VMC 311: Systematic Veterinary Bacteriology and Mycology (2+1)

PATHOGENICITY

CLASSIFICATION

Symptoms

Horses

• Acute form is very common and death may take place one day after edematous swelling of the throat and neck region.
• There may be symptoms of colic. In less acute, oedmatous swelling become generalized and death occurs after 2-3 days.

Cattle

• Bulls are more susceptible than cows. They have a mortality rate of 90%.
• There are three clinical causes of bovine anthrax.
• In peracute sepeticemia death occurs within 2 hours after animal collapsing with convulsions, sudden death in animals that appeared normal is common.
• In acute septicemia death occurs within 48 to 96 hours clinical signs include fever, anorexia, ruminal stasis, hematuria and blood tinged diarrhea.
• Pregnant animals may abort and milk production often abruptly decreases.
• Terminal signs include severe depression, respiratory distress and convulsions.
• In chronic cases, clinical signs are manifested for more than 6 days and are rare.
• B.licheniformis infection is associated with the feeding of contaminated silage and is responsible for abortion in cattle and sheep.

Sheep

• Disease is acute and death occurs rapidly after convulsions.

Pigs

• They have a greater natural resistance than herbivores.
• The usual signs are oedematous swellings in the region of throat and neck interfering normal respiration, enteritis and rise in temperature. The disease is not always fatal .

Dogs

• The throat will be inflamed and swollen, gastroenteritis

Lesions

• The carcass of animals will putrify rapidly and develop incomplete rigor mortis.
• The blood is dark,(tarry colored), clots poorly & exudes from the natural orifices.
• The spleen is greatly enlarged, dark and friable. The spleen reveals black cherry jam consistency.
• The LN (lymph node) at the region of initial infection site is hemorrhagic and edematous.
• Ecchymotic hemorrhages on the serosal surface of the abdomen, thorax, epicardium and endocardium are common.
• Subcutaneous edematous swellings are present on the ventral aspect of the neck

Note

• When suspected for anthrax care should be taken not to open the carcass. Muzzle piece or ear piece is usually sent for examination.