Primary Secretory Otitis Media (PSOM)
in the Cavalier King Charles Spaniel
Primary secretory otitis media (PSOM) -- also known as "glue ear" or "middle ear effusion" or "otitis media with effusion" (OME) -- 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. The mucus has also been referred to as "hyperintense material".
PSOM has been reported almost exclusively in cavaliers. 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 may have mis-diagnosed SM in cavaliers which actually have PSOM and not SM. Other breeds in which PSOM has been diagnosed are boxers, dachshund, and shih tzu.
The cause of PSOM is unknown. Dr. Lynette Cole reports that it is speculated to be due to a dysfunction of the middle ear or the Eustachian (auditory) tube: either (a) the increased production of mucus in the middle ear, or (b) decreased drainage of the middle ear through the auditory tube, or (c) both.
The auditory 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 (tympanic membranes) 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, Lennart Sjöström, and Nils Wallin-Håkanson, 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." Photo above shows mucus plugs removed from a cavalier. Courtesy, Downs Veterinary Practice, Bristol, UK.
In a 2010 study (and a 2013 report of the same study), UK veterinary researchers examined MRI scans of the skulls of 34 cavalier King Charles spaniels, each of which had been scanned twice over periods from one month to 46 months. They concluded in their report that PSOM is a progressive condition in the CKCS and can progress from none to unilateral or bilateral; or from unilateral to bilateral on sequential scans, and that PSOM is an acquired condition in the CKCS and will not resolve spontaneously once it has developed. However, a few breeders report that second MRI scans of their PSOM-affected cavaliers show that the PSOM has disappeared without treatment.
In another 2010 report, UK researchers found an association between PSOM and brachycephalic conformation in cavaliers. They stated: "in CKCS, greater thickness of the soft palate and reduced nasopharyngeal aperture are significantly associated with OME [otitis media with effusion, meaning PSOM]." However, they did not explain why PSOM is so nearly limited to the cavalier, while so many other breeds are brachycephalic.
EDITOR'S NOTE: A uniqueness of the CKCS's morphology is that the breed was created in the 1920s from a more extreme snub-nosed English toy spaniel -- the King Charles spaniel -- by breeding to elongate the muzzle, rather than to shorten it. It is as if the cavalier's muzzle has been treated like an accordion -- first compressed to create the predecessor King Charles spaniel, and then stretched. (See a profile of a 1910 English toy spaniel, at right.)
Infection as a cause of PSOM in the cavalier has been discounted by the researchers.
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, itchy ears, head tilt, excessive yawning, crying out in pain, ataxia, drooping ear or lip, inability to blink an eye, rapid eyeball movement, facial paralysis or nerve palsy, Vestibular disease, 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.
In a 2009 UK study of 23 cavaliers with PSOM, the researchers (who choose to refer to the disorder as middle ear effusion) tested the dogs' hearing with the Brainstem Auditory Evoked Reponses (BAER) test and found that, even though the dogs' owners considered their dogs' hearing capabilities to be normal, the BAER tests demonstrated a conductive hearing loss in ears affected by middle ear effusion (PSOM). See same study in 2011 Veterinary Journal.
A 2010 study has concluded that brachycephalic dogs may be predisposed to this condition, and that bilateral PSOM was associated with CKCS with more extreme nasopharyngeal conformation, than unaffected CKCS.
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 pars flaccida, a portion of 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.
In the MRI scan at the right, the two bowl-shaped bullae are shown to contain accumulated mucus. Courtesy, Downs Veterinary Practice, Bristol, UK.
Possible alternative instruments for diagnosis of PSOM include impedance audiometry, pneumotoscopy, tympanic bulla ultrasonography, and the brain-stem auditory evoked response test (BAER). Click here for a list of BAER test sites. Also, check our health clinics webpage for upcoming clinics offering BAER tests. Look for the symbol U
Veterinary dermatologists in the United States may be located on the American College of Veterinary Dermatology website.
Treatment traditionally has consisted of performing a myringotomy (see photo at right), making a small cut in the eardrum (tympanic membrane), followed by flushing the middle ear to force out the mucus plug. The photograph at right is of a myringotomy in progress. The ring in the middle of the photo is the eardrum. The tube tip at the top is the device used to flush the inner ear and force out the mucus. You may watch a close up video of a myringotomy actually being performed on a cavalier named Baylee on YouTube here.
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. However, Dr. Cole reports that "no long-term prospective studies have been published on the outcome after extrusion of the tympanostomy tubes as far as the length of time the bulla remains effusion free. In addition, no studies have reported on the efficacy of a more “permanent” or long-term tympanostomy tube for treatment of PSOM." In a February 2013 report, a team of UK researchers also have questioned the effectiveness of repeated tympanostomies.
An alternative procedure is a ventral bulla osteotomy (see photo above at right),which involves making an incision on the under side of the neck behind the jaw bone. The auditory bulla, a hollow bony sheath that encloses parts of the middle ear, then is exposed and is opened. In the photograph above at right, the exposed bulla is being opened.
Some specialist veterinarians have been prescribing N-Acetyl-L-Cysteine (NAC), a mucolytic -- mucus thinning agent or expectorant -- for cavaliers with PSOM, following surgeries. However, no studies have been performed to determine the effectiveness of NAC in managing PSOM.
