INSIDE TOPICS
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Keratoconjunctivitis sicca (KCS)
Primary secretory otitis media
Progressive hereditary deafness
Progressive retinal degeneration (PRD)
spainel
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Primary Secretory Otitis Media (PSOM)
in the Cavalier King Charles Spaniel
Primary Secretory Otitis Media (PSOM or P.S.O.M.),
also known as "glue ear", has become more frequently diagnosed in Cavalier King
Charles Spaniels recently. It consists of a highly viscous mucus plug which
fills the dog's middle ear and may cause the tympanic membrane to bulge.
PSOM has been reported almost exclusively in Cavaliers, and it may affect up to 40% of them. Because the pain and other sensations in the head and neck areas, resulting from PSOM, are similar to some symptoms caused by syringomyelia (SM), some examining veterinarians have mis-diagnosed SM in Cavaliers which actually have PSOM and not SM.
What it is
The eustachian tube connects the middle ear to the back of the nose. The tube serves to maintain equal air pressure both inside and outside of the middle ear, to allow the eardrums to vibrate properly. The tube also allows fluid from mucous membranes in the middle ear to drain through the nose. If the eustachian tube is not working properly, the air in the middle ear is absorbed, but it cannot be replaced, causing air pressure inside the middle ear to be lower than the air pressure outside, in the ear canal, creating a partial vacuum. This difference in air pressure causes the mucous fluid to collect inside the middle ear. The fluid then begins to become thicker and build up, becoming an ever-enlarging mucus plug.
In a ten year study conducted in Sweden and reported in 2003, 61 cases of primary secretory otitis media were diagnosed in 43 Cavaliers. In that study, conducted by Wiwian Stern-Bertholtz, MScVetMed, Lennart Sjöström, DVM DECVS, and Nils Wallin-Håkanson, DVM DACVO DECVO, they explain the condition technically as follows:
"The eustachian tube is kept closed by the surface tension caused by contact between air and mucus. A particular agent, identified as a combination of different phospholipids, decreases the surface tension in the eustachian tube of dogs, thus reducing the pressure needed to open the tube. When the tube is closed, the pressure in the middle ear is reported to become negative in relation to the pressure in the tube, which is equivalent to atmospheric pressure. This negative pressure, caused by lack of aeration, draws out the sterile transudate from the glandular tissues in the middle ear to the surface of the mucous membrane. The negative pressure remains and the process of accumulation of mucus carries on as long as the tympanic membrane is intact and the eustachian tube is closed. Failure to open the eustachian tube and thereby release the secretory products is believed to be the cause of secretory otitis media. An obstruction of the osseous part of the eustachian tube is reported to be the most common cause. In PSOM, the overfilling of the middle ear with mucus and the subsequent bulging of the tympanic membrane, and the pain and neurological signs that are common, indicate that the pressure within the middle ear is high rather than low, at least in the final part of the disease process."
Symptoms
The principal symptoms are moderate to severe pain in the head or neck, holding the neck in a guarded position, and tilting the head. Other signs may include scratching at the ears, yawning excessively, crying out in pain, ataxia, facial paralysis, some loss of hearing, seizures, and fatigue. These symptoms, in many cases, are very similar to those of syringomyelia and, to some extent, to those of progressive hereditary deafness. Therefore, the examining veterinarian should take care to consider these other possible causes of the dog's symptomatic behaviors.
Studies have concluded that brachycephalic dogs may be predisposed to this condition.
Diagnosis
PSOM may be detected by veterinary neurology or dermatology specialists from either magnetic resonance imaging (MRI) or a computed tomography (CT) scan. Both require that the dog be under general anesthesia. It also may be observed using an operating microscope with good lighting and at a suitable magnification. If the case is severe enough that the dog's tympanic membrane is bulging, the condition may be visible on x-rays and diagnosed with an otoscope. In extreme cases, the tympanic membrane may have ruptured and the mucus plug clearly seen.
Possible alternative instruments for diagnosis of PSOM include impedance audiometry, pneumotoscopy, tympanic bulla ultrasonography, and the brain-stem auditory evoked response test (BAER). Veterinary dermatologists in the United States may be located on the American College of Veterinary Dermatology website.
Treatment
Treatment traditionally has consisted of performing a myringotomy, making a small cut in the eardrum to remove the mucus plug from the middle ear, followed by flushing the middle ear. Topical and/or systemic corticosteroids and antibiotics then are administered. The procedure may have to be repeated, in some cases several times, depending upon how the dog responds. In a March 2008 study conducted by Australian researchers, they inserted tympanostomy tubes within the myringotomy incision in order to provide continual tympanic cavity ventilation and drainage. They found that in the cases of the three CKCSs which they operated on, all three dogs were asymptomatic at the time of follow-up, 8, 6 and 4 months later, and they concluded that the use of tympanostomy tubes may be an acceptable alternative to repeated myringotomy.
An alternative procedure is a ventral bulla osteotomy, which involves making an incision on the under side of the neck behind the jaw bone. The middle ear -- the bulla -- then is exposed and is opened.
