Hi Chris
Are you not on my FB friends list? all the links for anything to do with genetics and the GSD are there.
I will put here you can either go via Laboklin in Manchester who send it on for you it is £140 you can download order form here
LABOKLIN (UK)|Genetic Diseases | Dogs| Dwarfism (Pituitary Dwarfism / Hypopituitarism)
Dogs must have means of identification plus copy of pedigree.
Or you can go direct to Utrecht
For the genetic test, 4 ml. of blood (collected in an EDTA containing tube) is needed. The blood sample has to be shipped to:
Dr. H.S. Kooistra (H.S.Kooistra@uu.nl)
Department of Clinical Sciences of Companion Animals
Faculty of Veterinary Medicine, Utrecht University
Yalelaan 108
3584 CM Utrecht
The Netherlands
100 euros plus vat