Ear cleaning: the UK and US perspective

Clinical and Microbiological Performances and Effects on Lipid and Cytokine Production of a Ceruminolytic Ear Cleaner in Canine Erythemato-Ceruminous Otitis Externa

Erythemato-ceruminous otitis externa (ECOE) is the most common type of otitis in dogs and is generally associated with bacterial and/or yeast infections. The performance of an ear cleaner was assessed over two weeks in canine ECOE, associated with a mild or moderate secondary infection, in a prospective open-label study. Forty ear canals with ECOE that did not receive any type of aural treatment and were not cleaned for 7 days were included. Pruritus (PS), 0−3 Otitis Index Score (OTIS-3) and 0−4 scale cytology (CYTO) scores were assessed on Day (D) 0, D7 and D14. Concentrations of a panel of 13 cytokines on the ear canal surface and the lipid profile of the exudate were measured on D0 and D14. From D0 to D12 or D13, the dogs’ ears were cleaned daily if the secretion score (SEC) was 3/3, every second day if the score was 2/3 and every third day if the score was 1/3. PS, OTIS-3, SEC and CYTO were significantly lower on D7 compared to baseline (−40%, −31%, −36%, −34%, respectively; p < 0.0001). The same parameters decreased further on D14 (−60%, −53%, −61%, −73%, respectively; p < 0.0001) and amounts of interleukin 8 and chemokine KC-like were also reduced compared to baseline (−45%, p < 0.01; −36%, p = 0.3, respectively). The lipid profile was also modified, with a decrease in free lipids and an increase in bound lipids.

A Review of Recent Developments in Veterinary Otology

The knowledge gap between practical research and its implementation in veterinary practice is becoming harder to bridge, as researchers now have a plethora of journals in which to publish. This paper summarizes recent research from the latest publications related to ear disease in dogs which have implications for veterinary practitioners. The topics reviewed include 16s rRNA new-generation sequencing, the use of oclacitinib in pinnal ulceration, the etiopathogenesis of aural hematoma, contamination of the middle ear during elective myringotomy and how to avoid it, and the use of carbon dioxide lasers in chronic obstructive otitis.

Methicillin-resistant Staphylococcus schleiferi subspecies coagulans associated with otitis externa and pyoderma in dogs

Background:

Dermatological infections are the most common cases in the daily pet clinic. Since its discovery in 1990, Staphylococcus schleiferi subspecies coagulans have been reported more frequently in canine otitis externa and pyoderma and even in cases of zoonoses.

Aim:

Detect the presence of S. schleiferi subsp. coagulans of canine otitis externa and pyoderma, its antimicrobial resistance, and the presence of mecAgen.

Methods:

Three-hundred-thirty-one swabs from dogs with otitis externa and pyoderma were cultured on bacteriological agar for bacterial isolation and subsequent biochemical and molecular identification. The identified S. schleiferi subsp. coagulans were evaluated for their antimicrobial susceptibility using the Kirby–Bauer technique, including an oxacillin disk, and subsequently, a PCR was run to identify which ones had the mecA gene.

Results:

Thirty-four (22.97%) and twelve (6.56%) isolates were identified as S. schleiferi subspecies coagulans from otitis externa and pyoderma, respectively. Fluoroquinolones, the most widely used group of antibiotics in Peru, showed a susceptibility of 58.82% (20/34) in cases of otitis externa and 50% (6/12) in cases of canine pyoderma. Meanwhile, nitrofurantoin was the antibiotic with the best efficacy in both cases, with 97% (33/34) in otitis externa and 83% (10/12) in pyoderma. Furthermore, 40% (13/34) of S. schleiferi subsp. coagulans isolated from otitis externa were resistant to methicillin, and 85.29% (29/34) had the mecA gene. On the other hand, the only methicillin-resistant isolate from pyoderma was also the only one with a mecA gene.

Conclusion:

This study is the first report of S. schleiferi subsp. coagulans in Peru, finding a higher percentage than reported in other South American countries.

