Wobbler syndrome

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As wobbler disease (Syn. Cervical malformation , cervical spondylopathy , Cervical Spondylomyelopathie , spinal ataxia ) is in veterinary medicine a symptom complex denoted by nerve damage in the area of the spinal cord or spinal nerve in the cervical spine is caused ( spinal ataxia ). The term is derived from the unsafe (atactic) sequence of movements of the sick animal: "Wobbler" comes from the old German word "wobbeln" ("wiggle", English to wobble ). The wobbler syndrome occurs mainly in horses and dogs , and the cause is a multitude of different diseases. The healing success depends on the actual cause; some diseases have a good prognosis , others a bad prognosis .

The symptoms are caused by damage to the cervical cord , usually by compression, but rarely also by infection in horses. The clinical picture thus corresponds to the cervical spinal stenosis in humans (see also spinal stenosis ). The compression can result from a static narrowing of the spinal canal ( static wobbler). A dynamic wobbler is when the spinal cord is only compressed as a result of movement.

Wobbler Syndrome in the Dog

Occurrence

The wobbler syndrome was first described in 1967 in the Basset Hound . The disease occurs in numerous dog breeds . Studies from Great Britain and the USA show a clear breed disposition for Doberman and Great Dane , which, however, could not be demonstrated in a Swiss study. So far, the wobbler syndrome was Airedale Terrier , Alaskan Malamute , Australian Shepherd , Greyhound , Basset Hound, Beagle , Bernese Mountain Dog , Boston Terrier , Cocker Spaniel , Dachshund , Dalmatian , German Shepherd , Lhasa Apso , Newfoundland , Irish Wolfhound , Kuvasz , Labrador Retriever , Pointer , Poodle , Pyrenean Mountain Dog , Rhodesian Ridgeback , Giant Schnauzer , Rottweiler , Shih-Tzu and Weimaraner .

Large breeds of dogs are affected significantly more often, male dogs about twice as often as female dogs.

Disease origins and forms

X-ray of a congenital narrowing of the spinal canal behind the second cervical vertebra (arrows) in a Rhodesian Ridgeback . 1 skull, 2 humerus bones

The causes of wobbler syndrome in dogs are also manifold. Most often, congenital malformations ( atlanto-axial subluxation , malformations of the vertebral body or arch) or intervertebral disc disease are the cause, i.e. anomaly and degeneration according to the VETAMIN D scheme . But neoplasms , abscesses or osteochondroses can also lead to the development of the syndrome. Rapid growth and malnutrition are beneficial factors, and a connection with an excessive calcium supply has been proven in Great Danes .

Seim III and Withrow differentiate between different forms of wobbler syndrome:

  1. Congenital malformation of the vertebral body: There is a static as well as dynamic compression of the spinal cord from below in the area between the third and seventh cervical vertebrae (C3-C7). The disease occurs mainly in young animals. It has not yet been clarified whether it is genetic or whether it is caused by malnutrition or overload. The prognosis is unfavorable.
  2. Malformation of the vertebral arch or articular processes with hypertrophy of the ligamentum flavum : It occurs primarily in the Great Dane between C4 and C7 and leads to compression from above or from the side. The ligament is hypertrophied as a result of the increased mobility (instability). The compression is mostly static. The prognosis is good to uncertain.
  3. Chronic degenerative disc disease: Disc degeneration and hypertrophy of the annulus fibrosus in older animals lead to a herniated disc and thus to compression from below, especially in the area between C5 and C7. The cause is an overload of the intervertebral disc due to excessive mobility of the cervical spine. The compression can be static or dynamic. The prognosis is good.
  4. "Vertebral tipping" : misalignment of the vertebral body in the form of an upward rotation, especially between C5 and C7. This form occurs mainly in older Dobermans and is caused by a lack of accuracy of fit of the joint surfaces. The anterior articular surface is sloping backwards in the lower area and therefore does not match the posterior of the preceding vertebra. The compression is dynamic and the prognosis is good.
  5. Watch glass compression: The watch glass compression is a combination of the previous images and occurs mainly in younger Great Danes. This complex malformation leads to compression on all sides between C2 and C7 and has an unfavorable prognosis.

