View source for Myocarditis

==Introduction==
Most often due to an infective agent.  In most cases myocarditis is a result of a generalised infection, myocarditis is rarely an isolated primary condition.  
Classified as:

===Acute Suppurative===

Follows from the dissemination of septic emboli form suppurative foci therefore always follows pyaemia.  Original septic foci may be:
*Joint ill.
*Umbilical abcess.
*Metritis.
*Mastitis.
*Valvular endocarditis.

May also be a result of extension from the endocarium or pericardium.

===Acute non-suppurative===
[[Image:parvovirus dog.jpg|right|thumb|125px|<small><center>'''Parvovirus (dog)'''. Courtesy of T. Scase</center></small>]]

Usually results from a septicaemia or viraemia E.g [[Parvoviridae|Parvovirus]] infection in puppies.
Also includes:
*Foot and Mouth Disease.
*Leptospirosis.
*Pasteurellosis.
 
And can be classified according to the type of exudate:
* Necrotizing
*Lymphocytic
*Hemorrhagic
*Esinophilic
'''''Parvovirus Infection of puppies''''':

Parvovirus affects rapidly dividing cells which are found in the GI tract, and in the growing pup, the myocardium.  Myocardial cells divide up to approximately 2 weeks of age and so this is when the infection has an effect although clinical signs may not become apparent until later in life.

[[Image:Parvovirus myocarditis.jpg|right|thumb|125px|<small><center>'''Parvoviral Myocarditis'''. Courtesy of A. Jefferies</center></small>]]

Two cardiac syndromes exist:
*'''Sudden death, 3-8 weeks:''' Cardiac failure with pulmonary oedema etc.  Histologically see multifocal myocardial necrosis due to viral replication within the myocardium.  May see large basophilic intranuclear inclusion bodies.
*'''Puppies >8 weeks:''' See dyspoea, weakness, collapse and death within 24 hours.  In this case cardiac failure occurs due to myocardial fibrosis.

===Chronic===

Myofibrils replaced by fibrous tissue during healing.  May be a sequale of previous acute myocarditis.

===Parasites===

Parasites also may cause myocarditis.  parasitic larvae may encyst in the myocardium, including:
*Cysticercosis.
*Sarcocystis.
*[[Tissue_cyst-forming_coccidia|Toxoplasmosis]].

==Test yourself with the Myocardial Pathology Flashcards==

[[Myocardial Pathology Flashcards]]


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[[Category:Myocardial_Pathology]][[Category:Cardiovascular_System_-_Inflammatory_Pathology]][[Category:To_Do_-_Cardiovascular]][[Category:To Do - Major]]
[[Category:Cardiology Section]]