What is canine Geriatric Vestibular Syndrome:
https://www.vetinfo.com/canine-geriatric-vestibular-disease-symptoms.html

Vestibular disease in dogs is rare, but may be a devastating condition. The vestibular system is in charge of coordinating the dog’s movement and allows him to keep his balance and not get dizzy even after circling the room several times. The vestibular system is rooted in the dog’s inner ear and communicates with the dog’s brain giving the dog orientation skills. If the dog has vestibular disease, the symptoms will include staggering, lack of balance, uncoordinated eye and head movement. The symptoms may be mistaken for a stroke or a seizure, but the vet can give a proper diagnostics.

Symptoms of Geriatric Vestibular Disease:
When the dog has vestibular disease the communication between the inner ear nerves and the brain is defective. The typical symptoms of geriatric vestibular disease will include:
Head tilting, similar to the symptoms of ear mite infection
Irregular eye movement (up-down, from side to side)
Strabismus
Dizziness; the dog will look disoriented
Sudden collapse
Frequent vomiting
Staggering gait
Lack of appetite
Excessive salivation
Rolling from side to side
Difficulty standing up
Some of these symptoms can point to a stroke or a seizure, but a seizure’s duration is up to 5 minutes, while the dog with vestibular will display some of these symptoms all day long.

Causes of Canine Vestibular Disease:
The symptoms of vestibular disease can be frightening and you should get to the vet as soon as possible. Even if the geriatric vestibular disease is not as severe as a stroke or a seizure, the disease should be given proper attention.
Typically, vestibular disease is caused by a problem in the dog’s inner ear (peripheral vestibular disease). However, the problem may also originate in the brain (central vestibular disease).
Some of the most common causes of geriatric vestibular disease include:
Ear infections; if the infection is severe, it advances from the external ear to the middle ear and then to the inner ear, where the vestibular system nerves are located
Hypothyroidism or low thyroid hormone levels
Toxic medications used in the dog’s ear (especially drops containing alcohol)
Tumors located in the inner ear
Encephalitis
However, the geriatric vestibular disease may also be idiopathic, so the cause is unknown.

Treatment for Geriatric Vestibular Disease:
When vestibular disease that occurs in senior dogs and the cause is unknown will often resolve itself in a few days up to 1 week without any treatment.
The cause of vestibular disease must be determined to establish the right treatment. If the disease is caused by infections, the vet will prescribe medications to eliminate these infections. Thyroid drugs can also stimulate the production of thyroid hormones.
The administration of toxic ear drops must be discontinued.
The vet may also prescribe medication to control the dizziness and the nausea or other symptoms that may be upsetting the dog. Benadryl or Antivert can stop dizziness in canines.
Ensure that the dog is in a safe place, without sharp objects or stairs near, to prevent any accidents from happening.