What is PSOM?
PSOM is a form of otitis media (inflammation of the middle ear) that seems to affect the Cavalier King Charles spaniel (CKCS) in particular. Due to the mucoid nature of the disease and the fact that it is uncommonly associated with disease of the external ear canal, the condition has been referred to as PSOM or "glue ear".
What are the signs and symptoms of PSOM?
PSOM has been described in 43 CKCS dogs in one retrospective study in the veterinary literature (Stern-Bertholtz W, Sjostrom L, Wallin Hakanson N. Primary secretory otitis media in the Cavalier King Charles spaniel: a review of 61 cases. J Sm Anim Pract 2003; 44: 253-256). The presenting signs described from most to least common included pain localized to the head and neck, neurological signs (ataxia [incoordination], facial paralysis [drooping of the ear or lip, drooling saliva, inability to blink the eye], nystagmus [involuntary rapid movement of the eyeball], head tilt, seizures), itching around the ears, infections of the external ears, impaired hearing, and fatigue. These are some of the same signs seen with syringomyelia or progressive hereditary deafness which are diseases also identified in the CKCS. At the current time, there are no specific clinical signs that are associated with PSOM only.
How does PSOM differ from the more common infectious otitis media?
The biggest difference between PSOM and infectious otitis media are the prior infections of the external ear (otitis externa) seen in dogs with infectious otitis media. Infectious otitis media is usually due to an extension of an infection of the external ear (otitis externa) through the ear drum (tympanic membrane) into the middle ear. The most common clinical sign of infectious otitis media is recurrent otitis externa, which may manifest as discharge from the external ear, odor, redness of the external ear, pawing or rubbing the ear, head shaking and pain on palpation of the ear. In some instances, neurological signs may be present, as described for PSOM.
How does PSOM cause hearing loss?
There are two types of hearing loss, one is conductive and the other is sensorineural. Sensorineural hearing loss is due to an abnormality of the cranial nerve responsible for hearing, while conductive hearing loss is due to something impeding the ability of sound to get into the inner ear to the cranial nerve. The mucus present in the middle ear in CKCS with PSOM can cause conductive hearing loss by impeding sound from getting to the inner ear. Once the mucus is removed, hearing is restored. Hearing loss may recur if the mucus accumulates in the middle ear again. In the aforementioned study, the middle ear had to be flushed of mucus on more than one occasion in most dogs. Therefore, at the present time, we are unsure of the recurrence rate of PSOM after a middle ear flush.
Can hearing loss due to PSOM cause behavioral problems or changes?
Hearing loss in children due to secretory otitis media (SOM), a disease that appears to be similar to PSOM, has been associated with changes in speech, language, cognition and behavior. Therefore, it is possible that the hearing loss due to PSOM in the CKCS could result in behavioral problems or changes.
How do I know if my CKCS has PSOM?
As stated above, the clinical signs can be quite variable. Neurological signs described above or acute loss of hearing would be an indication to seek veterinary attention.
What should I do if I think my CKCS has PSOM?
The first step would be to schedule an appointment for your CKCS with your veterinarian for evaluation. However, diagnosis of PSOM and distinguishing the clinical signs from other diseases usually requires the expertise of a veterinary neurologist and/or veterinary dermatologist. Your veterinarian should be able to help you find a neurologist and/or dermatologist in your area who can further evaluate your CKCS.
Is PSOM unilateral or bilateral?
It appears that most CKCS have bilateral involvement, but it is possible for the disease to be unilateral.
What is the age of onset of PSOM?
In the above retrospective study, most of the dogs (86%) were between 3 and 7 years of age at presentation, but the ages ranged from 2 to 10. At the present time we are unsure if it occurs in puppies, and do not know how long it has to be present before clinical signs occur.
How can PSOM be diagnosed?
At the present time, the best test for diagnosis of PSOM is a CT scan or MRI. However, these tests will only tell you if there is material (fluid, mucus, pus, or a mass) in the middle ear. Plain radiographs (x-rays) may be helpful, but are not as sensitive as CT or MRI, meaning that a dog may have material in the middle ear, but it would not be identified on the radiograph. To specifically identify the material seen on the CT scan or MRI as mucus, a myringotomy (incision into the ear drum) must be performed if the ear drum is intact. For these procedures as well as the myringotomy, the dog must be under general anesthesia. Most of the CKCS with PSOM have an intact, bulging ear drum. However, a non-bulging tympanic membrane does not rule out the disease. A video otoscope is preferred to the conventional hand-held otoscope for the ear examination, since the video otoscope magnifies and illuminates the ear canal and ear drum to allow for a more thorough evaluation of the ear canal and a complete view of the ear drum. However, a normal ear exam does not rule out PSOM. Functional auditory tests may be useful in the diagnosis of this disease and include brain evoked auditory response testing (BAER, or hearing test) as well as impedance audiometry (testing to determine the status of the ear drum and middle ear), but to date the predictive value of these tests has not been studied. We are in the process of getting funded for a study to evaluate numerous tests for the diagnosis of PSOM.
What happens if PSOM goes undiagnosed for an extended period of time?
Currently we do not know how long a CKCS may have PSOM before clinical signs occur, so we are unsure if any complications may occur the longer the disease is present. Further, it is possible that the condition may be present in some dogs who may never show any clinical signs of the disease.
How can PSOM be treated?
Treatment is aimed at removal of the mucus from the middle ear. This is done by flushing the mucus out of the middle ear with the aid of a video otoscope or operating microscope and suctioning the mucus out of the ear canal. The mucus can be challenging to remove from the middle ear and external ear canal. In most instances, the mucus appears to be sterile, however, I recommend culturing the mucus to determine is there is a secondary infection present in the middle ear.
Are there any medical treatments for PSOM?
In the aforementioned study, after the middle ear flush, a number of treatments were utilized (topical and oral corticosteroids, topical and oral antibiotics, mucolytics), but their efficacy in prevention or treatment of the disease is unknown. To date, the only treatment with known efficacy is middle ear flushing.
What complications may occur as a result of flushing the middle ear?
Complications secondary to the ear flush include facial nerve paralysis, Horner's syndrome (elevation of the third eyelid), balance problems (falling over, difficulty rising), and deafness. These complications are usually uncommon and can be minimized by having this procedure performed by a veterinary dermatologist that has experience in middle ear flushing.
What is the cause of PSOM?
At the present time, the cause of PSOM is not known. Due to its similarity to secretory otitis media in children, there may be an underlying Eustachian tube dysfunction causing the disease. The Eustachian tube is the structure that connects the middle ear to the nasopharynx and allows equalization of pressure (ventilation) in the middle ear with atmospheric pressure, drains secretions produced within the middle ear into the nasopharynx, and protects the middle ear from nasopharyngeal sound pressures and secretions.
Is PSOM a genetic disease?
It would appear that this breed is genetically predisposed to developing the disease, but the mode of inheritance in not known.