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AS and the Glen

Aortic Stenosis



Aortic stenosis (AS) is a defect of the aortic valve, which causes a partial obstruction of blood flow from the heart. This hereditary defect may be mild and not affect the quality or longevity of the dog's life, or it may be severe and result in symptoms of exercise intolerance and syncope (fainting). It is also one of the causes of sudden death.

This page looks at aortic stenosis and the Glen of Imaal Terrier, and explains the reasoning behind the breed survey. More general information about AS can be found on the Aortic Stenosis page. To continue reading this page, please click on the links below or scroll down the page:


BACKGROUND TO AS AND THE GLEN


BREEGE'S DETAILS


RECOMMENDATIONS

BREED SURVEY

LINKS

 


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Written: Sept 03 [Updated after survey completed]


BACKGROUND TO AS AND THE GLEN

Breege was diagnosed with supravalvular AS
at the age of 2 years and 8 months

Our own Glen, Breege, was diagnosed with SUPRAVALVULAR AORTIC STENOSIS in September 2002, at the age of 2 years and 8 months. A heart murmur was picked up at her second annual vet check. As we had intended breeding from her in 2003, she was referred to a veterinary cardiologist for a definitive diagnosis. Breege was found to have a Grade 2-3/6 murmur, and ultrasound studies revealed a defect just above the aortic valve. To our knowledge, she is the first Glen of Imaal Terrier to have been diagnosed with aortic stenosis.

Prior to her appointment with the cardiologist, I tried to find out as much as I could about Breege's "family history" (FH) and whether there were any known heart problems in Glens. I was told that three male Glens had collapsed and died, suddenly and unexpectedly. They were a "home-grown" youngster of just four years, a ten-year-old import from Denmark and an eight-year-old import from Germany. All three Glens can be traced back, within three generations, to a bitch from Ireland i.e. she appears as a great grandparent in all three pedigrees. Breege's sire was one of these "sudden death" dogs. As far as I am aware, none of these Glens had been diagnosed with a heart murmur or aortic stenosis. However, there remains a question mark over all three Glens with regard to cause of death.

Since [i] AS is one of the causes of sudden death, [ii] AS is a known hereditary heart defect, and [iii] a "sudden death" Glen has produced a daughter with AS, we encouraged all Glen owners to have their Glen(s) heart-checked to exclude a heart murmur. Please see BREED SURVEY.

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BREEGE'S DETAILS

Heart murmur picked up at second annual vet check
Symptoms: None
FH: Sire sudden death at 8 years

S/B practice vet
Aug 02

S/B by veterinary cardiologist (first visit)
Sept 02

F/U with veterinary cardiologist
Aug 03
Sept 06

Age: 2 years and 7 months

Age: 2 years and 8 monthss

Age (Aug 03): 3 years and 7 months
Age (Sept 06): 6 years and 8 months

Murmur detected

Grade 2-3/6 murmur (mild)

Aug 03 ~ Murmur slightly "softer"
Sept 06 ~ No change

[Murmur not picked up during first annual check at 16 months]

Aortic outflow velocity:
~ 1.74m/sec (unsedated)*

Aortic outflow velocity:
Aug 03 ~ 1.7m/sec (unsedated)*
Sept 06 ~ 1.7m/sec (unsedated)

Referred to veterinary cardiologist

Diagnosis: Supravalvular AS

 

* Normal = 1.2m/sec

(Breege's litter sister was seen by a veterinary cardiologist in May 2003. Ultrasound showed no defect i.e. she does not have aortic stenosis. Her aortic outflow velocity was measured, to compare against Breege's, and it was measured at 1.2m/sec).

Breege only has a "mild" heart murmur and so she should go on to lead a full and active life. However, as aortic stenosis is known to be hereditary in some breeds of dog i.e. the defect can be passed from one generation to the next, we did not breed from Breege.


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RECOMMENDATIONS

Breege's veterinary cardiologist and Dr Bruce Cattanach (Steynmere Boxers), who is a canine geneticist, kindly answered my questions about aortic stenosis. I was particularly interested in whether or not they felt that "further investigation", within the breed, was warranted.

Veterinary cardiologist

Our veterinary cardiologist recommended that these Glens should have a thorough heart-check to exclude a heart murmur:
   ~ Breege's litter siblings (brothers and sisters).
   ~ First and second generation progeny i.e. pups and grand-pups, of any "sudden death" Glen.

Canine geneticist

From correspondence with Dr Cattanach in October 2002:

Dr Cattanach wrote "... if one wants to play safe further investigation is required. By this I mean, a breed survey using just auscultation [listening to the heart using a stethoscope]."

NB Dr Cattanach suggested that screening for heart murmur should, ideally, be undertaken by a veterinary cardiologist. However, we felt that we would achieve our aim of getting as many Glens as possible heart-checked, if we suggested that this was done as part of the annual check-up.

Q A Seall: "... should we prioritise the checking of Glens, or should we be encouraging everyone to have their Glen(s) checked, whatever their age?"
A Dr Cattanach: "I would go the survey route, although perhaps you could take a more limited survey first with relatives ... No need to worry about age at this point."

Q A Seall: "Do you have any recommendations for the testing of Breege’s litter-siblings if they are to be used for breeding?"
A Dr Cattanach: "I would have all siblings auscultated whether to be used for breeding or not - just to help evaluate the situation."

Q A Seall: "If [relatives of an affected dog] are checked and declared 'No murmur detected', can we safely assume that they do not have aortic stenosis ... is it possible for an animal to have the gene but not show the trait?"
A Dr Cattanach: "At this time I cannot say even in Boxers if a zero result means genetically free."

Q A Seall: "Am I correct in assuming that the reason for not breeding from an animal with mild aortic stenosis, [as Breege has been classified], is because it is possible to pass on a more severe form of the defect?"
A Dr Cattanach: "The answer to your question ... is, Yes."


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BREED SURVEY

A worldwide breed survey was initiated to try to determine the incidence of heart murmurs within the breed.

We asked Glen owners to request their vet to have a thorough listen to their Glen's heart, at their next annual check-up or visit to the surgery, to ascertain whether or not a heart murmur was present. We also asked owners to advise their vet that the examination was to provide information for a breed survey, following the recent diagnosis of AORTIC STENOSIS in a Glen of Imaal Terrier.

"Examination conditions must be appropriate for recognition of subtle cardiac malformations. Identification of soft cardiac murmurs is impeded by extraneous noise or by poorly restrained, anxious, or panting dogs."

[Reference: www.offa.org/cardiacguide.html - Limitations 3.]

NB Not all heart murmurs are caused by aortic stenosis e.g. some puppies can have "innocent" murmurs, which they outgrow; and some older dogs can develop heart murmurs related to an "acquired" heart condition of old age. So, if your Glen is found to have a heart murmur, it does not necessarily mean that s/he has got aortic stenosis.

Over period of just over two years, 66 Glens were specifically screened for heart murmur for the purposes of the survey. Apart from Breege, there were two other Glens with a heart murmur. One male was found to have a murmur at the age of 7 years, and the other, also a male, developed an aquired murmur at the age of 13 years. As no more young Glens with a heart murmur were identified, no further breed investigation was undertaken.


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LINKS

Aortic Stenosis
   More "general" information about aortic stenosis.

Breege's pedigree
   Three generation pedigree.


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