I am asking this question (not my dogs before we start).  I have a friend who breeds a small breed that a certain condition is known for, and thought that she is a wise responsible breeder, but a conversation I had with her today put me in doubt.  She is breeding her bitch at the moment and is taking her back for her 2nd mating tonight, she has had her health tests but she let slip that syringomyelia runs in the bitches line but she has tested clear at 2 years.  Am I wrong in thinking that she shouldn't be breeding this bitch?  Your thoughts appreciated.

Linda

Sorry for the heading admin hit send before thinking.

Sorry

Well she will not have a clear certificate for her bitch unless she is 2 1/2, however as all living Cavalieers have a line to either an affected dog or a carrier then breeding clear to clear(via scanning)is the only way that breeders have @ the moment, the dog featured on THAT program has the syrinx, yet his half brother is clear by MRI scan !!(wouldn't use the half brother but that's another story)

The official recommendations can be found here:
http://www.thecavalierclub.co.uk/health/syringo/guide.html
Its not a question of whether it runs in the lines, but whether both parents have been tested, what the results were, their ages etc.

> syringomyelia runs in the bitches line

It is believed that SM runs in all lines. Unless a cavalier has a glass skull then the only way to know if a Cav has this condition is by MRI scan.
The age of 2.5 years was decided upon by researchers and breed club to coincide with guidelines for Mitral Valve disease recommendations.
The neurologists I have spoken to have said that, taken in isolation, a clear scan at 2 years is likely to have an excellent outcome but that is not the breed guidelines. May I applaude your friend for at least having the bitch scaned in the first place.

May I applaude your friend for at least having the bitch scaned in the first place. That is exactly what I was thinking how many silly people think oh I'll have the litter and scan at 2 1/2 years old when it is too late by then. 

In an ideal world everything would be yes or no but with testing a responsible breeding it is impossible to throw "all" the babies out with the bath water.

Do you think truthfully that all health problems can be eliminated? reduced yes! Surly the genies can travel many generations back then re-appear. When doing my homework, I have found how some health checked parents have been clear, no problems, to then produce say 2 out of 5 pups with them. It will obviously reduces them, but! not eliminate.

Denese

Simple recessive conditions like CEA(CH)/TNS/CL can be easily provented from occuring by ensuring that at least one parent is normal by DNA test QED

Conditions like VWD can be acquired as opposed to inherited & hence the need for testing all breeding stock

Thats because genes are carried they are only "present" well the result of these genes are only present when one is affected by it.

Most things are carried genetically and only appear when they meet a marker.

> Most things are carried genetically and only appear when they meet a marker

Unless it is a polygenic condition or a sex linked condition or a dominant condition... Simple recessive conditions are where two of the same recessive gene are inherited, one from each parent, which I imagine is what you are referring to. I am not sure quite what the markers that you mean are.

I haven't looked at the reasearch on syringomyelia but i would imagine it is polygenic and more complex than a straightforward simple inheritance pattern.

I am not sure quite what the markers that you mean are.   just ask then :-)

As it is complex I choice this as a general word rather than say recessive or Polygentic, it covers a broad spectrum.

A polygenetic trait works "kind of" similarly to a recessive gene in practice hence the reason I didn't expand on them..but a bit comes from both it is just hard to find they bits.

MY point was that animals tested for being affected for something and be tested clear doesn't mean the dont carry a faulty gene as MOST hereditary conditions do not have tests yet.

And recessive conditions are 100% not simple sadly most wish they were  perhaps "simpler" than a polygenetic trait but certainly not simple.  One of two of the things seen in my breed is believed to be reccessive but no test yet.   You have to remember with recessive genes also although we have % affected guidelines the majority do not follow these % you see highs and lows and many no shows even with carry to carry matings.

SM is believed to involve at least three genes if not more & just because the dog has the all/any of the clinical signs(diagnosed by MRI scan) does not mean it will have all/any of the symptoms. This information came from Prof Geoff Syrett directly. It is a very complex condition

The genetic inheritace of CEA(CH)/CL/TNS/MDR 1 are straightforward recessive conditions for which there are DNA tests

> just ask then

That was partly what my reply was intended to do - I obviously didn't word clearly enough that I would like to know what you meant. :-) So what did you mean by markers?

I was using simple recessive as being a term often used for a recessive condition at a single gene locus. There is nothing simple about genetics. ;-)

> When doing my homework, I have found how some health checked parents have been clear, no problems, to then produce say 2 out of 5 pups with them. It will obviously reduces them, but! not eliminate.
>

Health screening for conditions like HD and SM is a bit like putting on your glasses, seat belt and keeping to the speed limit when driving your car. It's not going to guarantee that you'll never have an accident but it will substantially reduce your chances of having one.

Recesive genes... those tricky little blighters are hiding in amongst the DNA of the cell.... not showing up until they pair up and decide to show themselves. Not all genes are expressed (visible in the individual) but it doesn't mean they're not there... and just to complicate matters a little ..some are there ..waiting to be switched on !

> Health screening for conditions like HD and SM is a bit like putting on your glasses, seat belt and keeping to the speed limit when driving your car. It's not going to guarantee that you'll never have an accident but it will substantially reduce your chances of having one.

Love this quote tooolz :)

Should be writ large and made into a poster and a T-shirt

> Should be writ large and made into a poster and a T-shirt

I might just get it on a tee shirt to fit my size :-)

Toolz , what a great way of simplifying the reasons for testing!!!   I must remember that! Good one!

Hi evelyn,

Nice to see you :-)

tooolz
That is what I ment, reduce yes! try your best, do your best. but, no quarantee.
I think sometime people think that health checks are 100% a gurantee.

Denese