The neurological examination follows the general clinical examination when the preliminary report or initial examination of the animal has given evidence for disorders in the nervous system. By means of this special examination, the vet attempts to find the location of the problem in the brain, spinal cord or nerves that emerge from it. The animal’s breed and age as well as the preliminary description, e.g., how quickly the symptom occurred, provide valuable evidence about what disorder could be involved.
What is examined?
The most important points in the neurological examination are:
The animal’s general behaviour
Here it is noted how the animal behaves in the usual (home) and unusual environment (at the veterinary clinic). Abnormal behaviour in dogs and cats can be expressed, for instance, in disorientation, fearfulness or aggressiveness.
Body posture, head-holding and gait
The vet notes the animal’s head-holding and the line of its back. For assessing gait, the animal is shown to the vet in different forms of gait. Uncoordinated movements (ataxia), complete or incomplete paralysis of individual muscle groups or lameness due to pain can appear as pathological changes of gait.
The nerves that arise in the brain are known as cranial nerves. The optic nerve and olfactory nerve and those responsible for the sense of taste are examples of cranial nerves. There are twelve in total. Using special tests the vet examines the function of the individual nerves, each of which has a particular function in the body. The optic nerve is examined by the reaction of the pupils to light.
Normal postural reflexes enable the animal to stay in correct position and coordinate its movements. Precisely coordinated interplay of brain, spinal cord, nerves and balance organ is essential.
The postural reflexes are tested to see whether information about the position of the four limbs (proprioception) is intact. To do this, the animal has to jump on one leg, for example, while the other three are held up in the air by the vet.
When the tendon that connects a muscle belly to bone is struck with a reflex hammer, the muscle tenses due to conduction of nerve impulses. The spinal reflexes are reflexes that are transmitted via synapses in the spinal cord. A reflex in itself is the body’s unconscious response to a triggering stimulus. If a reflex response is increased or diminished, the vet can narrow down the damaged region in the nervous system.
Pain is of elementary importance for how the dog/cat feels and has a protective function as an early warning system to avoid harm. How painful a stimulus is for an animal cannot be judged with certainty as this is subjective. Only the animal’s defensive reaction to a painful stimulus is evaluated.
Further neurological investigations
After performing a neurological examination and narrowing down the different possible diagnoses, further investigations are carried out as needed. These consist primarily of blood and cerebrospinal fluid tests, imaging or electrodiagnostic tests of nerve impulse conduction (e.g., EEG). A biopsy is sometimes needed for a clear diagnosis and in a substantial number of cases, the explanation is provided only by pathological examination of the animal’s body.
Ideally, the vet makes a diagnosis by means of the neurological examination and further special tests, and this then leads to a recommendation regarding treatment and prognosis.
© AniCura, Katharina Weber MA