The University of Georgia College of Veterinary Medicine

The University of Georgia Veterinary Teaching Hospital

Neurology Service: Clinical Trials

Magnetic Resonance Imaging (MRI) study of Syringomyelia in Brussels Griffon/Griffon Bruxellois dogs

Find out if your dog qualifies for the study

Download the study application form here [fillable PDF]

The Neurology Service announces a new study funded by the American Kennel Club Canine Health Foundation Magnetic Resonance Imaging (MRI) study of Syringomyelia in Brussels Griffon/Griffon Bruxellois dogs

Much has been made of breed-related and possible inherited disorders in dogs recently. Since the genetic makeup of the dog has now been well-defined, it is possible to develop blood tests for these disorders and determine appropriate breeding programs.

In the last couple of years, a disorder of the nervous system has been identified in the Brussels Griffon breed which may indeed be hereditary and has been shown to be familial Grumbleface Pieterse – healthy, syringomyelia-free Brussels Griffon . Figure 1, right, shows a healthy, syringomyelia-free Brussels Griffon, Grumbleface Pieterse.

The disorder has been termed syringomyelia. Currently, we do not know exactly how common this disease is in the breed. This page describes what this problem is, and how it can be recognized and possibly treated. Additionally, funding for investigation of this disease in the Brussels Griffon has been awarded to the neurology service at the UGA College of Veterinary Medicine by the Canine Health Foundation (a branch of the American Kennel Club), and so details of the upcoming research project are included.

The study is in collaboration with Clare Rusbridge and Penny Knowler in the UK, world-renowned for their pioneering work in this disease in Cavalier King Charles spaniels over the last 10 years. Their preliminary investigations in Europe and Australia with Brussels Griffon breed groups have shown the need for this study. Indeed, this work has encouraged many Brussels Griffon clubs and groups all over the world to financially support further work, and all the veterinarians involved in this venture are extremely grateful for this.

What is syringomyelia?

Comparison of a normal canine MRI of the head and neck, and an MRI of the head and neck of a Brussels Griffon with Chiari-like abnormality and syringomyelia; images courtesy of Penny Knowler and Clare Rusbridge

Syringomyelia describes an abnormal fluid filled cavity within the spinal cord (see figures 2a and 2b, right). The fluid-filled cavity — or syrinx — typically is largest in the neck, but it can affect all regions of the spinal cord.

It can vary in size from being hardly noticeable to over 90% of the cross sectional area of the spinal cord. As the cavity gets bigger, the spinal cord in which it sits becomes damaged.

Syringomyelia can affect human beings with approximately 90% of people also having what is called a type I Chiari malformation, which is believed to be an underlying cause of the spinal fluid accumulation. A Chiari malformation is a complicated disorder whereby some of the brain is seen to protrude outside of the skull and sit on top of the spinal cord in the neck. The reason for this is often due to the skull being misshaped and smaller than is necessary to house the brain. Simplistically, a small skull leads to a small part of the brain pushing out of the hole at the back of the skull which leads to syringomyelia.

Quite how all the skull and brain defects lead to fluid build-up in the spinal cord is uncertain but it can be thought of as follows: the normal brain continuously produces fluid (cerebrospinal fluid or CSF) to nourish and protect its structures. The fluid normally flows out of the back of the skull and around the spinal cord. The brain can be viewed as a tap that can’t be turned off and is attached to a hose pipe. There is a continuous flow of water out of the hose pipe.

When there is an abnormality of the skull such as a Chiari malformation, it is as if a thumb is placed over the end or top of the hose pipe. The same amount of water passes through but now with a lot more pressure. This pressure can cause fluid to build up in the spinal cord, ultimately resulting in syringomyelia. The only way in this case to stop further buildup of the fluid is to either turn the tap off — which can’t be completely done — or remove the "thumb," which — when talking about the skull — means surgery.

Breeds currently identified with syringomyelia include the Yorkshire Terrier, Maltese Terrier, Chihuahua, Miniature Dachshund, Miniature and Toy Poodle, Bichon Frisé, Pug, Shih Tzu, Pomeranian, Staffordshire Bull Terrier, Boston Terrier, Pekingese, Miniature Pinscher, King Charles or English Toy Spaniel and French Bulldogs. Recently the condition has also been detected in the Brussels Griffon.

