Special Veterinary Pathology

BACTERIAL DISEASES

Gross specimens

• Actinomycosis - Jaw bone
• The affected jaw bone becomes enlarged and “honey comb like” as a result of rarefaction and regenerative proliferation
• Cut surface of the lesion is usually white and glistening
• Actinobacillosis – Tongue
• The tongue show small abscess.
• Diffuse proliferation of connective tissue sometimes causes great enlargement that the stiff partially mobile tongue protrudes from the mouth giving the characteristic “wooden tongue” appearance
• Tuberculosis - Lung – Bull calf
• The tubercular lesions are usually encapsulated,caseous, gritty and vary in size.
• They may be within the substance of the lung or may protrude from the surface.
• Tuberculosis - Lung –Miliary lesion
• Small,discrete,transluscent nodules scattered throughout the lung parenchyma are called as “MILLIARY” lesions.
• Tuberculosis - Lung
• The tubercular lesions are usually encapsulated,caseous, gritty and vary in size.
• They may be within the substance of the lung or may protrude from the surface

TB- Lungs-Multiple caseous nodules

• Tuberculosis – Pleura
• In the granulation tissue are formed tubercles which appear as clusters, resembling a bunch of grapes or pearls
• Tuberculosis - Lymph node
• Tubercular lesions are usually encapsulated, caseous, gritty and vary in size
• They may be within the substance of the lymphnode or may protrude from the surface

TB-Mesenteric lymph node-Multiple caseous
and calicified nodules

• Tuberculosis – Uterus
• Tubercular lesions are usually encapsulated, caseous, gritty and vary in size
• They may be seen protruing from the surface
• Black Quarter - Skeletal muscle
• The affected muscle is black,dry,sponge like with numerous gas bubbles and show “crepitating swelling” particularly at the extremities.
• Peculiar rancid or sweetish odour is noticed.
• Haemorrhagic septicaemia – Heart
• Petechiae are found on all mucous and serous membranes of epicardium and endocardium.
• Haemorrhagic septicaemia - Trachea –Buffalo
• Edema and haemorrhages on the mucosa of the upper nasal passages, larynx and trachea
• Haemorrhagic septicaemia – Liver
• Liver appears congested or with a few scattered greyish white necrotic foci
• Haemorrhagic septicaemia - Lung
• Fibrinous bronchopneumonia with various stages of hepatisation found.
• The interlobular septa are thickened and widened by infiltration with serous fluid producing marbling
• Strangles – Pharyngeal lymph nodes – Horse
• Lymph nodes are inflammed
• Abscesses may be formed which become encapsulated or rupture into the oral or pharyngeal cavities and discharges pus
• Glanders – Nasal septum – Horse
• Nodules which ulcerate and become confluent ,in the early stages unilateral serous nasal discharges later become purulent and blood tinged
• Upon healing ulcers replaced by characteristic “stellate” scar
• Glanders – Lungs – Horse
• Granulomatous nodules resembling tubercle but sometimes they coalesce
• In few cases disease is manifested as acute purulent bronchopneumonia
• Leptospirosis – Lung – Dog
• Tiny spherical haemorrhages of about few millimeters diameters are found on the pleural surfaces
• Leptospirosis – Kidney - Dog
• Kidneys are enlarged and surface is usually smooth ,capsule is tense and white or grayish.
• Haemorrhages are characteristically seen on the cortico-medullary junction