Paralysis of all four limbs, tetraparesis
Tetraparesis or weakness of all 4 limbs is usually caused by the diseases in the brain, neck and the peripheral nervous system. The diseases of the brain causing weakness of all 4 limbs are usually associated with abnormalities in mental status, behaviour and neurological deficits in the head. The diseases of the cervical spinal cord are usually causing also abnormal coordination of the limbs. In contrary the diseases of the peripheral nervous system are causing just pure weakness of the limbs. The neurological examination is usually helping the vet to decide which of the mentioned areas of the nervous system is affected and what further examinations are needed in order to make the correct diagnosis and plan the treatment.
We will discuss further just the diseases of the peripheral nervous system in this section. Diseases of the nerves (polyneuropathies) and muscles (polymyopathies) are rather frequent in dogs and cats, but their recognition is sometimes complicated as they can not be seen usually in x-rays or even magnetic resonance imaging and need special examination techniques. The usual clinical picture of the dog or cat with polyneuropathy (disease of multiple nerves) or polymyopathy (disease of multiple muscles) is weakness of all 4 limbs. The animal might be still walking or can be unable to stand. Sometimes the change in the voice (laryngeal paralysis), throwing up the food (regurgitation because of dilated oesophagus) or coughing (because of aspiration of the food) might be the first sign of the beginning disease.
The most striking sign on neurological examination is weakness of the spinal reflexes. In all suspected cases the thoracic x-rays and blood examinations should be performed as some of the diseases affecting nerves and muscles are of metabolic (low blood glucose or calcium) or hormonal (hypothyroidism, diabetes mellitus etc) origin. If the blood examination is not giving the clear answers about the origin of disease, than the electrodiagnostic examinations of the muscle and nerve should be performed and the muscle and nerve biopsy taken in order to arrive to the definitive diagnosis. The most frequent diseases causing the dysfunction of the peripheral nervous system are the immune mediated inflammatory conditions, followed by degenerative, infectious and paraneoplastic diseases.
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