The breed that has been most extensively studied is the Cavalier King Charles Spaniel, in which syringomyelia is observed in association with a Chiari malformation similar to that seen in humans. Chiari-like malformations have been described in dogs of many breeds, but the condition is over-represented in the Cavalier King Charles Spaniel — suggesting a familial/genetic basis.

What signs are seen in dogs with syringomyelia?

The most common signs associated with syringomyelia in people are pain, weakness, muscle wasting and spinal curvatures. The pain typically is more marked on one side of the neck, shoulder and arm; it has been described as having a burning, aching quality. There can also be pain at the base of the skull or back of the neck – in some cases this pain is made worse by coughing, sneezing, stooping or other positions.

There is considerable variation of clinical signs that relate to the Chiari-like malformation and syringomyelia in the dog. The most common clinical sign is neck pain or intermittent, non-specific discomfort. Affected dogs may suddenly scream and/or lie with the head on the ground between the paws after jumping up or during excitement. It is also common to sleep with the head in unusual positions — for example, in an elevated position.

Discomfort often appears worse in the evening and early morning or when excited. Discomfort can be associated with defecation, or may vary with weather conditions. A classic clinical sign is scratching at the neck and shoulders, which may represent a reaction to possible burning sensations in the skin; typically this occurs on one side only, while the dog is walking and often without making skin contact. Such behaviour is often referred to as an “air guitar” or “phantom” scratching.

Additional signs include varying degrees of weakness and incoordination (failure to track when trotting), head shaking and ear twitching, muscle wasting and abnormal curvature of the neck.

How can syringomyelia be diagnosed?

The abnormality of the skull cannot be accurately felt through the skin. X-rays of the skull may suggest Chiari malformation, but cannot confirm this or syringomyelia. The diagnosis of syringomyelia and Chiari malformation requires advanced imaging of the brain and neck, made possible with magnetic resonance imaging (MRI) (see figure 2 above).

Abnormalities of the skull, brain and spinal cord can all be clearly seen with this test, although a one-hour general anesthesia is necessary. The size of the spinal cord cavity can be accurately measured and has been shown to be related to how severe the pain is in individual dogs.

Why study this disease in the Brussels Griffon?

Preliminary evaluations of the Brussels Griffon suggest that there are a few dogs with Chiari malformation and/or syringomyelia. In affected dogs, a definitive cause for the syringomyelia has not been identified and an association with Chiari malformation has not been established. Based on these preliminary evaluations of Brussels Griffon dogs, we expect to identify some of this breed affected with syringomyelia using MRI, and deduce how common it may be in the Brussels Griffon.

We anticipate that these affected dogs will manifest similar clinical signs as have been reported in dogs with Chiari malformation or syringomyelia. Many of the Brussels Griffon dogs with syringomyelia will appear clinically normal to their owners. Additionally, we anticipate that some of the dogs with syringomyelia may demonstrate clinical signs different from those which have been previously documented in dogs with Chiari malformation or syringomyelia.

Characterizing the clinical signs associated with syringomyelia in the Brussels Griffon should allow owners and veterinary health care professionals the ability to not only identify other affected individuals but it also should allow for earlier therapeutic intervention preventing morbidity and mortality in affected dogs. Defining the morphological abnormalities in syringomyelia in the Brussels Griffon may provide insights into the underlying cause for syringomyelia and it should lead to appropriate therapeutic options for affected dogs.

Finally, this study should enable Brussels Griffon breeders the opportunity to preemptively alter the perpetuation of a disease process in the breed. If corrective measures are taken early enough, wide spread perpetuation of syringomyelia within the breed can be avoided. DNA will be collected for studying the genetics of this disease in association with the University of Montreal, Clare Rusbridge, Penny Knowler, and the Animal Health Trust, UK.

How can I find out if my dog would qualify for the study?

The study will target AKC registered Brussels Griffon dogs with or without clinical signs from as many U.S. states as geographically possible. Full five-generation pedigree information must be provided, but the AKC has agreed to help with this pursuit.

Dogs will be selected from as diverse breeding lines as possible. Priority will be given to dogs over 5 years of age which are related, with some showing signs and some normal; but dogs less than 18 months old may be accepted if related to older dogs within the study.