September 2013: UK's Downs Veterinary Practice reports PSOM case in CKCS. In a report posted by Downs Veterinary Practice of Bristol, UK, on its website, it describes a case study of a cavalier King Charles spaniel with primary secretory otitis media. It states: "Bilateral myringotomy was performed and the bullae were flushed with sterile saline; large amounts of yellow tinged mucus were removed from both bulla and sent for cytology and bacteriology. The dog was treated post operatively with meloxicam and amoxiclav pending culture results. The owners were contacted one week after surgery and reported an improvement in the dog’s hearing." The report also included a photo of the mucus plugs and an MRI scan showing the bullae filled with mucus fluid, which we have added to sections of this webpage.
September 2013: UK researchers' survey finds that chronic otitis media may be associated with higher grades of hearing loss. In an October 2013 study by a team of UK veterinary dermatologists, they report the results of questionaires answered by owners of 100 dogs referred for chronic otitis investigation, including six cavalier King Charles spaniels. They concluded that "Chronic otitis media may be associated with higher grades of hearing loss." NOTE: This study was not limited to dogs with PSOM.
April 2013: Dr. Charles Bluestone tones down his fantasy about CKCS evolution but still gets it all wrong. In an article* published in April 2013, Dr. Charles D. Bluestone (right) (along with his cohort J. Douglas Swarts and others) persists in likening PSOM in the cavalier King Charles spaniel with the human condition, but at least he has walked back his irresponsible prior statements about "greater than 50%" of cavaliers having PSOM (see our February 2012 entry), and that the cavalier "has been bred over 300 years to have a short snout." (See our November 2011 entry.) Instead, this time he gets the name of the disorder right (it's not "persistent", it's "primary"), and he more mildly states (with actual citations):
"Primary secretory OM [otitis media] is the term veterinarians use to describe chronic OM with effusion in canines. It has been reported to occur almost exclusively in short-faced canines, and its prevalence in the Cavalier King Charles spaniel breed is estimated at about 40%. ... Bluestone and Swarts have speculated that the Cavalier King Charles is a natural animal model, induced by artificial selection for those breed characteristics, which secondarily elicit chronic OM with effusion due to ET dysfunction."
But, they still get the "evolution" of the CKCS totally backwards. They write:
"Artificial selection of this breed has, until recently, focused on producing a shortened front-to-back diameter of the skull, a result of premature fusion of the coronal sutures."
This shows the authors' continued and seemingly intentional ignorance of the development of the cavalier breed from its King Charles spaniel roots -- with that breed's shorter skull -- in the 1920s. (See our Editor's Note above and our November 2011 entry below for the skull comparison.) We are not sure of what they mean by "until recently". Perhaps to them, "until recently" means "until the 1920s", some 90 years ago. Finally, as has been their modus operandi in the past, our federal tax money funded their little screed.
March 2013: Alabama specialist analyzes PSOM in 9-month old female CKCS. In the March 2013 issue of Clinician's Brief, Dr. Louis N. Gotthelf (right), a pet ear and skin specialist, reports a case study of a nine-month old female cavalier with neck stiffness and head tilt. His "bottom line":
"CKCS eardrums should always be evaluated. If PSOM is suspected, a high-magnification eardrum examination may require referral. PSOM can be asymptomatic in CKCSs, in which case myringotomy is not required; however, the owner should be educated to take appropriate steps if signs are displayed. The Take-Home: CKCSs often have a genetic defect of their eustachian tube that results in PSOM, which may be asymptomatic. Bulging eardrum and ear pain are typical of PSOM in CKCSs. PSOM should be differentiated from SM via eardrum evaluation and MRi (if necessary). Myringotomy can relieve PSOM signs. Antibiotics will not be helpful. Periodic treatment is required."
February 2013: UK researchers find PSOM is progressive in cavaliers and will not cure itself. In a February 2013 report in Veterinary Journal, a team of UK researchers (S. J. McGuinness, E. J. Friend, S. P. Knowler, N. D. Jeffery, C. Rusbridge) examined repeat MRIs (two each) of 34 cavalier King Charles spaniels for PSOM*. (See a September 2010 entry on this same study.) At the first scan, 23 of the CKCSs had no effusion, 10 had unilateral effusion, and 1 had bilateral effusion. They found that, from the first to the second MRI, 26.5% had progressed from no PSOM to unilateral or bilateral PSOM, or from unilateral to bilateral. None of the 11 dogs which had PSOM at the time of the first MRI had resolved themselves. Significantly, none of the affected cavaliers in this study displayed any symptoms of pain associated with the PSOM. The authors suggest that, "it is possible that the clinical signs [discomfort symptoms] seen in these [earlier reported] cases could be explained by undiagnosed syringomyelia."* The authors refer to the condition as "otitis media with effusion" (OME) because none of the dogs evidenced any associated pain.
The researchers conclude:
"In conclusion, this study suggests that OME is an acquired and progressive condition in the CKCS and will not resolve spontaneously once it has developed. As the clinical signs associated with OME are minimal, it is unclear if treatment is required. If treatment was required in any one case, an alternative method to repeated myringotomies or tympanostomy tube placement needs to be developed in order to treat the hearing loss associated with this condition."
