important veterinary disease

1. Blackleg Disease
(Black quarter)
Chorray Maar

2. Definition
 acute, infectious, non-contagious, febrile
 cattle and sheep
 Myositis—upper part of leg
 emphysematous swelling

3. Etiology
 Clostridium chauvoei
 gram positive, spore forming, rod shaped
 spores resistant to environmental changes and
disinfectants
 persist in soil for years

4. Route of Infection
 Ingested spores
 pass wall of GI tract/erupting teeth
 access to bloodstream
 deposited in muscle and other tissues (spleen, liver,
and alimentary tract)
 remain dormant indefinitely

5. Occurrence
• Worldwide
• When disease occurs number of animals affected
• Enzootic in particular areas
• Group of farms to individual in field
• case fatality rate 100%
• seasonal—warm months
• Excavation of soil

6. Risk factors
Cattle
infection is endogenous
 Lesions without history of
wounds
bruising or excessive exercise
precipitate disease
Most cases in cattle 6–24 m
old
calves as young as 6 wk
cattle as old as 10–12 yr
Sheep
always result of
wound infection
shearing cuts,
docking, crutching, or
castration
Navel wound
Lambing injuries
Fighting injuries
After Vaccination

7. Pathogenesis
 Spores by ingestion intestinal mucosa blood circulation
skeletal muscles and remain dormant
 Muscular fatigue or trauma to the muscle
 Producing anaerobic conditions
 Spores activate, proliferate, produce toxins
 necrotizing myositis / toxemia
 Toxins --- capillary damage, hemorrhagic edema and necrosis
 Gas production------gangrene and toxemia .

8. Clinical Findings
 Sever lameness
 Pronounced swelling of upper part of leg
 Depression
 Complete anorexia
 Ruminal stasis
 High temperature and pulse rate

9. Clinical Findings
 Early stages --- swelling hot and painful
 Later--- cold and painless
 Edematous and emphysematous
 Crepitation on palpation
 Discolored, dry and cracked skin

10. Clinical Findings
 Lesions on base of tongue, heart muscles,
diaphragm, brisket, udder
 Condition develops rapidly
 Death12-36 hrs after appearance of signs
 deaths without signs / clostridial cardiac myositis

11. Diagnosis
 Clinical signs
 No constant changes in hemogram and serum
chemistry
 Demonstration of organism
 Samples: Muscle in air tight container
Air dried impression smears
 PCR

12. Necropsy findings
 Lying on the side with the affected hind limb stuck
out stiffly---characteristic position
 Bloating and putrefaction occurs quickly
 Blood stained froth from nostrils and anus
 Incision ---- dark red to black swollen tissue with
rancid odor---gas bubbles

14. Black leg. Dark-red skeletal
muscle of a heifer showing
hemorrhage, necrosis, edema
and emphysema.
: Black leg disease. Heart muscle
showing dark red hemorrhagic and
emphysematous

15. 15http://w3.vet.cornell.edu/nst/nst.asp?Fun=Image&imgID=1404
Dark red to black of muscle often with a distinct odor of sour milk

16. 16

17. False blackleg
 C. septicum and C. novyi
 Mixed infection C. chouvoei and C. septicum

18. Differential diagnosis
 Malignant edema
 Anthrax
 Lightning stroke
 Bacillary hemoglobinuria

19. Treatment
 Penicillin--- Large doses (40,000IU/kg BW)
 Surgical debridement of the lesion including
fasciotomy
 Recovery rate is low
 Blackleg antiserum

20. Control
 Vaccination in enzootic areas
 Booster vaccination
 Prior to anticipated danger period

21. Control
 Maternal immunity --- 3 months
 In outbreak ---vaccinate unaffected animals
 Penicillin at 10000IU/kg BW IM
 Carcasses destroyed by burning or deep burial