Vertical Ear Canal Research Articles

A Case of Proliferative and Necrotizing Otitis Externa in a Scottish Fold Shorthair Cat

In this case report, the aim was to contribute to understanding PNOE's clinical presentation, histopathological features, and successful treatment approaches, emphasizing the significance of accurate diagnosis and appropriate management in affected felines. Proliferative necrotic otitis externa (PNOE) is a very rare skin disease of unknown etiology affecting the vertical ear canal and the concave surface of the auricle, which may be accompanied by secondary yeast or bacterial infections. In this case 8-month-old Scottish fold shorthair cat has fragile, papillomatous growths and caseous purulent exudate in the ear canal was presented. The differential diagnosis of this condition includes otoacariasis, plasma cell pododermatitis, papillomavirus and chronic bacterial or yeast otitis externa. Despite antimicrobial and antiparasitic based previous treatments, the lesions persisted. Histopathological examination revealed acanthotic epidermis, necrotic keratinocytes, and inflammatory cell infiltrates. Treatment involved methylprednisolone injection, topical pomades, and systemic antibiotics. The cat showed improvement after initial treatment week, with regression of lesions and cessation of ear discharge. Follow-up visits demonstrated continued improvement, and after two months, minimal sequelae remained. In conclusion, despite the unknown etiology of PNOE, the disease is quite responsive to immunosuppressive therapy, which is beneficial for both diagnosis and treatment.

Vertical canal auricular cartilage malformation in a Keetso cat with concurrent chronic otitis externa

AbstractA 7‐month‐old, male, neutered Keetso cat presented for assessment due to chronic recurrent otitis externa signs. Video otoscopic examination revealed corrugated stenosis of the vertical ear canal. A bilateral lateral wall resection was performed. Repeat examination 2 and 15 months after surgery showed no ongoing clinical signs. The Keetso cat is a new breed of cat with a small gene pool, with currently only two breeders worldwide. Significant features of the breed are polydactylism and externally curled pinnae (folded ears). The presence of cartilage malformation in the vertical ear canal may be associated with the chronic otitis externa and if occurring on a population level, presents a potential welfare concern for this breed.

Proliferative and necrotizing otitis externa in a kitten: Case report with literature review

Proliferative and necrotizing otitis externa (PNOE) is a rare dermatitis with unknown etiology affecting kittens between 2 to 6-months-old and adult cats. Its clinical signs are unique and diagnosis is based on skin histopathology. Lesions develop rapidly and in kittens may regress spontaneously. A 6.5-month-old, male, Siamese kitten was presented with chronic proliferative, erythematous and necrotic lesions covered with thick dark-brown keratinous debris on the concave aspect of both pinnae and the vertical ear canal leading to secondary otitis infection due to obstruction. Lesions were not pruritic or painful even though erosions and ulceration were seen focally. Previous treatment with commercial otic preparations was of no avail. Ear otoscopy could not be performed due to stenosis and ear canal cytology showed numerous bacteria intermingled with keratinocytes and debris. Radiography further confirmed ear canal stenosis. Histopathological examination revealed orthokeratotic and parakeratotic hyperkeratosis, epidermal hyperplasia with several apoptotic cells and neutrophilic crusts mixed with cocci. Topical treatment with 0.1% tacrolimus was prescribed twice daily and otic solutions for secondary otitis externa. Complete clinical cure was achieved two months after first admittance. This is the first report of PNOE in Greece. Topical tacrolimus appears to be an effective treatment for lesions that do not spontaneously regress.

Carbon dioxide laser surgery for chronic proliferative and obstructive otitis externa in 26 dogs.

