Paralysis of the hind limbs, paraparesis
Paraparesis or weakness of the rear limbs is one of the most frequent complains of the owners of dogs with problems of the spine. The onset of the problem might be acute or slowly progressive. In acute cases the dog might be completely normal and just a moment later unable to stand or walk normally any more. In chronic cases the disease might progress gradually making it sometimes difficult for the dog owners to see the changes as the patient is getting weaker very slowly. Often gradual worsening of the gait is interpreted as a normal ageing in the older patient and the search for the help from veterinarian is delayed. It is true that the older dogs are getting gradually weaker with time because of the muscle atrophy but ageing should not cause signs of paralysis or abnormal coordination.
The signs of paralysis might be mild showing just dragging or wearing of the toes, reluctance to move or go for a longer walk, sitting down frequently when walked or reluctant to jump in to the car. Signs can progress till the situation that the dog is falling spontaneously, firstly in turns, later also when walking straight. Dog with the weak hind limbs frequently is running as a rabbit (bunny hopping) as it tries to put both limbs together on the ground in order to have more power while running.
In cases with acute and severe hind limb weakness-paralysis the vet should be contacted immediately. Acute paralysis of both hind limbs is an emergency situation and time can be critical. It has been showed that the more severe is the paralysis and the more time it is lasting the worse the prognosis independently from the underlying disease.
The diseases of the thoracic and the lumbar spinal cord are the most frequent to cause weakness in the both hind limbs. The diseases causing hind limb weakness can be divided in to compressive and non-compressive. The signs of paralysis in compressive spinal cord diseases are caused by the pressure to the spinal cord coming from outside. The usual examples of typical spinal cord compressions are disk herniation, bleeding or fracture. In contrary, the non-compressive spinal cord diseases are caused by the changes inside the spinal cord without the pressure from outside. The typical example of such disease would be the interruption of blood supply to the spinal cord (like in fibrocartilaginous embolism) or the contusion of the spinal cord in trauma patients. The distinction between the two groups is the primary task of the early investigation of the paralysed patient. The compressive diseases need surgical decompression as soon as possible and the patients with non-compressive diseases should get the needed medical therapy. For this reason the myelography or the magnetic resonance imaging should be performed and the decision should be made if surgery is needed or not. In surgical therapy the pressure to the spinal cord is released so that the material which is pressing the spinal cord such as disk material, hematoma or bone fragment is removed and the spinal cord can recover its functions. In cases where no compression is diagnosed the medicaments are administered to help the spinal cord to come with trauma, blood supply interruption swelling and secondary inflammation.
Prognosis in the paralysed patient is mainly dependent on the grade of paralysis, the duration of the signs and the underlying condition. The best results are achieved when patients are examined and treated before the limbs are totally paralysed. In patients with total hind limb paralysis the prognosis might be guarded. In contrary, if the deep pain perception is present and the patient is still spontaneously moving the limbs the chances for recovery are usually good if the help is provided on time.
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