Heart & Blood FAQs


Do Aussies get heart diseases?

Heart disease is rare in Aussies but there are a few things that occur from time to time.  The most frequently seen are two congenital heart vessel defects, patent ductus arteriosus (PDA) and persistent right aortic arch (PRAA.)  Older Aussies sometimes have mitral valve disease.  Adult Aussies occasionally will be diagnosed with subaortic stenosis (SAS) or dilated cardiomyopathy (DCM.)

Is it necessary to have Aussies routinely screened for heart problems?

Because heart issues are rare in the breed, there is no need for routine screening of all breeding dogs.

However, because PDA and PRAA are the most common heart issues in the breed, it is advisable to check all puppies for to make sure they do not have murmurs.  This can be done as part of a routine puppy health check.  Not every murmur is a sign of PDA or PAA, but if a pup has one further testing may be necessary.

If an adult-onset heart disease is known to occur in a particular family of Aussies, screening of members of that family is advised.  Consult a veterinary cardiologist about the best way to proceed based on the specific disease at issue.  Have the OFA screening done as part of the process and mark the results “open” so they will be there to aid owners and breeders in the future.

My puppy has a heart murmur.  Is this something to worry about?

Not necessarily.  Many murmurs in young puppies are not significant and will go away as the puppy matures.  Murmurs can also indicate problems with the heart.  Patent ductus arteriosus is the defect most frequently encountered in Aussies, though it is not common.  Affected dogs will have a murmur.

Presumably your puppy has been seen by a vet if you know it has a murmur.  If the murmur had sounded bad, your vet would have done further testing to see what was wrong.   Have the puppy rechecked in a couple months.  If the murmur is still there, more testing may be advisable at that time.  But most likely it will have gone away and you’ll have nothing to worry about.

What is patent ductus arteriosus (PDA)?

PDA occurs when a fetal blood vessel that is supposed to go away before birth fails to do so.  It is one of the most common congenital birth defects in dogs.   As a result blood does not circulate properly.  When the ductus arteriosus remains (is patent), some of the blood continues to by-pass the lungs and therefore does not get properly oxygenated.  Severity of disease varies depending on how much blood is not going through the lungs.  Lack of oxygen in the blood triggers the heart to work harder, with the worst cases progressing to congestive heart failure.  The movement of the blood through this vessel causes a murmur.  In some cases you can feel the murmur simply by placing your hand over the puppy’s chest.

How do I know if my Aussie puppy has PDA?

A veterinarian may be able to diagnose PDA simply by listening to the heart.  A chest x-ray, echocardiogram, or cardiac ultrasound might also be needed.

What does having PDA mean for my puppy?

Young puppies will seem perfectly normal.  As the disease manifests you may notice coughing, difficulty breathing, lethargy, or exercise intolerance.  Some dogs with mild disease do not require treatment, though the disease will likely shorten their lifespans.  The more seriously affected need heart surgery, done as soon as possible to minimize further damage to the heart.  In the worst cases, the disease is fatal.

How common is PDA in Aussies?

Heart problems in general are rare in the breed, but PDA and another developmental blood vessel disorder called persistent right aortic arch (PAA) are the type that Aussies are most likely to have.  Even so, they are still rare.

Is PDA inherited?

Yes, but inheritance is complex.

What does producing a puppy with PDA mean for my breeding program?

Littermates of affected puppies should be checked for heart murmurs.  Dogs with PDA should not be bred.  Do not breed the parents together again, nor should you breed them or healthy full or half siblings of the affected dog close on the pedigree that produced PDA or to any dog that has a family history of PDA or persistent right aortic arch (PRAA) as we have sometimes noted both in the same family.

What is persistent right aortic arch (PRAA)?

PRAA occurs when the vessel that becomes the aorta arches to the right instead of the left, encircling the esophagus and sometimes the trachea.  Affected puppies regurgitate frequently and are at risk of aspiration pneumonia if regurgitated food is drawn into the trachea (windpipe.)  If the trachea is encircled PRAA may to some degree inhibit the passage of air.  The constriction of the esophagus can lead to megaesophagus, in which the esophagus becomes grossly over-expanded, making it very difficult for food to pass properly into the stomach.