Some dogs with chronic otitis externa (OE) develop proliferation of the tissues surrounding the opening of the external ear canal, resulting in obstruction. Traditionally total ear canal ablation with bulla osteotomy (TECABO) has been recommended. To evaluate the efficacy of a novel treatment using carbon dioxide (CO2 ) laser surgery and to describe the histopathological features of chronic proliferative and obstructive OE. Twenty-six dogs were included, 16 with bilateral and 10 with unilateral disease (42 ears were treated). Dogs with nonpatent horizontal ear canal or macroscopic calcification of the ear canal were excluded. For histopathological evaluation, tissue samples were collected from 11 dogs (17 ears). Hyperplastic tissue around the canal opening and within the vertical ear canal was dissected and ablated using a CO2 laser. Biopsy samples were evaluated for sebaceous and ceruminous gland hyperplasia, epidermal hyperplasia, inflammation and fibrosis. Following CO2 laser surgery there was a good or excellent outcome with substantial resolution of proliferative changes in 39 of 42 ears from 24 of 26 dogs. One surgery was sufficient in 21 dogs and three dogs had two surgeries. Two dogs had recurrence of proliferative tissue after one surgery and underwent TECABO. Two dogs had no recurrence of proliferative tissue after surgery, yet had persistent luminal infection and underwent TECABO. The remainder of the dogs were effectively medically managed long-term following surgery. Histologically, eight ears had a predominantly sebaceous gland response, three had a predominantly ceruminous response and six had a mixed glandular pattern. Epidermal hyperplasia, inflammation and fibrosis varied from mild to severe. Carbon dioxide laser surgery is an effective treatment of proliferative OE causing obstruction of the ear canal opening and vertical canal, and should be considered as an alternative to TECABO whenever possible.

Efficacy of greater auricular and auriculotemporal nerve blocks performed in rabbits

ObjectiveTo evaluate the efficacy, duration and safety of greater auricular and auriculotemporal nerve blocks in rabbits. Study designProspective, randomized, crossover, experimental study. AnimalsA total of 11 healthy adult Dutch-belted rabbits. MethodsThe rabbits underwent general anesthesia and injections of the greater auricular and auriculotemporal nerves using either bupivacaine (0.3 mL kg–1, 0.5%) or the same volume of saline. After anesthesia, the efficacy and duration of nerve blocks were assessed using analgesiometry forceps on the pinna and cotton-tipped applicators within the vertical ear canal. Rabbits were monitored for abnormal carriage of the ear and auriculopalpebral nerve block of the ipsilateral eye. Body weight, food intake, fecal output and fecal pellet diameter were measured daily for 6 days after the nerve blocks were performed and compared with baseline to assess short-term effects. ResultsThe greater auricular nerve was successfully blocked in 12/16 (75%) ears for mean ± standard deviation duration of 88 ± 52 minutes. In successfully blocked ears, altered ear position was noted in five/16 (31%) cases. The auriculotemporal nerve was blocked in one/16 ears for 120 minutes. The auriculopalpebral nerve was inadvertently blocked in three/16 ears. Food intake and fecal output decreased significantly during the treatment day but returned to pretreatment values after 24 hours. There was no change in body weight or fecal pellet diameter for either treatment. Conclusions and clinical relevanceThe results suggest that duration of the greater auricular nerve block with 0.5% bupivacaine was short-lived in the live rabbit. Auriculotemporal nerve block was only achieved in one ear; therefore, further studies are warranted to evaluate the contribution of these blocks in the pain management of rabbits undergoing auricular surgery.

Partial vertical ear canal resection in two cats.

An 18-year-old domestic medium-hair cat (cat 1) and a 16-year-old domestic shorthair cat (cat 2) were evaluated because of obstructive skin lesions involving the perimeter of the left external auditory canal. Otitis externa was present in affected ears secondary to obstructive soft tissue growths involving the outer margin of the external auditory canal and outer third of the vertical ear canal. Histologic examination of a preoperative biopsy sample revealed multiple ulcerated ceruminous gland adenomas in the affected ear of cat 1. Histologic examination of the submitted tissue from cat 2 confirmed ceruminous cystomatosis with surface colonization of yeast compatible with Malassezia spp. Both cats underwent partial resection of the upper third of the affected vertical ear canal and associated diseased skin. The incised margin of the pinna was sutured to the margin of the remaining portion of the vertical ear canal with absorbable sutures. Both cats were disease free over a 12-month (cat 1) or 10-month (cat 2) follow-up period. Cat 1 later developed a small ceruminous gland adenocarcinoma in the adjacent rostrolateral margin of the vertical ear canal 1 year after surgery; the mass was resected, and the patient was free of recurrence 4 months later. Partial resection was an effective alternative to complete vertical ear canal resection for lesions involving the upper third of the vertical ear canal in these cats; the partial resection procedure was deemed simpler to perform and less traumatic to the cat. Functional and cosmetic results were excellent, with preservation of the overall anatomy of the external auditory canal.

