Canine Pulmonic Stenosis
Pulmonary Stenosis Xray
As part of normal circulation
in the body, the right side of the heart (the right ventricle) pumps blood
to the lungs to receive oxygen. The oxygenated blood goes back to the left
side of the heart from which it is pumped out to the rest of the body.
is pulmonic stenosis?
related terms: Pulmonic stenosis, pulmonic stenosis with anomalous left
coronary artery, type A pulmonic stenosis (pulmonary ostium hypoplasia),
valvular pulmonic stenosis
Blood flows from the right ventricle of the heart through the pulmonic
valve into the pulmonary artery and thence to the lungs. With pulmonic stenosis,
there is partial obstruction of normal blood flow, most commonly due to
a malformation of the pulmonic valve ("pulmonic valve dysplasia") but the
abnormality may be immediately above or below the valve as well.
The effect of this partial obstruction is to force the heart to work
harder to pump blood to the lungs. The extent to which a dog will be affected
depends on the degree of narrowing (stenosis) of the valve area. With severe
stenosis the dog will likely develop congestive heart failure due to the
increased workload of the heart.
How is pulmonic stenosis inherited?
Pulmonic stenosis appears to be a polygenic threshold trait.
What breeds are affected by pulmonic stenosis?
Pulmonic stenosis is one of the most common congenital heart defects
in all species. There is a breed predisposition in the following breeds of
The English bulldog and the mastiff are at most risk for pulmonic stenosis.
In English bulldogs, pulmonic stenosis occurs commonly with an abnormal
left main coronary artery branch, arising from a single right coronary artery.
In this breed the condition is more common in males.
There is also an increased risk of pulmonic stenosis in the beagle,
wire-haired fox terrier, chihuahua, miniature schnauzer, samoyed, Boykin
spaniel, West Highland white terrier, cocker spaniel, Airedale terrier,
and Scottish terrier.
For many breeds and many disorders, the studies to determine the mode
of inheritance or the frequency in the breed have not been carried out,
or are inconclusive. We have listed breeds for which there is a general
consensus among those investigating in this field and among veterinary practitioners,
that the condition is significant in this breed.
What does pulmonic stenosis mean to your dog & you?
In its milder forms, the slight thickening of the pulmonary valve will
cause minimal or no obstruction and your dog will not be affected. However
with more severe thickening of the valve, the obstruction to blood flow
from the right side of the heart will cause varying degrees of heart damage
which worsens with age. With moderate-to-severe pulmonic stenosis, your dog
may experience signs associated with low cardiac output and/or right-sided
heart failure, such as respiratory difficulties, fainting, tiring with exercise,
abnormal cardiac rhythms, abdominal swelling due to an enlarged liver or
the accumulation of fluid because of failing circulation, or sudden death.
Based on your dog's physical examination and diagnostic tests such as
chest x-rays and an electrocardiogram, your veterinarian will discuss with
you the severity of the pulmonic stenosis. If there are significant changes
evident, he or she will suggest further tests to determine the pressure
gradient across the pulmonic valve. (Normally there is no pressure difference
between the right ventricle of the heart, and the pulmonary artery to the
lungs.) Where there is a pronounced pressure gradient, surgery to correct
the stenosis should be considered.
How is pulmonic stenosis diagnosed?
The first indication that your dog has a problem may be when your
veterinarian hears a heart murmur on an early physical examination. Alternately,
you may see signs in your dog related to heart disease, such as fainting
or fatigue with exercise. Your veterinarian will listen carefully to try
to determine the location of the murmur and to differentiate it from an
"innocent" murmur which disappears by about 6 months of age. If the murmur
is significant, your veterinarian will suggest further tests such as a chest
x-ray, electrocardiogram, and cardiac ultrasound to help determine the cause,
and to see what changes if any have already occurred in the heart as a result
of the defect. Once pulmonic stenosis has been diagnosed, Doppler echocardiography
or cardiac catheterization can be done to measure the pressure gradient
between the right ventricle and the pulmonary artery, to determine the severity
of the obstruction. Based on these test results your veterinarian will discuss
with you the long term prognosis for your dog and whether surgical correction
of the defect should be considered.
FOR THE VETERINARIAN:
MURMUR: systolic ejection murmur, loudest in pulmonic area near
left cranial sternal border, often equally loud along right cranial sternal
RV hypertrophy and right axis shift, right atrial enlargement, possibly
arrhythmia associated with hypertrophy.
right ventricular hypertrophy , poststenotic dilation of pulmonary artery
with distal pulmonary vessels reduced in size.
primary means of diagnosis of pulmonic stenosis, typically see mild
to moderate right atrial dilation, concentric RV hypertrophy, deformity
and narrowing in the pulmonic valve region, and poststenotic dilation of
the pulmonary artery.
jugular pulses may be evident.
In English bulldogs, pulmonic stenosis is commonly associated with a
left coronary artery anomaly which has important implications for surgical
How is pulmonic stenosis treated?
With mild-to-moderate stenosis, your veterinarian will monitor your
dog. No other treatment is necessary unless clinical signs develop which
are associated with heart disease. Surgery is an option in dogs with moderate-to-severe
pulmonic stenosis, with different techniques recommended depending on the
site of the stenosis. Because of the expertise and technical equipment required
and the surgical risk involved, surgery to correct pulmonic stenosis is generally
performed in a referral centre.
Surgery is more risky if atrial fibrillation or congestive heart failure
have developed. These conditions should be treated medically and the dog
stabilized before surgery is considered.
Medical management for congestive heart failure is similar no matter
what the cause, and consists of medications to support the heart muscle
and decrease the work load of the heart, together with dietary recommendations.
Affected individuals and their parents should not be used for breeding.
Siblings should only be used after careful screening. If any affected offspring
are born, breeding of the parents should be discontinued.
INFORMATION ABOUT THIS DISORDER, PLEASE SEE YOUR VETERINARIAN.
Bussardori, C. 1998. Breed related echocardiographic prognostic indicators
in pulmonic and subaortic stenosis. ACVIM-Proceedings of the 16th Annual
Veterinary Medical Forum: 140-142.
Bonagura, J.D. and Darke, P.G.G. 1995. Congenital heart disease.
In S.J. Ettinger and E.C. Feldman (eds.)Textbook of Veterinary Internal
Medicine, p. 892-943. W.B. Saunders, Toronto.
Patterson, D.F. 1996. The genetics of canine congenital heart
disease. ACVIM-Proceedings of the 14th Annual Veterinary Medical
Forum: 225-226. This reference has good information for breeders
and veterinarians regarding screening and genetic counselling for congenital
Thomas, W.P. 1995. Therapy of congenital pulmonic stenosis. In
J.D. Bonagura and R.W. Kirk (eds.) Kirk's Current Veterinary Therapy XII
Small Animal Practice, p. 817-821. W.B. Saunders, Toronto.
Copyright © 1998 Canine Inherited Disorders Database. All rights
This database is funded jointly by the Animal Welfare
Unit at the Atlantic Veterinary College, University of Prince Edward Island,
and the Canadian Veterinary Medical Association
Copyright © 1998 Canine Inherited
Disorders Database. All rights reserved.Revised: December 15, 2000.
with kind permission from:-
Crook, DVM,Coordinator, Sir James Dunn Animal Welfare Centre, Atlantic
Veterinary College,University of Prince Edward Island, 550 University
Ave.Charlottetown, PEI C1A 4P3
The above information is simply informational.
It's intent is not to replace the advice of a veterinarian nor to assist
you in making a diagnosis of your pet. Please consult with your own veterinarian
for confirmation of any diagnosis. Your pets life may depend on it.