CKCS MRI screening and breeding recommendations
January 2007
The diagnosis of syringomyelia is easily confirmed by MRI but neurologists have yet to define what is meant by the term 'clear' given that most cavaliers have a degree of skull malformation. The late onset of clinical signs and the number of asymptomatic dogs adds to the complexity of the condition. Not enough is known about long term progression to ascertain the optimum age young dogs should be screened for the disease. The research is an evolving process and hopefully a proven accurate and UNIVERSAL scheme will be developed eventually. Recent studies suggests that in the vast majority of cases the syrinx starts in the upper cervical spinal cord so if this is included then scanning of the entire cord (more expensive) may not ultimately be necessary. Any 'normal' dog without the occipital malformation which makes the skull small has a genetic advantage and should be used for breeding.

The following breeding recommendations were derived at the International Conference held in November 2006 and are made using current information and in response to breeder requests 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 syringomyelia 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. It is recommended that the offspring of any mating is also MRI screened before breeding. As the incidence of syringomyelia is so high in the breed there will be severe depletion of the gene pool if only clear dogs are used (i.e. other problems will develop). Therefore until the genetic defect is determined it is recommended that dogs with syringomyelia be used if they are valuable in another genetic sense e.g. good heart. The general principle of these guidelines is that dogs with code A are more desirable to use than B, etc but that dogs with a higher letter code may still be used in some limited circumstances.

International Syringomyelia Conference Nov 2006
Revised CKCS MRI screening and breeding recommendations arising from the International Conference

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 syringomyelia (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.

Note- The age cut off at 2.5 years has been decided so as to tie in with MVD recommendations and because most dogs with symptomatic SM will show signs before 3 years of age.

The following categories from the previous guidelines have been removed because of difficulty in accurately interpreting
   Previously A * - now A
   Previously B - now C

It is recommended
  1. That both the sire and the dam of a proposed mating are screened (any unscreened dog should be assumed to be "D")
  2. Offspring of any mating should also be MRI screened before breeding.
  3. Any dog screened before 2.5 years old has a second screen when older,
  4. That dogs are screened from 6 months of age
  5. That if a limited ("mini" ) MRI screen is performed that
    a) the minimum area covered is from approximately the level of the thalamus / corpus callosum to cervical vertebrae 5 (C5)
    b) Both TW1 and TW2 = sagittal images are obtained in addition to TW1 and /or TW2 transverse images through the upper cervical spinal cord.
    c) An assessment is also made for presence/absence of ear disease and ventricular enlargement.
  6. That interpretation of images is made by Diplomate level radiologists, neurologists and, in special circumstances, by orthopaedic surgeons with recognised expertise in this area.
Colour code: red = under 2.5 years blue = over 2.5 years, purple = any age
CODE
AGE (yrs)
 Syringomyelia Breed to
A
 Over 2.5 Absent or less than 2mm central canal dilatation in the C2-C4 region only A, C, D
C
 Under 2.5 Absent A
Rescan after 2.5 years.
D
 Over 2.5 Present but asymptomatic A
E
 Under 2.5 Present but asymptomatic SHOULD NOT BE BRED FROM
F
 Any Present and symptomatic SHOULD NOT BE BRED FROM
 
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