From recurrence to relief: managing canine otitis externa

Cookie's ear infection; inflammation and excessive cerumen from CAFR in Cookie’s ear prior to hydrolyzed protein diet trial. Photo courtesy of Dr. Brittany Lancellotti Cookie, a spirited three-year-old Labrador retriever, was the picture of health—except for her ears. Repeated bouts of otitis externa (OE) plagued and frustrated her and her owner. Despite multiple treatments, the infections returned. A thorough workup revealed canine adverse food reaction (CAFR) as the primary cause. By implementing a prescription hydrolyzed protein elimination diet, Cookie’s OE was controlled, and relapses were prevented. Her owner was taught how to perform individual ingredient challenges and address flares. Her case exemplifies how addressing underlying causes can transform the prognosis for pets suffering from OE. Otitis externa is inflammation of the ear canal, often accompanied by secondary bacterial or yeast infections. It is a common reason for pet owners to seek veterinary care. Although infections may resolve with treatment, recurrences are frequent if underlying causes are not addressed. Over time, inflammation can cause chronic, irreversible changes, making management increasingly difficult. Ear mass otitis externa severe – A large ear mass causing chronic OE in an older dog. Photo courtesy Dr. Brittany Lancellotti Understanding the primary, secondary, perpetuating, and predisposing (PSPP) factors is essential for creating an effective treatment plan.1-4 A large ceruminolith lodged in a horizontal canal of a dog with chronic otitis externa and excessive glandular production. Photo courtesy Dr. Brittany Lancellotti The PSPP framework The PSPP classification system breaks down the contributing factors of OE into four categories: 1) Primary causes are the triggers of disease in a previously healthy ear. Hypersensitivity disorders, such as environmental allergies, CAFR, and insect bite hypersensitivity, are the most common primary factors in dogs.5 CAFR is particularly significant, as up to 40 percent of dogs with CAFR develop OE before they are a year of age, emphasizing the need for a well-performed elimination diet trial in any young dog with more than one episode of OE.6 Erythema, hyperpigmentation, and scaling from chronic OE in a dog with allergic dermatitis. Photo courtesy Dr. Brittany Lancellotti Severe crusting of pinnal margins secondary to Sarcoptes scabiei mites. Photo courtesy Dr. Brittany Lancellotti Addressing primary factors requires a thorough diagnostic approach. For CAFR, elimination diet trials remain the gold standard, as serum tests lack reliability.7 Environmental allergies, or canine atopic dermatitis (cAD), typically present between one to three years of age and is a diagnosis of exclusion.8 cAD can be managed with allergen-specific immunotherapy for long-term control, which desensitizes animals to environmental triggers, reducing frequency and severity of flares in 60 to 70 percent of patients, leading to complete remission of disease in some pets.9,10 Endocrine diseases such as hypothyroidism and hyperadrenocorticism disrupt normal ear canal function and lower immune protection.8 Other primary causes may include foreign objects, such as grass awns, autoimmune diseases (sebaceous adenitis, pemphigus foliaceous), masses (benign or malignant), parasites (otodectes, demodex), and keratinization disorders.11 Foxtails (grass awns) removed from an ear with painful OE. Photo courtesy Dr. Brittany Lancellotti 2) Secondary infections occur when bacteria and/or yeast worsen ear disease in an already abnormal ear. Cytology is essential to identify infections, guide appropriate antimicrobial therapy, and evaluate treatment response.5,12 Common culprits include Staphylococcus, Malassezia, and Pseudomonas species. Topical antimicrobials are preferred over systemics for treating secondary infection because their high local concentrations can overcome resistance patterns observed in culture and susceptibility tests.5 The use of culture and susceptibility testing for secondary infections is of limited benefit in the management of OE.5 An ear canal is lined with mucoid biofilm in a dog with Pseudomonas OE. Photo courtesy Dr. Brittany Lancellotti 3) Chronic inflammation and other perpetuating factors can lead to significant and sometimes irreversible anatomical changes, such as stenosis, calcification, excessive cerumen, glandular hyperplasia, otitis media (OM) or biofilm. Biofilms, particularly from Pseudomonas, significantly impair the efficacy of antimicrobials.13 Treatments such as N-acetylcysteine, chlorhexidine, and hypochlorous acid have shown promise in addressing biofilms, but the gold standard remains thorough cleaning under anesthesia for physical removal of biofilm.5 Ceruminous gland hyperplasia in a cocker spaniel with chronic OE. Photo courtesy Dr. Brittany Lancellotti A cocker spaniel with severe, proliferative ceruminous OE secondary to hypothyroidism. Photo courtesy Dr. Brittany Lancellotti 4) Predisposing factors increase the likelihood of OE without directly causing disease. Breeds with pendulous ears, such as cocker spaniels, or narrowed horizontal canals, such as