secondary Cause?

• Infectious diseases often occurs after primary
  cause
• Pasteurella pneumonia after viruses or transport
• Bacterial or protozoal diarrhea after viruses
• Poor colostrum feeding
• Poor transition into lactation (ketosis, DAs,
  fatty liver)
• Ultimately, must get to
  the real cause

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Chronic Cases

• Long term infections - dont cure
• Chronic case- continued clinical signs-
• Weight loss, poor gain, milk production, not
  breeding
• Probably should be culled
• Can rest as dry cow, but may blow-upat
  calving
• Disease Carriers
• Infected cow or heifer
• Not showing any clinical signs or performance
  loss
• ID from previous infection or diagnostic test
• Can still shed infectious agents
• Shedding can be intermittent
• Times of stress more consistent shedding calving
• Contagious vs. Infectious

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Chronic Cases

• Contagious vs. Infectious
• All pathogens (bacteria, viruses, parasites,
  protozoa are infectious can invade and multiply
  in host tissue, and cause damage
• Some infectious agents are contagious spread
  from one infected animal to another
• Some contagious agents are highly infectious and
  pose a greater risk to herd mates

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Important Chronic Infections
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Chronic InfectionsDo we cull?

• Factors to Consider
• Milk production of cow
• Growth of heifer
• Health of cow
• Repro status
• Is it terminal?
• Highly contagious?
• Is herd problem likely to be limited or continue
  to increase?
• eg, Mycoplasma often be limited after initial
  introduction
• BVD can be limited with vaccine

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Chronic InfectionsDo we cull?

• Cull
• Poor performers
• Animals that continue to display clinical signs
• Animals that will likely transmit disease to
  others including offspring
• It depends
• Carrier animals
• Productive cows
• Low risk to rest of herd/offspring
• Consider keeping but not breeding again

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Cull Chronic Animals?
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Summary Infectious Disease and Cow Removal

• If a cow is dies.
• Try to get a diagnosis to
• Know if an infectious disease was involved, and
  which one
• Was it the primary or secondary cause?
• Culling Chronic Cows
• Clinical signs cull
• Carrier animals- it depends