Syringomyelia in dogs
Congenital Syringomyelia in dogs is a
relatively uncommon malformation of the spinal cord. This malformation results
from the incomplete closure or development of the neural tube, the tubular
structure in the embryo that differentiates into the brain and spinal cord.
This malformation results in cavitation of the spinal cord parynchema or tissue.
Syringomyelia may also occur secondary to
oedema (the accumulation of fluid) caused by neoplasms (tumours); spinal cord
trauma; vascular compromise or inflammation.
Syringomyelia may occur in isolation, or may
also occur in combination with Hydromyelia, that is the dilation of the central
canal within the spinal cord. The occurrence of these two conditions in
combination is referred to as Syringohydromyelia. These two conditions can
often not be distinguished on diagnostic imaging.
Syringomyelia occurs in various breeds ranging
from 12 weeks to 12 years in age. The prevalence of Syringomyelia in a
population of 555 Cavalier King Charles spaniels was 25% in dogs aged 12 months,
and this incidence increased to 50% in these small dog breeds older than 6
The clinical signs due to Syringomyelia are
variable, depending on the location and severity of the Syringomyelia, as well
as the presence or absence of other congenital central nervous system (CNS)
malformations. Other congenital CNS malformations that may occur in
combination with Syringomyelia include:
A bone marrow stem cell
disorder resulting in ineffective blood cell formation.
- Spina bifida
A condition where some
vertebrae overlying the spinal cord are not fully formed and remain unfused and
open. If the opening is large enough, a portion of the spinal cord may
protrude through the opening in the vertebrae.
- Sacrocaudal dysgenesis
development of the vertebrae in the sacrocaudal area (area of the sacrum closest
to the tail) that is often associated with abnormalities of innervation to the
anus, bladder, hind legs and tail.
The protrusion of the
spinal membranes and cord through a defect in the vertebral column.
The accumulation of
cerebrospinal fluid (CSF) resulting in the abnormal expansion of the cavities or
ventricles within the brain.
- Chiari malformations
Malformations of the
brain. Syringomyelia malformation associated with Chiari l malformation is
most common in small dog breeds, especially the Cavalier King Charles spaniels (CKCS).
Chiari-like malformation in the CKCS is inherited with an estimated incidence of
95%, of which Syringomyelia is present in more than 50% of dogs with Chiari-like
malformations. Approximately 35% of affected dogs exhibit clinical signs.
This condition has also been reported in Pekingese dogs, Maltese Terriers,
Miniature Dachshunds, Yorkshire Terriers, and a Saymoyed dog.
Syringomyelia that accompanies a Chiari-like malformation is thought to occur
following an abnormal CSF flow at the foramen magnum (a large opening in the
occipital bone of the cranium).
- Occipital dysplasia
malformation of the foramen magnum
- Dandy-Walker syndrome
brain malformation involving the fluid filled spaces around it.
The onset of clinical signs may be very severe
and of very short duration, or it may be progressive of a period of several
weeks, months or even years. Clinical signs may include any of the
- Paraparesis (partial paralysis of the limbs)
- Tetraparesis (paralysis of all four limbs)
- Scoliosis (sideways curvature of
the spinal column)
- Torticolis (contracting muscles of the neck causing
sustained twisting or frequent jerking)
- Spinal pain, most commonly localized
to the cervical (neck) region
- Persistent intense scratching over the shoulder
/ flank / ear / neck / sternum region
- Muscle atrophy (muscle wasting)
- Weakness, especially in the front limbs
- Decreased spinal reflexes
dysphagia (difficulty in swallowing)
- Pelvic (hind) limb proprioceptive
deficits (deficits in the awareness of posture, movement and changes in
- Urinary and faecal incontinence
- Bunny-hopping gait in the
- Progressive ataxia (failure of muscular coordination)
- May be overly sensitive to touch on
one side of the head, the neck, shoulder or sternum
The most consistent clinical sign seen in
Syringomyelia affected dogs, is pain localized to the cervical spine, which may
be characterised by sudden vocalization after jumping. This clinical sign
is reported in 35% of affected dogs.
CFS analysis is usually normal.
Electromyography or EMG (an electrical recording of muscle activity) may reveal
abnormal spontaneous potentials in cervical epaxial or thoracic muscles.
Myelography (an X-ray of the spine after the injection of a radio-opague
substance) may be negative or may reveal diffuse spinal cord enlargement and
presence of contrast agent within the central canal. Magnetic resonance
imaging (MRI) and computed tomography (CT) may help outline the extent and
location of the lesions. MRI is however superior in the detection of
Syringomyelia and Hydromyelia compared to myelography and CT. Often
Hydromyelia and Syringomyelia can however not be clearly distinguished from one
another on MRI images, as both result in focal or regional, usually elongate,
accumulations of CSF that appears hypointense on T1 images and hyperintense on
Medical treatment does not typically resolve
the clinical signs, and is therefore aimed at relieving the pain and other
neurological signs associated with the condition. Analgesics (pain
killers), drugs targeted at decreasing CSF production, and corticosteroids have
shown some benefit depending on the severity of the clinical signs. The
length of treatment depends on the clinical response. Surgery is also only
aimed at relieving the pain and other neurological signs associated with the
condition. the most common procedure is foramen magnum decompression.
81.25% of dogs that underwent this procedure had improvement or resolution of
clinical signs. 25% of these dogs however had a recurrence of clinical
signs within the follow-up period, presumably because of the scar tissue
formation at the surgical site. In dogs surgery appears to be less
successful compared to that in humans. Until a reliable surgical option is
defined, medical treatment is likely to be the mainstay of veterinary therapy.
The prognosis depends on the severity of
the clinical signs, and the response to medication.
For other congenital dog illnesses go to
Dog health conditions - A chart of many inherited dog health conditions
Defects of the vertebral column in dogs - Congenital conditions
Deafness in Dogs
Defects of the Nervous System of Dogs
Dog health conditions - A chart of many inherited dog health conditions
Canine Leukocyte Adhesion Deficiency - CLAD
Congenital Portosystemic -
Shunts in dogs
Bladder problems -
Ectopic Ureter in Dogs
Congenital conditions of the Skin Eyes and Ears of dogs
Syringomyelia in Dogs to Veterinary Articles
Veterinary articles supplied by Dr S Strydom and published
with kind permission of DIA Publishing - publishers of KUSA Dogs in Africa
Dr Sunelle Strydom qualified as a veterinarian in 2004 at the Faculty of
Veterinary Science, University of Pretoria. She has a passion for writing and
the sharing of knowledge to promote animal health and welfare. She has written
several articles for KUSA Dogs in Africa as well as for Vra vir Faffa on the
Landbouweekblad website at www.landbou.com
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