Current Research
4Drs. Andrew Hillier and Lynette Cole and others of the Dermatology Service at the Ohio State University's veterinary teaching hospital are conducting research into the prevalence of PSOM in the Cavalier King Charles Spaniel breed in the United States, as well as the mode of inheritance, data about the clinical signs of the disorder, alternative methods of diagnosing it (CT scan, tympanic bulla ultrasonography, BAER test, impedance audiometry, otoscopic examination, and pneumotoscopy), and methods of treatment. The diagnostic tests will be compared to the results of the CT scan for the diagnosis of PSOM, to determine which test or group of tests are the best to use for the diagnosis of PSOM.
In their August 2007 interim report to the American
Cavalier King Charles Spaniel Club's charitable trust, Dr. Cole reports
that 75 Cavaliers are to be "enrolled, placed under general anesthesia, and the
following diagnostics performed: CT scan, tympanic bulla ultrasonography, BAER
test, impedance audiometry, otoscopic examination, and pneumotoscopy. If the CT
scan is suggestive of otitis media (i.e. a soft tissue density present in the
tympanic bulla-the bony part of the middle ear), then a myringotomy (incision
into the ear drum) will be performed and the mucus flushed out of the middle
ear. Cytology and bacterial cultures will be performed on the mucus from the
middle ear. A BAER and CT scan will be performed post-middle ear flush on those
CKCS with PSOM."
Dr. Cole states that as of August 2007, 13 CKCS have been examined, with ages
ranging from 5 months to 9 years of age. Of those, 8 (62%) Cavaliers had PSOM (6
had PSOM in both ears, 2 had PSOM in one ear) and 5 (38%) did not have PSOM.
The doctors still are seeking Cavaliers to participate in this study. They may be reached by telephone at 614-292-3551 and email Dr. Hillier at hillier.4@osu.edu and Dr. Cole at cole.143@osu.edu and website www.vet.ohio-state.edu/876.htm The American Cavalier King Charles Spaniel Club's charitable trust has contributed a grant to help underwrite this project. Donate to the ACKCSC's Charitable Trust!
Related Links: Syringomyelia
Brachycephalic Airway Obstruction Syndrome (BAOS)
American College of Veterinary Dermatology
Veterinary Resources:
Insertion of a transtympanic ventilation tube for the teatment of otitis media with effusion. Cox C,J., Slack R.W.T., Cox G.J. J Small Animal Practice,1989, 30, 517-519
Primary secretory otitis media in the Cavalier King Charles spaniel: a review of 61 cases. Stern-Bertholtz W.; Sjöström L.; Wallin Håkanson N. J Small Animal Practice,30 June 2003, 44(6): 253-256(4).
Material in the middle ear of dogs having magnetic resonance imaging for investigation of neurologic signs. Owen MC, Lamb CR, Targett MP. Vet. Radiology & Ultrasound, Mar 2004, 45(2):149-155.
Primary secretory otitis media in Cavalier King Charles spaniels. Clare Rusbridge. J Small Anim Pract. 2004 Apr; 45:222.
Primary Secretory Otitis Media (Glue Ear). Hillier A., Cole L. CKCSC,USA Bulletin, Fall/Winter 2005:16.
Diagnosis and management of otitis media. Thomas, Randall C. Proceedings, No. Am. Vet. Conf., Vol. 20, Jan. 2006: 979.
Contrast-enhanced Computed Tomographic Imaging of the Auditory Tube in Mesaticephalic Dogs. Lynette K. Cole, Valerie F. Samii. Vet. Radiology & Ultrasound, Vol 48(2): 125-128, Mar 2007. Quote: "Auditory tube dysfunction has been speculated as the cause of primary secretory otitis media (PSOM), reported recently in the Cavalier King Charles spaniel.10 A simple, noninvasive technique is needed for evaluation of the canine auditory tube."
The method of application and short term results of tympanostomy tubes for the treatment of primary secretory otitis media in three Cavalier King Charles Spaniel dogs. Corfield GS, Burrows AK, Imani P, Bryden SL. Aust Vet J. 2008 Mar;86(3):88-94. Quote: "Primary secretory otitis media is an uncommon disease affecting predominantly Cavalier King Charles Spaniel dogs. Current treatment recommendations include repeated manual removal of the mucoid effusion from the tympanic cavity through a myringotomy incision and topical or systemic corticosteroids. The aim of this study was to assess the efficacy of tympanostomy tubes to provide continual tympanic cavity ventilation and drainage for the treatment of primary secretory otitis media in three dogs. Tympanostomy tubes were placed within a myringotomy incision in the pars tensa with the aid of an operating microscope. Clinical signs resolved rapidly in all cases following the procedure and all cases were asymptomatic at the time of follow-up, 8, 6 and 4 months later. Results of this study indicate that tympanostomy tubes provide continual tympanic cavity ventilation and drainage and may be an acceptable alternative to repeated myringotomy for the treatment of primary secretory otitis media."
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