Causes of otitis externa

Comparative performance of video-otoscopy and CT in the diagnosis of external ear disease in cats

OBJECTIVES

The aim of the study was to compare CT with video-otoscopy for detecting external ear canal masses in cats and to describe CT features of feline external ear disease.

METHODS

This retrospective study evaluated the external ear canals of cats that underwent both CT and video-otoscopy. Two blinded observers reviewed the CT scans and their findings were compared with video-otoscopy results evaluated by one blinded observer.

RESULTS

Of the 32 examined ears, 13 had an external ear canal mass detected by both CT and video-otoscopy. No false positives were identified. All 19 ears without masses were correctly identified as true negatives, resulting in perfect agreement for mass detection (kappa = 1.000). On histopathology, 9/13 masses were diagnosed as polyps, 1/13 masses was diagnosed as carcinoma, 2/13 did not undergo histopathology and 1/13 masses seen on video-otoscopy was diagnosed as otitis externa with granulomatous tissue formation. Of the 16 cats examined, 12 had a mass in the external ear canal diagnosed by video-otoscopy: six domestic shorthairs, five Maine Coons and one Oriental Shorthair cat. Of these cats, 11 had a unilateral mass and one had a bilateral mass. There was very low agreement between CT and video-otoscopy for ear canal wall enhancement and erythema (kappa = 0.033), as well as for ear canal thickening and stenosis (weighted kappa = 0.056). There was no significant difference between chronic and non-chronic clinical signs in terms of the presence of ear canal wall mineralisation (P = 0.223).

CONCLUSIONS AND RELEVANCE

There is high agreement between video-otoscopy and CT in detecting external ear canal masses in cats. However, there is very low agreement between CT and video-otoscopy for ear canal wall enhancement, erythema, thickening and stenosis. The presence of external ear canal mineralisation did not correlate with the chronicity of clinical signs.

Can We Minimize the Risk of Dogs Developing Canine Otitis Externa?-A Retrospective Study on 321 Dogs

Background: Canine otitis externa is a common presentation in small animal practice. The clinical signs vary individually from patient to patient. Regardless of the expression, they all decrease the quality of life. Therefore, this study aimed to identify factors that showed reduced odds for otitis externa. Methods: Clinical case records were searched for key terms regarding canine otitis. Statistical analyses were applied to evaluate associations with otitis externa. p-values of <0.05 were considered statistically significant. Results: Rhodesian Ridgeback and dogs with underlying infectious diseases had a reduced risk for otitis externa, while Retrievers and dogs with allergies had an increased risk. Furthermore, in the group of dogs with endocrinopathies, those with normal weight showed a reduced risk of developing canine otitis in comparison to those which were overweight. Conclusions: These results show a new point of view to reduce the prevalence of canine otitis by reducing the animals' weight due to an additional risk of otitis in obese or overweight dogs. Furthermore, for the first time, Rhodesian Ridgebacks were identified in our study population to have a lower risk of developing otitis externa. Thus, breeders should reflect-within other responsibilities for the quality of life in their offspring-on breed-specifics about otitis when planning ahead.

Effect of ear cleaning on treatment outcome for canine otitis externa

BACKGROUND

Ear cleaning is often recommended for management of canine otitis externa (OE). Few in vivo studies evaluate how ear cleaning affects treatment outcome.

HYPOTHESIS/OBJECTIVES

To determine the effect of ear cleaning on canine OE by comparing treatment outcome in cleaned versus noncleaned ears.

ANIMALS

Twenty-three client-owned dogs with ceruminous or purulent OE.

MATERIALS AND METHODS

Forty ears were randomised to one of two groups: 20 ears were wiped with dry or saline-moistened gauze (grp1), and 20 external ear canals received manual cleaning (grp2) with a commercial product. One millilitre of a commercial otic suspension containing hydrocortisone aceponate, miconazole nitrate and gentamicin sulfate was applied to affected ears every 24 h for five days. Cytological scores, modified otitis index score (OTIS3), pruritus Visual Analog Scale (PVAS), modified PVAS and client questionnaire were compared on Day (D)0 and D7.

