Short- and long-term outcomes of subtotal ear canal ablation and lateral bulla osteotomy in French bulldogs

Abstract

The objective of this retrospective study was to report the overall peri-operative complications and short- to long-term outcomes of subtotal ear canal ablation and lateral bulla osteotomy in French bulldogs with otitis media. Medical records from 2018 to 2021 were reviewed for preoperative neurological signs, surgical technique, postoperative complications, and long-term outcomes. Postoperative complications, such as a head tilt, nystagmus, ataxia, facial nerve dysfunction, as well as skin or wound infection, were recorded. Eighteen client-owned dogs (20 ears) were included in the study. Postoperative complications were observed in 5/18 dogs (6/20 ears) with 2 of them being considered major complications. Referring veterinarians and owner telephone follow-up (mean: 33 mo, range: 17 to 56 mo) were obtained for all patients. Total recovery was reported in 9/18 dogs (11/20 ears) with a postoperative improvement of the vestibular signs and facial nerve paresis within 8 wk. All dogs maintained the pinnas’ natural, erect morphology, and movement.

Introduction

Total ear canal ablation with lateral bulla osteotomy (TECA-LBO) is a surgical treatment for dogs with end-stage ear inflammatory disease, auricular neoplasia, aural cholesteatoma, extensive ear canal trauma, irreversible hyperplastic horizontal ear canal disease, or failure of more conservative ear surgeries, such as vertical ear canal ablation or lateral ear canal resection (1–7). Overall complication rates reported with TECA-LBO in dogs range between 21 to 82% (1,4–7). The most common complications are hemorrhage, facial nerve damage, chronic deep wound infection, abscessation, debilitating fistula, and loss of auditory function (1,4–6). The procedure involves a circumferential incision around the funnel-shaped auricular cavity and through the auricular cartilage at the base of the pinna, with excision of the entire ear canal, and osteotomy of the tympanic bulla to help expose and debride the tympanic cavity (1,5,6). The excision of the medial portion of the auricular cartilage and closure in an inverted T- or L-shaped suture line can affect the morphology of the pinna in dogs with erect ears (8–10).

A modification of this technique for dogs with erect ears has been previously described in 2001 (9). Subtotal ear canal ablation with lateral bulla osteotomy (SubTECA-LBO) is a modification of the original technique that preserves the distal portion of the vertical ear canal to try maintain erect ear carriage (8,9). The SubTECA-LBOs were performed in 18 dogs for the treatment of otitis media, otitis externa, or masses of the horizontal ear canal and otitis in the vertical ear canal with minimal involvement of the distal portion. In this report, all dogs with erect ear carriage maintained the erect morphology of the pinna (8).

Previous literature has reported the presence of variation in the conformation of the tympanic bulla in relation to volume, thickness, and location in brachycephalic breeds compared to nonbrachycephalic breeds (11). Soft palate defects and nasopharyngeal alterations are highly represented in brachycephalic breeds such as the French bulldog with airway obstruction. These anomalies can modify the auditory tube, hindering the natural drainage of the tympanic bulla, causing accumulation of fluid and favoring the formation of pathologies such as otitis media without concurrent otitis externa, making SubTECA-LBO a potential surgical alternative to standard TECA-LBO (12,13).

The purpose of this retrospective study is to review the indications, short- and long-term outcomes of subTECA-LBO performed in a cohort of French bulldogs. As far as the authors know this is the first report specifically evaluating subTECA-LBO in a single brachiocephalic breed such as the French bulldog.

Materials and methods

Case selection

Medical records of French bulldogs undergoing subtotal ear canal ablation and lateral bulla osteotomy at Hospital Veterinario ANICURA-VETSIA (Madrid, Spain) from 2018 to 2021 were reviewed retrospectively. Inclusion criteria were French bulldogs diagnosed with otitis media or space occupying lesions of the tympanic bulla with a minimum 17-month follow-up. Cases with masses or gross changes in the vertical ear canal secondary to otitis externa, such as erythema, hyperplasia, stenosis, mineralization, ceruminous or suppurative discharge, glandular changes, ulcerations or granulation tissue, and those with pinna injuries or deformations were not considered for SubTECA-LBO.

Data collection and outcome

Clinical records were retrospectively reviewed and surgical indication, age, sex, body weight, clinical and neurological signs, imaging findings, surgical technique, intra-operative complications, pathological, and microbiological diagnoses were recorded. The neurological examination was performed by a Board-certified neurologists (ECVN diplomate) or resident under direct supervision. All dogs underwent magnetic resonance imaging (MRI) or computed tomography (CT); these images were assessed by an ECVN diplomate or a Board-certified diagnostic imaging specialist (ECVDI diplomate).