Clinical picture

According to the numerous causes and thus different localizations, the clinical picture is very variable. It is also important whether the white matter of the spinal cord occurs more in the area of ​​the posterior cord (sensitive tracts) or the ventrolateral cord (descending motor tracts). The ataxia usually develops gradually and is more evident in the hind extremities than the anterior. The gradual course often means that the dog owner does not take the disease seriously for a long time. Only in 15% of cases does wobbler syndrome occur suddenly in the form of paraplegia or tetraplegia .

The most common picture are gait disorders. The gait is unsteady and the paws are usually stroked over the ground when showing, which leads to increased wear on the claws . The animals often stand there with their legs apart. In the further course there may be difficulties in getting up. Running in circles or doing turns usually makes the movement disorder clearer. Especially when walking at a faster pace, the stride length of the front limbs can be exaggerated. In contrast to inflammatory processes that are relevant for differential diagnosis ( encephalitis , meningitis ), consciousness is undisturbed here.

A painfulness of the neck area is not always present, even when the neck is bent and stretched during the examination. However, the affected dogs usually move the neck area only unwillingly. Very rarely, however, pain in the neck area can be the only symptom and neurological deficits are absent.

Diagnosis

Neurological examination

First are posture and position reactions ( wheelbarrow sample , support reaction , Hüpfreaktion , Aufrichtungsreaktion , table edges sample , corrective reaction ) tested. The reactions are mostly reduced or delayed, but can also be physiological if they are mild.

The reflexes of the hind limbs are usually increased ( hyperreflexia ) as a result of the failure of the inhibiting interneurons of the upper motor neuron ; this can be masked when muscle atrophy begins . A crossed extensor-flexor reflex is typical . In the forelimbs, if the neck swelling ( intumescencia cervicalis ) of the spinal cord is damaged, the reflexes are reduced ( hyporeflexia ) or completely absent ( areflexia ). In individual cases, spasticity can occur because the nerve pathways for the extensor muscles are less affected than those of the flexor muscles . The body reflexes ( pannicular reflex , vulva or bulbourethral reflex and perianal reflex ) are physiological.

roentgen

The X-ray diagnosis is essential for diagnosis. Since the patient has to be optimally positioned here, it can only be practically carried out with dogs under short anesthesia . Images are taken in the lateral and ventrodorsal (from the underside of the neck) beam path in normal position and with the neck flexed.

X-rays without contrast agent ("native images") are usually only of limited informative value. At most, "vertebral tipping" , step formation or wedge vertebrae can be diagnosed with certainty. Lewis suggested comparing the size between the entrance and exit of the vertebral canal of a vortex. A difference in size of more than 3 mm in a Doberman indicates the presence of a cervical malformation.

Since native images have only a low diagnostic reliability, X-ray images with contrast agent ( myelography ) must be followed, which can only be made under anesthesia. After administration of the contrast agent, normal and stress images (strongly bent and hyperextended neck, longitudinal pull) are taken. Constrictions of the spinal canal can be detected relatively reliably with myelography.

CT and MRI

A computed tomography (CT) may increase diagnostic confidence in uncertain cases. It is usually carried out after a myelography to narrow down the area to be examined. Here, too, contrast agent administration (CT myelography) is used, so any changes in the cervical vertebrae can be diagnosed relatively reliably. Limiting factors are the high costs and the fact that computer tomographs are mostly only available in specialized veterinary clinics. In addition, the dogs can practically not be positioned exactly in the computer tomograph, holding the animals is forbidden due to the radiation exposure.