October 2012: Dr. Cole publishes a definitive guide to PSOM. Dr. Lynette Cole (right) of Ohio State University has issued a definitive guide to diagnosing, treating, and managing primary secretory otitis media, along with a discussion of the possible pathogenesis of PSOM. In summary, she states:
"Primary secretory otitis media (PSOM) is a disease that has been described in the Cavalier King Charles spaniel (CKCS). A large, bulging pars flaccida identified on otoscopic examination confirms the diagnosis. However, in many CKCS with PSOM the pars flaccida is flat, and radiographic imaging is needed to confirm the diagnosis. Current treatment for PSOM includes performing a myringotomy into the caudal-ventral quadrant of the pars tensa with subsequent flushing of the mucus out of the bulla using a video otoscope. Repeat myringotomies and flushing of the middle ear are necessary to keep the middle ear free of mucus."
September 2012: UK Dr. Gert ter Haar heads RVC's new ear, nose, and throat clinic. UK's Royal Veterinary College has commenced an ear, nose, and throat referral clinic at the Queen Mother Hospital for Animals in London. Dr. Gert ter Haar heads the unit, which offers services including advanced diagnostics and treatment for PSOM in cavaliers, as well as CT and BAER diagnostics for deafness (plus hearing aid implants for selected patients), and diagnostics and treatment of cavaliers with brachycephalic airway obstruction syndrome (BAOS). Telephone 01707 666 365 for more information.
May 2012: OSU’s Dr. Cole needs normal hearing CKCSs for BAER tests, CT scans, and MRI scans. Dr. Lynette Cole of Ohio State University’s Veterinary Dermatology and Otology Service needs cavaliers between the ages of 1 to 2 years old with no history of hearing loss for a two-day evaluation by BAER hearing tests, computed tomography (CT) scans, and MRI scans. The study pays for all testing. She writes:
“In the dog breed Cavalier King Charles Spaniel (CKCS), hearing disorders may be due to conductive hearing loss, which may occur with primary secretory otitis media (PSOM), or due to sensorineural hearing loss, which may occur when there is damage or an abnormality of the sensory cells in the cochlea or the auditory nerve.”
If you are interested in possibly enrolling your cavalier in the study, contact Dr. Cole at telephone number 614-292-3551 or email firstname.lastname@example.org A pedigree is required for entry into the study, but will be kept confidential, as will all test results. Details of the study will be given individually on the phone or via email.
February 2012: Bluestone is still monkeying with the CKCS. Dr. Charles D. Bluestone, renowned self-styled chimpanzee descendant, is still monkeying with the Eustachian tubes of our cavaliers. (See December 2010 entry and November 2011 entry.) In a brief resume released by the University of Pittsburgh Medical Center, he states:
“Another ongoing research project involves a potential animal model, Cavalier King Charles Spaniel, which has a greater than 50% incidence of chronic otitis media effusion. Research being conducted with his colleagues in this animal involves histopathology of the middle-ear cleft in cadavers, and Eustachian tube function tests in live animals, conducted at the Ohio State University School of Veterinary Medicine in Columbus Ohio. ”
So now he tells us that the prevalence of PSOM in the CKCS is "greater than 50%". Each time he makes a public statement, the ante goes up, without ever providing any statistical data to support his assertions. This is much like the non-existent data supporting his claim to be descended from chimpanzees.*
* The notion of man's alleged descent from chimpanzees has long been rejected by evolutionists and creationists, alike.
November 2011: Bluestone keeps mucking up research of PSOM in the cavalier. In a video released in November 2011 by the University of Pittsburgh Medical Center, Dr. Charles D. Bluestone, noted self-styled chimpanzee descendant, insists he still is researching PSOM in the cavalier King Charles spaniel. (See December 2010 entry.) He claims to be basing his research on what in fact is the patently false premise that the cavalier "has been bred over 300 years to have a short snout." He goes on:
"So how did the Cavalier King Charles develop chronic persistent [sic] secretory otitis media? Their short snout changed the palatal anatomy. So the question is does the middle ear effusion with this very thick mucus in that Cavalier, it causes trouble by the way with hearing loss, have a consequence? There are two muscles that are related to this issue, the muscles that come from the palate, the tensor veli palatini, TVP, and the LVP muscles are altered causing the eustachian tube dysfunction, that’s our hypothesis. It’s a current research project which we are undergoing now."
As noted above, Dr. Bluestone also mis-names the disorder he claims to be researching. PSOM stands for "primary secretory otitis media". He oddly and repeatedly calls it "persistent" secretory otitis media. So he does not even know the name of the disorder, and he is under the abject mistaken belief that the cavalier "has been bred over 300 years to have a short snout" when, in fact, the breed was created less than 85 years ago, from the King Charles spaniel, and has been bred to have a longer snout. Note in the comparison of skulls at left: the King Charles spaniel skull is at the far left, and the skull of the cavalier King Charles spaniel is to its right.
(Specimens from the collections of the Albert Heim Foundation, Museum of Natural History, Bern.)
He also has upped his stated prevalence of PSOM in the breed from "up to 40%" to a flat "50%", all without providing any statistical data to support either assertion.* Once again, we can only hope that this misguided gentleman's federal funding runs out as quickly as possible.