RESULTS

There were no statistical differences between cytological scores, modified OTIS3, PVAS, modified PVAS or client assessments between groups at D7. Both groups had significant reduction in all treatment parameters from D0 to D7 with the exception of cytological rod scores that were only significantly decreased in cleaned ears. There was a significant difference in OTIS3 before and after cleaning on D0.

CONCLUSIONS AND CLINICAL RELEVANCE

Both groups achieved successful outcome regardless of cleaning. Ear cleaning may be more important when rod-shaped bacteria are present.

Action of mycocins produced by Wickerhamomyces anomalus on Malassezia pachydermatis isolated from the ear canal of dogs

This study aims to examine the effectiveness of mycocins produced by Wickerhamomyces anomalus in inhibiting Malassezia pachydermatis, a yeast commonly found in the ear canal of dogs. M. pachydermatis has a zoophilic origin and can be found in mammals, and frequently in dogs, where it mainly colonizes the ear canal region and the skin, leading to lesions that are difficult to treat. The antimicrobial mechanism was evaluated using dilutions of supernatant with enzymatic activity, which may include β-glucanases, glycoproteins known to act on microorganism cell walls. However, it is important to note that this supernatant may contain other compounds as well. β-glucanases in the mycocins supernatant were found at a concentration of 0.8 U/mg. The susceptibility of M. pachydermatis isolates was tested using the microdilution method. The isolates suffered 100% inhibition when tested with the culture supernatant containing mycocins. In the proteinases production test, 44% of the isolates tested were strong proteinases producers. Subsequently all these isolates suffered inhibition of their activity when tested in research medium containing mycocins supernatant at a subinhibitory concentration of β-glucanases. This shows that mycocins can inhibit the production of proteinases, a virulence factor of M. pachydermatis. The viability test showed the antifungal action of mycocins in inhibiting the viability of M. pachydermatis cells after a period of 8  hours of contact. These results support the antimicrobial potential of mycocins and their promise as a therapeutic option.

Prevalence of middle ear effusion in French bulldogs without clinical signs of otic disease: A retrospective study of magnetic resonance imaging (2017-2022)

BACKGROUND

Canine middle ear effusion (MEE) is usually asymptomatic, being an incidental finding when computed tomography or magnetic resonance imaging (MRI) of the head is performed for other reasons unrelated to otic disease. The clinical relevance of the presence of material in the tympanic bulla (TB) remains uncertain, and more detail about its prevalence and appearance in MRI are required.

OBJECTIVE

To assess the prevalence of presence of material within the TB of French bulldogs (FB) with no clinical signs suggestive of otitis (externa, media or interna) that underwent high-field MRI for other medical reasons.

ANIMALS

Two hundred fifty-two TB of 126 FB were included in this study.

MATERIALS AND METHODS

Nonexperimental retrospective study in which MRI images were evaluated by a board-certified veterinary radiologist.

RESULTS

Fifty-eight per cent of the dogs had material in the TB lumen (46% of the TB) and 59% were bilaterally affected. The signal intensity of this material related to the grey matter was variable on T1w and mainly hyperintense on T2w sequences.

CONCLUSION AND CLINICAL RELEVANCE

FB are predisposed to MEE. This is important when assessing imaging studies of TB of FB with chronic otitis externa, as high percentage of cases may have concurrent MEE. MRI findings in FB with MEE are characterised by a hyperintense signal to the grey matter on T2w in most cases and variable on T1w sequences.

