Preventive ear care for dogs and cats

Prevention of ear disease in dogs and cats depends on early detection of factors that predispose these animals to otitis externa. This article reviews the conditions and diseases that place the dog and cat at risk for otitis externa. Routine care of the ears is discussed, and otoscopic examination and techniques for cleaning the external auditory canals are described. Avoidance of potentially harmful therapeutic procedures and irritating or ototoxic pharmacologic substances is emphasized.     

Efficacy of boric-complexed zinc and acetic-complexed zinc otic preparations for canine yeast otitis externa

The purpose of this 2-week, double-blinded, controlled clinical trial was to evaluate the efficacy of topical amino acid-complexed zinc gluconate formulated with boric acid (ZGB) or acetic acid (ZGA) versus a topical placebo in the treatment of yeast otitis externa in dogs. Included in the study were dogs with otitis externa and a cytopathological finding of yeast organisms in the affected ear. Ears were treated with the placebo, ZGA, or ZGB medications. Yeast counts as well as clinical appearance of the ears were monitored. Results revealed that ZGB significantly reduced the number of yeast organisms in cases of otitis externa.     

Proliferative and necrotizing otitis externa in four cats

Proliferative and necrotizing feline otitis externa is a rare disorder of unknown aetiology. This condition was diagnosed by skin biopsy in three adult domestic shorthair cats (3-5 years old) and one kitten (6 months old). The affected cats had large tan to dark brown-black coalescing plaques covering the concave surface of the pinnae and external ear canals. Friable material from the plaques and a thick exudate occluded the ear canals. The cats had a secondary bacterial and/or yeast otitis. Prior to the histopathological diagnosis, all cats received numerous otic preparations as well as oral antibiotics and corticosteroids without resolution. Histologically, all cases had strikingly similar changes; acanthosis with pronounced hair follicle outer root sheath hyperplasia and neutrophilic luminal folliculitis, follicular keratosis and individually necrotic keratinocytes in the outer root sheath of hair follicles. One case was documented via skin biopsy to have persisted for 4 years. The adult cats were treated with topical 0.1% tacrolimus and all showed marked improvement although one cat was lost to follow up. The lesions completely resolved with topical tacrolimus alone in one cat and topical tacrolimus in addition to oral prednisolone in another cat.     

The pathology of the external ear canal in dogs and cats

A survey of factors which predispose the canine ear to otitis externa is presented. In resected ear specimens of 106 dogs, otitis externa without tumour was found on 58 occasions. In 46 dogs tumours were diagnosed in 15 cases with an otitis externa. In two dogs an inflammatory polyp was found. In the resected ear specimens of 48 cats, otitis externa was diagnosed 27 times, in 6 cases combined with an inflammatory polyp. In 21 cases neoplasia was present. The otitis externa was mainly a chronic proliferative inflammation characterised by hyperkeratinization, hyperplasia of the sebaceous and ceruminous glands, fibrosis and infiltration with plasma cells, lymphocytes and macrophages, often containing ceroid pigment.     

The pathology of the external ear canal in dogs and cats

Summary

A survey of factors which predispose the canine ear to otitis externa is presented In restected ear specimens of 106 dogs, otitis externa without tumour was found on 58 occasions. In 46 dogs tumours were diagnosed in 15 cases with an ototis externa. In two dogs an inflammatory polyp was found.

In the resected ear specimens of 48 cats, otitis externa was diagnosed 27 times, in 6 cases combined with an inflammatory polyp. In 21 cases neoplasia was present.

The otitis externa was mainly a chronic proliferative inflammation characterised by hyperkeratinisation, hyperplasia of the sebaceous and ceruminous glands, fibrosis and infiltration with plasma cells, lymphocytes and macrophages, often containing ceroid pigment.     

Evaluation of an ear cleanser for the treatment of infectious otitis externa in dogs

Thirty-one ears (16 dogs) with otitis externa originating from bacterial or yeast infections were enrolled in a study to evaluate the in vivo efficacy of an ear cleanser containing 2.5% lactic acid and 0.1% salicylic acid for the treatment of infectious otitis externa. The affected ears were treated with the ear cleanser twice daily for 2 weeks and evaluated after 1 and 2 weeks of treatment. The ear cleanser was effective in resolution of infection in 67.7% of the ears, and clinical signs of infectious otitis externa were significantly reduced within 2 weeks.     

