The neurological examination

2 The neurological examination

Examination of nervous system function is achieved by observation, palpation and inducing reflexes and responses. The following section will explain the significance of the tests and how to perform them.

Each section of the examination is simply a part of the jigsaw (Fig. 2.1). The whole picture becomes clear once all the information is in place.



Observe the animal. Notice its interaction with other animals and humans in the waiting room. Once in the examination room, remove any leads and allow the dog to wander around the examination room unrestricted unless there is a loss of balance, history of trauma, paralysis, or any possibility of aggression. This can be done while the history is being taken. Most dogs investigate new surroundings and then either rest, return to the owner for attention, or try and escape out of the examination room. If the latter occurs, ask the owner to restrain the dog. If the dog appears abnormally quiet, or is excessively timid, it is useful to walk the dog outdoors and see if its mental state changes. Ask the owner if the behaviour witnessed is the normal reaction of the animal at the veterinary practice or at home.

Most cats will refuse to exit their cat baskets. Once removed from this shelter, the normal cat usually seeks refuge under chairs, tables or behind waste bins, and refuses to move. Some normal cats do wander about the room and investigate and may or may not voluntarily return to the basket. It is a good idea to keep the cat confined until one’s full attention can be given to observation of both the mental state and the gait. This is to prevent the cat from jumping until the balance and strength have been assessed. It is also because of the fact that many cats will walk a little initially and then refuse to budge.

Notice if, and how, the animal responds to its name, noise and visual stimuli. Does it walk about the room without taking note of distractions? Does it bump into objects, get stuck in narrow places and have problems reversing out, or turn a particular way when changing direction? Does it stop and appear to stare into space, at a wall or into a corner? None of these behaviours are normal (Fig. 2.3).



Observe the animal while it sits, stands and moves about. For example, hindlimb weakness can manifest as an arched back with the hindlimbs positioned further cranially under the body (Fig. 2.4).

When sitting, the weak or paralysed hindlimbs may extend straight out between or amongst the forelimbs. The paretic animal is often slow to rise from a sitting position and the hindlimbs may not be fully extended when standing, or could be further apart than normal (abducted) (Fig. 2.5).

Watch for abduction of limbs which may slowly slide out to the side while the animal sits or stands. Note excessive flexion or extension of joints (Fig. 2.6).

Note the spontaneous movement of the neck. If the animal shakes its head or body, is the neck moved as vigorously as normal, or at all? Does the head turn when the animal changes direction or is the whole body, head-neck-trunk, moved as a unit? Is the head elevated into a normal position or is the spine held in one straight line? Restriction of neck movement is a sign of pain. Ventroflexion of the neck in cats is usually a sign of weakness. It may not be noticed if the cat is always lying down resting its head on the forepaws or ground. The neck may be lowered and the back may be arched in an effort to shift weight to the forelimbs in cases of hindlimb or back pain.

Watch for tremors of the trunk and the head at rest and during movement. Offer the animal something to smell and notice if there is any intention tremor of the head. Record the position of the head and if it is turned or tilted or both, and to which side (Fig. 2.7).

If the animal is recumbent, is it able to lift its head from the floor? And its forequarters? An animal in lateral recumbancy needs to lift its head before rising. If the neck is painful, or the animal is tetraparetic, it may not be able to rise unaided. Does it roll? Rolling is a sign of vestibular disease.

It is not necessary to perform the righting reflex by which an animal is held upside down off the ground by its pelvis. The normal response is for the animal to automatically assume a 45° angle to the horizontal with the forelimbs outstretched toward the ground. The sensory stimuli are from visual and vestibular input. If blindfolded, the normal animal will still assume the same posture. If vestibular dysfunction is present, the animal will curl up or writhe about.



Movement is initiated by the upper motor neuron (UMN), a collective name for the nerve cell bodies within the cerebrum and brainstem and their axons which form the descending motor tracts (fasciculi) of the brainstem and spinal cord. The UMN initiates and maintains normal movement and influences extensor muscle tone to support the body against gravity (Fig. 2.8).

Descending tracts

Cerebral lesions usually have little effect on the strength and coordination of the gait as the corticospinal tracts are of minimal importance in the small animal.

The UMN terminates on interneurons within the spinal cord which have an excitatory or inhibitory effect on the lower motor neuron (LMN). The LMN is the collective name for the motor neurons and their axons which directly connect to muscle. The term LMN encompasses the motor neurons of the cranial nerves as well as the peripheral and spinal nerves, their neuromuscular junctions and the muscles themselves. It also applies to the autonomic nervous system although the LMNs in that case may be referred to as preganglionic or postganglionic.

UMN and LMN lesions both cause weakness. Weakness may be observed by a slowness to rise from sitting, inability to support the body weight or an inability to initiate and sustain movement. Weakness is a diminution of voluntary movement. Paralysis is an absence of voluntary movement.

