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  Pulmonic Stenosis

 

Common names or abbreviations:

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Pulmonic stenosis

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Pulmonic stenosis with anomalous left coronary artery

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Type A pulmonic stenosis (pulmonary ostium hypoplasia)

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Valvular pulmonic stenosis

Description or definition:

bulletPulmonic stenosis is a congenital narrowing in the region of the pulmonary valve, which lies between the right ventricular chamber of the heart and the pulmonary artery. As part of the normal circulation 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.

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 dogs will likely develop congestive heart failure due to the increased workload of the heart. The hemodynamic consequences of pulmonic stenosis are the development of right ventricular concentric hypertrophy (enlargement) and reduced filling of the left ventricle. The right ventricular concentric hypertrophy causes reduced right ventricular compliance with reduced distensibility. The hypertrophied right ventricular wall is prone to initiate dysrhythmias.

Pulmonic stenosis can occur with other defects and it is one of the components of another congenital defect: Tetralogy of Fallot.

bulletThe stenotic lesion may occur in the:
bulletSubvalvular position – below the valve at the conus arteriosus or infundibulum.
bulletValvular position – within the valve itself (commonest site).
bulletSupravalvular position – above the valve in the pulmonary artery itself (rare)
 
bulletUsually, affected animals show no external signs of the disease and it is frequently diagnosed during routine examination of the heart with a stethoscope (auscultation). 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, if blood flow is seriously impaired, signs associated with right –sided heart failure may be seen including poor exercise tolerance, respiratory difficulties, abdominal swelling due to an enlarged liver, feinting (syncope), or sudden death.
 
bulletPulmonic stenosis appears to be a polygenic threshold trait – Polygenic traits are controlled by an unknown number of genes. The gene expression is influenced by a variety of factors including gender, nutrition, breed, rate of growth, and amount of exercise. These traits are quantitative traits – that is, there is a wide range within the population. Such traits include height, weight, character, working abilities, and some genetic defects. Heritability varies within different breeds, and within different populations of a particular breed. Because it is virtually impossible to determine the exact genotype for such traits, it is difficult to control defects with a polygenic mode of inheritance.
 
bulletPulmonic stenosis is reported to be the 2nd most prevalent congenital cardiac disorder in the dog.  Aortic stenosis being the most common congenital heart disorder.
 
bulletThere is a breed predisposition in the following breeds of dog:

English Bulldog, Mastiff, Beagle, Wire-Haired Fox Terrier, Chihuahua, Miniature Schnauzer, Samoyed, Boykin Spaniel, West Highland White Terrier, Boxer, Cocker Spaniel, Airedale Terrier and Scottish Terrier.

bullet Diagnosis can be broken down into two areas:
bulletPresumptive diagnosis:
bulletAuscultation of a left basilar systolic heart murmur.           
bulletNormal femoral arterial pulse
bulletRight ventricular enlargement on EKG
bulletRight ventricular enlargement on radiography
 
bulletDefinitive diagnosis:
bulletDoppler echocardiography
bulletCardiac catheterization
 
bulletDiagnostic findings:
bullet Radiology may show:
bulletRight ventricular enlargement
bulletBulge in the main pulmonary artery
bulletAscites (collection of fluid in the abdominal cavity)
bulletHepatomegaly (enlarged liver)
bulletEKG may show:
bulletNormal EKG
bulletRight ventricular enlargement criteria with moderate to severe pulmonic stenosis
bulletRight atrial enlargement
bulletMay be normal with mild cases
bulletDysrhythmias may be noted
bulletEchocardiography:
bulletRight ventricular hypertrophy
bulletStenosis of the pulmonic valve
bulletIncreased velocity of flow across the pulmonic valvular orifice by Doppler
bulletPulmonic regurgitation by Doppler
bulletRight ventricular enlargement
bulletTricuspid regurgitation by Doppler
 

 For moderate to severe pulmonic stenosis, the treatment of choice is surgery. However, the efficacy of surgical intervention remains to be substantiated. Surgery is more risky if atrial fibrillation or congestive heart failure has developed. These conditions should be treated medically and the dog stabilized, before surgery is considered.

A relatively new technique is now being used, called Balloon Valvuloplasty. A catheter with a small balloon on the end is guided to the position of the narrowing during heart catheterization. The balloon is then inflated to open the constriction. This procedure will reduce the morbidity and mortality associated with thoracic surgery, it appears to be good in the short-term, but long-term studies are needed.

bullet The prognosis for individuals with mild cases of pulmonic stenosis is that they can be expected to live a full life with this abnormality.

 For severe cases of pulmonic stenosis the dog may die suddenly if acute dysrhythmias develops (sudden death). Or the dog may develop signs of right sided heart failure and die in 6-12 months.

bulletAffected 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.

 

Links to sites about this disease:

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http://www.upei.ca/~cidd/Diseases/cardiovascular%20diseases/pulmonicstenosis.htm

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http://www.provet.co.uk/health/diseases/cardiac-pulmsten.htm

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http://www.vetgo.com

Resources:

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Clinical Cardiology Concepts for the Dog and Cat: Michael R. O’Grady DVM, MSc, Diplomate, ACVIM (Cardiology) & Lynne O’Sullivan DVM, DVSc, Diplomate ACVIM (Cardiology) – VetGo Cardiology.

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Pulmonic Stenosis: Provet Healthcare Information.

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Pulmonic Stenosis: Alice Crook, BSc, DVM & Brian Hill DVM, MS, DACVIM. University of Prince Edward Island. Canine Inherited Disorders Database.

This summary provided by:

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Olga I. Twombly

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WhiteFang Shilohs

 

 

Dedicated to improving the health of ISSR Shiloh Shepherds.

 


Copyright © 1998 - 2009. Shiloh Shepherd Dog™ Club of America.
All rights reserved. Revised: January 2008

The information on this website was written by ISSR breeders and other concerned individuals, however we are are NOT veterinarians. This information is being provided as a general overview, from information we were able to find about each disease through our own research. These summaries are not intended to be relied upon as medical or veterinary advice, nor do we consider ourselves experts in the veterinary field or in any of these conditions. While we do our best to provide the most up to date information, new research is constantly being done on these diseases. We recommend that you do further study and talk to your veterinarian on any topics you see here, as we cannot guarantee that the information posted here is the most current information available.  This site was originally designed and maintained by Debbie Knatz.