Cauda equina syndrome in dogs

The cauda equina syndrome - even degenerative lumbosacral stenosis (DLSS) or Lumbosakralstenose - is an older house dogs of medium and large breeds common degenerative neurological disease caused by severe pain and in the further course of paralysis is characterized. It is caused by compression of the nerve roots at the end of the spinal cord, the so-called cauda equina , as a result of degenerative processes in the spine at the transition from the lumbar spine to the sacrum . The disease corresponds in many respects to the cauda equina syndrome in humans.

Occurrence

Degenerative lumbosacral stenosis is a very common condition in older dogs. It occurs primarily in representatives of dog breeds that are heavier than 20 kg. The poodle , which also often falls ill, is an exception . The large dog breeds particularly affect the German Shepherd , Giant Schnauzer , Siberian Husky , Doberman , Rottweiler and Boxer .

Disease emergence

The cause of the disease are degenerative changes in the spine. The transition from the last lumbar vertebra (L7) to the first cross vertebra (S1) is particularly affected , and more rarely the transition from the penultimate to the last lumbar vertebra (L6 – L7). The last lumbar or first cross vertebra is often designed as a so-called " transition vertebra ", that is, it shows structural features of the other spinal column section, which is often associated with instability. At this point the spinal canal is also very shallow. The spinal cord has already come to an end at the lumbar-cross junction, and the long nerve roots ("cauda equina") of the sacral plexus run in the spinal canal , which is responsible for supplying the muscles of the pelvis and tail as well as most muscles of the hind limbs.

The lumbar-cross transition is exposed to constant stress when running and jumping. These can lead to wear and tear in older dogs, which leads to osteoarthritis . Obesity and overwork are favorable factors. This leads to remodeling processes on the vertebrae, thickening of the inter- arch ligament and the upper longitudinal ligament , subluxation and, under certain circumstances, a herniated disc , with chronic (type II) herniated discs causing the disease. Other causes are tumors in the spinal canal, fractures and dislocations . Developmental changes such as osteochondrosis dissecans of the vertebral endplate of the sacrum and congenital constrictions also play a role. The latter occur mainly in small breeds of dogs.

These processes lead to a narrowing of the spinal canal ( stenosis ), which creates mechanical pressure on the nerve roots and can damage the nerve fibers . The compression can also act on the supplying blood vessels and thus cause an under-supply of blood and thus additional nerve damage.

Clinical picture

The clinical symptoms of a lumbosacral stenosis develop insidiously and are therefore often overlooked by the animal owner or are not taken seriously as "normal" signs of aging over a long period of time. Affected animals become lazy to walk, are unwilling to climb stairs and are reluctant to jump. The cause is pain and paralysis in the affected area. The pain diminishes after extended periods of rest ( pit rest ) and becomes more severe with exercise. "Warming up" can lead to an apparent improvement.

In the course of the disease, slight paralysis (ask paresis ) a. At first they are only indistinct, such as B. in a greater angulation of the hind limbs. As a result of the dragging gait, the claws wear out more on the front side ("toe grinding"). Progressive paralysis of the tail is also possible. As the disease progresses, muscle atrophy of the posterior muscles and faeces and urinary incontinence as a result of paralysis of the anus and bladder sphincters.

The surface sensitivity is usually not impaired.

Diagnosis

The first indications are a pain reaction in the lumbar and lower back area. To do this, the tail is hyperextended, the hip joints hyperextended and strong manual pressure is exerted on the lumbar-cross transition. The reflexes of the hind limbs ( flexor reflex , tibialis-cranialis reflex , patellar tendon reflex ) and the perineal reflex are often preserved or at least weakened.

X-ray imaging is routinely used as an imaging method . However, stenoses are not always clearly visible on x-rays, especially if there is a lateral narrowing. A myelography may confirm the diagnosis, but the shell of the dura mater is sufficient ( dura mater ) in 20% of cases only to the last lumbar vertebra. Computed tomography and magnetic resonance tomography are the safest , but these are also the most expensive methods and are only available in a few veterinary facilities.

Other painful processes in the region such as bone fractures , dislocations , trauma with bruising or edema , tumors in the spinal canal, abscesses and arthroses of the hip joint, and coccygeal myopathy must be excluded from the differential diagnosis . The Diskospondylitis and Fibrokartilaginöse embolism show a similar clinical picture, but occur mostly highly acutely. Degenerative myelopathies also develop slowly, but they are not painful.

therapy

In cases where only pain symptoms are present, conservative therapy can be tried. It consists of strict restrictions on freedom of movement, i.e. strict rest in the box, possibly with the use of anti-inflammatory glucocorticoids . Success also depends on the dog's temperament. If it is possible to dissuade him from excessive movement, the arthritic processes can heal by reducing the stress on the lumbar-cross junction. Weight reduction is strongly recommended for overweight dogs.

In severe cases, surgical therapy is necessary, which depends on the underlying process and aims to remove the mass and thus the pressure on the cauda equina. They may be in a removal of the vertebral arch ( laminectomy ), pathologically altered spinal column parts as the intermediate sheet strip of the disc, of the articular processes ( Fazettektomie ) and in the extension of nerve exit holes ( Foraminektomie means of suitable), or the stabilization of the lumbar cross-Uber passage osteosynthesis made.

The prognosis is usually good as long as there is no significant paralysis. In contrast to the spinal cord itself, the nerve fibers of the cauda equina have a very high regenerative capacity. With very large and temperamental dogs, however, a long healing time can be expected, in which things such as strict restrictions on movement are difficult to achieve.

literature

• Günther Schwarz: Spinal column diseases . In: Peter F. Suter and Hans G. Nobody (eds.): Internship at the dog clinic . Paul-Parey-Verlag, 10th edition 2006, pp. 1064-1082. ISBN 3-8304-4141-X
• Andrea Tipold et al .: Degenerative lumbosacral stenosis . In: Andre Jaggy (ed.): Atlas and textbook of small animal neurology . Schlütersche 2005, pp. 324–326. ISBN 3-87706-739-5
• Frank Steffen, Katharina Hunold, Gernot Scharf, Mark Flückiger: Degenerative lumbosacral stenosis (cauda equina syndrome) in the German Shepherd (PDF; 601 kB) . In: dogs . No. 11, 2008. Scientific supplement from the Albert Heim Foundation.
• Nele Ondreka: X-ray characteristics of the lumbosacral transition in the German shepherd compared to other breeds and genetics of these characteristics in the German shepherd . VVB Laufersweiler Verlag, Giessen 2010, ISBN 3-8359-5508-X . (Inaugural dissertation to obtain the degree of Dr. med. Vet. At the Department of Veterinary Medicine at the Justus Liebig University in Giessen. December 21, 2009, urn : nbn: de: hebis: 26-opus-73188 (full text))

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