Grade A /Over 2.5 years old /SM absent or less than 2mm central canal dilatation in the C2-C4 region only /Breed to A, C, D dogs
Grade C /Under 2.5 years old /SM absent /Breed only to A dogs and rescan after 2.5 years of age
Grade D /Over 2.5 years old /Syrinx present but dog asymptomatic /Breed only to A dogs
Grade E /Under 2.5 years old /Syrinx present but dog asymptomatic /Do Not Breed
Grade F /Any Age /Syrinx present and dog symptomatic /Do Not Breed
Recommended that both the sire and the dam of a proposed mating are screened (any unscreened dog should be assumed to be "D")
These breeding recommendations are made using current information and in response to CKCS breeder request for guidelines. It has yet to be proven if this guide is appropriate. The aim of these recommendations is to reduce the incidence of symptomatic SM in the breed, NOT to create litters of puppies guaranteed not to have SM as the chance of producing an affected dog cannot be predicted without knowing the inheritance.