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
13.
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
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