TV4101 - Degenerative Valvular Disease in Dogs

Has various names MVI = mitral valve insufficiency

Preferred name - myomatosis mitral valve disease (MMVD)

Larger breeds more predisposed to dilated cardiomyopathy

• More rapid and lethal than MVi

Can also be seen in tricuspid (30% of cases)

Even little leaks of aortic and pulmonic is senn too

Can have all 4 valves leaking at once

Signalment

Daschund, king charles, poodles, anything small and fluffy

Big dogs can get it too but predmon smallies

Lesions

• Degen of valve along with chordae tendinae attached to valve cusp

• Pale shrivelled up nodules should be a pale pink membrane

Chordae tendinae is used to keep valve shut

Certain genetic mutations and deficiencies in dogs that control certain signalling and certain serotonin receptors that cause mitral valve disease or sometimes it doesn’t

May not have mutation but still get it Why? We dunno

There is no single mutation that definitively causes MVD

Genetic Theories

• Genetic hitchiking maybe? Genes for MVD hitchiked with genes of being small

• Genetic changes overtime from dingo → daschund or schnauzer changes shape of thoirax → chages CV parameters?

Mechanical factors

• Complex shape and mechaniscs of mitral valve where it closes causes strains? and how the individual responds to cell injury → MVD??

  • Cells of MV similar to endothelium of Blood vessels → important in inflammation potentially

Insluin growht factor

tRANSFORMING GROWTH FACTOR

Unsure if cause or effect

Atrial wasting - how much blood is wasted back into left atrium

When V contracts what has less resistance? Pathway back into atrium or pathway up the aorta?

At end of diastole psi is 80 mmHg while 120mmHg is for systolic

Severe cases have difficulty breathing and cyanosis

Coughing?? - is quite controversial if it is associated Heart failure or not

wHY MIGHT MVD BE ACUTE?

Management dependant on what stage its at

80% of cases is benign - animal dies most likely of other causes

20% is when shit goes bad fast

May or may not need an echocardiogram as well

Classic dog with heart failure

Haziness from oedema

Sometimes b4 you see obvs congestion you see these enlarged pulmonary veins preceding oedema development

Dog with enlarged left atrium (cardiomegaly)

A- breeds that are highly predisposed i.e. at risk of developing , don’t have any clinically dtectd heart disease

B1 and B2

B1 - B1 will only have mitral leak - no remodelling yet

B2 - evidence meaning enlarged left atrium or left atrium and a large left ventricle

C is congestive heart failure

D is dying of heart failure

ACE inhibitor has limited value when treating it alone but can be used if treating something additional like hypertension or proteinuria

Spironolactone - may have use but due to way the study was conductedits a bit dicey