brachycephalic dogs, are at higher risk of more frequent or severe infections if they have a primary disease. Environmental factors, like swimming or over-cleaning, can also predispose dogs to recurrent infections from excessive moisture. An inflammatory polyp filling the horizontal canal of a French Bulldog with chronic OE. Photo courtesy Dr. Brittany Lancellotti A horizontal ear canal with significant narrowing due to the brachycephalic anatomy of a French bulldog. Photo courtesy Dr. Brittany Lancellotti Owners should be educated on mitigating risks through preventive care and proper cleaning techniques. Excessive hair can trap exudate. Caution should be used when plucking hair, because inflammation from traumatic removal can increase risk of infection. When necessary to resolve infection, hair removal should be done with appropriate analgesics and anti-inflammatories. Cerumenolytic cleaners help minimize exudate trapped within hirsute ears rather than risking inflammation by plucking for long-term maintenance. Copious hair and tricholith in a labradoodle with relapsing OE. Photo courtesy Dr. Brittany Lancellotti Diagnostics: the foundation for treatment A comprehensive diagnostic workup is essential to identify PSPP factors. History should cover duration, seasonality, and associated systemic problems. Physical examination should include otoscopy to assess the canal, tympanic membrane (TM), and the presence of foreign objects or masses. In brachycephalics with narrow horizontal canals, seeing the TM is difficult. In a study of 75 client-owned French bulldogs and pugs, only five of 150 ears evaluated had visible TMs during awake otoscopic examination using a video otoscope.13 Other areas commonly affected by allergic dermatitis and endocrinopathies, including paws/claws, axillae, inguinal skin, and lip/facial/perivulvar/tail folds should be evaluated to help identify primary causes. Additional diagnostics, such as hormone testing, anesthetic video otoscopy, and imaging, may be needed in chronic or refractory cases. General anesthesia should be considered when there is concern about a foreign object (e.g., grass lawn), mass (e.g., soft tissue, ceruminolith, tricholith), otitis media, biofilm production, or ongoing infection despite appropriate antimicrobial and anti-inflammatory treatment. Myringotomy through a video otoscope is indicated when there is an abnormal appearance of the TM on otoscopic examination or the middle ear on advanced imaging, with or without clinical signs of OM or interna.14 A multifaceted approach to treatment Managing inflammation: Glucocorticoids are highly effective for reducing inflammation and reversing chronic changes. Topical formulations are suitable for mild cases, while systemic steroids may be needed for severe disease.5 For long-term management, alternatives such as modified cyclosporine provide steroid-sparing benefits for severe, proliferative OE.5,10 For ears that are erythematous but less edematous, Janus Kinase inhibitors like oclacitinib or ilunocitinib, can be considered due to less anti-inflammatory action of these medications.10 Lokivetmab is antipruritic only and will not decrease inflammation associated with OE. Controlling secondary infections: Topical antimicrobials should be selected based on cytology. For topical antibiotics, the European Medicines Agency recommends fusidic acid be used with prudence, aminoglycosides and florfenicol be used with caution, and fluoroquinolones and polymixin B be restricted.5 Antifungals including azole (e,g., clotrimazole, miconazole, or posaconazole), allylamine (terbinafine), and polyene (nystatin) classes are usually effective in Malassezia otitis.5 Fluoroquinolones and aminoglycosides, such as gentamicin and polymyxin B, are often recommended for Pseudomonas, as indicated by rods on cytology.15 Addressing perpetuating factors: Perpetuating factors may require long-term maintenance cleaning, antiinflammatory therapy, and advanced interventions. Video otoscopy allows for deep cleaning and removing foreign objects, masses, and tenacious debris. Surgical options, such as total ear canal ablation, should be reserved for end-stage disease, only after referral to a veterinary dermatologist.5 Above: A French bulldog with chronic, proliferative OE and multiple perpetuating factors including excessive cerumen, glandular hyperplasia, and edema. Below: The same French bulldog after 3 weeks of glucocorticoids and 6 weeks of modified cyclosporine to reverse the severe inflammatory changes. Photos courtesy Dr. Brittany Lancellotti Preventing relapses: client education Owner adherence is critical to preventing relapses. Teaching proper ear-cleaning techniques and recommending appropriate cleaners can make a significant difference. Cerumenolytic agents are ideal for emulsifying wax, while drying agents help prevent infections in dogs whose ears are sensitive to moisture after bathing or swimming.11 Behavioral techniques, including cooperative care training, can improve the pet’s tolerance for ear treatments. Tools such as positive reinforcement, anxiolytics, and demonstrations can empower owners to maintain their pet’s ear health at home. Conclusion Cookie’s story underscores the