Myxo AV Degen Flashcards
Describe the pathophysiology of Myxomatous AV Valvular degeneration
- thickening and contraction of valve leaflets
- valve becomes incompetent and there is regurgitation of blood into atrium
- chordae tendinae thickened and may rupture, causing prolapse of valve into the atrium
What are the effects when there is only little regurgitation during MAVVD?
- heart compensates by increasing sympathetic tone, increasing cardiac output
- dog is asymptomatic
What are the effects of increased regurgitation during MAVVD?
- left atrial enlargement that compresses left main bronchus against aorta, causes coughing
- rupture of left atrium and cardiac tamponade can occur
What are the clinical signs of MAVVD?
- asymptomatic murmur
- coughing if airway compression
- syncope from arrhythmias
- L CHF (acute or chronic)
- left atrial rupture and cardiac tamponade
- sudden death
How are mild/moderate cases of MAVVD with CHF treated?
- oral furosemide (tapor off)
- ACE inhibitor
- restricted Na diet
How are severe cases of MAVVD with CHF treated?
- supplement O2
- IV furosemide (until RR decreases)
- vasodilator
What are the possible outcomes of endocarditis?
- CHF (aortic insufficiency)
- pulmonary edema and death
- dysrhythmias
- septic emboli
- polyarthritis and gomerulonephritis
What are the clinical signs of endocarditis?
- malaise, anorexia
- weight loss
- shifting lameness
- signs from septic emboli (GI, renal, seizures, CHF)
What is seen on physical exam of a dog with endocarditis?
- fever
- murmur
- bounding pulse
- dysrhytmias, CHF
- joint swelling
What is the best diagnostic tool for endocarditis?
ultrasound
blood cultures
What are the causes of pericardial effusion in dogs and in cats?
Dogs: neoplasia most common
- idiopathic
- CHF, decreased albumin, pericarditis, hemorrhage, foreign bodies
Cats: FIP and lymphoma
What is seen on physical exam of an animal with pericardial effusion?
- pale mm, increased CRT
- muffled heart sounds, decreased pulses
- vein distension
- ascites
Describe the life cycle of heartworms
- microfilaria produced by females in lungs, go into circulation and survive for 2 years
- microfilaria in blood picked up by mosquito, move to mouth and become L3
- mosquito bites dog and L3 transmitted, then molts to L4
- L4 migrates SQ for few months
- L4 becomes L5, penetrates veins, travels to right heart and pulmonary artery
- L5 develops to adult over 3 months
Describe the pathogenesis of heartworms
- damaged endothelium (increased permeability, edema, coughing)
- platelets and growth factors cause proliferation of smooth muscle in pulmonary arteries (thickening/narrowing of vessels)
- live worms: vasocontriction, bronchoconstriction, inflammation and fibrosis in lungs
- dead worms: proliferation of smooth muscle, granulomas, thrombus, lung consolidation, CHF
- Wolbachia app. in worms
Describe the prophylaxis treatment for heartworms
- prevents animals from becoming re-infected
- use for 2-3 months, then treat with adulticides