How do I know if my Aussie puppy has PRAA?

Once the puppy starts eating solid food it will regurgitate frequently and may choke on their food.  Regurgitated food will be undigested and may be in a tubular shape. PRAA pups are often very thin even though they have ravenous appetites.  The vet will rule out other possible causes of vomiting.  Diagnosis is confirmed with a chest x-ray.

What does having PRAA mean for my puppy?

PRAA can be corrected surgically; surgery must be performed as early as possible to prevent permanent damage to the esophagus.  There is a long period of post-operative care that starts with a liquid diet and requires that the puppy be held upright during and for a period after eating; when solid food is introduced the pup will have to be fed several small meals per day.

How common is PRAA in Aussies?

Heart problems in general are rare in the breed, but PRAA and another developmental heart vessel defect called patent ductus arteriosus (PDA) are the types that Aussies are most likely to have.  Even so, they are still rare.

Is PRAA inherited?

Yes, but inheritance is complex.

What does producing a puppy with PRAA mean for my breeding program?

If you haven’t already done so, get any littermates checked for heart murmurs.  Dogs with PRAA should not be bred.  Do not breed the parents together again, nor should you breed them or any of their healthy puppies to their near relatives or to any dog that has a family history of PRAA or PDA as we have seen both occur in the same families.

What is subaortic stenosis (SAS)?

SAS is a narrowing of the area just below the heart valve leading to the aorta, the major blood vessel leading out of the heart.  The stricture overloads the right ventricle of the heart.

How do I know if my Aussie has SAS?

Signs of SAS often don’t develop until around 18 months of age.  They include coughing, fainting, murmur, exercise intolerance, high heart rate, and lethargy.  If SAS has gone undiagnosed in an older dog it can die suddenly.  The condition may be detected when a murmur is noted by an examining vet; location in the heart and when during the heartbeat the murmur is loudest are indicative of SAS.   Definitive diagnosis requires echocardiography.

What does having SAS mean for my dog?

Prognosis for the affected dog varies.  Some never show signs of disease, while for others it is fatal.  Surgery usually does not help.  There is no effective treatment for SAS though if the disease advances medication may relieve some symptoms.  Long-term prognosis is often a shortened lifespan.

How common is SAS in Aussies?

It is rare.

Is SAS inherited?

It is in several breeds where it is much more common.  It should be assumed to be inherited in Aussies.

What does SAS mean for my breeding program?

Affected dogs should not be bred.   This disease can be devastating.  Littermates should not be bred and serious consideration should be given to retiring the parents.  At the very least they should never be bred to each other again or to any near relatives of their own or the other parent’s.  The male should not be used frequently.  Anyone having puppies from them should be made aware this is a potential. Other relatives might be bred but only to mates that do not have a family history of SAS.

What is mitral valve disease (MVD)?

The mitral valve is located between the two chambers on the left side of the heart.  MVD, also called Myxomatous Mitral Valve Disease, is a gradual degradation of that valve which allows small amounts of blood to flow the wrong direction through the valve causing the heart to work harder.  Eventually it leads to congestive heart failure.

 How do I know if my dog has MVD?

In early stages the only sign is a heart murmur.  If that is not detected the first signs apparent to an owner would be those of congestive heart failure:  Coughing, lethargy and fainting.  However, if the dog is being presented for routine veterinary care the murmur will be found.  Chest x-rays, electrocardiogram and echocardiogram may be used to confirm the diagnosis.

 What does having MVD mean for my dog?

MVD cannot be cured.  Mitral valve replacement surgery is possible but the dog must be relatively healthy.  Treatment is confined to managing the heart failure through medication and low-sodium diet.  Optimal weight – neither heavy nor thin – must be maintained and it may be necessary to limit physical activity.  Depending on age of onset and progression, MVD can shorten lifespan.

 How common is MVD in Aussies?

Rare.  Most dogs are over 10 years when diagnosed.

Is MVD inherited?

