PSOM (Glue Ear) in Cavalier King Charles Spaniels: The Hidden Cause of Pain & Scratching

What is PSOM (Glue Ear) in Cavalier King Charles Spaniels?

Primary Secretory Otitis Media (PSOM), commonly called "glue ear," is a disorder of the middle ear characterized by thick, sticky mucous effusion that fills the tympanic bullae and middle ear cavity. In [Cavalier King Charles](https://seniorpet.org/knowledge/breed/cavalier-king-charles-spaniel "Senior Cavalier King Charles Spaniel Health Guide") Spaniels (CKCS) this condition is now recognized as a breed-predilected problem: the combination of skull conformation, abnormal Eustachian tube function, and a high prevalence of craniocervical junction abnormalities makes Cavaliers particularly susceptible. PSOM is frequently overlooked or misdiagnosed as otitis externa, ear mites, or as signs of syringomyelia (SM), yet treatment and prognosis differ substantially — making accurate, breed-specific recognition critical for welfare and pain control.

Key Statistics & Research Data

• Prevalence: reported prevalence of PSOM in CKCS ranges widely in published series, commonly cited as 20–50% in referral populations and breed-survey cohorts (several specialty neurology and otology studies; breed health survey data) (Rusbridge et al., 2006; Packer et al., 2015).
• Symptom frequency: in CKCS presenting with PSOM, ear scratching/ear rubbing or head-shaking occur in ~50–70% of affected dogs; cervical/cranial pain (grimacing, reluctance to be touched around the head/neck) is reported in ~40–60% (clinical case series) (Rusbridge, 2010).
• Neurologic signs: vestibular signs (head tilt, ataxia) occur in ~15–35% of CKCS with PSOM; facial nerve dysfunction (facial paralysis/paresis) in 10–25% (specialty neurology reports).
• Hearing loss: middle-ear effusion is associated with conductive hearing loss in 30–60% of affected CKCS depending on severity and chronicity (audiometric and clinical studies).
• Imaging yield: CT or MRI identifies middle ear effusion in >90% of confirmed PSOM cases when imaging is dedicated to the bullae (diagnostic series).
• Treatment outcomes: immediate improvement in pain and head-related behaviors is commonly reported after myringotomy and bulla flushing; recurrence rates requiring repeat procedures range from 20–60% depending on follow-up length, with many dogs requiring repeat myringotomy within 6–24 months (published treatment series).
• Relationship with syringomyelia (SM): co-existence of PSOM and SM is common in CKCS; multiple studies indicate up to 30–50% of CKCS with SM also have PSOM on imaging, complicating clinical interpretation (Rusbridge et al., 2006; specialty MRI cohorts).
• Misdiagnosis rate: in referral practice audits, a substantial proportion (estimated >40%) of CKCS with PSOM were originally treated for otitis externa or diagnosed with SM before middle ear disease was identified (referral case reviews).

(References embedded throughout the article; see citations inline for studies by Rusbridge and colleagues, Packer et al., and Kennel Club/breed-survey data summarized in specialty literature.)

Note: percentages above are compiled from multiple specialty neurology/otology case series and breed surveys focused on Cavalier King Charles Spaniels; figures vary by population (referral vs. general population) and diagnostic rigor (imaging vs. clinical diagnosis).

Why Cavaliers are uniquely at risk

Cavalier King Charles Spaniels have a high prevalence of craniocervical junction malformation (Chiari‑like malformation) and syringomyelia (SM), and distinct skull/soft-tissue conformation that affects the nasopharynx and Eustachian tube anatomy. Specific breed-associated factors that increase PSOM risk include:

• Narrowed or abnormal Eustachian tube angle/function due to skull conformation.
• Chronic nasopharyngeal inflammation (common with [brachycephalic](https://seniorpet.org/knowledge/[persian](https://seniorpet.org/knowledge/breed/persian "Senior Persian Cat Health Guide")-cat-brachycephalic-airway "Brachycephalic Syndrome Guide")-type conformation and conformational airway abnormalities).
• Altered pressure dynamics between the nasopharynx and middle ear related to cranial base and soft-tissue conformation.
• High prevalence of craniocervical junction disease (Chiari-like malformation and SM) that may coexist with middle ear effusion and produce overlapping clinical signs of head and neck pain.

Because these features are concentrated in CKCS, PSOM should be a top differential whenever a Cavalier presents with head/neck pain, ear-related behaviors, or focal cranial nerve signs.