Clinical Techniques: When and how to do a myringotomy - a practical guide

A myringotomy is a surgical incision made in the tympanic membrane (TM). This gives access to the middle ear for sampling, flushing and instilling topical therapy. It should be considered whenever the TM is intact and there is clinical evidence of otitis media, abnormal TMs and/or abnormal diagnostic imaging. Samples should be collected for cytological investigation and culture, and then the external ear should be cleaned and dried (if required). Myringotomies should be performed under general anaesthesia and, wherever possible, using a video otoscope; the enhanced view and instrument ports facilitate the technique and reduce the risk of complications. The myringotomy incision should be made in the caudoventral quadrant of the TM using an appropriately sized urinary catheter to collect samples and flush the middle ear cavity. A thorough understanding of the anatomy, technique and potential ototoxicity of topical therapy is needed to minimize the risk of neurological and other complications. The TM usually heals within 35 days if kept free of infection.

Cytological and microbiological characteristics of middle ear effusions in brachycephalic dogs

Background

Middle ear effusion is common in brachycephalic dogs with similarities to otitis media with effusion in children. Association with the cranial and eustachian tube morphology and bacterial infection is suspected in both species.

Hypothesis/objectives

To determine cytological and bacteriological features of middle ear effusions in dogs, provide information on histological features, and further assess the dog as a model of the human disease.

Animals

Sixteen live dogs, 3 postmortem cases of middle ear effusion, and 2 postmortem controls.

Methods

Prospective; clinical investigation using computed tomography, magnetic resonance imaging, video‐otoscopy, myringotomy; cytological assessment of 30 and bacteriology of 28 effusions; histology and immunohistochemistry (CD3 for T‐lymphocytes, Pax5 for B lymphocytes and MAC387 for macrophages) of 10 middle ear sections.

Results

Effusions were associated with neurological deficits in 6/16 (38%) and concurrent atopic dermatitis and otitis externa in 9/16 (56%) of live cases. Neutrophils and macrophages predominated on cytology (median 60 [range 2%‐95.5%] and 27 [2%‐96.5%]) whether culture of effusions was positive or not. In histology sections, the mucosa was thickened in affected dogs but submucosal gland dilatation occurred in affected and unaffected dogs. There was no bacterial growth from 22/28 (79%) of effusions. Bacteria isolated from the other 6 (21%) were predominantly Staphylococcus pseudintermedius (4/6, 67%).

Conclusions and Clinical Importance

Clinical, morphological, and cytological findings in middle ear effusions of dogs and people suggest similar pathogeneses. Middle ear effusion of dogs could be a useful model of human otitis media with effusion. Such comparisons can improve understanding and management across species.

In vitro and in vivo efficacy of tea tree essential oil for bacterial and yeast ear infections in dogs

ABSTRACT: Otitis externa is a common complaint in dogs. Bacteria and yeasts are commonly involved and may perpetuate inflammatory reactions inside the ear canal. Otoscopy, cytological examination of secretion and microbiological culture embody forms of diagnosis. Cytology also has great use in accessing treatment evolution. Therapy usually consists of cleaning ear canals and subsequent use of antibiotics or antifungal products. As some of them may cause hypersensitivity and even ototoxicity, searching for new pharmacological bases is currently necessary and justifies this study, which aimed to evaluate in vitro and in vivo efficacy of tea tree essential oil for bacterial and yeast ear infections in dogs. Twenty-eight dogs from a particular shelter in Cuiabá (Mato Grosso, Brazil), presenting clinical signs of otitis externa, were enrolled in this clinical trial. In all of them, clinical and cytological evaluations, as well as culture and susceptibility testing of the affected ears were carried out. From each dog, one ear was treated with 5% tea tree essential oil lotion and the other with standard otic formulation, according to the type of infection (bacterial, yeast or both). In vitro susceptibility testings of all ear cultures, to the same drugs used in treatment, were also carried out. Culture results showed 62.5% bacterial and fungal infection, 33.9% bacterial infection and 3.6% fungal infection, from the 56 ear samples collected. The most common microorganisms isolated were Staphylococcus intermedius, Staphylococcus aureus, Proteus mirabilis and Malassezia pachydermatis. Gram-positive bacteria were susceptible to gentamycin in 60.5% and resistant in 16.3% of the samples. Five percent tea tree essential oil formulation produced a 5mm clear zone of inhibition around the disks in one of the 63 samples evaluated. Pure (100%) tea tree essential oil formulation produced a 10mm clear zone of inhibition around the disks in four of the 63 samples evaluated, a 9mm zone in three samples, an 8mm zone in 16 samples, a 7mm zone in seven samples, a 6mm zone in two samples and there was no clear zone in 31 samples. Inhibition zones were produced by strains of Staphylococcus intermedius, Staphylococcus hyicus, Corynebacterium sp., Proteus mirabilis and Enterobacter sp. tea tree essential oil ear solution significantly induced remission of clinical signs both in bacterial and yeast ear infections. It also reduced as much Malassezia pachydermatis ear infection as the nystatin solution used in this study, while gentamycin solution showed better antibacterial effect. More studies should be conducted to evaluate in vitro diffusion properties of tea tree essential oil. Good antimicrobial spectrum and the absence of adverse reactions confirm the importance of developing a tea tree formulation as an alternative therapy for ear infections in dogs.