It is inherited in some breeds but is also a common old dog degenerative heart issue.  In dogs over 10 years it is probably due to wear and tear.  In younger dogs, particularly if they are several years younger, it might be inherited.

What does MVD mean for my breeding program?

Don’t breed dogs that develop MVD.  If the dog is under 10 years and there are other members of the family who are affected the disease should be assumed to be inherited.   Do not repeat the cross that produces it.  Parents and healthy full and half siblings should not be bred close on the pedigree that produced MVD and only to mates with no family history of MVD in dogs under 10.

What is dilated cardiomyopathy (DCM)?

Cardiomyopathy is an inflammation of the heart muscle.  Dogs with DCM have an enlarged heart with oversized chambers and thin walls.  The damaged heart is unable to pump blood effectively.  Usually only one side of the heart is affected, most frequently the left.  DCM can be secondary to taurine deficiency, myocarditis, low blood potassium, abnormal heart rhythms, global myocardial ischemia, and as a toxic side effect of some drugs.  The majority of cases, however, are of unknown origin.

The sudden, unexpected death of an apparently health adult sometimes associated with DCM can also be a sign of Hemangiosarcoma, the Aussie’s most common cancer.  DCM might be assumed if no necropsy is done.

How do I know if my dog has DCM?

Your dog may pant excessively, have shortness of breath, cough, be lethargic or intolerant of exercise, anorexia, show reluctance to lie down, not be able to rest comfortably, or collapse.  A vet will do an exam and various tests to rule out other types of heart disease.  An echocardiogram will be used to confirm diagnosis of DCM.  If an Aussie dies suddenly and DCM is being considered, hemangiosarcoma should be ruled out.

What does having DCM mean for my dog?

Age of onset is usually 4-10 years of age but sometimes occurs earlier.  There is no cure for DCM but the dog can be treated with medication and nutritional supplements to delay onset of heart failure.  DCM will eventually prove fatal.

Is DCM common in Aussies?

DCM is very rare in Aussies.

Is DCM inherited in Aussies?

Probably not.  However, if more than one member of a family has been diagnosed with DCM and hemangiosarcoma has been ruled out in each case it would be best to assume inheritance.

What does DCM mean for my breeding program?

In the case of multiple affected dogs in a family, don’t repeat the crosses that produced it, breed parents and full and half siblings away from the affected pedigrees and only to mates with no family history of DCM.

What is Pelger-Huet Anomaly (PHA)?

Pelger-Huet Anomaly (PHA) causes abnormalities in blood cells called granulocytes.  PHA may be mistaken for infection or early stage leukemia. 

How do I know if my dog has PHA?

If your dog sometimes has abnormally small litters, that might be a sign of PHA.  The only way to know for sure is through screen done with a blood smear.  The smear should be read by a veterinary pathologist or a vet, though most vets aren’t familiar with PHA and don’t know how to evaluate the smear.

What does having PHA mean for my dog?

Aside from the possibility of producing small litters, your dog is very unlikely to have negative health impacts from PHA.  Carriers of a single copy of the gene have some minor abnormalities in their blood cells.  Affected lines will have an irregular pattern of small litters and neonate deaths.

How common is PHA in Aussies?

According to the 2009-10 ASHGI health survey 1% of Aussies are PHA positive, meaning they have one copy of the gene.  (Dog’s with two copies die before or shortly after birth.)

Is PHA inherited?

Yes.  PHA an incomplete dominant with incomplete penetrance.  It is incomplete dominant because dogs with one copy have abnormal blood cells but those with two die.   It is incompletely penetrant because sometimes a dog with the mutation will not be detectable on the blood smear though most will.  Therefore, to inherit the mutation that causes PHA a dog must have at least one parent that is PHA positive on testing; however it possible that a PHA positive dog might have PHA negative parents as a result of the incomplete penetrance, though at least one of them would have the mutation.

Is there a DNA test for PHA?

Not at this time (2013).

Then how do I test for PHA?

It requires a blood smear on a microscope slide.  Someone knowledgeable needs to look at the smear and determine whether the cell abnormalities typical of PHA are there or not.  Dogs with the abnormal cells are PHA positive; those who have normal cells are PHA negative.