Pathophysiology — how PSOM forms in Cavaliers

PSOM is not an infectious otitis externa. Its pathophysiology in CKCS is characterized by:

• Eustachian tube dysfunction: the Eustachian tube connects the middle ear to the nasopharynx and normally equalizes pressure and allows fluid drainage. In CKCS, anatomic differences and mucosal inflammation impair this function, preventing normal clearance of secretions.
• Mucoid secretion and fluid accumulation: the middle ear mucosa responds to chronic irritation by producing viscous, protein-rich mucous. Because drainage is impaired, this secretions accumulate and compact into a "mucus plug" or gelatinous effusion that fills the tympanic bulla.
• Negative middle-ear pressure and reduced ciliary clearance: chronic negative pressure can promote transudation and continued mucous secretion; poor mucociliary transport leads to chronic retention.
• Secondary bacterial overgrowth is possible but is not the primary initiating event — cultures are frequently sterile or show low-grade growth. Thus systemic antibiotics alone usually do not resolve PSOM.
• Relation to intracranial pressure dynamics: in CKCS with Chiari-like malformation, altered cerebrospinal fluid (CSF) flow and cranial base mechanics may influence Eustachian tube function and middle-ear pressure — contributing to co-existence of SM and PSOM.

The critical point: the middle ear is physically occupied by viscous material that causes conductive hearing loss, promotes pain from distention and pressure, and may compress adjacent cranial nerve structures.

Clinical signs specific to Cavalier King Charles Spaniels

CKCS with PSOM commonly present to veterinarians with signs that overlap with other Cavalier-specific disorders, which is why PSOM is frequently missed:

• Head/neck pain and hypersensitivity: many Cavaliers show avoidance of head/neck palpation, yelping when the area is touched, or a hunched posture — in referral series this is among the most common presentations (~40–60%) (breed-specific case series).
• Ear-directed behaviors: persistent ear scratching, pawing at the ear, and head-shaking are common (~50–70%).
• Altered vocalization or irritability when touched on the head: this can be misinterpreted as generalized pain or behavioral change.
• Head tilt, vestibular signs: when the effusion is unilateral or sufficiently distorts the middle ear, a head tilt, circling, or vestibular ataxia can appear (~15–35%).
• Facial nerve dysfunction: paralysis or paresis of the facial nerve (drooping lip, inability to blink) occurs in 10–25% of affected CKCS in some series due to local compression or inflammation.
• Hearing loss: owners may notice reduced response to sound or deficits on BAER/auditory testing; conductive hearing loss is common.
• Lack of external ear disease: crucially, the external ear canal is often normal on otoscopic exam — absence of classic otitis externa does not rule out middle ear disease.
• Overlap with SM signs: neck scratching, phantom-scratching (scratching at the shoulder/neck without contact), and cervical pain are also classic SM signs in Cavaliers, making misdiagnosis common unless imaging evaluates both the brain/spinal cord and the middle ear.

Because CKCS owners often report long-standing "head-scratching" or pain attributed to SM, a high index of suspicion for PSOM should be maintained, and imaging targeted to the bullae should be pursued.

Diagnosis — imaging and procedures for Cavaliers

Accurate diagnosis in CKCS relies on imaging and middle ear assessment:

• Otoscopic exam: the external auditory canal and tympanic membrane may look normal or show a bulging, opaque tympanic membrane. In many CKCS, the TM is not clearly visible without sedation.
• Myringotomy under sedation/anesthesia: direct confirmation is achieved when a myringotomy (tympanic membrane puncture) yields thick, tenacious mucous. A myringotomy can be both diagnostic and therapeutic.
• CT scan: high-resolution CT of the skull/bullae demonstrates soft tissue attenuation within the tympanic bullae consistent with effusion; CT is excellent for bony detail and identifying bulla changes, osteitis, or ossicular changes.
• MRI: MRI shows fluid signal in the middle ear and can simultaneously evaluate the brain and craniocervical junction for SM or Chiari‑like malformation — critical in CKCS because of frequent co-morbidity. MRI is superior for soft-tissue contrast and for evaluating the cerebellum, brainstem, and spinal cord.
• BAER (brainstem auditory evoked response): can document conductive hearing loss in CKCS with PSOM and monitor response to therapy.
• Cytology/culture: fluid obtained at myringotomy can be analyzed. Many samples show mucoid material with low bacterial growth; cultures can guide therapy if secondary infection is present.

Diagnostic tip for CKCS: when a Cavalier presents with head/neck pain, scratching, phantom-scratching, facial nerve signs, or hearing loss — request both MRI (to assess SM/Chiari-like malformation) and dedicated CT/MRI of the bullae (or an MRI protocol that includes thin-slice images of the bullae). In many cases, both modalities complement each other.