Microbiological Survey and Evaluation of Antimicrobial Susceptibility Patterns of Microorganisms Obtained from Suspect Cases of Canine Otitis Externa in Gran Canaria, Spain

A retrospective study of microbiological laboratory results from 2020 to 2022, obtained from a veterinary diagnostic laboratory of the island of Gran Canaria, Spain, focused on canine otitis cases, was performed. The objective of this study was to analyze the pathogen distribution, antimicrobial susceptibility, prevalence of multidrug resistant phenotypes and the role of coinfections in otitis cases in order to provide up-to-date evidence that could support effective control strategies for this prevalent pathology. A total of 604 submissions were processed for the diagnosis of canine external otitis. Of the samples analyzed, 472 were positive for bacterial or fungal growth (78.1%; 95% CI: 74.8-81.4%). A total of 558 microbiological diagnoses were obtained, divided in 421 bacterial (75.4%; 95% CI: 71.8-79.0%) and 137 fungal (24.6%; 95% CI: 20.9-28.1%) identifications. Staphylococcus pseudintermedius, Malassezia pachydermatis and Pseudomonas aeruginosa were the most prevalent microorganisms detected in clinical cases of otitis. High level antimicrobial resistance was found for Pseudomonas aeruginosa (30.7%), Proteus mirabilis (29.4%), Staphylococcus pseudintermedius (25.1%) and Escherichia coli (19%). Multidrug-resistant phenotypes were observed in 47% of the bacteria isolated. In addition, a 26.4% prevalence of methicillin-resistant Staphylococcus pseudintermedius was detected. The high prevalence of antimicrobial resistant phenotypes in these bacteria highlights the current necessity for constant up-to-date prevalence and antimicrobial susceptibility data that can support evidence-based strategies to effectively tackle this animal and public health concern.

Tolerability of Otic Solutions Containing Different Enrofloxacin Concentrations in Dogs with Healthy Ears

Otitis externa (OE) is a common disease in dogs, and topical medications are the preferred treatment. Compounded solutions of enrofloxacin are commonly used in practice to treat bacterial OE; however, the tolerability of different concentrations of this antibiotic in the ear canals of dogs has not been evaluated. The objective of this study is to determine if a higher concentration of enrofloxacin applied to the external ear canal is clinically tolerated in dogs with healthy ears. Sixteen client-owned dogs with bilateral healthy ears and no previous history of OE were enrolled. Injectable enrofloxacin 2.27% diluted with sterile sodium chloride in 1:1 (11.35 mg/mL) and 2:1 (15 mg/mL) ratios were applied into the dogs' right and left ears, respectively, q 12 hr for 14 days. Based on video otoscopic examination, clinical score for canine OE (OTIS3) results before application were ≤1 for all dogs. During the study and at the conclusion, all scores remained ≤2, which is considered normal. No cytologic inflammatory cells were seen in any of the dogs' ears throughout the study. Different concentrations of enrofloxacin solution applied topically were well tolerated by dogs with healthy ears and can be considered for the treatment of dogs with bacterial OE.

In Vitro Activity of Farnesol against Malassezia pachydermatis Isolates from Otitis Externa Cases in Dogs

Chronic otitis externa of dogs is a significant problem due to the prevalence and complexity of the treatment of such animals. There is evidence that in 60-80% of cases of infectious diseases microorganisms located in the biofilm phenotype play the main role. Microorganisms in the biofilm phenotype have a number of advantages, the most significant of which is considered to be increased resistance to various external factors. Among them, a special place is occupied by resistance to antibiotics. In recent decades, research has been conducted at an increasing scale on the role of biofilm infections in various pathologies in veterinary medicine. The etiology and therapy of dog otitis externa caused by Malassezia pachydermatis biofilm has not been fully studied. This is why we consider relevant the scientific and practical aspects of research on the etiology and therapy of dog otitis externa from the position of biofilm infection. In this work, it has been statistically proven that there is a relationship between the optical density of Malassezia pachydermatis biofilms and their sensitivity to drugs, and this relationship is statistically significant. In addition, we have demonstrated that Farnesol has a good antibiofilm effect at a concentration of more 1.6 μM/mL (24% OD decrease of biofilm), and its highest antibiofilm effect (71-55%-more than a half) was observed at a concentration of 200-12.5 μM/mL.

Evaluation of hypochlorous acid as an ear flush in dogs with chronic otitis externa

BACKGROUND

Chronic otitis externa (OE) in dogs frequently requires anaesthetised ear flushing.

