1. Unit 13: General Animal Diseases

2. Unit 13: General Animal Diseases
Blackleg
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
Most common from 4 mos to 2 yrs

3. Unit 13: General Animal Diseases
Cause
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
May die suddenly without symptoms
Death usually w/in hrs
Sudden, high fever
Labored breathing, lameness

4. Unit 13: General Animal Diseases
Swelling in heavily muscled areas
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

5. Unit 13: General Animal Diseases
Prevention
Calves
Vaccinate twice at 2 wk intervals
Between 2 & 6 mos of age
Revaccination may be warranted in high risk areas each year
Sheep
In high risk areas: vaccinate every 2-4 wks prior to shearing, castrating, docking

6. Unit 13: General Animal Diseases
Do not open carcasses of suspected blackleg deaths
Burn where they die, if possible
Treatment
If caught early, high doses of penicillin
Best control is w/ vaccination

7. Unit 13: General Animal Diseases
Swine Erysipelas
Infectious disease affecting swine of all ages
Most common in young & growing pigs
Occurs in a variety of forms
Can result in large death losses
Most economic losses caused by chronic form
General unthriftiness and poor performance
Can affect other animals & humans
May cause economic losses in turkeys & sheep

8. Unit 13: General Animal Diseases
Cause
Bacterial infection
Highly resistant to natural means of eradication
Lives and reproduces in alkaline soils
Can survive in dead carcasses > 1yr
Spreads by direct contact
Often introduced to a herd through breeding stock or feeder purchases

9. Unit 13: General Animal Diseases
Clinical signs
Three forms:
Acute
Sudden death of 1 or more animals
Very high fever
Appetite affects vary
Vomitting
Skin blotchiness
Severe joint pain

10. 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

11. Unit 13: General Animal Diseases
Prevention
Sound herd health management
Biosecurity
Vaccination program
Killed or MLV
Revaccinate breeding stock twice/yr
Treatment
Acute form: treat w/ most any form of antibiotic (penicillin, oxytetracycline, tylosin, chlorotet.)
No practical treatment for chronic form

12. Unit 13: General Animal Diseases
Johne’s Disease
Aka paratuberculosis
Primarily occurs in ruminants
Increasing importance in the U.S.
Emerging as a significant economic disease
Herds w/ 10% infection rate – lose ~$230/cow/yr
From decreased production of subclinical cows

13. Unit 13: General Animal Diseases
Cause
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

14. Unit 13: General Animal Diseases
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
Clinical Signs
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
Prevention
Don’t permit feeding utensils to come in contact w/ manure
Tractors, skid loaders, etc.
Separate calves from their mother ASAP
Feed only colostrum from negative test cows
Don’t use pooled colostrum

16. Unit 13: General Animal Diseases
Feed milk replacer or used a pasteurizer instead of waste milk
House calves away from cow manure areas to prevent cross-contamination
Treatment
No cure available
Some drug therapies can prolong life and improve body condition, but doesn’t eradicate disease

17. Unit 13: General Animal Diseases
Dangers of Johne’s
Questions of infections passing to humans
How could it be transmitted?
What is the related human disease?
What effect could this have on the dairy industry?