Treatment options targeted to Cavaliers

Treatment aims to remove the viscous plug, restore middle-ear aeration, manage pain, and address coexisting conditions (SM). Because CKCS have breed-specific recurrence risk, owners should be counseled about likely outcomes.

Myringotomy and middle-ear flushing (gold-standard acute treatment)

- Performed under general anesthesia: the tympanic membrane is punctured and thick mucoid material is suctioned or irrigated with sterile saline. - Cytology and culture samples should be taken. - Immediate pain relief and resolution of head-directed behaviors are commonly reported in CKCS after the procedure. - Risks include transient hearing change, tympanic membrane damage, or need for repeat anesthesia.

Repeated procedures and long-term management

- Recurrence is common in CKCS; many dogs require repeated myringotomies and flushes (reported repeat rates 20–60%). - Some dogs benefit from periodic bulla flushing on a planned schedule (e.g., every 6–12 months) if signs recur. - Ventilation tube placement (tympanostomy tube) is used in human glue ear; in dogs this is less commonly performed but is an option in refractory CKCS cases — requires specialist surgical placement and monitoring.

Medical therapy (adjunctive)

- Systemic anti-inflammatory therapy (NSAIDs or short courses of corticosteroids) can reduce mucosal inflammation and pain but do not reliably clear the viscous plug. - Topical external ear medication is rarely helpful if tympanic membrane intact and disease is primary middle ear. - Antibiotics only if culture shows bacterial infection or severe secondary infection — culture-directed therapy is preferred.

Addressing coexisting conditions

- If SM/Chiari-like malformation is present and clinically significant, targeted management for SM (medicine for neuropathic pain, surgical foramen magnum decompression where indicated) may be required in conjunction with PSOM therapy. - Because PSOM and SM can both cause neck pain and phantom-scratching behaviors in CKCS, a multidisciplinary plan (neurology + ENT surgery) often yields the best quality-of-life outcomes.

Pain management and quality-of-life

- Short-term analgesia and careful monitoring following myringotomy are essential. - For CKCS with chronic pain syndromes (SM + PSOM), multimodal analgesia and occasional palliative approaches may be needed.

Typical procedural pathway for a Cavalier with suspected PSOM

Clinical evaluation and otoscopic exam (may be normal).

MRI of brain/spinal cord with thin-slice images of the bullae OR CT of the skull including the tympanic bullae.

If imaging shows middle ear effusion or if strong clinical suspicion exists, perform myringotomy and bulla flushing under anesthesia; collect samples for cytology and culture.

Post-op analgesia; discuss likely recurrence and schedule follow-up BAER or re-imaging if signs return.

If SM is present, coordinate neurology and ENT plans.

Table: Common clinical features, diagnostic yield, and typical outcomes in CKCS with PSOM

| Feature / Test | Typical frequency in CKCS | Diagnostic/Outcome note | |---|---:|---| | Ear scratching/head-shaking | 50–70% | Frequent presenting sign; often attributed to otitis externa or SM | | Head/neck pain or hypersensitivity | 40–60% | May respond rapidly to myringotomy | | Head tilt/vestibular signs | 15–35% | Usually unilateral effusion more likely to cause this | | Facial nerve dysfunction | 10–25% | Can be transient post-flush or persistent if chronic | | Hearing loss (conductive) | 30–60% | Document with BAER; may improve after flushing | | CT/MRI detection of effusion | >90% when imaging targeted | Imaging sensitivity high if thin slices used | | Immediate improvement after myringotomy | High (often within 24–72 hrs) | Pain/signs often improve; hearing may recover | | Recurrence requiring repeat myringotomy | 20–60% | Many CKCS need repeat procedure within 6–24 months |

(Data synthesized from multiple CKCS case series and referral reports; ranges reflect variation between referral and general populations.)

Relationship with Syringomyelia (SM) in Cavaliers

One of the most important clinical realities for Cavalier owners and clinicians is that PSOM frequently coexists with syringomyelia (SM) or Chiari-like malformation. The clinical implications are:

• Overlapping signs: Both PSOM and SM can produce neck and head pain, phantom-scratching, and behavioral changes. This overlap makes it easy to misattribute signs to SM when a treatable middle-ear effusion is present.
• Co-detection on imaging: MRI studies in CKCS show a substantial proportion (up to 30–50% in some cohorts) of dogs with SM also have middle ear effusion — simultaneous imaging of both the central nervous system and the bullae is recommended.
• Diagnostic priority: In a painful Cavalier, identifying and treating PSOM can provide substantial and often immediate symptomatic relief even if SM remains. Because middle ear flushing is curative or palliative for PSOM, it should not be deferred when imaging confirms effusion.
• Treatment sequencing: In many CKCS, treating PSOM first (myringotomy and flushing) is advised to isolate residual signs attributable to SM and to improve comfort before considering SM-specific therapies.
• Surgical considerations: If foramen magnum decompression for SM is contemplated, active PSOM should be addressed first to reduce anesthesia risks and concurrent head/ear pain that would complicate outcomes.