Resection of a ceruminous adenocarcinoma in a horse by a modified vertical ear canal ablation

SummaryA 13‐year‐old Swedish Warmblood mare was presented for evaluation of a mass on the medial aspect of the left vertical ear canal. The mass was initially resected using monopolar loop diathermy. Histopathological diagnosis of the excisional biopsy was a low‐grade malignant ceruminous adenocarcinoma. The clinical and histopathological features of this previously unreported neoplasm in the horse are described. A modified vertical ear canal ablation was performed in order to remove the base of the neoplasm with adequate free margins. The surgical technique is described. No recurrence was noted 2 years after surgery and the appearance and function of the pinna were retained.

BAER Testing in a Dog with Bilateral External Ear Canal Atresia

A 3 yr old male castrated Labrador retriever presented for evaluation and treatment of bilateral atresia of the external ear canals. The owners reported that the dog could hear only loud and high-pitched noises. Computed tomography of the head revealed intact vertical and horizontal ear canals filled with debris and a debris-filled right tympanic bulla. Air- and bone-conducted brainstem auditory evoked response (BAER) testing revealed an elevated response threshold to air-conducted stimuli and greater amplitude waveforms evoked by bone-conducted stimuli. The ear canals were surgically corrected via lateral ear canal resection. BAER testing postoperatively revealed a decrease in the air-conducted BAER threshold. This case is an example of the use of bone-conducted BAER testing to aid in the diagnosis of conductive deafness, and in determining prognosis for normal hearing after surgical treatment of external ear canal atresia.

Proliferative and necrotising otitis in a kitten: first demonstration of T‐cell‐mediated apoptosis

Otitis externa in cats is relatively uncommon. This report describes a case of a rare, visually distinctive, proliferative and necrotising otitis in a three-month-old Persian kitten. The cat had proliferative, erythematous and necrotic tissue covering most of the proximal pinnae and vertical ear canals. On histopathological examination, the most striking feature was the existence of scattered apoptotic-appearing keratinocytes within severely hyperplastic epithelium. For the first time, immunohistochemistry was used to show a closed association between CD3(+) T cells and caspase-3 stained keratinocytes, consistent with a keratinocyte apoptosis by epidermal-infiltrating T cells. Treatment was initiated using topical tacrolimus twice daily and an ear cleanser once daily. A marked improvement was observed after 10 days of treatment and the lesions completely resolved over a period of three weeks. The origin of T cells directed against keratinocytes is currently unknown.

Identification and antimicrobial susceptibility patterns of bacteria causing otitis externa in dogs

