Clean Run - August 2017 - 63

Vestibular
Disease

in the Agility Dog
By Ryan M. Gallagher DVM, DACVIM (Neurology)
© aniMals living With vestiBUlar Disease FB Page

Few things can be as alarming as a sudden onset of vertigo in your canine athlete. Within minutes dogs can go from
tackling the agility course to quite literally being unable to stand or orient
themselves.

Anatomy

August 17 | Clean Run

The signs associated with vestibular dysfunction can be dramatic and quite distressing. Oftentimes, vestibular dysfunction can be confused with a seizure. However, rather than convulsions or loss of consciousness, vestibular dysfunction tends
to cause anxiety to the dog and repeated attempts to orient themselves. This can
lead to the dog scrambling to try to get its feet underneath itself, but without a
sensation of which direction is up the dog may be unsuccessful. The following signs
are quite specific for a problem affecting the vestibular system and can be useful in
differentiating the episode from other neurologic problems.
* Head tilt: Dogs with vestibular disease
will very commonly have a head tilt,
usually to the side of the problem.

The vestibular system simply refers to
the organs and portions of the nervous
system that perceive and process information relating to sense of balance.
Vestibular disease refers to any problem that is disrupting this sensation.
Within the skull, adjacent to the inner
ear, are spaces (semicircular canals and
vestibule) which contain receptors that
sense movement of the head with respect to gravity and acceleration. These
receptors connect to a nerve (the same
nerve used in hearing!) that sends impulses to portions of the brainstem
and hindbrain where the sensation is
processed and integrated into other
sensations, such as vision. The primary
function of this system is to allow dogs
to unconsciously perceive gravity and
movement and control their posture,
head position, and even coordinate
certain eye movements related to visual tracking. It is a paired system, with an
organ and nerve associated with both
inner ears. A problem in any portion of
this system can cause signs associated
with a loss of sense of balance.

Recognition and Clinical Signs

* Change in posture and gait: With the
vertigo-like sensation, dogs will often
be very unsteady on their feet. A very
wide-based stance is typical, and steps
taken will be very uncertain. Dogs may
stumble or fall in the direction they are
tilting. In severe cases, pets may find
themselves unable to stand or even alligator roll.
* Abnormal eye movements (nystagmus): The vestibular system coordinates
certain eye movements, and deficits will
cause characteristic, often rapid, jerking
involuntary eye movements. The eye
movements may be side-to-side, upand-down, or rotary.
Nausea: Animals will often become
nauseous with the onset of vertigo and
may vomit initially. Declining food intake is very common initially. Usually, as
the dog acclimates to the sensation, the nausea subsides.

Table of Contents for the Digital Edition of Clean Run - August 2017