Getting PHA testing done can be difficult.  A veterinary pathology lab should be able to read the smear, but many do not.  A small animal vet with competence in blood cytology could, if willing.  The best thing to do if you need to test dogs is network with other breeders to see if they know where to get testing done.  Your vet may need to make the smear and ship it to the place it will be read.

Another note about the PHA test – this is not a DNA test; it is possible to get false negative results because some dogs with the mutation have normal blood cells.

What dogs should be tested?

There is no need to test non-breeding dogs.  Since PHA is uncommon there is no need to screen every breeding dog.  Full siblings and offspring of PHA positive dogs should be tested, as should their parents if they weren’t tested already.  Because of the possibility that a dog may have the mutation but still test PHA negative, breeding offspring of PHA negative dogs who have a PHA positive parent should also be tested. With two PHA negative generations you could be reasonably confident that the PHA mutation is absent.  A pattern of producing small litters (fetuses with two copies of the mutation may be reabsorbed), stillbirths, or neonate deaths warrants testing of the parents.

What do PHA test results tell me?

If a dog is PHA negative you probably have nothing to worry about though there is a small possibility that it may not test positive due to the incomplete penetrance of the gene.  Dogs that test PHA positive need to be bred to PHA negative mates to prevent the small litters, stillbirths and/or neonate deaths associated with having two parents with a copy of the mutation.

What does PHA mean for my breeding program?

PHA positive dogs may be bred to PHA negative mates.  This should be treated as a fault and efforts made to breed away from it however quality should not be sacrificed because of the presence of this mutation.  PHA positive males should not be used at public stud.

What is Von Willebrand’s Disease (VWD)?

Primary Von Willebrand’s Disease (VWD), a blood clotting disorder similar to hemophilia, is extremely rare in Aussies.  The disease can also be secondary to thyroid disease

How do I know if my dog has VWD?

Affected dogs may show a tendency to bleed excessively any time blood vessels are opened through accident or during medical treatments.  Damage to blood vessels that does not break the skin may manifest as swelling in limbs or other areas.  Diagnosis can be made either with blood tests to detect deficiencies of the VWD clotting factor or with DNA tests.

What does it mean for my dog if it has VWD?

There are three forms of the disease, Types I, II, and III.  Type I is the least severe and Type III being the most.  Type 1 dogs may be sub-clinical.  Type III dogs have a serious clotting deficiency and the disease can be life-threatening if not treated.  Gene therapy treatments have been developed for this disease.

How common is VWD in Aussies?

VWD is extremely rare in Aussies

Is VWD inherited?

Yes, if it is primary disease.  If it is secondary to autoimmune thyroiditis it isn’t, but the thyroid disease is.

Is there a DNA test for VWD?

There are DNA tests for all three types of VWD.  All are recessive, so dogs will either be clear, affected, or carrier.

What does VWD mean for my breeding program?

Affected dogs, whether or not they show clinical signs, should not be bred.  Carriers may be bred to clear-tested mates with preference given to clear-tested offspring to carry on with.  First-step relatives of tested carrier and affected dogs which are to be used for breeding should be tested so their own status is known.

The breeder I got my bitch from recently informed me my girl’s dam has vonWillebrands Disease.  I tested my girl and she came back borderline.  All this happened right AFTER I’d bred her.  Are the puppies going to be OK?  Should I test them?

Von Willebrand’s Disease (VWD) is rare in Aussies.  It can also be an unusual side effect of thyroid disease, which is not rare.  The first thing I’d recommend is that you and your bitch’s breeder make sure you aren’t dealing with secondary VWD due to thyroiditis.

If the sire of your litter normal, none of the pups would be affected.  Your girl’s test result – if this is primary VWD – indicates your girl might be a carrier.  So far as I know there is not yet any DNA test for VWD so you can’t find out for sure.

As for your litter:  I’m not up-to-date on VWD testing protocols because I rarely encounter it in our breed, but as I recall it requires a blood sample.  In young puppies this may not be possible depending on how much sample they need.  Check with your vet or the laboratory that is doing the test.