Myocarditis and Cardiomyopathy:

• Myocarditis is a focal or diffuse inflammation of the myocardium with myocyte degeneration and/or necrosis.
• Cardiomyopathy refers to disease of myocardium resulting mainly form genetic mutation in which myocardium loses contractility and unable to pump sufficient blood resulting in dilatation of heart.
• Myocarditis may be acute or chronic in nature, suppurative or Parenchymatous

Etiology:

Bacterial infection: Strangles, bacteremia following naval-ill, Tuberculosis especially in horses, tick pyemia in lambs, Clostridium chauvoei, Histophilus somni, extension of infection from pericarditis, endocarditis

Viral infection: FMD, African horse sickness, equine viral arteritis, equine infectious anemia, equine herpes virus-1 in fetus, swine vesicular disease, parvovirus in piglets, PRRS virus in piglets, Bluetongue in sheep

Parasitic infection: Strongylus infection (migrating larvae), cysticercosis, Sarcocystis spp, Neospora caninum

Nutritional deficiency: Vitamin E or selenium deficiency in all large animals, chronic copper deficiency in cattle, iron deficiency in calves and piglets, copper or cobalt deficiency in lambs

Toxicity:

• Inorganic poisons such as arsenic, mercury, phosphorus, selenium,
• Gossypol from cotton seed cake
• Fluoroacetate (1080) and poisoning by Acacia georgina, Gastrolobium and Oxylobium spp., Dichapetalum cymosum
• Plants and weeds, including members of Ixiolena, Pachystigma, Pavette, Asclepias, Geriocarpa, Cryptostigia, Albizia, Cassia, Digitalis, Urechites, Pimeiea, Astragalus, Fadogia, Cicuta, Colchicum, Kmwinskia, Vicia, Cicuta, Trigonella, Bryophyllum, Palicourea, Lupinus, Lantana, Kalanchoe, Homeria, Hymenoxys, Eupatorium spp.
• Grasses, including Phalaris tuberosa, corynetoxins in Lolium rigidum infested with nematodes and Corynebacterium spp. (also tunicamycin in rain-damaged infected wheat, pigs), cantharidin in hay infested with blister beetles (horses)
• Drugs including succinylcholine, catecholamines, xylazine (ruminants) monensin – especially in horses, but also cattle, sheep, and pigs – lasalocid and salinomycin in horses, pigs, cattle and sheep, maduramicin in cattle and sheep fed poultry litter, and Adriamycin

Venoms: Rattlesnake venom in horses, Vipera palaestinae

Embolic infarction: Emboli from vegetative endocarditis or other embolic disease such as bracken fern poisoning in cattle

Tumor or infiltration: Viral leukosis of cattle, Other cardiac neoplasia, Cardiomyopathy in horses due to amyloid infiltration of the myocardium

Inherited: Congenital cardiomyopathy in adult cattle in Holstein- simmental crossbred, glycogen storage disease in sheep

Unknown or uncertain etiology: Myocardial necrosis and haemorrhage, exertional rhabdomyolysis of horse, sudden death of calves from acute heart failure

Clinical Findings:

• In early case or case with mild to moderate myocardial damage, decreased exercise tolerance is prominent signs
• Increased heart rate and heart size
• There is marked arrhythmias, particularly tachyarrhythmias
• Enlargement of heart, dyspnoea
• Early exhaustion and collapse
• Blood stasis, chronic venous congestion
• In late stage or severe myocardial damage, there may be sudden death in animals with acute heart failure or severe dyspnoea or congestive heart failure

Diagnosis:

• On basis of history and clinical findings
• On basis of laboratory findings; elevated SGOT, SGPT and lactose dehydrogenase activity
• ECG and echocardiography

Differential diagnosis:

• Congestive heart failure
• Other disease causing decreased exercise intolerance

Treatment:

• Correction of primary causes with appropriate measures.
• Symptomatic treatment should be carried out.
• Digitalization is helpful.
• Medical treatment doesnot help in large animals.