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.     

Breed variations in histopathologic features of chronic severe otitis externa in dogs: 80 cases (1995-2001)

OBJECTIVE: To compare pathologic changes of the horizontal ear canal associated with chronic severe otitis externa between Cocker Spaniels and dogs of other breeds. DESIGN: Retrospective study. ANIMALS: 80 dogs with severe otitis externa that required total ear canal ablation with lateral bulla osteotomy. PROCEDURE: Medical records were reviewed for breed, sex, and age at time of surgery. Histologic specimens from the horizontal ear canal were evaluated by a single examiner for overall tissue response pattern and scored for sebaceous gland hyperplasia, ceruminous gland hyperplasia, ceruminous gland ectasia, fibrosis, pigment-laden macrophages, and osseous metaplasia. RESULTS: 48 of 80 (60%) dogs were Cocker Spaniels. Thirty-five of 48 (72.9%) Cocker Spaniels had a predominately ceruminous tissue response pattern; only 9 of 32 (28.1 %) dogs of other breeds had the same pattern. Other breeds most commonly had a pattern dominated by fibrosis (n = 13 [40.6%]); fibrosis was the predominant pattern in only 4 of 48 (8.3%) Cocker Spaniels. Discriminant analysis and K-means clustering of 4 histopathologic criteria correctly classified 75% of the dogs as Cocker Spaniels or all other breeds. CONCLUSIONS AND CLINICAL RELEVANCE: Cocker Spaniels are at increased risk for chronic severe otitis externa requiring total ear canal ablation with lateral bulla osteotomy, indicating that earlier and more aggressive management of the primary otitis externa and secondary inflammation is warranted in this breed. Cocker Spaniels with chronic severe otitis externa have distinct differences in pathologic characteristics of the horizontal ear canal, compared with other breeds.     

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.     

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.     

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.     

Inflammatory middle ear disease of the dog: the pathology of otitis media

Inflammation within the middle ear cavity was recognised in 62 of the ears of 42 dogs with chronic otitis externa and otitis media, after biopsy or necropsy of the middle ear. The pathological changes in the middle ear resembled those reported in other species or after the experimental induction of otitis media in dogs. Perforations in the tympanic membrane were rarely found; on the contrary, the membrane was often thickened. However, the question of whether a perforation in the tympanic membrane must occur before otitis externa can extend to otitis media was not resolved.     

Total Ear Canal Ablation Clinical Results in the Dog and Cat

The clinical results of 39 consecutive ear ablations (in 28 dogs and three cats) performed over a 15-year period were reviewed. Indications for ear canal ablation included hyperplastic tissue stenosis of the horizontal ear canal (23), failed lateral ear resections (13), and horizontal ear canal neoplasms (3). Ear ablation was successful in alleviating persistent signs of otitis in eight of 15 dogs with horizontal ear canal stenosis due to hyperplastic tissue, seven of 10 dogs with unsuccessful lateral ear resections, and two of five animals (three cats and two dogs) with horizontal ear canal neoplasms (follow-up time periods greater than 5 months). Surgical complications occurred following 82% of the ablations; wound infections (41%) and facial nerve damage (36%) were most common. Local wound and antibiotic therapy successfully treated prolonged drainage following ablation in five of nine dogs. Bulla osteotomy and drainage were successful in the treatment of three dogs (four ears) that were unresponsive to medical therapy with postoperative ear fistula following ablation, one of two dogs with prolonged ear drainage following ablation for failed lateral ear resection, and one dog with recurrence of signs of inner ear disease following ablation (follow-up period, 1 month to 4 years; mean, 3.4 years). Facial nerve damage caused by ablation was transient in nine of 14 ears, with most deficits returning to normal within 2 weeks.     

Effects of ear type and weather on the hospital prevalence of canine otitis externa

A retrospective study of 8975 dogs seen at 15 university veterinary medical teaching hospitals in North America (1975 to 1978) found that dogs with pendulous ears and heavy ear canal hair had significantly (P less than 0.01) more otitis externa than dogs with other ear types. Dogs with erect ears, regardless of the amount of ear canal hair, had less risk (P less than 0.01) of the disease than mongrel dogs. Direct evidence is available for the first time showing that monthly variations in ambient temperature, rainfall and relative humidity explain, to a large extent, the monthly variations in the hospital prevalence of canine otitis externa in different geographic regions.     

Long-term evaluation of the pull-through technique for vertical canal ablation for the treatment of otitis externa in dogs and cats

Between January 1985 and May 1987 53 ears of 35 dogs and five cats with chronic otitis externa were operated on using the pull-through technique for vertical canal ablation. Their postoperative follow-up is analysed, evaluated and described in detail.     

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.     

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.     

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.     

Effects of otitis on hearing in dogs characterised by brainstem auditory evoked response testing

Hearing function was measured in normal dogs and in dogs with otitis using brainstem auditory evoked response testing. Data were obtained from 86 normal ears and from 105 ears with otitis, cntegorised into four degrees of severity. The data were analysed to illustrate the differences between the hearing function in the normal and abnormal ears and to estimate the degree of impairment associated with differing degrees of pathology. While severe hearing loss seemed to be present in the dogs with more severe otitis, only two individuals were identified as being totally deaf in the affected ears and no dogs were identified in which the cleaning and examination processes had caused damage to hearing function. Cleaning the ear canal produced measurable improvements in hearing in several dogs, indicating the profound effect of physical obstruction of the external ear canal by debris. It is concluded that most dogs with chronic otitis externa are not totally deaf and that the hearing impairment that does occur has the characteristics of conductive hearing loss.     