Static compressions can be easily visualized using magnetic resonance imaging (MRI). Up to now, dynamic constrictions can only be recognized on the basis of secondary changes, since the coils have not yet been optimized for veterinary medicine. Nevertheless, MRI is the safest imaging method for diagnosing cervical malformations. Here, too, the main problems are poor availability and high costs. In addition, intervertebral disc bulges can occur in clinically healthy dogs, so that there is a risk of overinterpretation of the MRI findings.

therapy

Operative therapy

There are two basic surgical methods: decompression and stabilization of the affected vertebral segments, which can also be combined depending on the case. An exact diagnosis is essential for choosing the right therapy.

The standard procedure for herniated discs is the so-called " ventral slot ". This involves proceeding from the underside of the neck to the intervertebral disc, removing the underside of the anulus fibrosus of the intervertebral disc, milling a hole in the vertebral body and removing the herniated disc material. The (dorsal) laminectomy is the standard method if the herniated disc is located more laterally and further back . Here, the vertebral arch (i.e. the roof of the vertebral canal) of the narrowed area is removed so that the spinal cord can evade compression from below to above. This procedure is much more difficult and risky than the ventral slot , a possible injury to the vertebral artery can lead to bleeding.

Stabilizing procedures aim to eliminate the excessive mobility of the vertebrae in relation to one another. For this purpose, the spinous processes (can spinous processes are) with a metal plate connected to the hinge projections ( articular processes ) are screwed together or wired (usually with a ventral slot combined) or the vertebral body through cortical screws, plate or by Steinmannägel and polymethyl methacrylate are connected. The onset of an autologous (from the same animal mostly from the iliac removed) bone graft after distraction of the spine may also be used for stabilization.

Conservative therapy

The wobbler syndrome is in principle considered to be treated surgically. However, since surgical intervention is also associated with risks, conservative therapy may be sufficient for mild forms and stable processes without a significant deterioration in the condition. It includes strict immobilization of the dog (short walks, being on a leash, preventing games and jumps, using a harness). In young dogs, it makes sense to check the composition of the food (calcium). For acute pain, analgesic non - steroidal anti-inflammatory drugs can be used.

Wobbler Syndrome in Horses

Disease emergence

In horses, there are three different causal complexes for the development of wobbler syndrome:

  1. Juvenile wobbler syndrome: This most common form occurs in foals and yearlings and is a disruption of the maturation of the apophyses of the cervical vertebrae , which is accompanied by arthrotic changes in the vertebral joints. In addition, there is usually trauma caused by the horse rolling over with a strongly bent neck while romping around. The ligamentous apparatus of the spine is stretched, and every further downward movement of the neck leads to slipping in the affected vertebral area ( dislocation ) and to crushing of the spinal cord. This leads to inflammation of the spinal cord , later to degeneration . Usually the conduction pathways responsible for proprioception (lateral and posterior ducts ) are affected first, and later possibly also the motor pathways.
  2. Herniated disc : In older horses, it is primarily herniated discs or space-consuming processes that lead to spinal cord damage.
  3. Infections : Some viral diseases , especially the herpes virus infections with EHV-1 and EHV-4 , can cause inflammation of the spinal cord and thus cause wobbler syndrome.

Clinical picture and diagnostics

Horses with wobbler syndrome gradually develop a poorer, unsteady gait, which is particularly noticeable when leading with abrupt turns. When turning to the right, the animals often buckle in the left ankle . When walking or trotting, the legs are jerked out and stopping suddenly causes difficulties. Backward pedaling in particular is severely impaired and can lead to overturning. If the front or rear legs are crossed, the return to the normal position is delayed ( corrective reaction ). The movement disorders become particularly evident when the horse is blindfolded, as the movements then depend entirely on the disturbed proprioception and cannot be corrected by the visual sense. In addition, impairment of the gait pattern when leading over bumps in the ground can also be determined, which is related to the change in the posture of the neck of the animal in this situation.

The diagnosis is made by the veterinarian using an X-ray examination of the cervical spine. Herpes virus infections in horses tend to manifest themselves as a disease of the respiratory tract or in miscarriages , only rarely as a disease of the spinal cord ( paralytic syndrome ), and are therefore only rarely a possible trigger for a wobbler.