Self-ear cleaning practices and the associated risk of ear injuries and ear-related symptoms in a group of university students

Self-ear cleaning is the insertion of objects into the ear canal to clean it, a widespread practice that has the potential to compromise its integrity as a natural, selfcleansing mechanism, and a risk factor for possible injuries. The practice is common among young adults and highest in university than any other graduates. This study aimed to determine the self-ear cleaning practices and associated risk of injury and related symptoms in undergraduate students at KwaZulu-Natal University. The descriptive survey utilized a self-administered questionnaire. Of the 206 participants that responded, 98% engaged in self-ear cleaning, with 75% indicating that it was beneficial. The commonest method (79.6%) being the use of cotton buds, with an associated injury rate of 2.4%. There was no statistically significant associations between those who used or did not use cotton buds and the symptoms experienced. The complications indicate that self-ear cleaning does pose a risk for injury, necessitating more community information and education.

[In vivo-efficacy of an ear medication using gelatin powder as a vehicle for the therapy of canine otitis externa]

OBJECTIVE

Otitis externa is normally treated with daily topical medication. Longer application intervals may be useful to facilitate therapy. In this study, the in vivo efficacy of a gel preparation containing marbofloxacin, dexamethasone and enilconazole was compared to that of a commercial otologic agent containing marbofloxacin, dexamethasone and clotrimazole based on clinical signs, ear cytology and bacterial/fungal cultures.

MATERIAL AND METHODS

A gel preparation (group A) or a registered otologic agent (group B), respectively, was applied to 41 dogs. A total of 50 ears (25 per group) were analysed. The gel preparation was administered on days 0 and 5; the combination preparation was administered daily according to the manufacturer's recommendations. Dogs were reevaluated clinically and cytologically after 5 and 10 days. Initially and after 10 days, ear swabs were taken for bacterial and fungal cultures.

RESULTS

No significant clinical or cytological differences were found between the groups. Significantly more isolates resistant to marbofloxacin were identified in group A after 10 days, although >98% of marbofloxacin was still detectable in vitro after 15 days.

CONCLUSION

The clinical and cytological efficacy of a gel containing defined active agents applied twice 5 days apart was comparable to that of an authorised otologic agent applied once daily. There appears to be an increased risk with the gel in that a resistance to fluoroquinolones develops. Local adverse effects are also possible.

CLINICAL RELEVANCE

A gelatine preparation containing active agents may be an alternative to daily topical therapy of canine otitis externa. The development of resistances is possible.

Topical ear treatment - options, indications and limitations of current therapy

Topical otic products form an integral part of the overall management of otitis externa. With an ever increasing array of ear drops and cleaners to choose from, appropriate selection of therapy can be difficult. The investigation of all cases of otitis externa should consider primary and secondary causes and predisposing and perpetuating factors. This article considers topical therapy under these same broad headings and discusses, through literature review, the various properties of the components of the ear cleaning solutions and drops.

Ceruminal diffusion activities and ceruminolytic characteristics of otic preparations - an in-vitro study

Background

An in-vitro setup was established in order to determine a) the diffusion activities of eight otic preparations (Aurizon®, Eas Otic®, Epi Otic®, Otifree®, Otomax®, Panolog®, Posatex®, Surolan®) through synthetic cerumen, and b) the ceruminolytic capacity and impregnation effects of these products. The main lipid classes of canine cerumen produced with moderate, non-purulent otitis externa were determined by thin layer chromatography and were subsequently used to produce a standardised synthetic cerumen (SCC). SCC was filled into capillary tubes, all of which were loaded with six commercially available multipurpose otic medications and two ear cleaners, each mixed with two markers in two experimental setups. These two marker compounds (Oil red O and marbofloxacin) were chosen, since they exhibit different physicochemical drug characteristics by which it is possible to determine and verify the diffusion activity of different types of liquids (i.e. the otic preparations). A synthetic cerumen described in the literature (JSL) was also used for comparison as its lipid composition was different to SCC. The diffusion activities of the otic preparations through both types of synthetic cerumen were studied over 24 hours. A second in-vitro experiment determined both the ceruminolytic activity and impregnation effect of the otic preparations by comparing the weight loss or weight gain after repeated incubation of JSL.

