Myocardial pathology

Question 1

Subepicardial hemorrhage

Answer 1

Common agonal change (changes during death)
Associated with asphyxia/ anoxia
Hemorrhage on the epicardial surface going into the myocardium

Question 2

Hemorrhagic diathesis

Answer 2

Sweet clover toxicosis (dicoumerol)
Rodent toxicosis (Warfarin, brodifacoum)
Bracken fern (pteridium aquilinum)
Disseminated Intravascular Coagulopathy (DIC)

Question 3

Sweet clover toxicosis

Answer 3

Calves most susceptible
Sheep and horses more resistant
Causes hemorrhage on the epicardial surface

Question 4

Bracken fern (Pteridium aquilinum) toxicosis

Answer 4

Bone marrow aplastic pancytopenia → thrombocytopenia → hemorrhage

Question 5

Bacterial associated myocarditis

Answer 5

Listeria monocytogenes
A. equuli and Strept. equi equi (horse)
Cornynebacterium pseudotuberculosis / caseous lymphadenitis (small ruminants)

Question 6

Bacteria causing mycocarditis in cattle

Answer 6

Histophilus somni
Clostridium chauveoi (Blackleg disease)
Fusobacterium necrophorum (sequela to rumenitis)

Question 7

What lesions does bacteria cause in the myocaridum?

Answer 7

Chronic suppurative- purulent exudate with fibrous CT surrounding the abscess → heart failure
Necrosis + hemorrhage with butter odor (blackleg disease)

Question 8

What lesions does Cornyebacterium pseudotuberculosis cause?

Answer 8

Necrosis
Caseous lymphandenitis (focal)

Question 9

Viral associated myocarditis

Answer 9

Canine parvo 1 and 2, herpesvirus, distemper
Psuedorabies virus
Porcine circovirus 2 + pravo
Encephalomyocarditis (pigs)
Foot and mouth disease (tiger striping)

Question 10

Encephalomyocarditis virus (pigs)

Answer 10

Biventricular involvement
High mortality
Affects the nervous system and heart

Question 11

What lesions will viral disease cause in the myocardium?

Answer 11

Necrosis (eosinophilic fibers), suppurative inflammation
Intranuclear IBs (parvo in puppies)
Lymphocytes predominate
Tiger stripes (necrosis)

Question 12

Parvovirus

Answer 12

Mycocardial virus in young puppies
Basophilic inclusion bodies
Eosinophilic fibers = necrosis

Question 13

Parasites associated with myocarditis

Answer 13

Sarcocystis sp.
Trypanosoma cruzi (Chagas)
Toxoplasma gondii
Neospora caninum
Cysticerci
Trichnella spiralis

Question 14

Sarcocystis spp.

Answer 14

Myocardial sacrosporidosis
Normal large bacteria found in cattle
Unharmful unless ruptured → eosinophilic myocarditis

Question 15

Necrotizing myopathies from vitamin E and selenium deficiency

Answer 15

White muscle disease in ruminants (calcification and necrosis)
Mulberry heart disease in pigs

Question 16

Mulberry heart disease (pigs)

Answer 16

Myocardial hemorrhage → dietetic microangiopathy → fibrinoid necrosis of arteriole walls
Causes thrombi and myocardial necrosis

Question 17

Necrotizing myopathies from toxicities

Answer 17

Monensin (horses and pigs)
Doxorubicin (dogs)
Cantharidin- blister beetle (horse)
Oleander

Question 18

Hydropic/ Fatty change (reversible)

Answer 18

Arrythmogenic RV cardiomyopathy (boxers)
Myocyte loss with replacement by fatty or fibrofatty infiltration (+/- myocarditis)
RV dilation

Question 19

Mineralization

Answer 19

Degenerative myopathy
Age-associated, secondary to previous injury
Metastatic and dystrophic

Question 20

Brown atrophy/ xanthosis

Answer 20

Degenerative myopathy
Malnourishment and age-associated
Lipfuscin accumulation (dark brown/ black)