Litters of normal dogs are also valuable, especially if they are known to be related to dogs showing signs. Dogs should not be receiving treatment for any other diseases, and should be medically suitable for general anesthesia — therefore, dogs over 10 years old may not be suitable. However, dogs as old as 12 years have undergone MRI. Questions regarding enrollment or requests for enrollment can be addressed by e-mailing abgstudy@uga.edu.

Download the study application form here [fillable PDF]

What will happen to my dog during the study?

Study patients will be evaluated through the Veterinary Teaching Hospital (VTH) of the University of Georgia, or by other participating centers in the U.S. that are currently being confirmed. Each study patient will be under the care and supervision of a board-certified veterinary neurologist. Other centers in Australia and Europe potentially can be involved in this study, but funding would need to be determined locally.

The evaluation of each dog will consist of several steps:

Step 1: Clinical Evaluation
A thorough history will be collected at the time of admission to the Teaching Hospital. A clinical scoring sheet will be filled out to assess the clinical signs — including frequency of scratching, frequency of vocalization and limb paresis.

Neurological examinations will be performed by a board-certified veterinary neurologist. Examination results will be recorded in the medical records of each study patient. Blood tests and urine samples will be collected for general health assessment pre-anesthesia. Blood samples also will be stored along with AKC pedigree information for future research into the potential inherited nature of this disorder.

Step 2: Magnetic Resonance Imaging (MRI)
The MRI unit will be operated by a certified MRI technologist. Image planning will be done under the guidance of a board-certified veterinary neurologist and will be exactly the same for each center involved. The imaging procedure will take approximately 45 minutes for each dog. Each dog’s images will be stored as electronic files on a secure server.

All MRIs will be performed under general anesthesia by a board-certified veterinary anesthesiologist who is aware of the breeds’ sensitivity to anesthesia. A general anesthesia is necessary for the MRI to enable an expedient, comfortable and safe study which would not occur under a heavy sedation. The premedication used will consist of a midazolam, glycopyrrolate, hydromorphone combination administered intravenously; induction of anesthesia will be achieved with propofol, and anesthetic maintenance will be accomplished using inhalational isofluorane and constant oxygenation. The MRI facility at the University of Georgia is complete with state-of-the-art MRI-compatible anesthesia equipment which enables constant physiological monitoring during the procedures.

Lumbar spinal cerebrospinal fluid will be collected from all study patients immediately after the MRI, under general anesthesia, using routine techniques. This will be important to evaluate the possible role of inflammation in this disease which may prove to be valuable in the determination of future treatments. However, concern about this test should not discourage participation and can be discussed on an individual basis. This procedure will take no more than 10 minutes to perform.

Cerebrospinal fluid will be assessed by a board-certified veterinary clinical pathologist. At the conclusion of the evaluation of each study patient, dogs will be recovered from anesthesia, appropriately cared for under the supervision of board-certified anesthesiologist, and will be able to go home the same day.

Step 3: MRI Grading
Once the study is complete, all the MRIs will be evaluated and statistics will be used to investigate how common syringomyelia and Chiari malformation are, and whether they are associated with any clinical signs. The study is completely confidential. The initial results of an individual dog’s tests can be discussed with the owners on the day of the scan.

Further evaluation of the results for the purpose of the study may take several weeks. Since Chiari malformation/syringomyelia has been shown to have a hereditary basis in the Cavalier King Charles Spaniels, the MRI report will also provide a grading scale inline with the Cavalier King Charles Spaniel recommended breeding guidelines (see Table 1 below).

Grade	Age (years)	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	NO
F	Any	Present and symptomatic	NO

Questions?

Further questions about the study, dog enrollment, and the techniques used can be forwarded to the researchers at the UGA College of Veterinary Medicine (abgstudy@uga.edu). All communications will be dealt with in the strictest confidence.

Donations

The ABGA, AKC-CHF, and the researchers involved in this grant (#1004) encourage study participants and interested parties to make a donation of $100 toward the study, as continued funding for this project is necessary. Donations may be arranged through Meg Prior (meg@megpriorconsulting.com) or the AKC-CHF through Erica Werne (EAW@akcchf.org).

Funds for Neurology Research and Treatment

Give a gift online to The Small Animal Medicine Fund at the Arch Foundation for the University of Georgia. When you go through the checkout process, be sure to indicate that you wish for the funds to support neurology research in the "special instructions" box.

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This page was last updated September 5, 2008.