* Click here for some more interesting reading about Dr. Bluestone's credibility.
December 2010: Pitt Medical Center's self-styled chimpanzee descendants muck up PSOM study of cavaliers on taxpayers' dime. Drs. Charles D. Bluestone (left), a human ear, nose, and throat specialist, and J. Douglas Swarts (middle), an anthropologist, both at the University of Pittsburgh Medical Center, who apparently still harbor the disproven belief that humans evolved from chimpanzees (They even include a tiresome skull comparison of the two completely separate species, in profile, and therefore, so do we; the chimpanzee is at far right), have also gratuitously and erroneously concluded in their federally-funded "research" article, Human evolutionary history: Consequences for the pathogenesis of otitis media, that "up to 40%" of cavalier King Charles spaniels have PSOM because they have been "artificially selected to have a shortened front-to-back diameter of the skull, a term called brachycephaly". This is an utter (and easily provable) falsehood. So much for their scientific method.
We suppose that if one must "publish or perish" (and with a taxpayer-funded grant, to boot), these two had to come up with something no one else would dare think to write about. But how do they get around the fact that PSOM is essentially unique to the cavalier, while many other canine breeds are brachycephalic, and some even more so? The answer is, they do not. There is a little value in their article, however, because Dr. Lynette Cole provided them with some quite accurate (albeit not new) information about PSOM in the cavalier, which is summarized below. Dr. Cole's input makes that part of the article worth reading.
But the scariest part of the article is their statement (threat?) near the end that:
"The underlying pathogenesis of the Cavalier's ME disease is currently under investigation in our laboratory."
We sure hope not. Leave that to Dr. Cole, please.
September 2010: UK researchers find PSOM (OME) to be progressive. A team of UK veterinary researchers (S.J. McGuinness, E.J. Friend, C. Rusbridge, P. Knowler and N. D. Jeffery) examined MRI scans of the skulls of 34 cavalier King Charles spaniels, each of which had been scanned twice over periods from one month to 46 months. They concluded in their report that PSOM (OME) is a progressive condition in the CKCS and can progress from none to unilateral or bilateral; or from unilateral to bilateral on sequential scans, and that OME is an acquired condition in the CKCS and will not resolve spontaneously once it has developed. (See also a February 2013 entry on this same study.)
July 2010: UK researchers find association between PSOM and brachycephalic conformation in cavaliers. In their report, they find, "in CKCS, greater thickness of the soft palate and reduced nasopharyngeal aperture are significantly associated with OME [otitis media with effusion, meaning PSOM]."
2010: Ohio State Vet School needs cavalier
cadavers for Eustachian tube study. Dr. Lynette Cole of the
Dermatology Service at the Ohio State University's veterinary teaching
hospital is seeking deceased cavaliers and candidates for euthanasia,
with or without PSOM, for a study of the muscles which open the
Eustachian tube. The study will include dissections of the Eustachian
tube, its muscles, and the inner ear, and imaging with advanced MRI. The
veterinary research is in conjunction with an OSU medical school
otolaryngology study of secretory otitis media in humans. The
otolaryngologists are looking for abnormalities within the muscles that
open Eustachian tube, that prevent secretions from being removed from
the tube, thereby causing a build-up of the mucus causing secretory
Dr. Cole asks: "If at all possible, I would prefer to have the cavalier brought to me at the Ohio State University for euthanasia. Please contact me prior to make proper arrangements. If that is not possible, please have your veterinarian refrigerate the dog after euthanasia, and then have your veterinarian contact me." Contact Dr. Cole at telephone number 614-292-3551, email email@example.com
September 2009: Drs. 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 firstname.lastname@example.org and Dr. Cole at email@example.com 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.
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.Sm.Anim.Prac., Sept. 1989;30(9):517-519. Quote: "In this paper, a case of otitis media with effusion ('glue ear') is described in a Cavalier King Charles spaniel. Its presentation, diagnosis and surgical management by the insertion of a trans-tympanic ventilation tube (grommet) is discussed."
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). Quote: "Sixty-one episodes of primary secretory otitis media (PSOM) were diagnosed in 43 Cavalier King Charles spaniels over a 10-year period. The principal findings were signs of moderate to severe pain localised to the head or cervical area, and/or neurological signs. Diagnosis was made by examination of the tympanic membrane and middle ear with the aid of an operating microscope under general anaesthesia. A bulging, but intact, tympanic membrane was found in most cases. he cytological and bacteriological examinations that were carried out in a few cases, and the macroscopic appearance of the contents of the middle ear, suggest that infection is not a part of the pathogenesis of PSOM. Following myringotomy, a highly viscous mucus plug was found filling the middle ear. Treatment, consisting of removal of the mucus plug, flushing of the middle ear, and local and systemic medical therapy, had to be repeated between one and five times. The prognosis was good in all cases. PSOM is an important differential diagnosis in Cavalier King Charles spaniels with signs of pain involving the head and neck, and/or neurological signs."