Bacterial agents are considered important pathogens causing external otitis in dogs. It is essential to carry out bacterial culture and antimicrobial susceptibility test in the case of otitis externa, particularly for chronic or recurring cases. Sterile swab samples were obtained from terminal part of vertical ear canals of 74 dogs with otitis externa for cytology, bacterial culture and antimicrobial susceptibility test. Cytologic smears were stained using Gram and Giemsa staining methods. Aerobic bacterial culture performed on blood agar and MacConkey agar. Among total number of 92 isolated bacteria, 68 were Staphylococcus intermedius. Other isolated bacteria included: Pseudomonas aeruginosa, Proteus mirabilis, Escherichia coli, Pasteurella canis, and six other species of coagulase-negative Staphylococcus. Antimicrobial susceptibility test were performed for all isolated bacteria using 14 antibiotics. Based on the results of this study, all isolated Staphylococcus spp. were sensitive to amikacin, enrofloxacin, and rifampin, and had low resistance to gentamicin, cephalothin and ceftriaxone. More than half of gram-positive isolates were resistant to penicillin and ampicillin. Generally, all isolated gram-negative bacteria, were sensitive to amikacin and enrofloxacin, and had low resistance to ceftriaxone and gentamicin. They were highly resistant to penicillin, eythromycin, and cephalothin. Regarding the results of this study, in cases of uncomplicated otitis externa, it is possible to select antimicrobial drugs merely based on cytology, but it is recommended to perform bacterial culture and antimicrobial susceptibility test. However, in complicated or refractory cases, antimicrobials should be selected based on bacterial culture and antimicrobial susceptibility test.

Erratum

The canine ear consists of the pinna, external ear canal, middle ear and inner ear. The external ear is composed of auricular and annular cartilage. The auricular cartilage of the pinna becomes funnel shaped at the opening of the external ear canal. The vertical ear canal runs for about 1 inch, then forms the horizontal ear canal, which is composed of auricular and annular cartilage. The middle ear consists of an air-filled tympanic cavity, three auditory ossicles, and tympanic membrane. The tympanic membrane is a semitransparent membrane divided into the pars flaccida and pars tensa. The tympanic cavity consists of a small epitympanic recess, a large ventral bulla and the tympanic bulla proper. On the medial wall of the tympanic cavity is the promontory, which houses the cochlea. The cochlear (round) window is located in the caudolateral portion of the promontory, covered by a thin membrane. The vestibular (oval) window is located on the dorsolateral surface of the promontory, covered by a thin diaphragm over which the footplate of the stapes is attached. The auditory tube is a short canal that extends from the nasopharynx to the rostral portion of the tympanic cavity proper. The auditory ossicles are the bones that transmit and amplify air vibrations from the tympanic membrane to the inner ear. The inner ear is housed in a bony labyrinth in the petrous portion of the temporal bone. The bony labyrinth contains the membranous labyrinth with its sensory organs responsible for hearing and balance.

Anatomy and physiology of the canine ear

The canine ear consists of the pinna, external ear canal, middle ear and inner ear. The external ear is composed of auricular and annular cartilage. The auricular cartilage of the pinna becomes funnel shaped at the opening of the external ear canal. The vertical ear canal runs for about 1 inch, then forms the horizontal ear canal, which is composed of auricular and annular cartilage. The middle ear consists of an air-filled tympanic cavity, three auditory ossicles, and tympanic membrane. The tympanic membrane is a semitransparent membrane divided into the pars flaccida and pars tensa. The tympanic cavity consists of a small epitympanic recess, a large ventral bulla and the tympanic bulla proper. On the medial wall of the tympanic cavity is the promontory, which houses the cochlea. The cochlear (round) window is located in the caudolateral portion of the promontory, covered by a thin membrane. The vestibular (oval) window is located on the dorsolateral surface of the promontory, covered by a thin diaphragm over which the footplate of the stapes is attached. The auditory tube is a short canal that extends from the nasopharynx to the rostral portion of the tympanic cavity proper. The auditory ossicles are the bones that transmit and amplify air vibrations from the tympanic membrane to the inner ear. The inner ear is housed in a bony labyrinth in the petrous portion of the temporal bone. The bony labyrinth contains the membranous labyrinth with its sensory organs responsible for hearing and balance.

