DetailsCreated on Monday, 06 August 2012 12:22
CAVEAT: The Brussels Griffon Forum provides information on the Breed for public education not for private download unless otherwise stated. If you wish to have these resources for your own reference, please contact Dr. Platt for permission. Do not attempt to remove from the site, it is monitored and you will be tracked.
In March 2012, Dr. Simon Platt addressed the American Brussels Griffon Association in a presentation which provided the latest information regarding the diagnosis and prevalence of Syringomyelia and Chiari-like Malformation in the Brussels Griffon. In July 2013, Dr. Platt was interviewed by the AKC Health Foundation. The audio can be heard here. Permission has been granted by the Foundation for use on the BGForum website.
Dr. Platt has generously allowed the Brussels Griffon Forum permission to publish the slideshow from the ABGA 2012 workshop along with an earlier paper citing testing done in the Breed in the United States in 2009. The content of that paper you will find below.
Ruth Pereira of the BGForum was instrumental in initiating the American Kennel Club Canine Health Foundation's Brussels Griffon Grant #1004 and is a member of the Founders Society of the AKC/CHF.
EVALUATION OF SYRINGOMYELIA IN AMERICAN BRUSSELS GRIFFON (ABG) DOGS.
A.C. Freeman, S.R. Platt, M. Kent, E. Huguet. University of Georgia, College of Veterinary Medicine, Athens, GA.
The aims of this study were to investigate the ABG for (i) the prevalence of skull abnormalities; (ii) the prevalence of SM; (iii) an association between lateral ventricular size, cerebellar size and SM; and (iv) associations between SM, skull abnormalities, CSF abnormalities and clinical signs.
Currently 85 ABGs have been recruited and all have undergone brain and spinal MRI evaluation (3.0T General Electric Signa HDx, Milwaukee, WI) at UGA College of Veterinary Medicine. All dogs were evaluated neurologically, recording deficits and the presence of spinal pain.
MRI sequences acquired included T2W, T1W pre- and post-contrast, and T2W FLAIR, sagittal and transverse. Cervical spinal cord central canal (CC) and or syrinx size and its percent area of spinal cord was measured using MRI commercially available software. The presence of Chari- like malformation (CM) was assessed by recording the presence of caudal cerebellar deviation and/or foramenal vermal herniation. Lateral ventricle and cerebellar volume was expressed as a percent of the cerebrum and intracranial volume respectively. Forty-five dogs underwent atlanto- occipital cerebrospinal fluid tap at the time of MRI and the white blood cell (WBC) count was recorded. Standard statistical tests were used to compare the measured variables between groups with and without skull abnormalities, spinal pain and neurological signs.
The mean age of the 32 males and 53 female dogs was 50.4 months (range 8-135; median 44 months). Neurological deficits and neck pain were noted in 27% and 19.7% of dogs respectively. All neurological deficits were proprioceptive dysfunction and did not include paresis or ataxia or cranial nerve dysfunction; 7% of dogs exhibited both neck pain and neurological deficits.
Cerebellar deviation and vermal herniation were present in 49% and 60% of dogs respectively; the later varied in degree and is currently being quantified but for most dogs was very mild. Thirty percent of dogs had both defects; 90% of dogs had one defect; 40% had no herniation (main determinant of Chiari-like malformation); 10% were completely normal.
Syrinx / Syringomyelia (SM) / Central Canal (cc) dilation
Mean height of the CC was 2.3mm (0-7.2mm). Fifty three percent of CCs were greater than 2mm in height which has been assessed as a cut off for grading in the CKCS; therefore 53% had SM (12% were completely normal); the mean length of these lesions was 2.03 vertebrae (0.5-7). Syrinx height and extent were significantly higher in dogs with neurological signs (size p=0.01; extent p=0.0004). There were no significant differences in syrinx sizes and extent in dogs with or without skull abnormalities or spinal pain. There were no associations of syrinx height or extent with CSF WBC count or age of dog. Intact females had a significantly lower syrinx extent than intact males (p=0.009). There were no significant differences in presence of spinal pain or neurological signs between dogs with or without skull abnormalities. There was a significant negative association of ventricular percentage and cerebellar percentage (p<0.0001); the smaller the cerebellum the more likely the ventricles will be larger. There was a significant association of ventricular percentage with syrinx percentage (p=0.0015) and height (p=0.0007); the larger the syrinx, the more likely that the ventricles would be large. Mean CSF white cell count was 4.97/µl (normal <5; range 0-39).
This study suggests that SM (53%) and CM (60%) are seen in ABGs. Syrinx size and extent are associated with neurological signs and ventriculomegaly is associated with both small cerebellar size and large syrinx size. However, SM may not be associated with CM in the ABG as defined by cerebellar herniation and deviation and is not associated with CSF inflammation.
1. The Ohio State University is unable to scan dogs as part of this study although negotiations are ongoing
2. UCLA are in the final stages of negotiation and may be able to scan dogs in the next month.
3. Genetic analysis of the DNA of affected and unaffected dogs in conjunction with pedigree analysis is being undertaken aiming to produce a blood test for a genetic abnormality to help with breeding guidelines. However, the question as to what characteristic on the MRI is unacceptable remains open and suggests that a long term study is necessary scanning dogs from this study at a later date.
4. More intricate skull measurements are being made to look for associations with SM as there is no current link established in this breed between CM and SM.
At the time of writing this report, UGA College of Veterinary Medicine (CVM) has scanned 85 Brussels Griffons with the original target number being 100. We have 2-3 more dogs registered to scan at UGA but we feel that the ‘pool’ of regional BGs as well as those with owners willing to travel to Athens has dried up. We are still in negotiations with UCLA and remain hopeful that they can scan a reasonable number of dogs so that we may exceed our target. The negotiations with OSU CVM stalled based on difficulties with pricing and scanning a few dogs at one time. I do not remain hopeful about that opportunity.
The results of the study so far can be listed as follows and are expressed as percentages of dog:
- Skull shape abnormality causing a cerebellar shape abnormality – 90%
- Skull shape abnormality causing herniation of the cerebellum (=Chiari-like) – 60%
- Presence of central canal dilation >2mm diameter / cyst accumulation – (Syringomyelia) – 53%
- No evidence of any central canal – 12%
- Neurological dysfunction – 27%
- Neck Pain – 21%
- Both Neck pain and neurological dysfunction – 7%
1. The larger the cyst in the cord the more likely neurological signs – no minimum ‘safe’ size identified yet
2. Cyst size not related to pain
3. Cyst size not related to skull abnormalities (Chiari)
4. Skull abnormalities potentially causing hydrocephalus
At this time, we do not know (I) what should be considered normal regarding skull shape; (II) What is responsible for syrinx development; (III) which dogs are at risk of developing syrinxes; (iv) Why syrinx presence in some dogs does not cause clinical signs.
1. Genetic analysis of dogs with syrinx and or Chiari
2. Further measurements of skull sizes
3. Defining neurological deficits to see how many have anything notable by owners vs. subtle changes on exam by us