Neurological signs and results of magnetic resonance imaging in 40 cavalier King Charles spaniels with Chiari type 1-like malformations. Lu D, Lamb CR, Pfeiffer DU, Targett MP. Vet Rec. Aug 2003;153(9):260-3. Quote: "In human beings a Chiari type 1 malformation is a developmental condition characterised by cerebellar herniation and syringohydromyelia. Abnormalities compatible with such a malformation were identified by magnetic resonance imaging in 39 cavalier King Charles spaniels with neurological signs and in one neurologically normal cavalier King Charles spaniel that was examined postmortem. The dogs with these abnormalities had a wide variety of neurological signs, but there was no apparent correlation between the neurological signs and the severity of cerebellar herniation, syringohydromyelia or hydrocephalus."
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. Quote: "The aim of this study was to determine the prevalence and potential significance of finding material in the middle ear of dogs having magnetic resonance (MR) imaging. Of 466 MR studies reviewed, an increased signal was identified in the tympanic bulla in 32 (7%) dogs. Cavalier King Charles spaniels, Cocker spaniels, Bulldogs, and Boxers were over-represented compared to the population of dogs having MR imaging. Five (16%) dogs had definite otitis media and one (3%) had a meningioma invading the middle ear. Of the remaining dogs, 13 (41%) had possible otitis media and 13 (41%) had neurologic conditions apparently unrelated to otitis media. The most common appearance of material in the middle ear was isointense in T1-weighted images and hyperintense in T2-weighted images. There was no apparent correlation between the signal characteristics of the material and the diagnosis. Enhanced signal after gadolinium administration was observed affecting the lining of the bulla in dogs with otitis media and in dogs with unrelated neurologic conditions. In dogs without clinical signs of otitis media, finding an increased signal in the middle ear during MR imaging may reflect subclinical otitis media or fluid accumulation unrelated to inflammation. Brachycephalic dogs may be predisposed to this condition."
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. 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."
A Practical Guide to Canine and Feline Neurology. Curtis W. Dewey. John Wiley & Sons; 2008; 273.
Effect of Middle Ear Effusion On The Brainstem Auditory Response Of Cavalier King Charles Spaniels. T. R. Harcourt-Brown, J. E. Parker, N. D. Jeffery. 22nd ESVN Annual Symposium, Sept. 2009; J Vet Intern Med, Jan/Feb 2010;24(1):242. Quote: "The purpose of this study was to investigate the effect of middle ear effusion on the Brainstem Auditory Evoked Reponses (BAER) of  cavalier king charles spaniels. BAER’s were obtained from dogs following Magnetic Resonance (MR) imaging screening for syringomyelia. Middle ear effusion was diagnosed if the auditory bulla was completely filled with material that was isontinense to brain parenchyma on T1 weighted images and hyperintense on T2 weighted images. Dogs with otitis externa were excluded from the study. BAER’s were obtained at sound intensities ranging from 10 to 100 dB nHL (normal hearing level). The BAER threshold was determined for each ear as the last trace that showed a recognisable wave V. The latency of wave V was recorded for each intensity where it was identified and the interwave latency between waves I and V was calculated at 90 dB nHL. ... Each dog’s hearing was considered normal by their owner. The median BAER threshold was 60 dB for ears with effusion and 30 dB for those without. The proportion of ears with abnormal BAER thresholds (4 30 dB nHL) was greater for ears with effusion (11/16) than those without (8/30) (Fishers exact test, p = 0.011). Severity of hearing loss for ears with effusion was calculated by linear regression of wave V latencies to be 23 dB (95% confidence 18 to 31 dB). The mean interwave latency between waves I and V at 90 dB for ears with and without effusion was not significantly different (Students t-test, p > 0.05). These data show that middle ear effusion is associated with conductive hearing loss of 21–30 dB in affected ears."
Relationship between pharyngeal conformation and otitis media with effusion in Cavalier King Charles spaniels. Hayes GM, Friend EJ, Jeffery ND. Vet Rec. 2010 Jul 10;167(2):55-8. Quote: "Otitis media with effusion (OME) is a common incidental finding in otherwise normal Cavalier King Charles spaniels (CKCS). ... The incidence of OME as an incidental finding in a sample of 68 CKCS undergoing MRI was 54 per cent in this study, which is comparable to previously reported incidences of 47 per cent ... and 28 per cent ... in this breed. The CKCS in this study were reported to be ‘clinically normal’ by their owners, who did not report clinical signs of neurological disease or otitis in these dogs. ... In this study, measurements made on MRI were used to determine whether there was an association between OME and brachycephalic conformation. The results confirm that association and also demonstrate that, in CKCS, greater thickness of the soft palate and reduced naso-pharyngeal aperture are significantly associated with OME. ... An overlong soft palate has long been accepted as contributing to the [brachycephalic airway] syndrome, but more recently the importance of abnormally thick soft palates has also been recognised ... [B]rachycephalic airway syndrome may occur as a consequence of the selection for morphological neotony in this breed ... Although the aetiology is probably multifactorial, OME is more frequently found in patients with more severe anomalies of nasopharyngeal conformation. Changes within the nasopharynx may impair auditory tube drainage. ... These results suggest that auditory tube dysfunction and OME may represent a previously overlooked consequence of brachycephalic conformation in dogs."
Breed Predispositions to Disease in Dogs & Cats (2d Ed.). Alex Gough, Alison Thomas. 2010; Wiley-Blackwell Publ. 53.
