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Idiopathic Vestibular Disease in Older Dogs

Could it be a stroke? Geriatric Vestibular Disease – a sudden balance problem in elderly dogs 

It happened suddenly, virtually overnight. Ten-year-old Harley woke up unable to walk properly. She kept losing her balance, stumbling and falling over


Her head was tilted severely to one side and her eyeballs kept flickering constantly from side-to-side. She didn’t want to eat, vomited a couple of times, and seemed quite miserable. Her owners were very upset. 

Since Harley was old, they were convinced it was the beginning of the end, maybe a stroke. 

Harley at her first visit displaying a mucky discharge (L)
 and at 3 weeks; she also had a dry eye problem 
due to a concurrent deficit with her right facial nerve (R)
Watching Harley in such distress, the owners were considering euthanasia. But the vet convinced the owners to wait and, with supportive care, over a few weeks Harley made an almost complete recovery

She still had a residual head tilt but was back to her normal happy, active self. What Harley suffered from was a disease called Geriatric Vestibular Disease or Idiopathic Vestibular Disease.

This is not uncommon in elderly dogs. Whilst quite distressing to watch, most dogs almost completely recover over several weeks.

What is Geriatric Vestibular Disease?

Geriatric Vestibular disease or Idiopathic Vestibular Disease occurs in elderly dogs, with an average age of occurrence of 10-12 years old. 

The onset is sudden, and the cause is unknown. It causes problems with balance. An affected dog will not like being held upside down and may feel nauseous, stop eating, and even vomit

With this disease, usually balance on only one side (left or right) is affected. The dog may keep stumbling and lean, roll, circle, or fall to one particular side. The head will usually tilt, often severely, towards the same affected side

The eye position may look abnormal (eyeballs looking downwards) and the eyeballs may dart rapidly from side-to-side or round-and-round, a symptom known as nystagmus. In people with vestibular disease, they describe experiencing vertigo: the sensation that they, or their surroundings are spinning. 
Dogs can’t tell us if they are experiencing this but, given the anatomy is the same, it is quite possible. Certainly, dogs suffering from this disease seem to be quite agitated and miserable.

Approximately a third of animals with this disease also experience problems with their facial nerve on the affected side. The facial nerve controls blinking, tear production, and sensations and movement of the face. If this nerve is affected, the dog may be unable to blink or produce tears. This can cause the eye to become dry, which can cause damage to the surface of the eye. 


A dry eye is uncomfortable and if left untreated, permanent damage to the eye surface may lead to partial or full vision loss.

What controls balance in dogs?

In the inner part of each ear lies a structure (the vestibular apparatus) that helps sense balance and body orientation relative to the ground. 

A nerve (the vestibulocochlear nerve or cranial nerve VIII) travels from each inner ear to the brainstem, transmitting information about sound, balance, and body orientation to the brain. 

The information about balance and orientation is then relayed to the eyes, to coordinate eye position relative to changes in head position. 

The information is also relayed to the body’s muscles to keep the animal upright and control posture. If these signals are disrupted, the animal develops symptoms of vestibular disease: problems with balance and falling over, trouble controlling the position of the eyes, and nausea and vomiting.

Causes of balance problems in dogs

There are many causes of balance problems (or vestibular symptoms) in dogs. 

Geriatric Vestibular Disease is just one common cause in elderly dogs, although how exactly it causes the problem is unknown. Another relatively common cause of balance problems is bacterial or fungal infections within the inner earLess commonly, tumours or other growths inside the ear can also cause balance problems. 

Causes of balance issues within the brain itself tend to be more serious. Such causes include meningitis, tumours, trauma, and blood clots. We need to know the cause of the balance problem to determine the correct treatment and prognosis. 

For example, dogs with Geriatric Vestibular Disease usually make an almost complete recovery over several weeks, on their own without treatment, whereas a middle ear infection will require appropriate antibiotics. 

Diagnosis

The problem with Geriatric Vestibular Disease is that there is NO TEST to confirm diagnosis. It is diagnosed after excluding all other causes of vestibular disease. But doing so can be tricky and expensive. Diagnosis is usually tentatively diagnosed based on age, symptoms, and improvement without treatment.

a) The thorough neurological examination


To diagnose the cause of vestibular disease, we first start with the symptoms. Symptoms of vestibular disease vary depending on where the problem is in the inner ear, in the nerve before it enters the brain, or within the brain

When the problem is outside of the brain, symptoms usually affect only one side of the body. It causes what we call peripheral symptoms: a head tilt to one side, leaning to one side, and quick eye movements, usually from side-to-side or round-and-round. The animal will lean towards and the head will tilt towards the side where the problem is located.

When the problem is located within the brain itself, it often affects both sides and causes what we call central symptoms: head swaying from side-to-side, walking with legs out wide to avoid falling over, and quick eye movements up-and-down (but sometimes side-to-side or round-and-round). A problem within the brain will also often cause other neurological problems, causing additional symptoms such as dragging the legs, unusual body movements, or changes in behaviour. 