OBJECTIVES

To evaluate hypochlorous acid as an ear flushing and antimicrobial agent in dogs with chronic OE.

ANIMALS

Twenty dogs with chronic OE caused by the same organisms bilaterally.

MATERIALS AND METHODS

One ear was flushed under anaesthesia with hypochlorous acid, the other with saline solution. Subsequently, the ear flushed with hypochlorous acid was cleaned with the same solution twice daily for 2 weeks, the other ear with a commercial ear cleaner. An ear medication containing miconazole, polymyxin B and prednisolone was used once daily in both ears. Clinical scores were determined before the flush. Ear cytological results were obtained, a hearing test was conducted before and after the ear flush, and a culture was taken directly after flushing. Ears were evaluated after 2 weeks of therapy.

RESULTS

Yeast was present in the ears of 11, cocci in one and a mixed infection in eight dogs. Five ears were negative on culture after flushing with hypochlorous acid, one after the saline flush. Clinical and cytological scores decreased significantly with both solutions after 2 weeks of treatment. There was no difference between treatments in any of the scores at any time point between treatments and in the results of the hearing test before and after the flushing procedure. Adverse effects were not seen.

CONCLUSIONS AND CLINICAL RELEVANCE

Hypochlorous acid is a suitable cleaning solution for canine OE.

An epidemiological study of the predictors of multidrug resistance and methicillin resistance among Staphylococcus spp. isolated from canine specimens submitted to a diagnostic laboratory in Tennessee, USA

Background

Understanding drivers of multidrug resistance (MDR) and methicillin resistance, which have increased among canine staphylococcal isolates, is essential for guiding antimicrobial use practices. Therefore, the objective of this study was to identify predictors of MDR and methicillin resistance among Staphylococcus spp. commonly isolated from canine clinical specimens.

Methods

This retrospective study used records of canine specimens submitted to the University of Tennessee College of Veterinary Medicine Clinical Bacteriology Laboratory for bacterial culture and antimicrobial susceptibility testing between 2006 and 2017. Records from 7,805 specimens positive for the following Staphylococcus species were included for analysis: Staphylococcus pseudintermedius, Staphylococcus aureus, Staphylococcus coagulans (formerly Staphylococcus schleiferi subspecies coagulans), and Staphylococcus schleiferi (formerly S. schleiferi subsp. schleiferi). Generalized linear regression models were fit using generalized estimating equations (GEE) to identify predictors of MDR (defined as resistance to three or more antimicrobial classes) and methicillin resistance among these isolates.

Results

Multidrug resistance (42.1%) and methicillin resistance (31.8%) were relatively common. Isolates from skeletal (joint and bone) specimens had the highest levels of MDR (51.3%) and methicillin resistance (43.6%), followed by cutaneous specimens (45.8% multidrug-resistant, 37.1% methicillin resistant). Staphylococcus species, specimen site, and clinical setting were significant (p < 0.01) predictors of both outcomes. Compared to S. pseudintermedius, S. schleiferi had higher odds of methicillin resistance, while S. coagulans and S. schleiferi had lower odds of MDR. The odds of both MDR and methicillin resistance for isolates from hospital patient specimens were significantly higher than those from referral patients for urine/bladder and otic specimens. Odds of MDR among isolates from skeletal specimens of hospital patients were also higher than those of referral patients.

Conclusions

Staphylococcus isolates in this study had substantial levels of MDR and methicillin resistance. Differences in the odds of these outcomes between referral and hospital patient isolates did not persist for all specimen sites, which may reflect differences in diagnostic testing and antimicrobial use practices with respect to body site or system. Judicious antimicrobial use, informed by culture and susceptibility testing, is important to limit treatment failures and curb selection pressure.

Otitis media and interna with or without polyps in cats: association between meningeal enhancement on postcontrast MRI, cerebrospinal fluid abnormalities, and clinician treatment choice and outcome

OBJECTIVES

The aim of this study was to evaluate the association between meningeal enhancement (MgE) and cerebrospinal fluid (CSF) analysis results, their individual association with bacteriology results from affected ear samples and whether these test results influenced clinicians' therapeutic choice in cats with otitis media and interna (OMI).