Plasma and ear tissue concentrations of enrofloxacin and its metabolite ciprofloxacin in dogs with chronic end‐stage otitis externa after intravenous administration of enrofloxacin

The purpose of this study was to measure the concentrations of enrofloxacin and its metabolite ciprofloxacin following intravenous administration of enrofloxacin in the plasma and ear tissue of dogs with chronic end-stage otitis undergoing a total ear canal ablation and lateral bulla osteotomy. The goals were to determine the relationship between the dose of enrofloxacin and the concentrations of enrofloxacin and ciprofloxacin, and determine appropriate doses of enrofloxacin for treatment of chronic otitis externa and media. Thirty dogs were randomized to an enrofloxacin-treatment group (5, 10, 15 or 20 mg kg(-1)) or control group (no enrofloxacin). After surgical removal, ear tissue samples (skin, vertical ear canal, horizontal ear canal, middle ear) and a blood sample were collected. Concentrations of enrofloxacin and ciprofloxacin in the plasma and ear tissue were measured by high performance liquid chromatography. Repeated measures models were applied to log-transformed data to assess dosing trends and Pearson correlations were calculated to assess concentration associations. Ear tissue concentrations of enrofloxacin and ciprofloxacin were significantly (P < 0.05) higher than plasma concentrations. Each 5 mg kg(-1 )increase in the dose of enrofloxacin resulted in a 72% and 37% increase in enrofloxacin and ciprofloxacin concentrations, respectively. For bacteria with an minimal inhibitory concentration of 0.12-0.15 or less, 0.19-0.24, 0.31-0.39 and 0.51-0.64 microg mL(-1), enrofloxacin should be dosed at 5, 10, 15 and 20 mg kg(-1), respectively. Treatment with enrofloxacin would not be recommended for a bacterial organism intermediate or resistant in susceptibility to enrofloxacin since appropriate levels of enrofloxacin would not be attained.

外側鼓室胞骨切術を併用した全耳道切除術における術前細菌培養検査の有用性の検討

The total ear canal ablation and lateral bulla osteotomy (TECABO) technique was performed on dogs withotitis media. All examined dogs had a severely stenosed or occluded ear canal. Swab specimens were obtainedin the vertical ear canal prior to operation, and in the tympanic cavity during surgery. Isolates from the verticalear canal and tympanic cavity were then compared for each ear. In all cases, the kinds of bacteria isolatedfrom these two parts were the same or the kinds of isolates from the tympanic cavity included those from thevertical ear canal. The susceptibility patterns of these isolates from both parts tended to be almost identical.The paper suggests that when TECABO is performed, data on the susceptibility patterns of isolates from thevertical ear canal can be used until the susceptibility patterns of bacteria obtained from the tympanic cavity areidentified.

Repair of Oronasal Fistulae Using Auricular Cartilage Grafts in Five Cats

To describe repair of chronic palatine defects in cats, with free cartilage graft harvested from either the pinna (scapha) or vertical ear canal (annular cartilage). Retrospective study. Cats (n=5) with chronic oronasal fistula. Cartilage was harvested from either the scapha or annular cartilage and epithelium removed. After preparation of the edges of the palatal defect by separation of the oral and palatal mucosa circumferentially, the graft was inserted between the epithelial layers and secured without tension. The graft acted as a scaffold for migration of granulation tissue and epithelialization. Oronasal fistulae were successfully repaired in 5 cats (3 pinna grafts; 2 annular cartilage grafts); 1 cat required a second graft after the first graft was dislodged. Auricular cartilage provides a reliable framework for repair of oronasal fistulae in cats. Chronic oronasal fistulae refractory to conventional repair can be treated by use of auricular free graft (pinna or annular cartilage) without disfigurement. Use of annular cartilage to support palatal repairs offers surgeons an additional option when other methods have failed. We recommend using conchal cartilage as the initial treatment approach for repair of small oronasal fistulae in cats.

Microbial Flora in the Ears of Healthy Experimental Beagles

There are studies of the microbial flora of the normal canine ear canal, but it is difficult to compare their results because the parts of the ear examined are not described, and various breeds of dogs were used. Therefore, we used only beagles to study the normal microbial flora in three parts of the ear: the pinna, the anthelix, and the vertical ear canal. The rates of bacterial isolation from the three parts were 91.8%, 70.5% and 48.8%, respectively. The corresponding rates of isolating yeasts was 48.8%, 81.4%, and 83.7%, respectively. These results show that the physiologic factors of the three parts of the ear from which the samples were obtained must be radically different.

