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Preventing and minimizing disease
Overview incl. vaccine cycles
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D I S E A S E O F F O O D A N I M A L S A N D H O R S E D. O ’ T O O L E D E P T V E T S C I E N C E S P A T B 4 1 1 0
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Minimizing and controlling disease
1. Continuing education
2. Biosecurity
3. Genetics
4. Disinfectants
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5. Preconditioning
6. Using veterinarians
7. Using laboratories
8. Antibiotics
9. Anti-parasitic compounds
10. Vaccines
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Your continuing education
Good sources:
Your production records Neighbors/family Veterinarian Stock Growers/Wool Growers
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Industry publications Standard textbooks (e.g., Merck veterinary manual)
More iffy:
WWW
Vaccine, feed and drug manufacturers Use them but be skeptical
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Biosecurity
Closed herd insofar as possible Know what you buy Isolate sick/post-abortion animals Investigate/control unusual disease events When you or a neighbor has a wreck, learn from it Check incoming animals for diseases of concern
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Check incoming animals for diseases of concern Quarantine purchases Good fences Secure dead pile away from traffic areas Control trash and junk Address issues of concern: Toxic plants Toxic soils (selenium) Interactions with disease-vector wildlife and rodents
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Genetics
Select for stock that do well in your area:
Resistance to endemic infectious agents Acclimated to climate/geography
Care with inbreeding
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Pay attention to possible genetic disease:
Genetic: consistent “phenotype” Generally: present at birth (or abortion) - first year of life If purebred: breed society web pages/journals If AI, contact originator of semen Discuss with veterinarian: is it genetic? Bring to D-lab for workup 1/15/
Genetically engineered animals
6 Currently used for producing protein drugs for human use Potential for producing animals resistant to specific diseases
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Overseen by FDA No required label as transgenic 21% public does not want GE animals entering marketplace as food (2008)
a. Milk protein promoter DNA b. Therapeutic protein gene c. Terminator sequence d. Other DNA sequences
- Inactivate most harmful infectious agents
- Effectiveness depends on: –Type of organism (spores vs. bacterial vs. viral) –Organic material (milk, manure) inactivates disinfectants i i
Disinfectants 7
- Appropriate contact time + sufficient concentration –Use disinfectant with labeled effectiveness against agent
- Some commonly sold disinfectants ineffective –Types:
- Environmental surfaces – highly toxic
- Tissue contact – less toxic
- Excellent disinfectants: sunlight/air and quicklime 1/15/
Anti-parasitic drugs
Compounds that control parasitic infections:
Anthelmintics: nematodes (worms) Coccidiostats/coccidiocidal (coccidiosis) Topical or systemic compounds (lice)
Resistance in nematodes a growing problem
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Resistance in nematodes a growing problem
Usage:
Treatment of ill animals vs. entire herd Parasitic diseases tend to be HERD diseases Prevention: Dose on entry into feedlot Dose, then move Strategic use during season – e.g., at turnout, and/or in fall 1/15/
Vaccines
A safe form of infectious agent
Modified live vaccine (MLV) vs. inactivated (killed) vs. subunit products
Give strategically BEFORE risk period
In some diseases, you can vaccinate during outbreak
N % ff ti ( 8 % id d d)
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None 100% effective (~70-80% considered good)
“Herd immunity”
Huge choice – use veterinary advice
Less effective when animals stressed
Handle property:
Avoid mishandling (heat; cold; contamination)
Understand need and timing of boosters
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The two major vaccine types
MLV
“Attenuated” organisms
Better immune response
“Cold chain”
Inactivated
Generally safer
More expensive
More boosters
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Cold chain
Risks in pregnant animals
Generally better for viral
diseases
No “reversion to virulence”
Adjuvant issues
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Why vaccines fail
Disease outbreak due to agent different to one you vaccinated for Strain variation Some agents more than others (e.g., RNA viruses vs. DNA viruses) O h l i
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Overwhelming exposure Stress No vaccine 100% Assume ~80% of vaccinated animals protected Dependence on “herd immunity” If you suspect genuine vaccine failure, take it up with your veterinarian, biologics manufacturer, and/or USDA CVB
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Vaccines do not exist for all infectious agents 12
No vaccine (in USA):
TB and Johne’s Scrapie and BSE Caseous lymphadenitis (“thin ewe syndrome”) Tularemia
Vaccine controlled by USDA or state veterinarian:
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Brucellosis; FMD; BTV; anthrax
Too expensive to use for all stock:
Rabies
Small production runs:
Many sheep/goat vaccines
Of limited effectiveness:
EPM; foot rot; human stupidity
Using a D-laboratory
Work through veterinarian Bring representative samples of problem: Live terminally affected animal > freshly dead animal > field necropsy samples > rotten carcass Garbage in = garbage out Try to be patient – it often takes more than one carcass to
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y p sort out a problem, esp. abortions/perinatal death/CNS disease Use laboratory familiar with local problems/production systems Give a history – that guides the process List YOUR concerns If report does not make sense, talk to diagnostician (or have veterinarian do so) and discuss – that’s how we learn
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Take home
Most diseases in production animals: “endemic”:
Your job is keep a lid on them, not eliminate them You will see BRD before you see FMD or BSE
Biosecurity vaccination
Use time-tested practical approaches
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Use time tested practical approaches
Simpler is better Do what is practical and you can sustain over the years
Use effective tools, esp., disease/production
records, biosecurity, vaccination, veterinarians,
antibiotics, disinfectants, judicious lab testing,
good written records
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