Transcript Unit 13: General Animal Diseases

Unit 13: General
Animal Diseases
Unit 13: General Animal Diseases
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Blackleg
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Acute, highly contagious, febrile, non-contagious
Affects cattle & sheep
Most common in Midwestern, Southern, and
Western U.S. (where cattle are on grass)
Affects all ages
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Most common from 4 mos to 2 yrs
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Cause
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Caused by anaerobic bacteria Clostridium
Ingestion of spores from contaminated pastures
Spores enter blood system from digestive tract
and colonize in muscle tissues
Clinical Signs
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May die suddenly without symptoms
 Death usually w/in 12-36 hrs
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Sudden, high fever
Labored breathing, lameness
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Swelling in heavily muscled areas
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Neck
Loin
Legs
First hot and painful
Become cold, painless, and filled w/ gas
Pressure to skin results in crackling sound
Carcasses bloat & decompose quickly
Very infectious in sheep
 Ultra-high temperature
 Recoveries are rare
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Prevention
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Calves
 Vaccinate twice at 2 wk intervals
 Between 2 & 6 mos of age
 Revaccination may be warranted in high risk areas each
year
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Sheep
 In high risk areas: vaccinate every 2-4 wks prior to
shearing, castrating, docking
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Do not open carcasses of suspected blackleg
deaths
 Burn where they die, if possible
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Treatment
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If caught early, high doses of penicillin
Best control is w/ vaccination
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Swine Erysipelas
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Infectious disease affecting swine of all ages
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Occurs in a variety of forms
Can result in large death losses
Most economic losses caused by chronic form
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Most common in young & growing pigs
General unthriftiness and poor performance
Can affect other animals & humans
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May cause economic losses in turkeys & sheep
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Cause
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Bacterial infection
Highly resistant to natural means of eradication
Lives and reproduces in alkaline soils
 Can survive in dead carcasses > 1yr
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Spreads by direct contact
Often introduced to a herd through breeding stock
or feeder purchases
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Clinical signs
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Three forms:
 Acute
 Sudden death of 1 or more animals
 Very high fever
 Appetite affects vary
 Vomitting
 Skin blotchiness
 Severe joint pain
Unit 13: General Animal Diseases
 Subacute
 Less severe symptomology
 Some skin lesions
 Course of the disease is much shorter
 Chronic form
 Causes most dramatic physical changes
 Lose portions of their skin, tail, ears, feet
 Dark, firm skin lesions leaving ugly scars
 Stiff, swollen, painful joints
 Lameness in one or more legs
 Bacteria localizes in joints and/or heart valves
Unit 13: General Animal Diseases
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Prevention
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Sound herd health management
 Biosecurity
 Vaccination program
 Killed or MLV
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Revaccinate breeding stock twice/yr
Treatment
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Acute form: treat w/ most any form of antibiotic
(penicillin, oxytetracycline, tylosin, chlorotet.)
No practical treatment for chronic form
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Johne’s Disease
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Aka paratuberculosis
Primarily occurs in ruminants
Increasing importance in the U.S.
Emerging as a significant economic disease
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Herds w/ 10% infection rate – lose ~$230/cow/yr
 From decreased production of subclinical cows
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Cause
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Bacterial infection caused by Mycobacterium
paratuberculosis
Ingestion of organism in contaminated milk, feed,
water
Nursing calves born to infected mothers have high
risk for infection
Organism is shed in extremely high numbers from
infected animals before clinical symptoms
 Fecal contamination considered to be #1 mode of
infection
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Animals up to 6 mos most susceptible for infection
Bacteria enters the S.I. tissue
Diagnosis through ELISA blood test, or fecal
culture
 Can easily have false negative tests due to low
shedding numbers and low antibody levels early in life
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Clinical Signs
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Persistent diarrhea, unresponsive to treatment
Maintain good appetite
Rapid weight loss, w/ no fever
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Disease often doesn’t become evident until 3-5
yrs of age
 Only subtle symptoms may be apparent earliers
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Prevention
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Don’t permit feeding utensils to come in contact w/
manure
 Tractors, skid loaders, etc.
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Separate calves from their mother ASAP
Feed only colostrum from negative test cows
 Don’t use pooled colostrum
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Feed milk replacer or used a pasteurizer instead
of waste milk
House calves away from cow manure areas to
prevent cross-contamination
Treatment
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No cure available
Some drug therapies can prolong life and improve
body condition, but doesn’t eradicate disease
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Dangers of Johne’s
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Questions of infections passing to humans
 How could it be transmitted?
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What is the related human disease?
What effect could this have on the dairy industry?