Aortic or Subaortic stenosis ( SAS ) is serious inherited heart disease that has become the second most diagnosed canine heart problem. Several breeds are predisposed to the condition; among those are Newfoundlands, German Shepherds, Golden Retreivers, and Rottweilers. The serverity of the condition ranges from mild, in which a slight heart murmer is the only defect, to extreme in which case there can be sudden death due to significant heart tissue damage.

In layman's terms, SAS is the narrowing of the pathway for blood leaving the heart. The narrowing is in the form of a lesion that lies just below the surface of the artery, distrubting the flow of blood. Although rarely seen in cats, there has been a significant increase in SAS appearing in puppies. The heart murmur can be detected as early as six to eight weeks of age, or develop as late as three to four years of age in the milder cases.

Dogs with mild cases of SAS generally live full, normal lives as great pets. They should not be used in breeding programs since SAS is a genetic heart defect. Dogs with moderate to severe SAS may need medication and are at risk for exercise intolerance, fainting, heart failure, irregular heart rhythms, infections on the heart valve and sudden death. Your veterinarian will advise you on the correct course of treatment for your dog.

What to Watch For

• The presence of a murmur in a puppy especially in breeds at risk
• Poor exercise capacity
• Cough
• Difficult breathing
• Collapsing
• Fainting
• Illness with fever

Diagnosis
Diagnostic tests are needed to recognize SAS and exclude other diseases. Tests may include:

• Complete medical history and physical examination including examination with a stethoscope (cardiac auscultation)
• An echocardiogram (ultrasound of the heart) with Doppler is needed to make a definitive diagnosis. If possible see a veterinary cardiologist for this examination.
• A chest X-ray may be recommended especially if there are signs of heart failure.
• An electrocardiogram (EKG) or a 24-hour electrocardiogram may be recommended to identify abnormal heart rhythms.

Treatment
For mild cases there is no treatment. For more serious cases treatments for SAS may include one or more of the following:

• Surgery and cardiac catheterization procedures have been used to dilate or cut out the affected area; however these procedures do not significantly increase long-term survival.
  
• Drugs for heart failure may be prescribed should an irregular heartbeat develop.

Home Care and Prevention
The severity of your dog's SAS will determine your home care regime. As always, your veterinarian will tell you exactly what needs done. Mild cases of SAS pose no real activity/exercise limitations but more advanced cases may require some exercise restriction or medical therapy.

Learn to measure your dog's rectal temperature. If your dog is acting sick and has a fever (temperature greater than 103) call your veterinarian immediately. Also schedule regular examinations (every 6 to 12 months) and possibly chest X-rays and/or an echocardiogram.