CONGENITAL DEFECTS

CHIHUAHUAS, MALTESE, POODLE, POMERANIAN, SHELTIE PUPPIES COMMONLY AFFECTED

Normally, the ductus arteriosus carries blood from the pulmonary artery to the aorta during fetal development. It bypasses the lungs of the fetus.

The duct should close in the first 12-24 hours after birth. If it does not, the blood begins to shunt from the aorta into the pulmonary artery and hyperperfuse the lungs.The left side of the heart will have an increase in blood return and become volume overloaded.

THIS IS CALLED A LEFT-TO-RIGHT SHUNT

CLINICAL SIGNS: A loud murmur best heard over the left base Sometimes called a “machinery” murmur or a

continuous murmur If the shunt is small some animals may be

asymptomatic In large shunts the animal will develop left-sided

heart failure Pulmonary edema Cough Exercise intolerance Tachypnea Weight loss

ECG: wide range of arrhythmias including APCs and VPCs

Echocardiography (ultrasound) Radiographs: left atrial and ventricular enlargement

EXCELLENT PROGNOSIS WITH SURGICAL CORRECTION: LIGATION OF THE DUCTUS ARTERIOSUS

CLIENT INFO: 64% OF ANIMALS WILL DIE WITHIN 1 YEAR IF

NOT TREATED SURGICALLY Dogs with this condition should not be used

for breeding

During fetal life, the foramen ovale is an openingi n the interatrial septum, allowing shunting of blood from the right atrium to the left atrium in order to bypass the nonfunctioning fetal lungs. It should close at birth. If it doesn’t, after birth, the blood will shunt from left to right resulting in overload of the right side of the heart.

Atrial Septal Defect

CLINICAL SIGNS: ATRIAL SEPTAL DEFECTS Result in overload of the right side of the

heart → dilation and hypertrophy of the right-sided chambers

Systolic murmur Right-sided heart failure Radiographs: right ventricular enlargement Echo: right ventricular dilatation

Blood is shunted from the oxygen-rich left ventricle into the right ventricle. The blood goes through pulmonary circulation and right back into the left atrium and ventricleresulting in volume overload of the left side of the heart. The right ventricle may dilate as well.

CLINICAL SIGNS: VENTRICULAR SEPTAL DEFECTS: Animals with small defects may have minimal or

no signs Larger defects may result in acute left-sided

heart failure, usually by 8 weeks of age A harsh holosystolic murmur

CLIENT INFO: Repair of these defects requires open-heart

surgery or cardiopulmonary bypass. These procedures are uncommon in the dog and cat

Most of these animals will eventually experience development of congestive heart failure

Chihuahuas, English Bulldogs, are commonly affected. CAUSE: polygenic inheritance

In pulmonic stenosis, the right ventricular outflow tract is narrowed, either at the valve itself, just below it, or just after it.

The most common form of pulmonic stenosis involvesa deformed pulmonary valve such that the valve leafletsare too thick, the opening is too narrow, or the valve cuspsare fused.

The heart must pump extra hard to get blood throughThis unusually narrow, stiff valve.

The right ventricle becomes thickened from all this extra work. The right atriumMay become dilated and hypertrophied.

NORMAL CANINE CHEST RADS

THIS DOG HAS PULMONIC STENOSIS –THE HEART LOOKS “PREGNANT” IN THEFRONT DUE TO RIGHT VENTRICULARENLARGEMENT

CLINICAL SIGNS: Syncope Tiring on exercise Right-sided congested heart failure Left basilar (base) murmur Right ventricular enlargement Radiographs: right ventricular enlargement,

dilation of the pulmonary artery, pulmonary underperfusion

Echo: right ventricular hypertrophy and enlargement, dilation of the main pulmonary artery

A special balloon is inserted into the valve where it is inflated and the obstruction is broken down.

Unfortunately, medical management is notvery beneficial in these cases. Beta-blockersmay be used to relax the heart muscle and possibly dilate the stenosis.

LESION DEVELOPS IN THE FIRST 4-8 WEEKS OF LIFE

Newfoundland, Boxer, Golden Retriever, and Bull Terrier are most commonly affected

There is a scar-like narrowing just below the aortic valve. The heart must pump extra hard to get blood through the narrowed area. The blood is pushed through in a turbulent fashion creating a heart murmur.

THE HARD WORK RESULTS IN LEFT VENTRICULAR HYPERTROPHY, LEFT ATRIAL ENLARGEMENT, AORTIC DILATION

CLINICAL SIGNS: Fatigue Exercise intolerance (low cardiac output) Syncope Systolic murmur at the left heart base ECG: evidence of left ventricular

enlargement - ↑ QRS height Echo: left ventricular hypertrophy,

subvalvular fibrous ring, aortic dilation

TREATMENT Balloon catheter dilation – has been done

with variable and temporary results Medical management: THE GOAL IS TO

SLOW THE HEART RATE AND DECREASE CONTRACTILITY; PROPRANOLOL (BETA-BLOCKER WILL DO THIS)

CLIENT INFO: Should not be used for breeding Acute, left-sided congestive heart failure is

possible Sudden death is not uncommon

DCM HCM PDA Aortic stenosis

Pulmonic stenosis

•1 – dogs•Enlarged Heart bronchile constriction•Dilated Flappy muscle•Nutritional: no taurin in cats

•1 – Cats•Saddle thrombus•Rarely in dogs (hereditary)•Noncompliant heart muscle

•Aorta – pulmonary a – lungs back L side

•Stenotic aortic valve causes LV hypertrophy•High pressure in aortic valve can lead to aortic dilatation

•Stenotic pulmonic valve•Pregnant heart

•L sided heart failure (HF)

•LV hypertrophy

•RV hypertrophy•R sided HF

•Increased HR•Cough

•Increased HR•Weakness in hindlimbs, acute pain, rear cold feet

•Pulmonary edema

•Sudden death if aorta ruptures

•Digoxin: increased contractibility

•Beta blocker: Slow HR•Diuretic•Blood thinner•No cure

•Treat surgically or die

•No breeding •Balloon valvuloplasty