importance of addressing primary factors early. By identifying and managing her CAFR with a hydrolyzed protein diet, her owners spared her years of discomfort. This proactive approach exemplifies the value of a thorough diagnostic process and individualized care. Chronic proliferative OE in an older Yorkshire terrier with hyperadrenocorticism that was reversed with treatment of HAC and use of modified cyclosporine to reverse end stage ear disease. Photo courtesy Dr. Brittany Lancellotti Otitis externa is a multifaceted condition requiring a holistic approach to diagnosis and management. By understanding PSPP, veterinarians can create targeted plans that address underlying causes and prevent relapses. Cookie’s journey serves as a reminder of the profound impact early intervention and client education have on quality of life. Brittany Lancellotti, DVM, DACVD, is the founder and host of Your Vet Wants You to Know, practices at Veterinary Skin and Ear in Los Angeles, and is Fear Free certified. She graduated with honors from WesternU and enjoys teaching nationally, internationally, and virtually. Client education tools, such as the Your Vet Wants You to Know podcast, can provide owners with more information on OE (episodes 44, 45), CAFR (episode 2), diet trials (episode 17), video otoscopy (episode 48), and cooperative care for ear cleaning (episode 56). Looking for more dermatology insights? Dr. Lancellotti will be speaking on the latest anti-pruritic/inflammatory therapies for allergies at 2025 VMX: Session Title: Shake it Off! – Relief from Otitis Externa Tuesday, Jan 28, 1:40 pm, Location S320E Acute, painful ear infections are common and stressful for pet owners, and chronic, relapsing otitis externa is frustrating for owners and the veterinary team. This discussion will review where many of these frustrations stem from and provide helpful tools for relief, such as Fear Free techniques and communication tools. Addressing and preventing relapse of otitis externa involves a thorough understanding of Primary causes of otitis externa, common Secondary infections and sampling techniques, Perpetuating factors that occur with chronicity which make resolution of infection more challenging, and Predisposing issues that put animals with primary diseases at a higher risk of relapse. Treatments for allergic dermatitis, a common primary trigger for otitis externa, will be discussed to help select the most effective therapy while minimizing risks. References Koch S. The challenge of chronic otitis in dogs: from diagnosis to treatment. Today’s Veterinary Practice. April 14, 2017. Bajwa J. Canine otitis externa - treatment & complications. Can Vet J. 2019;60(1):97-99. Saridomichelakis MN et al. Aetiology of canine otitis externa: a retrospective study of 100 cases. Vet Dermatol. 2007;18(5):341-347. O’Neil DG et al. Frequency and predisposing factors for canine otitis externa in the UK - a primary veterinary care epidemiological view. Canine Med Genet. 2021;8(1):7. Nuttall T. Managing recurrent otitis externa in dogs: what have we learned and what can we do better? JAVMA.2023;261(S1):S10-S22. Olivry T, Mueller RS. Critically appraised topic on adverse food reactions of companion animals (7): signalment and cutaneous manifestations of dogs and cats with adverse food reactions. BMC Vet Res. 2019;15 Mueller RS, Olivry T. Critically appraised topic on adverse food reactions of companion animals (4): can we diagnose adverse food reactions in dogs and cats with in vivo or in vitro tests? BMC Vet Res. 2017;13(1):275. Hensel P et al. Canine atopic dermatitis: detailed guidelines for diagnosis and allergen identification. BMC Vet Res. 2015;11(1): Olivry T et al; International Committee on Allergic Diseases of Animals. Treatment of canine atopic dermatitis: 2015 updated guidelines from the International Committee on Allergic Diseases of Animals (ICADA). BMC Vet Res. 2015;11:210. Outerbridge CA, Jordan TJM. Current knowledge on canine atopic dermatitis: pathogenesis and treatment. Adv Small Anim Care. 2021;2:101-115. Miller WH Jr et al. Muller & Kirk’s Small Animal Dermatology. 7th ed. Saunders; 2012 Choi N et al. Comparison of two ear cytological collection techniques in dogs with otitis externa. Vet Dermatol. 2018;29(5):413-e136. Töpfer T et al. Brachycephaly in French bulldogs and pugs is associated with narrow ear canals. Vet Dermatol. 2022;33(3):214. Cole L, Nuttall T. Clinical techniques: when and how to do a myringotomy - a practical guide. Vet Dermatol. 2021;32(3):302-e82. Chan WY et at. Biofilm production by pathogens associated with canine otitis externa, and the antibiofilm activity of ionophores and antimicrobial adjuvants. J Vet Pharmacol Ther. 2019;42(6):682-692. Bailey, SS, Atterbury, RA. Pseudomonas Spp. in Canine Otitis Externa. Microorganisms. 2023;11 (11): 2650. Paterson S. Topical ear treatment—options, indications and limitations of current therapy. J Small Anim Pract.2016;57(12):668-678.

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From recurrence to relief: managing canine otitis externa

A comprehensive guide of what to look for and what to do for this doggedly persistent condition.

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