6. Myxomatous mitral valve diseases in dogs (occurrence, diagnosis, differential diagnosis, treatment) Flashcards
MMVD INFO and pathogenesis?
The most common acquired cardiac disease in dogs
Older dogs>Younger dogs; Small breeds; Males>Females
King Charles Cavalier Spaniel; Dachshund; Poodle
Mitral valve > Tricuspid valve
Synonyms: Mitral valve disease; Valvular; Chronic valvular disease;
Endocardosis/endocardiosis; Degenerative valvular disease
Overview
PATHOGENESIS (BRIEF)
Controlled by 2 pathways: TGF-β & serotonin pathways
Chronic endocardiosis → Chronic valvular degeneration
Degeneration of the AV valve’s layers → Mitral valve prolapse
Mitral valve involvement → ↑Pulmonary pressure →
Cardiogenic pulmonary oedema
Tricuspid valve involvement → ↑Venous pressure →
Signs of Right-side heart failure
Pathophysiology, Compensatory mechanisms and pathological lesions?
Clinical signs of MMVD?
CLINICAL SIGNS
§ If signs of LS-HF are present: Pulmonary oedema;
Tachypnoea; Dyspnoea
§ If signs of RS-HF are present: Ascites; Jugular distension
& pulsation
§ Holosystolic/systolic murmur
§ Systolic click (3-heart-sound rhythm)
DIAGNOSIS
Physical exam
§ Systolic heart murmur (left apical)
§ Signs of LS-HF
§ Signs of RS-HF
Diagnostic imaging
Echocardiography: Gold standard – Diagnostic
§ Regurgitation of blood from the valves (see fig 5.3)
§ Atrial & ventricular dilation
§ Thickening of valves
§ Rupture of chordae tendineae
Radiography: Chamber enlargement (mainly LS); Lung oedema
ECG: Determination of any arrhythmias; May also indicate
LA/bilateral enlargements & LV dilation
§ Ventricular myocardial lesions & CHF →
Ventricular premature beat & sinus tachycardia
§ Left atrial enlargement →
Atrial arrhythmias (atrial premature complexes;
Atrial Fib.)
§ Left atrial & ventricular enlargement →
Grading of valvular diseases and treatment?
Endocarditis?
Endocarditis
Rare condition; Large breeds;
PATHOGENESIS
Caused by bacterial infection → Bacteraemia
Staphylococcus spp.; Streptococcus spp.; E. coli; Bartonella spp.
Predisposing factor: Aortic stenosis
Complications: CHF; Immune-mediated disease; Thromboembolism