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.

FC‐46 Methicillin‐resistant Staphylococcus intermedius organisms from the vertical ear canal of dogs with end‐stage otitis externa

Methicillin‐resistant staphylococci (MRS) have been isolated from the ears of dogs with otitis externa; however, the specific location of the sample and the condition of the ear were not disclosed. The purpose of this study was to identify MRS from the vertical ear canal in dogs with end‐stage otitis externa. Swab samples were obtained from one vertical ear canal of 26 dogs undergoing a total ear canal ablation and bulla osteotomy. Swab samples were routinely processed for bacterial culture. No topical or oral antimicrobial agents had been administered within 24 h of obtaining the sample. Testing for oxacillin (methicillin) resistance was performed with the disk diffusion test (DD) and confirmed with the oxacillin screen agar test (OSA) for staphylococcal organisms. Twenty‐three staphylococcal organisms [21 Staphylococcus intermedius (SI), 2 coagulase‐negative staphylococci (CNS)] were isolated from 17 dogs. On the DD, 15 organisms were susceptible (13 SI, two CNS), one was intermediate (SI), and seven were resistant (all SI) to methicillin. On the OSA, one SI that was intermediate on DD was susceptible, and of the seven that were resistant on DD, five SI were susceptible and two SI were resistant to methicillin. Both methicillin‐resistant S. intermedius (MRSI) were susceptible to chloramphenicol, polymyxin B and trimethoprim‐sulfadiazine. In dogs with end‐stage otitis externa, MRSI may be an important pathogen. Had OSA not been performed to confirm MRS, five of seven staphylococcal organisms would have been erroneously reported as resistant to certain antibiotics, which may have affected antibiotic selection and treatment of the otitis. Funding: Bayer Animal Health, The Ohio State University Canine Research Fund, American College of Veterinary Dermatology, Ohio Animal Health Foundation.

The cytology of the external ear canal in the normal dog and cat.

This study was conducted on 50 normal dogs and 52 normal cats in order to characterize the normal cytological findings in specimens taken from the vertical ear canal by swabbing. Yeast were detected in 96% of the dogs and 83% of the cats. Gram-positive cocci were found in 42% of the dogs and 71% of the cats. Rods were not seen. In dogs, the median numbers per high-power microscopic field (400x magnification) for yeast, cocci and keratinocytes were 0.2, 0 and 3.9, respectively. In cats, the median numbers were 0.2, 0.3 and 8, respectively. Nucleated keratinocytes were occasionally observed in both species, and should not be mistaken for a pathological process (parakeratotic hyperkeratosis).

Treatment of traumatic separation of the auricular and annular cartilages without ablation: results in five dogs.

Five dogs were diagnosed as having unilateral separation of the otic cartilages (auricular and annular). Four dogs had sustained prior trauma (hit by a car). Clinical signs were typical of ear canal stenosis and included swelling at the base of the ear (n = 2), periotic fistulation (n = 2), head tilt toward the affected side (n = 2), and pain when opening the mouth (n = 1). Palpation revealed separation of the horizontal and vertical ear canals. Otoscopic findings included a shallow ear canal and a pseudotympanic membrane across the proximal end of the auricular cartilage. Findings at surgery confirmed the diagnosis of cartilage separation and included an exudate-filled horizontal ear canal and a blind-ending vertical ear canal. Surgical treatment involved isolating the distal end of the annular cartilage (horizontal ear canal), opening and evacuating the horizontal ear canal, and suturing the open end of the annular cartilage to the skin. The length of annular cartilage was variable among the dogs, although each dog had sufficient horizontal canal to appose skin to otic epithelium. The vertical ear canal was not surgically dissected or manipulated. The mean follow-up period was 46 +/- 14 months (range, 31 to 68 months). All five dogs had patent horizontal ear canals when examined at the follow-up examination.