UMN lesions are differentiated from LMN lesions by the quality of spinal reflexes and muscle tone. UMN lesions result in a loss of descending inhibition and a subsequent increase in muscle tone and spinal reflexes is observed. LMN lesions remove innervation to the muscles and a decrease in muscle tone and spinal reflexes is seen.

Observing the gait alone does not provide sufficient information for the clinician to assign the lesion to a specific part of the nervous system (i.e. LMN vs. UMN). Spinal reflexes must be tested and muscle tone must be assessed (Table 2.1).

Table 2.1 Characteristics of the motor supply

  UMN lesions LMN lesions
Paresis or paralysis Yes Yes
Spinal reflexes Normal to increased Decreased or absent
Muscle tone Normal to increased Decreased or absent
Atrophy Gradual (disuse) Rapid (denervation)

It is also important to note that certain orthopaedic diseases can change the gait in a way that suggests neurological disease. Equally, lameness may result from certain neurological diseases. Thus, while observation is crucial, the clinician must actually touch the animal in order to differentiate orthopaedic from neurological causes of abnormal gait.

Strength is only one aspect of the gait. Balance and coordination change the direction and extent of limb movement. Cerebral lesions can result in circling, pacing, head pressing; movements which appear normal in execution but apparently purposeless in function, with a propulsive, relentless quality. The circling is towards the side of the cerebral lesion (Fig. 2.9).

Proprioception is the perception of the body in space. Position and movement of the head is chiefly detected by the vestibular apparatus in both inner ears (special proprioception). Receptors in muscles, tendons and joints project sensory information into the CNS (general proprioception). This is then transmitted to the cerebrum (conscious proprioception) and to the cerebellum (unconscious proprioception) by ascending pathways. Projections to the cerebellum enable it to regulate the gait. Cerebellar lesions do not cause weakness. Reduced or absent proprioception causes ataxia. Associated deficits found on examination help localize the lesion to the vestibular system, the cerebellum, the spinal cord, or the cerebrum. (Lesions of the special proprioception receptors are common. Lesions of the general proprioception receptors are rare.) Ataxia is a sensory phenomenon.


Observe the animal’s ability to move. Normal animals are able to rise and walk unaided on floors with no grip (linoleum, floorboards). Weak and ataxic animals should ideally be examined on a non-slip surface. If the animal is paraparetic, support it under the abdomen so that any movement of the hindlimbs can be seen. If the animal is unable to rise, enlist assistance to hold the animal in a normal standing position and slowly move or coax it forward without releasing support. This is to determine if the animal is ambulatory tetraparetic (weak but able to walk unaided) or non-ambulatory tetraparetic (unable to walk without assistance). Sometimes paraparetic animals will not move the hindlimbs when a sling supports their abdomen. Remove the sling, and support the hindquarters with a hand under the inguinal area, or with a hand on either flank. Have an assistant coax the animal forward and watch for any hindlimb movement.

Neurological deficits are noticeable when the animal is walking. Lameness shows up at faster gaits. Observe the gait from the side, front and from the rear. Squat down to observe the footfall of smaller dogs and cats (Figs 2.10, 2.11).

Walk the dog in small-radius circles: ask the owner to stay in the centre of the circle and lead the dog in a clockwise then anticlockwise direction. Watch for circumduction of the outer hindlimb; the limb on the periphery of the circle may swing out to the side in an arc when advanced. This indicates either a proprioceptive deficit, restricted movement of the joints, or increased muscle tone. If the dog will not cooperate by walking in tight circles, watch the limbs when the animal turns and changes direction in the examination room when off the lead.

Watch the dog step up and over any door sills or steps and note if the paws are dragged or scraped against the step.

Allow cats to walk around the examination room. If they refuse to move, place them on the opposite side of the room to their owners or basket, which may encourage them to walk.




When the body is pushed laterally and the shoulder is no longer vertically aligned with the paw, the limb hops laterally so that the paw is once again ‘under’ the shoulder and weight-bearing is achieved. An abnormal response is a delayed movement of the limb, an exaggerated movement of the limb (hypermetric and overreaches, the paw being placed too far laterally), no movement or collapse of the limb. Slow movement with a decreased range and collapse of the limb indicate weakness of the limb. A delayed onset of movement with preservation of strength is common with cerebellar lesions. A delayed onset with collapse of the limb indicates weakness.

Compare one forelimb with the other. Compare one hindlimb with the other. The normal hindlimb appears stiff and is placed slightly wider when hopped than would occur in a normal forelimb when hopped!

Strength is subjectively graded as



Sep 3, 2016 | Posted by in SMALL ANIMAL | Comments Off on The neurological examination

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