The tricky thing is a problem within the brain may initially appear to affect only one side before progressing to involve both sides and additional symptoms may be subtle and easily missed. In up to a third of cases, we may initially misdiagnose symptoms as peripheral when the problem is actually within the brain. With time and repeated examinations, as more symptoms develop it may become more obvious that the problem is within the brain. 

b) The ear examination 


Geriatric Vestibular Disease always causes peripheral symptoms. Once we diagnose peripheral balance symptoms, the next questions are: Is it definitely peripheral? Is the problem in the inner ear? Or is it Geriatric Vestibular Disease? Of those animals correctly diagnosed with peripheral balance problems, around 40-68% will have Geriatric Vestibular Disease. Most of the remaining cases will have an inner ear infection.

The facial nerve and sympathetic nerve to the eye also run through the inner ear, so problems in the inner ear can also affect these nerves. The sympathetic nerve controls the ‘flight and fight’ response to the eye: wide open eyes and larger pupils in response to a threat. If that nerve is affected, the eyelids will droop and the pupil will be pinpoint. 


Around a third of dogs with Geriatric Vestibular Disease also have facial nerve problems. But if the sympathetic nerve is also affected, the problem is more likely in the inner ear and not Geriatric Vestibular Syndrome.

To check for an ear infection, we can look down the ear. If there is infection in the outer ear and the ear drum is ruptured, there will most certainly be infection within the inner ear. But, if the ear drum is intact, we can’t see into the inner ear. It can be hard to tell if there is a problem within the inner ear without further tests.

c) Magnetic Resonance Imaging (MRI)

The gold standard for diagnosing and excluding causes of vestibular disease is Magnetic Resonance Imaging. MRI is the best method for identifying infection and defects in the inner ear and brain. But it is also rather expensive, requires referral, and is beyond the cost limits of many owners. 

A simple x-ray of the head can sometimes identify pus or masses in the inner ear, but it is not always reliable. Another test is to stick a needle into the inner ear to examine for pus or abnormal cells, although this is also often a specialist procedure.

d) Watchful waiting

If owners elect not to do further tests and the symptoms and age fit with Geriatric Vestibular Syndrome, sometimes it is a matter of watchful waiting and supportive care. It becomes a bit of a guessing game. 

Do we give antibiotics in case there is an inner ear infection? Do we give anti-inflammatory medication in case something is causing inflammation of the nerve? Or do we just control for nausea and vomiting and see if the balance symptoms resolve on their own?

If the symptoms start to resolve over a few days, then it is most likely Geriatric Vestibular Disease. If there is a progression and worsening of symptoms, then it probably isn’t Geriatric Vestibular Disease and most likely there is another cause.

Treatment

If the dog truly has Geriatric Vestibular Disease, there is no specific treatment to cure or shorten the progression of the disease. Affected dogs usually recover almost completely, on their own without treatment, over several weeks. Sometimes, at the end, residual symptoms remain, particularly a head tilt or problems with a dry eye (if the facial nerve was also affected).

One aim is to monitor the dog for evidence for signs of progression that might indicate another cause of the vestibular disease. Another aim is to reduce the nausea and keep the dog eating and as comfortable and safe as possible during the recovery period. Anti-vomiting medication is usually given and appetising, easy to digest food, like boiled chicken. 

If the dog also has a problem with dry eye, artificial tears should be applied regularly at least 3-4 times per day to keep the eye lubricated. If the dry eye persists long-term, medication may be given to help enhance tear production. 

Supporting owners during this time is also important. It can be quite distressing to watch an affected animal with this disease and owners need to know that recovery is quite possible.

Prognosis

The prognosis for Geriatric Vestibular Disease is generally excellent. The eyeball flickering usually resolves first, within a few days. The problems with balance and the head tilt take longer to resolve and usually gradually improve over 1-2 weeks. Some mild symptoms, particularly a head tilt, may persist, but most dogs do return to their normal happy selves. 

Occasionally, some dogs may have one or more repeat episodes at later times.

written by Dr. Meredith Crowhurst, February 2020 for Australian Dog Lover (all rights reserved).


About the Writer

Dr Meredith Crowhurst is a Melbourne-based locum veterinarian. 
Melbourne University graduate with more than a decade of experience, she has extensive consultation and surgical experience and has worked with dogs, cats, rabbits, guinea pigs, rats, mice, birds, and various other animals.

Meredith understands the importance of the human-animal bond. Her aim is to treat pets and their owners with empathy and compassion, delivering the best standard of care.

Previously, Meredith completed a Bachelor of Arts/Bachelor of Science degree and completed her PhD in the biomedical sciences. As well as treating animals, Meredith’s aim is to educate and make medical science knowledge accessible for all


You can contact her at www.empathichealthwriting.com.au/ and follow her on Instagram at instagram.com/drmerryoliveveterinarian


References

1. Vestibular disease in dogs: association between neurological examination, MRI lesion localisation and outcome.
Bongartz U, Nessler J, Maiolini A, Stein VM, Tipold A, Bathen-Nöthen A.
J Small Anim Pract. 2020 Jan;61(1):57-63.

2. Reliability of interpretation of neurologic examination findings for the localization of vestibular dysfunction in dogs.
Boudreau CE, Dominguez CE, Levine JM, Mankin J, Anderson KM, Voges AK, Fosgate GT.
J Am Vet Med Assoc. 2018 Apr 1;252(7):830-838

3. Chapter 63: Head Tilt, in Small Animal Internal Medicine. Nelson RW and Couto KM. 6th edition. Elselvier, 2020: 1113-1114.
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