Results

Canine cerumen is mainly composed of triglycerides, sterol esters, fatty acid esters and squalene. The diffusion experiments showed a high diffusion efficacy along with a high impregnation effect for one test product. All the other products exhibited a lower diffusion activity with a mild to moderate impregnation effect. A mild ceruminolytic activity was observed for the two ear cleaners but not for any of the otic medications.

Conclusions

The present study demonstrates that there are significant differences in the diffusion characteristics and ceruminolytic properties of the eight tested otic preparations.

Bacterial contamination of commercial ear cleaners following routine home use

Ear cleaning solutions are designed for repeated use, which raises the possibility for bacterial contamination leading to recurrent or persistent infectious otitis. The purpose of this study was to investigate the prevalence of bacterial contamination of commercial ear cleaners following routine home use in dogs and to describe the characteristics that are associated with contamination. Used ear cleaner bottles and information regarding their use were obtained from canine owners visiting veterinary dermatologists. Both the bottle applicator tips and the solution contents were cultured for aerobic bacteria. Bacterial contamination was present on 10% of the bottle tips and in 2% of the solutions. Isolated bacteria included Staphylococcus pseudintermedius, Bacillus spp., coagulase-negative Staphylococcus spp., Micrococcus spp. and Burkholderia cepacia. The contamination rate was significantly higher on the applicator tips than in the solutions (P = 0.0076). The applicator tip contamination rate was significantly higher in expired samples (17%) than in-date samples (4%; P = 0.0277). The bottle sizes were significantly larger for the samples with contaminated applicator tips compared with noncontaminated tips (P = 0.0455). The contamination rate was significantly higher when Tris-EDTA was an ingredient. Cleanliness of the bottle, contact with the ear canal and infection status of the ear at time of culture had no bearing on the contamination rate. In summary, with routine home use of commercial ear cleaners, pathogenic bacterial contamination is of minor concern. This concern may increase when expired products or larger bottles of ear cleaner are used and when Tris-EDTA is an ingredient.

Treatment of canine otitis externa using video otoscopy

Otitis externa in 27 toy poodles and 40 miniature dachshunds was treated using a video otoscope. A distinct concavity (external tympanic concavity) was observed at the junction between the ventral part of the external surface of the tympanum and the ear canal to which a considerable amount of hair and debris had adhered. All hair and debris adhering to the external tympanic concavity were removed, and systemic antibiotic and antifungal agents were administered, after which all of the dogs recovered. The pattern of hair growth observed in the external tympanic concavity could be characterized according to the breed of dog. All of the toy poodles presented with curly hairs, while the miniature dachshunds had upright or flat-lying hairs.

In vitro investigation of ceruminolytic activity of various otic cleansers for veterinary use

Knowledge of the ceruminolytic activity of commercially available ear cleansing products assists the practitioner to choose the best available product for specific clinical situations. The aim of this study was to quantify and compare the ceruminolytic activity of commercially available canine ear cleansers. For this purpose, the ceruminolytic activity of 13 ear cleansers was evaluated using a standardized synthetic cerumen (SSC) that mimics the composition and texture of canine cerumen. The test products were incubated with mild agitation for 20 min with 500 mg of SSC previously compacted at the bottom of a test tube. Ceruminolytic activity was then assessed by quantifying the SSC removed by decantation. This procedure was repeated five consecutive times on each tube simulating repeated applications in the canine ear canal. Good repeatability among replicates was found in this assay, allowing direct comparisons between products. The final percentage of SSC elimination ranged from none (similar to water), between 8 and 39% for three products and up to 90% for one product (P<0.001). It is concluded that, in the experimental conditions used in this study, only 1/13 products had significant ceruminolytic activity.