In large horses, a radiological examination using CT or MRI is either not possible at all or only available to a very limited extent. For this reason, myelography (conventional X-ray examination with contrast agent in the spinal canal) of the cervical spine of a horse is an alternative. In this way, a narrowing of the spinal canal as a cause of ataxia in horses can be ruled out with relative certainty. The puncture of the spinal cord canal in the cervical spine is sensible, especially under ultrasound control, due to the proximity of the medulla oblongata and a considerable risk of injury in the event of defective punctures.

therapy

Treatment for wobbler syndrome can be medication or surgery. Long-term administration of glucocorticoids , possibly in combination with anabolic steroids , selenium , vitamin E and cobalt , can be tried. The affected unstable vertebral connection can be surgically stiffened with screws.

Statements about the prognosis can only be made with caution. The juvenile form can heal completely in milder cases.

Web links

Commons : Wobbler Syndrome  - Collection of pictures, videos, and audio files

Literature and Sources

  1. ^ AC Palmer, ME Wallace: Deformation of cervical vertebrae in Basset Hounds. In: Vet. Rec. 80/1967, pp. 430-433.
  2. ^ A b c A. Jaggy, J. Lang: Cervical spondylopathy ("wobbler syndrome") in dogs. In: Switzerland. Arch. Tierheilk. 128/1986, pp. 385-399.
  3. ^ HA Hazewinkel et al .: Influences of chronical calcium excess on the sceletal developement of growing great danes. In: J. Am. Anim. Hosp. Assoc. 21/1985, pp. 377-391.
  4. ↑ a b c d H. B. Seim, SJ Withrow: Pathophysiology and diagnosis of caudal cervical spondylomyelopathie with emphasis on the dobermann pinscher. In: J. Am. Anim. Hosp. Assoc. 18/1982, p. 241.
  5. ^ GD Lewis: Cervical spondylomyelopathy (wobbler syndrome) in the dog. A study based on 224 cases. In: J. Small Anim. Pract. 30, 1999, pp. 657-665.
  6. ^ JK Kealy: X-ray diagnostics in dogs and cats . Enke Verlag, Stuttgart, 2nd edition. 1991, pp. 435-473.
  7. ^ GD Lewis: Radiological assessment of the cervical spine of the Dobermann with reference to cervical spondylomyelopathy. In: J. Small Anim. Pract. 32/1991, pp. 75-82.
  8. ↑ NJH Sharp et al: Computed tomography in the evaluation of caudal cervical spondylomyelopathie of the Dobermann. In: Vet. Radiol. Ultrasound. 36/1995, pp. 100-108.
  9. ↑ D. Lipsitz et al: Magnetic resonance imaging features of cervical stenotic myelopathy in 21 dogs. In: Vet. Radiol. Ultrasound. 42/2001, pp. 20-27.
  10. ↑ S. De Decker et al .: Diagnosis, treatment and prognosis of disc associated Wobbler syndrome in dogs. In: Eur. J. Comp. Anim. Pract. 19, No. 2, 2009, pp. 133-140.
  11. ^ CW Betts: An overview of cervical spondylopathy. In: Small Animal Practice. 27/1982, pp. 255-260.
  12. ↑ a b c O. Dietz among others: Diseases of the nervous system. In: Olof Dietz, Bernhard Huskamp (Hrsg.): Handbuch Pferdepraxis. 2nd Edition. Enke Verlag, Stuttgart 1999, ISBN 3-432-29262-7 , pp. 623-650.
  13. ↑ F. Audigie, J. Tapprest, D. Didierlaurent, JM Denoix: Ultrasound-guided atlanto-occipital puncture for myelography in the horse. In: Vet Radiol Ultrasound. 45 (4), Jul-Aug 2004, pp. 340-344. PMID 15373262 .
This version was added to the list of articles worth reading on September 17, 2006 .