Progression of Otitis Media with Effusion in the Cavalier King Charles Spaniel. S.J. McGuinness, E.J. Friend, C. Rusbridge, P. Knowler and N. D. Jeffery. Abstract at 23d ECVN symposium, Sept. 2010. Investigation of 34 MRI scans of CKCS having 2 scans as part of CMSM screening. Interpreted by the same author (S.J. McGuinness). The scans were classified according to negative, unilateral or bilateral OME based on the absence or presence of hyperintense material on T2 weighted MRI images. ... A total of 34 dogs had 2 MRI scans a median of 20 months apart (range 1 to 46); the incidence of OME at the first MRI was 32%, which increased to 50% at the time of the second MRI, which is comparable with previous studies. At the time of the first MRI, 23 CKCS had no effusion, 10 had unilateral effusion and 1 had bilateral effusion. By the second MRI, 3 cases had progressed from unilateral to bilateral; 5 had progressed from no effusion to effusion being present (4 negative to unilateral, 1 negative to bilateral) and 8 of those having effusion at the first scan remained the same. No cases that had OME at the first MRI had resolved at the time of the second MRI and no case had clinical signs that could be associated with OME. This study demonstrates that OME is a progressive condition in the CKCS and can progress from absent to unilateral or bilateral; or from unilateral to bilateral on sequential scans. It also suggests that OME is an acquired condition in the CKCS and will not resolve spontaneously once it has developed."
Human evolutionary history: Consequences for the pathogenesis of otitis media. Charles D Bluestone, J. Douglas Swarts. Otolaryngology -- Head & Neck Surgery; Dec 2010; 143(6):739-744. Quote: "Among veterinarians, chronic ME effusion (termed primary secretory otitis media) is a well-known disease in the Cavalier King Charles Spaniel. It has been reported to be present in up to 40 percent of these animals. The effusion is mucoid and fills the entire ME. Diagnosis is made by operating microscopic examination, computed tomography scanning, or magnetic resonance imaging (MRI), and has been confirmed at the time of myringotomy. Myringotomy and tympanostomy tube placement has been recommended for treatment. This breed has been artificially selected to have a shortened front-to-back diameter of the skull, a shape termed brachycephaly, which arises due to premature fusion of the coronal sutures. The term neotenous (retention of juvenile characteristics into adulthood) is also appropriate for these breeds. The Cavalier snores habitually like other brachycephalic dogs, including the English Bulldog, a breed that has been reported to be the only animal known to develop obstructive sleep apnea. The snoring is undoubtedly secondary to its constricted pharynx, a consequence of the shortening of the snout. ... Figure 5 compares the head shape of a Cavalier King Charles Spaniel, with its extremely short face, to that of a Golden Retriever, which has a classic prognathic snout. The Cavalier King Charles Spaniel is an animal model of chronic OM with effusion. It has been “artificially selected” (Charles Darwin's term) for its short snout and globular head, but an unintended consequence of breeding for this characteristic is the propensity for chronic OM with effusion. In a recently reported study using MRI, veterinarians from England found that not only did the Cavalier have OM (54%), but another brachycephalic breed, the Boxer, also had ME disease (32%), which was not present in Cocker Spaniels, a mesaticephalic breed. The investigators suggested that the reduced nasopharyngeal space in the Cavalier and Boxers, when compared with the Cocker Spaniel, predisposed them to OM. It might be that one or both of the paratubal muscles is dysfunctional due to the abnormal palatal anatomy in these breeds and is the cause of their OM. The underlying pathogenesis of the Cavalier's ME disease is currently under investigation in our laboratory. Analogously, one could speculate that with the loss of their prognathic face, humans became susceptible to OM, an unintended consequence of “natural selection” for another adaptation (again, Darwin's term), as described above."
Middle ear effusions in dogs: An incidental finding? H.A. Volk, E.S. Davies. Vet.J. June 2011; 188(3):256-257
Effect of middle ear effusion on the brain-stem auditory evoked response of Cavalier King Charles Spaniels. Thomas R. Harcourt-Brown, John E. Parker, Nicolas Granger, and Nick D. Jeffery. Vet.J. June 2011; 188(3):341-345. Quote: "Brain-stem auditory evoked responses (BAER) were assessed in 23 Cavalier King Charles Spaniels with and without middle ear effusion at sound intensities ranging from 10 to 100 dB nHL. Significant differences were found between the median BAER threshold for ears where effusions were present (60 dB nHL), compared to those without (30 dB nHL) (P = 0.001). The slopes of latency–intensity functions from both groups did not differ, but the y-axis intercept when the x value was zero was greater in dogs with effusions (P = 0.009), consistent with conductive hearing loss. Analysis of latency–intensity functions suggested the degree of hearing loss due to middle ear effusion was 21 dB (95% confidence between 10 and 33 dB). Waves I–V inter-wave latency at 90 dB nHL was not significantly different between the two groups. These findings demonstrate that middle ear effusion is associated with a conductive hearing loss of 10–33 dB in affected dogs despite the fact that all animals studied were considered to have normal hearing by their owners."
Diagnosis of primary secretory otitis media in the cavalier King Charles spaniel. VCole LK, Samii VF, Wagner S, and PJ Rajala-Schultz. Dermatol April 2011;22:297.
