Canine Cardiomyopathies

Question 1

What breeds tend to get dilated CMO?

Answer 1

Large/giant breeds. A high proportion of some breeds are affected

Question 2

What CMO do boxers get?

Answer 2

Their own unique CMO –> Arrhythmias and sudden death, not necessarily with dilatation

Question 3

CMOS can be secondary to …

Answer 3

Nutrition, toxic, infectious and endocrine issues.

Question 4

Generally, your prognosis for a CMO is

Answer 4

Guarded to poor

Question 5

Boxers get their own CMO, which is …

Answer 5

Arrhythmogenic right ventricular CMO of boxers (BOXER CMO)

Question 6

Boxer CMO is distinct from DCM, but …

Answer 6

Some boxers will get common or garden DCM instead of boxer CMO

Question 7

Outline the incidence of DCM in dogs.

Answer 7

Large to giant breeds
4-10 years of age
M>F
Rare in dogs

Question 8

50% of the male of this breed, and 33% of the female of this breed, will eventually develop DCM

Answer 8

Doberman pinschers

Question 9

Outline the aetiology of DCM

Answer 9

Idiopathic

Strong genetic predisposition in some breeds

Question 10

Explain the understanding between genetic predispositions to DCM in Great Danes, Portuguese Water Dogs, and boxers

Answer 10

Great Danes - X linked recessive in some
Portuguese Water Dogs - Autosomal recessive
Boxers - Autosomal dominant

Question 11

DCM most likely represents the end stage of a variety of pathological conditions

Answer 11

I should already fucking know this but I forgot

Question 12

Briefly explain the pathophysiology of DCM

Answer 12

Decreased ventricular contractility - systolic dysfunction - low output HF
- weakness, syncope, cardiogenic shock
Progressive chamber enlargement, failure of valve leaflets to coast, eventual diastolic “stiffness:
- R & L sided CHF

Question 13

Atrial fibrillation is a common pathological development in DCM dogs. The consequences of this are

Answer 13

Loss of the atrial kick, persistent tachycardia, lower cardiac output and disease progression

Question 14

As well as atrial fibrilation, what other arrhythmia tends to develop in DCM dogs that can cause sudden death?

Answer 14

Ventricular tachyarrhythmias.

Question 15

Thinking of a spectrum of conditions, with syncope, arrhythmias and sudden death (far left), and atrial fibrillation (right), place the breeds “boxer, Doberman, Great Dane and Irish wolfhound” on this spectrum. Think about where CHF fits into this picture as well.

Answer 15

Syncope. Atrial fibrillation
Arrhythmias
Sudden death.

Boxer. Doberman. Great Dane. Irish wolf hound

Question 16

Age of dogs with CHF due to DCM (generally)? Male or females worse?

Answer 16

Generally 4 - 10

Males show clinical signs earlier

Question 17

What stage often precedes the clinical stage of CMOs such as DCM? How can this be detected?

Answer 17

Prolonged occult stage.

Echocardiography

Question 18

What are the clinical features of CMO dogs such as those with DCM

Answer 18

Exercise intolerance
Weakness
Lethargy
Tachypnoea
Dyspnoea
Cough
Anorexia
Abdominal swelling
Syncope
Loss of muscle mass (marked)

Question 19

Two major factors involved in your diagnosis are:

Answer 19

Compatible signalment and history

Systolic mitral and or tricuspid murmur (may be quiet/soft)

Question 20

Why might the systolic mitral and or tricuspid murmur be quiet/soft in DCM dogs?

Answer 20

Weakened muscular contractions

Question 21

List possible signs that may or may not be present in CMO dogs such as those with DCM

Answer 21

Gallop
Irregularly Irregular arrhythmia, pulse deficit
MMB pallor change with slow CRT, cold extremities and weak femoral pulses
Signs of CHF

Question 22

What are the treatment principles for DCM dogs?

Answer 22

A diuretic to relieve congestion
A positive inotrope to support ventricular function
An ACEI to oppose RAAS, reduce salt and water retention and mildly vasodilation
Anti-arrhythmic drug(s) as needed

Question 23

Do we treat during the occult stage? If so, how?

Answer 23

It is uncertain if this actually helps. May use an ACEI (enalapril), diuretic (spironolactone), Beta-blockers and anti-arrhythmic drugs.

Question 24

How do we treat the overt stage of DCM?

Answer 24

Similar to CVHD with anti-arrhythmic therapy often needed
EXERCISE RESTRICTION initially
Frusemide (lowest effective dose)
Pimobendan
ACEI

Question 25

What are two drugs we may consider giving (and are likely to give) in DCM dogs

Answer 25

Digoxin

Spironolactone (with digoxin)

Question 26

If using digoxin in DCM dogs, what do we worry about?

Answer 26

Toxicity. It may put the animal off their food. If the dog shows even the faintest sign of this, stop the drug (especially if vomiting).

Question 27

Outline the monitoring principles of DCM dogs

Answer 27

Resting RR & effort at home
Heart/pulse rate & rhythm at home
Body weight/condition score
Serum electrolytes, creatinine
ECG/Echo
Arterial blood pressure measurement
Serum digoxin conc. Monitoring

Question 28

What is the prognosis for DCM dogs?

Answer 28

Guarded to poor
Variable by breed
6 - 12weeks survival from onset of CHF
25-40% are still alive >6 months

Question 29

List some causes of secondary CMOS

Answer 29

Doxorubicin
Some other toxins like poisonous plants
L-carnitine, taurine
Myocardial infarction
Tachycardia-induced CMO

Question 30

What are some causes of myocarditis?

Answer 30

Infective

Traumatic

Question 31

In a nutshell, CMOs are …

Answer 31

Primary heart muscle diseases of uncertain aetiology. Usually, there is poor conractility, dilatation, with or without arrhythmias –> CHF