Primary Secretory Otitis Media (PSOM) is a condition of the middle ear which becomes plugged with highly viscous mucus and may cause the tympanic membrane to bulge and rupture. It is similar to the condition known as “glue ear” in children.
This is not caused by an infection and the cause is unknown though it is thought that it might be a dysfunction of Eustachian tube in the Cavalier, where there is an abnormal production of mucus or a decreased drainage of fluid through the Eustachian tube or even a combination of both factors.
Some speculate that there may be a link between the condition PSOM and the brachycephalic anatomy of the breed but at present the condition seems to be primarily reported in the Cavalier King Charles Spaniel, not other brachycephalic breeds. However since some of the symptoms of PSOM mimic symptoms of Syringomyelia, recognition of this condition (PSOM) may be heightened in the Cavalier and merely under-reported in other breeds; much as it happened in the early days of research in Syringomyelia where some researchers considered that condition peculiar to Cavaliers and later research found it commonly in other breeds as well.
Many of the symptoms are similar to those found in dogs with Syringomyelia. They include neck pain, head tilt, scratching at ears, ear itch or pain, facial paralysis, Vestibular disease, crying out in pain, lack of co-ordination, hearing loss, yawning and fatigue.
Diagnosis is usually made by a veterinary neurology or dermatology specialist through use of MRI or CT scans; though other methods of detection may be possible such as a BAER test or ultrasound. In severe cases where the tympanic membrane has bulged or rupture it may even be possible to see this on x-ray.
Treatment for this condition is surgery with a small slit made in the eardrum and then the inner ear is flushed to clean out the mucus. Corticosteroids and antibiotics are then administered to the dog. This procedure may have to be repeated in some cases. Just treating with antibiotics does not seem to work.
The condition is thought to be inherited in the Cavalier King Charles Spaniel; mode of inheritance unknown.