Identification and antimicrobial susceptibility of bacteria and yeasts isolated from healthy dogs and dogs with otitis externa

The bacterial and fungal flora of the external ear canal of dogs with otitis externa and of healthy dogs were studied. The most frequently isolated microorganism from otitic ears was Staphylococcus intermedius (58.8%), followed by Malassezia pachydermatis (30.9%), Streptococcus canis (29.9%), Proteus spp. (14.4%) and Escherichia coli (10.3%). A statistical analysis of our results showed that the prevalence of these microorganisms is significant in dogs with otitis externa. Furthermore, the antimicrobial susceptibility patterns of isolated strains were determined. Majority of all bacterial isolates were most susceptible to gentamicin. Malassezia pachydermatis, the most prevalent yeast in this study, showed an excellent level of susceptibility to all antifungal agents tested.     

Chronic Otitis Externa and Otitis Media Treated by Total Ear Canal Ablation and Ventral Bulla Osteotomy in Thirteen Dogs

Ventral bulla osteotomy was combined with total ear canal ablation for the treatment of chronic otitis externa and otitis media in 13 dogs (14 ears) that had been refractory to medical and surgical treatments. Resolution of disease occurred in 11 dogs (12 ears). One dog with unilateral disease underwent a second operation before achieving a good result. One dog was euthanatized for persistent unilateral disease after three surgical procedures. The recurrence of disease in these two dogs (15%) was associated with remnants of ear canal integument within the osseous horizontal canal or tympanic bulla. Facial paralysis occurred in four dogs (31%) and there were no complications in eight dogs (62%). This technique shows no advantage over lateral bulla osteotomy combined with total ear canal ablation for the treatment of chronic otitis externa and otitis media.     

Subtotal ear canal ablation in 18 dogs and one cat with minimal distal ear canal pathology

A modified technique for performing total ear canal ablations is described. This technique requires less dissection than the standard technique and maintains a portion of the distal vertical ear canal. Subtotal ear canal ablations were performed in 18 dogs and one cat for the treatment of otitis externa or masses of the horizontal ear canal. Animals with otitis externa had minimal involvement of the distal ear canal. Dermatological problems associated with the remaining ear canal and pinnae occurred in eight animals and resolved with medical management. Normal ear carriage was maintained in all animals with erect ears. Further investigation is required before the procedure can be recommended as a treatment for otitis externa not caused by masses or anatomical abnormalities of the horizontal ear canal in dogs with pendulous ears.     

The association of Pityrosporum pachydermatis with the normal external ear canal of dogs and cats

The frequency of Pityrosporum pachydermatis within the non-otitic external ear canals of dogs and cats has been investigated and an assessment of the abundance of the yeast made by microscopic and cultural techniques. It was present in varying amounts in 49% of clean dog ears and 23% of clean cat ears. Microscopically, 14% of the ears were found to contain the yeast in large numbers. A further 3 % of ears examined showed excessive cerumen production and all these contained the yeast.
The prevalence of P. pachydermatis in non-otitic ears of both dogs and cats was similar to that previously reported in otitic ears.     

Diagnosis and medical treatment of otitis externa in dogs and cats

A review of otitis externa in dogs and cats is presented. Aetiology, includes primary causes: ectoparasitoses, allergic diseases, endocrine disorders, pyodermas, trauma and irritation, contact dermatitis, auto-immune skin diseases, drug eruption, keratoseborrhoeic skin disease, tumours and pseudoneoplastic lesions, as well as secondary causes: bacteria and yeasts. Clinical aspects are variable but a practical classification distinguishes two forms: erythematoceruminous otitis externa and suppurative otitis externa. Diagnosis is made in five steps which are clinical examination, direct examination of cerumen (erythematoceruminous otitis externa) or bacterial culture and sensitivity testing (suppurative otitis externa), direct impression smears, cleaning and otoscopy, and diagnosis of underlying skin disease. Medical therapy includes cleaning of the external ear canal and local therapy (acaricides, antifungal agents, antibiotics, corticosteroids, other topical agents, the appropriate selection of an optic preparation being essential). Treatment of underlying skin disease is always necessary. Otitis externa is in fact a dermatological disease complex (like pododermatitis). Although local secondary infections (bacterial and fungal) must be managed in every case, there are grounds for including otitis externa in a larger frame.     