Pre- and post-operative neurological signs such as head tilt, nystagmus, ataxia, and facial nerve paresis or paralysis were also documented. As previously defined, facial nerve paralysis causes a loss of motor function due to a neural mechanism, and paresis was defined as incomplete paralysis (4).

Postoperative complications were classified as major in those cases requiring surgical therapy or showing neurological impairment that was not present preoperatively, and as minor in those requiring medical therapy. Short-term outcome included any data recorded intraoperatively to suture removal (14 d). Similarly, we used “mid-term outcome” for data recorded between 2 wk and 6 mo postoperatively, and long-term outcome for data recorded more than 6 mo postoperatively. For long-term outcome evaluation, a questionnaire administered by telephone (Appendix 1) including assessment of residual neurological impairment such as head tilt, nystagmus, ataxia and facial nerve dysfunction and alteration of the erect morphology of the pinna, was completed individually for each case by the referring veterinarians and owners.

Surgical procedure

Dogs were premedicated with dexmedetomidine (3 μg/kg; IM) and methadone (0.2 mg/kg; IM), induced with propofol (2 to 4 mg/kg; IV) and maintained with isoflurane and oxygen after orotracheal intubation. At least 30 min before starting the surgery, all dogs were treated with clavulanic potentiated Amoxycillin at 20 mg/kg IV.

The sub TECA-LBO was performed by a Board-certified surgeon (ECVS diplomate) or resident under direct supervision as previously described (8). The dogs were positioned in lateral recumbency with the affected ear uppermost and the neck elevated by using a rolled towel. The ear canal, pinna, and skin were routinely clipped and aseptically prepared.

A vertical incision was made following the vertical ear canal from just ventral to the external acoustic opening to ventral to the horizontal ear canal. The mid portion of the vertical ear canal was isolated and freed from its surrounding soft tissue attachments. Gelpi retractors were used to aid visualization. At this point, the ear canal was transected. The ventral portion of the vertical canal and the horizontal canal were then dissected and removed as for a standard TECA. Following lateral bulla osteotomy and curettage, the medial and lateral vertical ear canal cartilages were apposed with multiple simple interrupted or cruciate sutures using absorbable monofilament material (2-0 polydioxanone suture; Ethicon, Bridgewater, New Jersey, USA) avoiding penetrating the epithelium of the vertical canal. Subcutaneous and skin closures were then performed in a routine manner. In no case, was a surgical drain placed in the wound after surgery (Figure 1).

Figure 1.

A — A skin incision is made over the vertical ear canal. B — The mid-portion of the vertical ear canal is separated from the surrounding tissues and carefully elevated passing a blunt instrument (Metzenbaum scissors) under the canal. C — The vertical ear canal is transected, ~15 mm of the proximal portion of the vertical ear canal should be preserved. D — The medial and lateral vertical ear canal cartilages are apposed with simple interrupted or cruciate sutures avoiding the epithelium.

Postoperative analgesia included meloxicam (0.1 mg/kg; PO, q24h), methadone (0.2 mg/kg; IV, q4h) for the first 12 h after surgery followed by buprenorphine (15 μg/kg; IV, q6h) until discharge. The dogs were hospitalized for 24 to 48 h after surgery and discharged with an Elizabethan collar. Lubricant ointment/drops were placed in the ipsilateral eye every 6 to 8 h until a complete palpebral reflex returned. All dogs were administered a 3- to 4-week course of clavulanate potentiated amoxicillin (20 mg/kg; PO, q12h) and a 2-week supply of meloxicam (0.1 mg/kg; PO, q24h). The antibiotics were maintained or changed depending on culture result. Topical eye lubrication was administered on those dogs with the inability to voluntary blink until full recovery.

Results

Study population

Twenty subTECA-LBO procedures were completed in 18 French bulldogs; 10 (56%) females and 8 (44%) males. Twelve procedures (60%) were completed on the left ear and 8 (40%) were completed on the right ear. The mean age of the dogs was 6.4 y (range: 2.1 to 12.4 y) and the mean body weight was 12.5 kg (range: 9.3 to 20 kg). These procedures were performed unilaterally in 16 dogs and staggered bilaterally in 2 dogs (Cases 1 and 8). All dogs were diagnosed with otitis media by MRI or CT. Some ears (7/20; 35%) had otitis externa in the horizontal ear canal.

Clinical findings

The most common preoperative clinical signs were head tilt (16 ears; 80%) and ipsilateral facial nerve deficit (15 ears; 75%), presenting paralysis in 4 of them. Other vestibular signs, such as horizontal nystagmus and ataxia, were observed in 6 ears (30%) and 7 ears (35%), respectively.