Genetic Connection: A Guide to Health Problems in Purebred Dogs, Second Edition. Lowell Ackerman. July 2011; AAHA Press; pg 59. Quote: "Primary secretory otitis media (PSOM), sometimes referred to as glue ear, is a poorly defined disorder of the middle ear that is most commonly reported in the Cavalier King Charles spaniel. ... The cause of PSOM has not been determined, but because of the predominance of Cavalier King Charles spaniels affected, a genetic link is suspected."
Primary Secretory Otitis Media in Cavalier King Charles Spaniels. Lynette K. Cole. Vet Clin Small Anim; Oct. 2012. Quote: "Primary secretory otitis media (PSOM) is a disease that has been described in the Cavalier King Charles spaniel (CKCS). Signs suggestive of primary secretory otitis media include hearing loss, neck scratching, otic pruritus, head shaking, abnormal yawning, head tilt, facial paralysis, or vestibular disturbances, with an individual Cavalier King Charles spaniel presenting with one or multiple signs. A large, bulging pars flaccida identified on otoscopic examination confirms the diagnosis. However, in many CKCS with PSOM the pars flaccida is flat, and radiographic imaging is needed to confirm the diagnosis. Current treatment for PSOM includes performing a myringotomy into the caudal-ventral quadrant of the pars tensa with subsequent flushing of the mucus out of the bulla using a video otoscope. Until a treatment is found to prevent the mucus from recurring or the cause of the disease is identified and controlled, repeat myringotomies and flushing of the middle ear will be needed to keep the middle ear free of mucus. At present, the cause of PSOM is unknown; however, it has been speculated to be due to a dysfunction of the middle ear or auditory tube (increased production of mucus in the middle ear) or decreased drainage of the middle ear through the auditory tube, or both. Until a treatment is found to prevent the mucus from recurring or the cause of the disease is identified and controlled, the fact that these CKCS had a relapse of PSOM is not surprising."
Electrodiagnostic Evaluation of Auditory Function in the Dog. Peter M. Scheifele, John Greer Clark. Vet.Clinics of N.A.:Sm.Anim.Prac. Nov. 2012; 42(6):1241-1257. Quote: "Given the high incidence of deafness within several breeds of dogs, accurate hearing screening and assessment is essential. In addition to brainstem auditory evoked response (BAER) testing, 2 other electrophysiologic tests are now being examined as audiologic tools for use in veterinary medicine: otoacoustic emissions and the auditory steady state response (ASSR). To improve BAER testing of animals and ensure an accurate interpretation of test findings from one test site to another, the establishment of and adherence to clear protocols is essential. The ASSR holds promise as an objective test for rapid testing of multiple frequencies in both ears simultaneously."
Progression of otitis media with effusion in the Cavalier King Charles spaniel. S. J. McGuinness, E. J. Friend, S. P. Knowler, N. D. Jeffery, C. Rusbridge. Vety.Rec. Feb. 2013. Quote: "Previously, the term ‘Primary secretory otitis media’ (PSOM) has been used to describe an effusion present in the tympanic bullae of Cavalier King Charles Spaniels (CKCS) (Stern-Bertholtz and others 2003). All these cases were associated with moderate to severe pain and/or neurological signs. As no cases in our study had associated pain, and due to the chronicity of the condition, the authors have classified the condition described in this study as OME [otitis media with effusion]. This study aimed to determine if, once present, OME resolved without treatment; and also if OME in the CKCS was a progressive condition. ... At the time of the first MRI scan, 23 CKCS had no effusion, 10 had unilateral effusion and one had bilateral effusion. By the second MRI scan, nine cases had progressed (26.5 per cent), three from unilateral to bilateral effusion; six to acquire an effusion (five negative to unilateral effusion; one negative to bilateral effusion). Eight CKCS having effusion in the bullae at the first MRI scan remained with this effusion (either unilateral or bilateral) at the time of the second MRI scan (Fig 2). No cases that had OME at the first MRI had resolved at the time of the second MRI. No dog had a hearing test as part of the investigation. ... The incidence of OME in CKCS in this study was 32 per cent at the first MRI scan and 50 per cent at the second MRI scan and is comparable with previous studies (Owen and others 2004, Hayes and others 2010). In this study, six cases progressed from having no effusion to either unilateral (five cases) or bilateral (one case) OME. ... The dogs reported in [previous] studies were described as having severe clinical signs including vocalising and pain localised to the head or cervical area; none of these cases underwent an MRI scan at the time of treatment, and it is possible that the clinical signs seen in these cases could be explained by undiagnosed syringomyelia. ... The possibility of extrusion of the tympanostomy tube (Cox and others 1989), the inability to allow the dog’s ear to become wet and the possibility for tracking infections make the tympanostomy tube less suitable for long-term use in the CKCS, as the anatomical changes that are the likely cause of the OME are present in the adult (Hayes and others 2010). In conclusion, this study suggests that OME is an acquired and progressive condition in the CKCS and will not resolve spontaneously once it has developed. As the clinical signs associated with OME are minimal, it is unclear if treatment is required. If treatment was required in any one case, an alternative method to repeated myringotomies or tympanostomy tube placement needs to be developed in order to treat the hearing loss associated with this condition.