Inflammatory polyps of the middle ear in 5 dogs

OBJECTIVE: To describe inflammatory polyps of the middle ear in 5 dogs. STUDY DESIGN: Case series. ANIMALS: Five dogs with ear disease. METHODS: Medical records (1995-2001) were reviewed to identify dogs with inflammatory polyps of the middle ear. Signalment, clinical signs, ancillary diagnostic procedures, treatment, postoperative complications, and outcome were recorded. Owners and referring veterinarians were contacted to document outcome. RESULTS: Dogs with inflammatory polyps of the middle ear were male and aged 4 to 13 years. Two dogs had bilateral polyps, whereas 3 had unilateral polyps. The most common clinical presentation was otitis externa and media, with radiographic evidence of otitis media. Polyps were treated by ventral bulla osteotomy (VBO) in 1 dog and total ear canal ablation with lateral bulla osteotomy (TECA-LBO) in 4 dogs. Polyps consisted of a fibrovascular stroma infiltrated with neutrophils, macrophages, lymphocytes, and plasma cells. The overlying epithelium was frequently ulcerated. Immediate postoperative complications included a seroma after VBO (1 dog) and transient unilateral facial nerve paralysis after bilateral TECA-LBO (1 dog). No recurrence occurred within 9 to 69 months. CONCLUSIONS: Unilateral or bilateral, inflammatory polyps can occur in the middle ear of dogs in association with otitis externa and media. No recurrence occurred after surgical removal of the polyps. CLINICAL RELEVANCE: Inflammatory polyps of the middle ear in dogs can be a cause of otitis externa/media. Surgical removal of aural polyps has a good prognosis.     

Surgical management of 43 cases of chronic otitis externa in the dog

: Over a seven-year period, chronic otitis externa was surgically managed in 43 dogs at the University Veterinary Hospital of University College Dublin. Lateral ear canal resection (LECR) was undertaken in nine of the 43 dogs: results were unsatisfactory, with a failure of the surgery in five of eight dogs and one dog lost to follow-up. Once end-stage otitis externa, with or without otitis media, is diagnosed, total ear canal ablation and lateral bulla osteotomy (TECA/LBO) is the best treatment option. In this series, 37 of 43 dogs underwent TECA/LBO and of the 29 dogs for which follow-up results were obtained 27 (93%) had an excellent or improved outcome to surgery. Complications following all procedures were most common in cases with a concurrent dermatopathy; therefore, definitive diagnosis and medical treatment for skin and ear disease is essential.     

Morphologic measurements of the external horizontal ear canal of dogs

Microscopic anatomy of the horizontal part of the external ear canal was evaluated in 24 dogs. Sixteen dogs were from breeds known to have a predisposition to otitis externa. The remaining 8 dogs were from breeds that do not have a predisposition to otitis externa. Dogs were separated into groups according to predisposition to otitis externa: group 1-predisposed dogs without otic inflammation, group 2-predisposed dogs with otic inflammation, and group 3-nonpredisposed dogs without otic inflammation. Qualitative microscopic evaluation of distribution of hair follicles revealed hair within proximal, middle, and distal regions of the horizontal ear canal in all breeds. The degree of keratinization was directly proportional to the presence of otic inflammation and was excessive in group-2 dogs. Quality of sebaceous glands within the horizontal ear canal was similar among dogs with and without otitis externa, whereas the quantity of apocrine tubular glands was significantly increased (P less than 0.05) in dogs with otitis. Quantity of apocrine tubular glands was also greater in group-1 dogs than in group-3 dogs. Thickness of the soft tissue in the external ear canal increased in direct proportion to the progression of disease and was greatest in the proximal region of the affected ear canal. Soft tissue located caudally between nonopposing ends of the annular cartilage, within the proximal region of the horizontal ear canal, contained few glands and hair follicles in dogs without otitis externa. In dogs with otitis externa, this region was infiltrated by distended apocrine tubular glands.     

Use of ImageJ software for histomorphometric evaluation of normal and severely affected canine ear canals

Morphological studies comparing normal and diseased ear canals use primarily subjective scoring. The aim of this study was to compare normal and severely affected ears in dogs with objective measurements using ImageJ software. Ear canals were harvested from cadavers with normal ears and from dogs that underwent total ear canal ablation for unresolved otitis. Histopathology samples from ear canals were evaluated by semi-quantitative scoring and also by using ImageJ-software for histomorphometric measurements. The normal ears were compared to the severely affected ears using the 2 methods. The 2 methods were significantly (P < 0.0001) correlated for epidermal hyperplasia, ceruminous gland dilation, and hyperplasia and tissue inflammation, which were significantly greater in the severely affected ears (P < 0.0001). This study demonstrated that there is a very high correlation between the 2 methods for the most markedly affected components of otitis externa and that ImageJ software can be efficiently used to measure and evaluate ear canal histomorphometry.     

