Because Rat Terriers are a hunting breed, used for freeing farms of vermin or aiding the hunter in finding & catching small game, it is important
that breeders work together to prevent genetic diseases that can seriously impair their abilities to perform the tasks for which they are bred. 

What is Primary Lens Luxation? PLL is an inherited disease where the tiny threads (Zonules) that hold the lens of the dog's eye in place weaken and eventually 
let go of the lens. Once the lens is luxated either fully or partially (subluxated) the vitreous fluid in the eye becomes blocked and pressure builds up within 
the eye. This secondary glaucoma can cause blindness if not treated quickly. 

In early September, 2009 I received word that one of my 5 yr old puppies had glaucoma in one of his eyes. We had no previous record of dogs in 
his immediate pedigree having issues like this, so his owner and I assumed it could have just been either a fluke or an injury related issue. Later that 
same month by chance, this puppy owner ran into the owner of his full brother. She notified me that the full brother had a eye issue as well, where 
the lens had luxated and caused this glaucoma. He was treated immediately w/ surgery and his vision was preserved.  At this point, I sought out answers
as to what could have caused this issue, and did what I could to figure out how it was inherited. We had other dogs who were full siblings from later litters, 
I wanted to be sure that I was fully informed, so that I could answer questions for others who owned related dogs. 

My quest for information led me to post about this issue on a Rat Terrier forum, and I had requested that anyone with dogs related to my dogs who have 
had this issue please contact me. I heard from those who had distant relatives, and have had this issue, which they identified as Primary Lens Luxation. 
At that point, I pulled up a chair and google searched every site related to this disease. Many sites that I came up with were related to terrier breeds which
have had this issue run through their breed & where it is considered common. I looked up studies and ran across a study at Oxford University and one through
the University of Missouri, who were simultaneously announcing the discovery of a DNA marker in some Terrier breeds and cattle dogs. According
to the most recent (September) posting on the University of MO website, a new DNA test was being made available through the Orthopedic Foundation For Animals. 
Incredible news! 

The studies revealed that this disease is now known to be inherited as an autosomal recessive. This means both parents must carry the issue in order to pass it on. 
This information ruled that both my dogs, who are healthy themselves, are carriers of this disease and that's why we had affected puppies. Knowing how the disease 
is passed on has freed us as breeders, to know what we are working with before a dog is even bred. The DNA test will help us to prevent crossing two carriers and producing affected puppies, if that is indeed our goal. 

So which dogs can we breed? Dogs identified as Normal, Carrier or Affected can ALL be bred. However, Affected or Carrier dogs can only produce normal and unaffected offspring when bred to Normal dogs.  Carriers should not be bred to one another, nor should affected dogs if we want to reduce the number of affected dogs in the population. That is pretty simple, and our goal as responsible breeders should be to eliminate issues like this so that our breed can continue to be competitive in sports, hunting and of course, be wonderful and healthy pets that many have grown to love. 

-Carmeta French