Genetic Testing
CHG
DNA testing has revealed the existence of Neonatal Hypothyroidism (more accurately known as Congenital Hypothyroidism with Goiter, or CHG) in Tenterfield Terriers.
History has proven that denial of inheritable disease in various breeds has led to many breeds now undergoing high levels of regulation by the ANKC and litter registration restrictions. We do not want to see this happen within the Tenterfield Terrier breed and this is why we are choosing to provide this information to our members.
What is it?
Neonatal Hypothyroidism is a disease affecting only young puppies and it is fatal. For many years now we believe that incidence of Neonatal Hypothyroidism has been misdiagnosed by breeders and vets alike as ‘fading puppy syndrome’.
Basically pups appear completely normal and progress as normal up until 2 weeks of age. They, then start deteriorating, develop feeding difficulties, loose co-ordination, loose the ability to regulate their own body and temperatures, their eyes and ears fail to open, develop a fluffy coat and growth is very stunted. Affected pups do not survive long enough to make it to their 6 week vaccination either by demise or euthanasia.
Are their any risks of selling an affected pup?
Absolutely not. Pups affected by this disease do not survive long enough to make it to 8 weeks of age.
Can a carrier ever be affected by this?
No. The information we have to hand is that at no time will a carrier ever develop any conditions directly related to this defective gene.
What does this mean for our breeding programs?
We need to educate ourselves about this disease and make breeding choices that will assist in the control and possible elimination of this disease in Tenterfield Terriers.
Research has shown that this disease is an autosomal recessive gene. What this means is, to end up with an affected pup you need to obtain a double up of the defective gene. That is, both parents must be carriers. Consequently, if only one of a breeding pair is a carrier, they will never produce an affected pup, but will produce puppies that may be carriers.
To further explain this, a mating of carrier to clear will result in approximately 50/50 ratio of carrier & clear puppies.
I should also highlight that a clear to clear mating will never result a carrier pup, let alone an affected pup.
What do we do now?
First off is to arm yourself with all available information. There is absolutely no need to panic or eliminate any or all carriers from your breeding programs. The exclusion of carriers from our already small breeding pool with only do our breed harm by concentrating undesirable characteristics and essentially taking our development back many, many, years. Testing is the way of the future!
By testing, you arm yourself with the knowledge to make informed breeding choices and at this early stage it gives us room to move forward over the coming years, to work towards the reduction and eventual elimination of this disease within our breed. However, the total elimination of this disease will likely take decades to happen. But it will only happen once all Tenterfield Terrier breeders take responsibility.
Why should we test?
We are all obligated by the ANKC Code of Practice to do all that we can to identify and eliminate inheritable diseases by making informed breeding choices.