Chronic otitis externa/media with total ear canal ablation and bulla curettage in a North American bison (Bison bison).

An adult female North American bison (Bison bison) with a chronic otitis externa/media of the right ear was examined because of a 4-mo history of intermittent anorexia, apparent painful behavior, and auricular discharge from the right ear. Computerized tomography (CT) demonstrated osteolysis of the tympanic, petrous, and squamous aspects of the temporal bone with soft tissue replacement and sclerosis of the right bulla. A total ear canal ablation with bulla curettage was performed, and cefazolin-impregnated polymethacrylate beads were left within the right bulla and the remnant temporal bone. Six months after the surgery, the bison had no clinical signs of otitis media.     

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.     

Potential factors affecting the outcome of dogs with a resection of the lateral wall of the vertical ear canal.

The records of 60 dogs that had a resection of the lateral wall of the vertical ear canal (Zepp) were examined. The surgical outcomes were evaluated in association with the following variables: breed, sex, age of onset of the otitis externa, duration of the disease before the surgery was performed, treatment received for the otitis externa, the status of the ear and tympanic membrane at the time of the surgery, the culture results, and concurrent medical problems. The outcome of surgery was acceptable in 45% and unacceptable in 55% of the cases. Breed was the only factor that could be correlated with the outcome. The procedure failed in 86.5% of the cocker spaniels. When surgical outcomes in breeds other than cocker spaniels were evaluated, 63% were acceptable and 37% were unacceptable. Sharpeis were found to have an ear canal of small diameter compared with that of other breeds and a tendency to have better outcomes.     

Surgical management of chronic otitis secondary to craniomandibular osteopathy in three West Highland white terriers

Three West Highland white terriers were presented for investigation of left‐sided para‐aural abscessation. CT revealed chronic otitis media with extensive osseous proliferation surrounding the horizontal and vertical ear canals contiguous with the expanded temporal bone, consistent with a unilateral variant of craniomandibular osteopathy. A left total ear canal ablation with lateral bulla osteotomy was performed in all dogs. An ultrasonic bone curette (Sonopet; Stryker) proved useful when removing the osseous proliferation in two dogs. Histopathological examination of the ear canals was consistent with craniomandibular osteopathy and the treatment led to resolution of the presenting clinical signs in all dogs. To our knowledge, this is the first report of craniomandibular osteopathy engulfing the external ear canal, presumably leading to chronic otitis media and para‐aural abscess formation. This is also the first reported use of an ultrasonic bone curette in canine otic surgery.     

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.     

Wound contamination and antimicrobial susceptibility of bacteria cultured during total ear canal ablation and lateral bulla osteotomy in dogs.

OBJECTIVE: To detect contamination of wound sites from surgical handling of excised tissues during total ear canal ablation and lateral bulla osteotomy in dogs, and to compare susceptibility of bacterial isolates to cefazolin with susceptibility to other antimicrobial agents. DESIGN: Prospective clinical study. ANIMALS: 13 dogs. PROCEDURE: Dogs were treated surgically for otitis externa and media via total ear canal ablation and lateral bulla osteotomy. Specimens for aerobic bacterial culture were obtained from SC tissue immediately following skin incision, tissues excised from the osseous bulla (after transection of the horizontal ear canal and lateral bulla osteotomy), and from SC tissue prior to skin closure. Antimicrobial susceptibility of bacterial isolates to various antibiotics was determined by use of a broth dilution assay. RESULTS: There was a significant association between isolation of Streptococcus canis and Escherichia coli from specimens from the osseous bulla and specimens from the SC tissues prior to skin closure, indicating contamination of the SC tissues during surgery. Seventy percent of bacterial isolates were susceptible to cefazolin. CLINICAL IMPLICATIONS: Measures to limit bacterial contamination resulting from tissue handling during total ear canal ablation and lateral bulla osteotomy are necessary. Bacteriologic culture of tissue of the osseous bulla and determination of antimicrobial susceptibility are recommended. Administration of cefazolin alone may not be efficacious for antimicrobial prophylaxis.     

Virtual otoscopy for evaluating the inner ear with a fluid-filled tympanic cavity in dogs

The feasibility of virtual otoscopy (VO) imaging was evaluated in five dogs with experimentally induced otitis media, two control dogs, and two canine patients with otitis media. VO images of the tympanic cavity and ossicles were generated with commercially available software using raw computed tomography (CT) data. Eight out of 10 ears inoculated with pathogen exhibited obvious clinical signs associated with otitis externa. CT images revealed soft tissue density material occupying the tympanic bulla compatible with otitis media in three dogs with experimentally induced otitis media and two patients. No remarkable features were observed on the radiographs. Four different VO views (ear canal, tympanic bulla, eustachian tube, and ossicular chain) were created. Promontory, cochlea window, tympanic, and septum bulla as well as ossicles were easily and clearly distinguished except for the incus and stapes of the clinical patients. VO images were not more suitable than images created with conventional CT for accurately diagnosing otitis media in this study. However, it appears that VO could be more feasible for assessing the complex structure of the inner ear in dogs with fluid-filled tympanic cavities since fluid accumulation within the tympanic bulla did not affect the evaluation of bony tissue in the middle ear on VO images.