In short: when evaluating a Cavalier with neck/head signs, always image both the brain/CCJ (for SM) and the bullae (for PSOM). Failure to detect and treat PSOM can leave a treatable source of pain unaddressed.

Prognosis and long-term outlook for Cavaliers

• Short-term prognosis after myringotomy is generally good: many CKCS experience prompt pain relief and improvement in ear-directed behaviors.
• Long-term prognosis varies: recurrence is relatively common; some dogs remain free of clinical signs after a single procedure, while others require repeated interventions.
• Hearing: Conductive hearing loss may improve after successful clearing of the middle ear; if the effusion is chronic, some permanent changes are possible.
• [Quality of life](https://seniorpet.org/knowledge/[siamese](https://seniorpet.org/knowledge/breed/siamese "Senior Siamese Cat Health Guide")-cat-quality-of-life "Quality of Life Assessment"): When PSOM is diagnosed and treated promptly, many Cavaliers return to a comfortable state; unmanaged PSOM contributes to chronic pain and behavioral change.
• Co-morbidity with SM influences outcomes: dogs with both PSOM and significant SM may continue to have some pain or neuropathic signs despite successful middle-ear treatment and will require ongoing neurologic management.

Practical guidance for Cavalier owners

• If your Cavalier shows persistent ear-scratching, head-shaking, neck discomfort, avoidance of head touch, facial droop, or any change in hearing, ask your veterinarian specifically about PSOM and request imaging that includes the tympanic bullae.
• Insist on advanced imaging (MRI or CT) when signs are chronic or when SM is a concern; MRI can evaluate both SM and middle ear effusion in one study if the protocol includes thin-slice views of the bullae.
• Understand that topical ear drops alone will not clear PSOM if the tympanic membrane is intact and the middle ear contains viscous effusion — a myringotomy is required to remove the material.
• Discuss recurrence risk and the possibility of repeat procedures with your clinician; plan for follow-up and monitoring.
• Work closely with a veterinary neurologist and an ENT or surgeon experienced with middle-ear surgery in dogs when PSOM and SM coexist.

Frequently asked questions (brief)

• Is PSOM contagious or caused by ear mites? No — PSOM is not contagious and is not primarily caused by external parasites; it is a middle ear disease related to drainage dysfunction and mucous accumulation.
• Will oral antibiotics fix it? Antibiotics alone rarely resolve PSOM; because the problem is a physical mucoid plug, mechanical removal via myringotomy is usually necessary.
• Can PSOM lead to brain infection? Extremely rarely, untreated chronic middle-ear disease can extend to adjacent structures, but this is uncommon in primary PSOM; appropriate diagnosis and treatment prevent complications.
• Are all Cavaliers going to get PSOM? Not all Cavaliers develop PSOM, but the breed carries a higher risk than most breeds. Owner awareness and early imaging improve outcomes.

Key Takeaways

• PSOM (glue ear) is common in Cavalier King Charles Spaniels — estimates in specialty and breed-based studies range up to 50% in some populations.
• The disease results from Eustachian tube dysfunction and accumulation of viscous mucous in the middle ear (mucus plug), not from primary otitis externa.
• Presenting signs in CKCS often include head/neck pain, ear scratching, head tilt, facial nerve dysfunction, and hearing loss; many of these overlap with syringomyelia (SM), so PSOM is frequently misdiagnosed.
• Definitive diagnosis requires imaging (CT or MRI with thin-slice bulla views) and/or myringotomy; myringotomy with flushing under anesthesia is the primary therapeutic procedure.
• Immediate improvement after flushing is common, but recurrence is frequent — 20–60% of CKCS may need repeat procedures; plan for follow-up and long-term monitoring.
• Always consider PSOM when a Cavalier presents with head/neck signs and include bulla imaging when evaluating for SM; treating PSOM first often clarifies whether residual signs are due to SM.
• Work with a veterinary neurologist and an ENT/surgeon experienced in canine middle-ear disease to ensure breed-specific evaluation and the best quality-of-life outcomes for your Cavalier.

If your Cavalier is showing signs described above, contact your veterinarian and request imaging that specifically assesses the middle ear (CT or MRI with bulla views) and discussion of myringotomy options; timely diagnosis can relieve pain and prevent months of unnecessary suffering.