This In healthy dogs, the Vestibular system is responsible

This paper will focus on Vestibular Disease in elderly dogs, more specifically Idiopathic Vestibular Disease, often colloquially referred to as “Old Dog Disease” due to its prevalence in older canines.  The vestibular system is part of the body’s auditory system, and forms part of the nervous system.  I have chosen this to study as previously, my elderly dog suffered two attacks of Vestibular Disease, and as such I have an interest in the illness. The nervous system is comprised of two parts: Central Nervous System, made up of the brain itself and the brain stem, and the Peripheral Nervous System which consists of the nervous system outside of the brain. This includes all of the sensory organs, cranial and spinal nerves and autonomic nerves; these are nerves which are involved with involuntary actions such as heart rate and blood flow. The nervous system allows the animal to receive feedback from its environment via their sense organs (eyes, ears, nose, tongue and skin), and react appropriately to stimuli. The central and peripheral systems work together, to relay information and action to each other in order to process and react to the world around them. In healthy dogs, the Vestibular system is responsible for sustaining posture, balance, and informing the brain of the animals’ position in relation to its environment. The diagram below shows the three parts of the ear: outer, middle and inner. The outer ear is made up of the pinna, which assists with amplification and direction of sound, which leads to the ear canal. The ear drum then separates the outer ear from the middle ear, and its function is to convert vibrations in the air causing sound into vibrations in the fluid of the cochlea by passing those vibrations through the ossicles to the oval window, which separates the middle and the inner ear. Within the inner ear lies the vestibular system, and it is within this part of the ear that Idiopathic Vestibular Disease can occur.In healthy dogs, the Vestibular system is responsible for sustaining posture, balance, and informing the brain of the animals’ position in relation to its environment. It is comprised of a receptor which is located close to the middle ear, which feeds information to a short nerve, which then passes this information on to the lower stem of the brain. This information is then passed to the cerebellum, which takes in information from all of the sensory organs and nerves, and spinal cord, and controls motor movements as necessary. Within the receptor there is the vestibule, and three semi-circular canals that preside within the inner ear. Of particular importance within the inner ear is the otolith organ. It consists of two parts, namely the utricle which senses changes in horizontal positioning, and the saccule which senses vertical movement, such as ascending in an elevator. Both the semi-circular canals and the otolith organs are filled with fluid.  They work much like a spirit level, feeding each other information which is then passed on to the brain to maintain (and regain as necessary) balance, and proprioceptionA common ailment affecting older dogs is Idiopathic Vestibular Disease, meaning that it has no known underlying cause. It is simply known that there is an inflammation of the Vestibular System which is causing symptoms. It is diagnosed by rapid onset and little to no immediate improvement, even with medical treatment – although symptoms may improve gradually over days or even weeks. Possible causes can include trauma to the head or inner ear, using drugs which are toxic to the inner ear, tumours, bacterial or fungal infections of the inner or middle ear, or hypothyroidism. Typically, if the patient presents as an older canine with no detectable ear infections, no recent trauma and no history of hypothyroidism, further investigation is not required as the symptoms are attributed to Idiopathic Vestibular Disease. 3Its onset can be rapid and very distressing for owners to witness. Usually, one side of the Vestibular System is affected, meaning the brain is only receiving half of the information it should, and this sends the sensory system into chaos. Symptoms may seem immediately life threatening, as the dog is unable to stand, may walk in circles and even vomit. However, this is not the case; whilst it is not pleasant for the dog the symptoms themselves are not a danger to life. Ongoing illness may become a quality of life issue if the patient is not recovering as expected. Symptoms may include:•    Circling (walking or spinning in circles)•    Wide gated stance as the dog struggles to balance•    Falling over or rolling to one side•    Nystagmus (involuntary ‘flickering’ movement of the eyes from side to side)•    Strabismus (abnormal position of the eyes in their sockets)•    Vomiting•    Motion sickness•    Head tilt (pictured below)•    Shaking of the head•    Ataxia (staggering, stumbling)In elderly patients, there is often no investigation done to diagnose, as the symptoms are consistent and as the disease is of idiopathic nature, there is no underlying cause to be seen. In younger animals, or those with vertical nystagmus (the eyes flicker up and down as opposed to side to side – this can indicate a more serious condition involving the central nervous system) an MRI can be done to determine a cause and treatment regimen. Upon presentation to the veterinary surgeon, the dog will be examined thoroughly, with femoral pulses and rectal temperature being taken, as well as using an otoscope to have a look into the ear canal to rule out any infection of the ears. Should any infection be found, the vet will administer ear drops and/or antibiotics as necessary, as well as an anti inflammatory if the patients temperature is dangerously high.In cases of true Idiopathic Vestibular Disease, there is no cause to be found, so vets may prescribe and antibiotic and anti inflammatories as a precaution. As many patients will be suffering from motion sickness, the vet may prescribe an antiemetic drug to help with feelings of nausea. In cases where the patient is not on long term NSAID treatment for conditions such as arthritis, and none have been given to treat high temperature, the vet may prescribe a corticosteroid injection to dogs who are not showing improvement after a few days of TLC. Nystagmus should disappear within 3-5 days of onset, and in the case of a head tilt, if this is persists for more than 6 months after the attack, it is likely to be permanent but is not of any concern.Some animals, especially the very elderly, will become greatly distressed due to the symptoms. If they are generally in good health otherwise, a vet may prescribe a short course of relaxants such as Diazepam to help keep them calm until the symptoms subside, or treatment takes effect.  In animals who show little to improvement over 2 weeks, it is sometimes necessary to euthanize the dog due to a vast deterioration in quality of life.However, it must be said that most dogs will not require medical intervention, and no treatment course has yet been proven to decrease recovery time.  Whilst the symptoms of Idiopathic Vestibular Disease may be very distressing for owners and pets, it is not immediately life threatening. However, the animal should have a thorough examination by a veterinary professional to rule out any other underlying cause, and to be given any treatment as necessary. That being said, most dogs will recover on their own within 1-2 weeks of onset with lots of TLC and considerations from their owners.