Neck Stiffness & Head Tilt in a Young Spaniel. Louis N. Gotthelf. Clinician's Brief. March 2013: 23-25. Quote: "A 9-month-old female Cavalier King Charles spaniel presented for apparent neck pain when walked on a leash. History: The owner reported neck stiffness and head tilt. After the leash had been removed, the signs continued to persist for more than 24 hours. The puppy appeared bright, alert, and responded when called. Examination: Physical examination did not elicit a painful response when the head and neck were manipulated in any direction. A slight head tilt was observed when the puppy walked freely in the clinic; however, laboratory diagnostics were not performed. Evaluation may reveal a bulging eardrum, indicative of primary secretory otitis media (PSOM). PSOM of Cavalier King Charles spaniels (CKCSs) commonly occurs as head and neck pain that may be difficult to localize. With pressure in the bulla, Horner syndrome or facial nerve palsy may be evident. Vestibular disease may be present with increased bulla pressure and can manifest as nystagmus or head tilt. Breed-Specific Considerations: Careful examination can reveal an abnormal or bulging eardrum. Clinicians adept at visualizing a normal eardrum with a handheld otoscope can detect a bulging eardrum; the tip of the cone has to be small yet long enough to make the bend in the ear canal. The tip of the otoscope cone should be placed in the horizontal ear canal close enough to the eardrum to focus on the tympanic membrane. A highly magnified, well illuminated examination should be done with a video otoscope to determine eardrum status. Bottom Line: CKCS eardrums should always be evaluated. If PSOM is suspected, a high-magnification eardrum examination may require referral. PSOM can be asymptomatic in CKCSs, in which case myringotomy is not required; however, the owner should be educated to take appropriate steps if signs are displayed. The Take-Home: CKCSs often have a genetic defect of their eustachian tube that results in PSOM, which may be asymptomatic. Bulging eardrum and ear pain are typical of PSOM in CKCSs. PSOM should be differentiated from SM via eardrum evaluation and MRi (if necessary). Myringotomy can relieve PSOM signs. Antibiotics will not be helpful. Periodic treatment is required."
Use of a hearing loss grading system and an owner-based hearing questionnaire to assess hearing loss in pet dogs with chronic otitis externa or otitis media. Carly L. Mason, Susan Paterson1, Peter J. Cripps. Vet. Dermatology; Oct. 2013;24(5):512–e121. Quote: "Background: Hearing loss is important when assessing the suitability of dogs with otitis externa/media for medical or surgical therapy. Hypothesis/objectives: To assess an owner-completed questionnaire as an indicator of hearing loss and a canine hearing loss scoring system in chronic canine otitis. Animals: One hundred hospital population dogs referred for chronic otitis investigation [including 6 cavalier King Charles spaniels]. Methods: Owners completed a questionnaire to assess their dog's response to common household noises. The presence of otitis externa or media was determined and brainstem auditory-evoked response measurements were performed on each dog. The minimal hearing threshold (MHT) in decibels normal hearing level (dB NHL) was recorded and categorized according to the human World Health Organization grading system into five grades from 0 to 4 with cut-off values of ≤25 dB NHL, 26–40 dB NHL, 41–60 dB NHL, 60–80 dB NHL and ≥81 dB NHL. Results: The questionnaire correctly determined normal hearing in grade 0 cases, but did not reliably detect unilateral or grade 1 bilateral hearing loss. For dogs with bilateral hearing loss ≥ grade 2, questionnaire sensitivity was 83% [24 of 29, 95% confidence interval, (CI) 64–94%] and specificity was 94% (67 of 71, 95% CI 86–98%). Higher grades of hearing loss were significantly associated with the presence of otitis media (P < 0.01). Conclusions and clinical importance: The questionnaire may be a useful in-practice screening tool in chronic canine otitis for moderate to severe bilateral hearing deficits (MHT ≥41 dB NHL). The hearing loss grading system may help clinicians make therapeutic decisions. Chronic otitis media may be associated with higher grades of hearing loss."
CASE REPORT: Primary Sectetory Otitis Media in a Cavalier King Charles Spaniel. Downs Veterinary Practice. Quote: "Bilateral myringotomy was performed and the bullae were flushed with sterile saline; large amounts of yellow tinged mucus were removed from both bulla and sent for cytology and bacteriology. The dog was treated post operatively with meloxicam and amoxiclav pending culture results. The owners were contacted one week after surgery and reported an improvement in the dog’s hearing. ... PSOM can cause deafness, neck pain and vestibular disease. It occurs predominantly in Cavalier King Charles Spaniels, and should be considered as a differential diagnosis along with syringomyelia, cervical disc disease and progressive hereditary deafness. ... Diagnosis of PSOM can be challenging. In one report an operating microscope was used to examine the tympanic membrane as it can be difficult to accurately assess opacity of the tympanic membrane or changes in pressure with an auroscope. In this case, MRI clearly revealed bilateral fluid accumulation in the bullae. When presenting signs include head and neck pain, this imaging modality is invaluable in differentiating PSOM from syringomyelia secondary to Chiari malformation. Treatment of PSOM is surgical; myringotomy with subsequent flushing of the bulla is the standard recommendation. In addition, steroids have reportedly been used in conjunction with lavage of the bullae. In some cases, repeated surgeries may be required as the underlying abnormality leads to a potential recurrence of signs."