Black Quarter
Syn: Black leg, Choary Mar, Quarter ill.
Clostridial myonecrosis, acute, fetal, emphysematous
myonecrosis. It is an acute bacterial disease caused by”Clostridium chauvoe”.
Epidemiology
This disease is more common in cattle and sheep. It is mild
in nature in buffaloes and goats. The common age is 6 month – 2 years. In case
of sheep, all ages are equally susceptible. It is commonly seen in season of
summer and fall. It is most common in well fed animal as compared to
mal-nourished animals. It also severe in nature in cross bred animals.
Black quarter disease can cause mortality in cattle and
sheep in hilly and sandy areas of Pakistan. It is endemic in hilly areas. Why
it become endemic because contaminated pasture and soil is responsible for it.
As spore of bacteria is very much resistant, therefore it is also seen in wet
bottom land where flood is common.
Etiology
Clostridium chauvoei – Gram positive, strictly
anaerobic bacillus, spore forming bacteria
Clinical Signs
In Cattle:
i)
High grade fever
ii) Gaseous
swelling under the skin. Primarily in the area of quarter , shoulder, flank,
chest and neck.
iii) Limping,
stiffening
iv) Lack
of appetite, as swelling become painful, hot and progressive.
v) Skin
become dry, hard and dark in color – if you palpate the swelling, you may feel
the crapitation.
vi) Rapid
breathing and cessation of rumination and depression.
Death will occur within 24-48 hours.
In some cases, animal without showing any clinical signs. In
USA, another type of blackleg, which is visceral or septicemic black leg also
discovered, in which there is no swelling of skin but animal suffer from black
leg.
Pathogenesis
Primarily transmission occur via oral route. Contamination
pastures contain spores which are then ingested goes to the skeletal muscles
and remain for indefinite period of time (inactive form). Then it becomes
active by any injury, excessive exercise it will turn the spores into
vegetative cells which will start multiplication
– Toxins goes in circulation and septicemia develops. It is
denotes with the group of
potent toxins e.g.
alpha toxin:
necrotizing leukocidin Beta
toxin --- deoxyribunuclease
Gamma toxin:
Hyaloronidase Delta toxin: Hyaloronidase
All endotoxins cause necrosis of muscles, cause lysis of
RBCs and hemoglobin release (due to which on PM, dark red colored muscles are
found).
Diagnosis
It is based on clinical signs which depends on age of the
animal, geographical region, season. If you take exudate, you can demonstrate
spore and if you perform biochemistry you will find serum geatinine,
phosphokinase cause damage to the skeletal muscles.
Lesions
a) Putrefaction
– very rapid due to whole body anaerobe.
b) Sweet
and sore odour produce rancid smell.
c) Bloat
is common after death
d) Froath
come out from the anal orifice.
e) In
between the connective tissue & muscles, bloody serum and gas bubbles you
will find.
Treatment
Window opportunities for treatment is nil because fast onset
of clinical signs. - Antibiotics: such as “Oxytetracycline” is used [Dose rate:
10 mg/kg]
and treatment must repeat for several days.
Other supportive treatment must be carried on but recovery
rate is very much low even after recovery, muscle takes months to recover to
its original position.
Vaccination
Vaccination is very important, if it is prepared by
veterinary research institute (VRI) LHR and a single shot give protection for 6
months. 2nd shot must be given after 15 days, immunized for I year.
In the endemic areas, annual vaccine must be done at dose
rate: 5 ml/275 kg body weight on week of April fool day every year.
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