Bacterial cultures and histopathological findings

Intraoperative culture samples were positive in 13 of 20 ears (65%). All cultures were obtained from epithelium samples of the tympanic bulla or via bacterial swab. The most common bacterial isolate was Staphylococcus pseudointermedius (6/13 ears). Other common bacterial isolates included Enterococcus spp. (4/13 ears), Pseudomonas aeruginosa (1/13 ears), and Proteus mirabilis (1/14 ears). Malassezia pachydermatis was observed in Case 4. There was no growth in 7 of 20 ears (35%). Tympanic bulla biopsy specimens were obtained in 17 of 20 ears (85%) with cholesteatoma being the most common histopathologic finding (12/17 ears; 70%).

Short-term outcome

Intraoperative hemorrhage from the retroglenoid vein was observed in 1 ear (Case 3). This hemorrhage was controlled by diathermy without any further consequences. Postoperative complications were observed in 5/20 ears (4/18 dogs). Four ears developed minor complications (Cases 5, 8, 11), all of which were controlled with medical treatment. Immediate surgical wound infection was observed in Case 8 (right-side ablation) and Case 11. Skin infection associated with the remaining vertical ear canal and pinna were observed in Cases 5 and 8 (bilateral ablation), all of were treated with topical medications (miconazole, prednisolone, polymyxin b ointment; q12h) during a period of 2 and 3 wk, respectively. A major complication was observed in 1/20 ears (Case 18). This case developed an iatrogenic temporary facial nerve paresis that lasted 3 wk.

Mid-term outcome

Other major complications were observed in Case 17 (1/20 ears). This case developed a deep infection 4 mo after surgery, secondary to recurrence of cholesteatoma, which required revision surgery.

Long-term outcome

Referring veterinarians and owner telephone follow-up (mean: 33 mo, range: 17 to 56 mo) were obtained for all dogs. All dogs maintained the pinnas’ natural erect morphology and movement. Total recovery was reported in 9/18 dogs (11/20 ears) with a postoperative improvement of the vestibular signs and facial nerve paresis within 8 wk. At the time of publication, 5/18 dogs (5/20 ears) maintained a slight head tilt and 4/18 dogs (4/20 ears) had a facial nerve paralysis; these signs were all present before surgery. The dogs with facial nerve paralysis developed intermittent corneal ulcers of the ipsilateral eye. Some dogs died (5/18) from causes unrelated to the study (range: 20 to 42 mo after surgery).

Discussion

Standard TECA-LBO is the most frequently performed surgical technique for the treatment of irreversible otitis media and cholesteatomas in dogs (4–7,13–15). Other options such as ventral, caudal, or intraoral bulla osteotomy have been also reported in the veterinary literature with variable success rates (16,17). SubTECA-LBO is an alternative surgical technique to standard TECA-LBO in cases of otitis media, otitis externa, or masses of the horizontal ear canal and otitis in the vertical ear canal with minimal involvement of the distal portion in dogs with erect ear carriage where maintenance of the erect morphology of the pinna is a desirable goal (8). Compared with Standard TECA-LBO there are no significant differences in overall complication rates (8,9). In brachycephalic breeds, only 2 pugs undergoing subTECA-LBO have been previously reported, due to the ear morphology in this breed erect ear carriage was not evaluated/assessed (8). In this study, all dogs maintained the erect morphology and the normal movement of the pinna after the surgery. To the authors’ knowledge, this is the largest report of subtotal ear canal ablation with lateral bulla osteotomy in a single brachycephalic breed.

In our study, overall postoperative complications were observed in 6/20 ears (30%). These results are similar to the subTECA-LBO study of Mathews et al (8), in 2006 and the current standard TECA-LBO literature (4,6,7). Skin infection associated with the remaining vertical canal/pinna and immediate surgical wound infection were the most common complications reported in our study (4/20 ears; 20%), all these ears were successfully treated with medical management without the need for surgical revision. The results herein better than those described in the study by Mathews et al (8), in which dermatological problems were described in 46% of the cases. This variation in results may be due to the erect ear carriage nature in our entire population, since the pedunculous ears morphology present in the Mathews et al (8) study can affect the retention of heat and moisture in the ear canal, predisposing the ear to the development of otitis (18).