The efficacy of an antiseptic and microbial anti-adhesive ear cleanser in dogs with otitis externa

A new antimicrobial ear cleanser was evaluated for the treatment of bacterial and yeast ear infection in dogs. Forty-five dogs with erythemato-ceruminous or purulent otitis externa were randomly allocated to two treatment groups: reference ear cleanser (Epiotic, Virbac) or test ear cleanser (Epiotic Advanced, Virbac). Ear cleansing was performed twice daily for 2 weeks, and no other treatment was allowed. By week 2, clinical (exudate quantity, erythema, stenosis, excoriation, and odor) and discomfort (pain, ear scratching, and head shaking) scores were significantly decreased (P < .0001 for all) and no microbial overgrowth could be detected in 25 (64.1%) and 32 (68.1%) ears treated with Epiotic and Epiotic Advanced, respectively. The new pH-balanced, propylene glycol-free test ear cleanser, which incorporates microbial adhesin-blocking carbohydrates, proved as effective as the reference acidic formula.     

Evaluation of a cuprimyxin-hydrocortisone acetate suspension in the treatment of otitis externa in dogs and cats.

The therapeutic efficacy of a 0.5% cuprimyxin plus 1% hydrocortisone acetate-water-base suspension was evaluated in 130 clinical cases of otitis externa in dogs and cats in various geographic areas of the United States. The otic microbial flora was studied before treatment in 125 (96%) of the dogs and cats, with multiple isolates recovered from mated from 70%, yeasts from 65%, and fungi from 5% of the animals. Evens though multiple drug reistance was frequently observed in the bacterial flora, all bacteria and yeast isolates were sensitive to cuprimyxin. Of the 130 treated animals, a statistically significant (P less than 0.01) favorable response was obtained in 84,6% and no response in 13;1%; in2.3%, the condition became worse. An adverse reaction (pain at the time of first application) was observed in 1 (0.8%) animal.     

Surgical Management of Rabbit Ear Disease

Clinical signs associated with otic disease in rabbits (Oryctolagus cuniculus) are very similar to those demonstrated in dogs and cats. The surgical treatment options to resolve diseases involving the rabbit ear are also comparable with those used for canine and feline species. However, there are key anatomic and physiologic differences that must be accounted for to perform proper surgical treatment on a rabbit that has been diagnosed with ear disease. This article describes the diagnostic and treatment options for otitis externa, otitis media, and otitis interna, with an emphasis on surgical procedures and the important distinctive otic features of the rabbit patient. The ventral bulla osteotomy procedure is recommended for management of otitis media in rabbits without otitis externa. In rabbits with pathology in the external ear canal and the middle ear, total ear canal ablation and lateral bulla osteotomy should be performed. This combined procedure will allow the surgeon to address pathology in both sites, with the ultimate goal of resolution of the underlying disease etiology. Lateral ear canal resection is only appropriate in rabbits with otitis externa without otitis media; however, this surgical procedure may not resolve the otitis externa. If this is a concern, a total ear canal ablation should be done because it offers a greater chance of success.     

Measurement of body temperature by use of auricular thermometers versus rectal thermometers in dogs with otitis externa

OBJECTIVE: To compare measurements of body temperature obtained with auricular thermometers versus rectal thermometers in dogs with otitis externa. DESIGN: Prospective study. ANIMALS: 100 client-owned dogs: 50 with and 50 without clinical evidence of otitis externa. PROCEDURE: Dogs were evaluated for the presence of otitis externa on the basis of clinical signs, otoscopic examination, and cytologic evaluation of ear exudate. Auricular and rectal temperatures were obtained simultaneously in all dogs prior to and following ear examination. RESULTS: There was a high correlation between auricular and rectal temperatures in dogs with otitis externa both prior to and after ear manipulation. Significant differences were not detected in temperature measurements among dogs with different degrees of otitis externa. CONCLUSIONS AND CLINICAL RELEVANCE: Auricular temperature readings obtained by use of an auricular thermometer in dogs with otitis externa are accurate measurements of body temperature, compared with rectal temperature measurements. Temperature measurements are reliable before and after examination of the ear canal.     

Comparison of bacterial organisms and their susceptibility patterns from otic exudate and ear tissue from the vertical ear canal of dogs undergoing a total ear canal ablation

The purpose of this prospective study was to compare bacterial organisms and their susceptibility patterns from otic exudate and ear tissue from the vertical ear canal of six dogs with end-stage otitis undergoing a total ear canal ablation. Twenty-six organisms, 13 from the exudate and 13 from the tissue, were morphologically and biochemically similar, and their susceptibility patterns were compared. There were discrepancies for only 5 antibiotics for 4 organisms from 3 dogs. Culture of otic exudate from the vertical ear canal of dogs with chronic end-stage otitis externa provides an accurate reflection of the bacterial species present and the antimicrobial susceptibility patterns of these infections.