In our population, all dogs had neurological signs before the surgical procedure. Head tilt (80%) followed by facial nerve dysfunction (75%) were overrepresented. The main cause of those clinical signs was peripheral vestibular syndrome caused by otitis media. These findings are similar to those reported in a recent study published by Orlandi et al (19), describing peripheral vestibular syndrome clinical signs in a population of dogs. To the author’s knowledge, no published studies are available to determine the persistence of neurological deficits in patients with peripheral vestibular syndrome and facial nerve deficits due to otitis media treated surgically. In our study, 9/18 dogs had persistence of neurological deficits: head tilt in 5 dogs and facial nerve dysfunction in 4 dogs. From 15 cases with facial nerve deficits at the time of presentation 11 recovered completely normal function. Voluntary eye lid movement was not recovered in the 4 dogs with facial paralysis. All dogs improved from vestibular syndrome signs, although slight head tilt persisted on 5 of them. In general, these long-term results are similar to those previously reported by Orlandi et al (19); however, this paper doesn’t specifically address patients with otitis media.

Previous studies reveal significant differences in bacterial isolates and sensitivity patterns in samples from the external ear canal, middle ear, and contaminated subcutaneous tissues of dogs undergoing TECA-LBO (20). In our study, all cultures were obtained from an epithelium sample or direct bacterial swab from the tympanic bulla. The most common bacteria isolated was Staphylococcus pseudointermedius. Other bacteria such as Enterococcus spp., Pseudomonas aeruginosa, and Proteus mirabilis were isolated as well. Our results are similar to middle ear culture results previously reported in the literature (21,22). We based our postoperative antibiotic protocol on that described by Spivak et al (4) who suggested a minimum of 1 wk of postoperative antibiotics if the culture was negative and an additional 2 to 3 wk of antibiotics if the intraoperative bacterial culture result was positive (4). However, we decided to modify this approach by also prescribing empiric antibiotics for 3 to 4 wk in cases with a negative culture based on previous literature that has suggested culture and sensitivity is not the gold standard for detection of otopathogens (possibility for false negatives) and that PCR is more sensitive that bacterial cultures (22).

Middle ear cholesteatoma was diagnosed in 70% of our population. Middle ear cholesteatoma is a serious complication of chronic otitis media in dogs (13–15). Alterations in the natural drainage of the tympanic bulla such as that often present in brachycephalic breeds can potentially influence middle ear disease development. A recent study determined a high prevalence of inflammation and middle ear effusion in French bulldogs (23), this could be a potential explanation for the development of cholesteatoma in this breed and its high prevalence in our population. Further studies are required to assess the predisposition of cholesteatoma development in brachycephalic breeds. Cholesteatoma has been previously treated with TECA-LBO and trans-canal endoscopic procedure (TEP) followed by medical treatment. As far as the authors are aware this study is the first to report using subTECA as a treatment option for cholesteatoma. Our results are comparable with both techniques. Recurrence has been reported in 25 to 52% of TECA-LBO treated cholesteatomas within 7 to 12 mo after and in 30% of TEP-treated cholesteatomas 4 mo after initial treatment (11–13,24). In the cases treated by TEP, ear flushing was performed weekly initially, then every 2 wk, and finally once per month as part of long-term medical management. In our study revision surgery was required in only 1 case (1/12 ears; 8%) with deep infection due to cholesteatoma recurrence (4 mo after surgery). These results are lower than those in other previous studies (11–13,24). However, in our opinion, assessment of cholesteatoma recurrence is challenging based on the persistence of neurological deficits in postsurgical animals, making it difficult to evaluate a possible recurrence on initial stages. In our population, worsening of clinical signs was not observed during the length of our study.

This study has several limitations inherent with clinical retrospective studies. In our study most dog had facial nerve paralysis before initiation of the subTECA-LBO procedure making very difficult the assessment of postoperative iatrogenic facial nerve neuropraxia and cholesteatoma recurrence.

In conclusion, and based on our results, subTECA-LBO should be considered as an alternative to standard TECA-LBO in French bulldogs with irreversible middle ear disease and minimal external ear changes as defined in this study. Complications are generally minor in nature and similar to standard TECA-LBO with the added benefit of maintaining a normal appearance and movement of the pinna.

Appendix I.

Questionnaire
1.	Is your dog still alive? For how long was your dog alive after surgery/when did your dog die? Date/time period Was ear disease/surgery the main reason for euthanasia/cause of death?
2.	Was head tilt present after surgery? Did your dog show head tilt after surgery? No, completely recovered Partially recovered Head tilt still present For how long was your dog affected by head tilt? Time period
3.	Did your dog show facial nerve paralysis after surgery? (lip droop, inability to voluntarily blink, absent palpebral reflex) Completely recovered Partially recovered Facial nerve paralysis still present For how long was your dog affected by facial paralysis/paresis? Time period If affected, has he/she suffered with corneal ulcers?
4.	Have you noticed any skin issues/otitis externa on the operated ear?
5.	Has ear carriage been affected/changed?
6.	Did your dog have any recurrent symptoms of otitis media after surgery? (head tilt, ataxia, nystagmus, facial paralysis) Did your dog need revision surgery on the same ear after the first procedure?