METHODS

This was a multicentre retrospective study carried out over an 8-year period. Cats diagnosed with OMI, with or without a nasopharyngeal polyp, leading to peripheral vestibular signs were included. Only cats for which MRI with postcontrast T1-weighted sequences and CSF analyses available were included. Cats with intra-axial MRI lesions or empyema were excluded.

RESULTS

Fifty-eight cats met the inclusion criteria. MgE was reported in 26/58 cases, of which nine had an abnormal CSF result (increased total nucleated cell count [TNCC] or total protein); 32/58 cases had no MgE, of which 10 showed abnormal CSF results. There was no association between bacteriology results (external ear canal or bulla) and MgE or abnormal CSF results. CSF abnormalities were statistically significantly more common in acute cases (n = 16/37) than in chronic cases (n = 3/21; Fischer's test P = 0.04). Prednisolone was prescribed in 10/16 cases with increased TNCC. Among the 42 cases with normal TNCC, 15 received prednisolone and 13 received non-steroidal anti-inflammatory drugs. Various antimicrobial drugs were prescribed in 53/58 cats. Duration of antimicrobial treatment was similar, regardless of positive bacterial culture (5.58 vs 4.22 weeks), abnormal CSF (5.83 vs 4.76 weeks) or MgE (5.33 vs 4.90 weeks).

CONCLUSIONS AND RELEVANCE

No association was found between the CSF and MgE results. Furthermore, no association was found between MgE, CSF or bacteriology findings. In addition, abnormal CSF results might lead the clinician to treat with corticosteroids, but they did not have any impact on duration of antimicrobial treatment. CSF abnormalities were seen significantly less frequently in chronic cases. The outcome tended to be poorer when MgE was detected on MRI.

Antibiotic Resistance and Species Profile of Enterococcus Species in Dogs with Chronic Otitis Externa

Otitis externa, a common disease in dogs, has different etiologies. Enterococcus is a Gram-positive bacterium that frequently causes opportunistic ear infections. Here, we determined the distribution of Enterococcus in canine otitis externa via time-of-flight mass spectrometry and biochemical tests and evaluated their resistance patterns to 10 commonly used antibiotics. Among the 197 Enterococcus isolates, E. faecalis (48.7%; 96/197) was the most common, followed by E. faecium (21.3%; 42/197), E. casseliflavus (11.7%; 23/197), E. hirae (10.7%; 21/197), E. avium (3.6%; 7/197), E. gallinarum (2.5%; 5/197), E. canintestini (1.0%; 2/197), and E. durans (0.5%; 1/197). All isolates were tested for antibiotic resistance using the Kirby-Bauer disc diffusion method. Enterococcus faecalis strains were highly resistant to erythromycin (45.8%) and rifampin (34.3%) but were generally susceptible to penicillin class antibiotics. In contrast, E. faecium isolates were highly resistant to penicillin class antibiotics (ampicillin, 61.9%; penicillin, 71.4%). Most importantly, E. faecium demonstrated high resistance to most of the antibiotics used in this study. Multidrug resistance was found in 28.4% of the isolates (56/197). This study shows prevalence and antibiotics resistance profiles of Enterococcus species in canine chronic otitis externa. The results can contribute to establish therapeutic strategies of Enterococcus infections and be used as a comparable index of antibiotic resistance of Enterococcus in the future.

Antimicrobial Resistance and Virulence Factors of Proteus mirabilis Isolated from Dog with Chronic Otitis Externa

Otitis externa is among the most prevalent diseases in dogs. If the underlying cause is not addressed, bacterial reinfection becomes frequent, necessitating antibiotic administration for an extended period of time. Prolonged treatment promotes the emergence of antibiotic-resistant bacteria and increases the risk of their transmission from animals to humans. This study aimed to analyze the antibiotic resistance pattern of the emerging pathogen Proteus mirabilis to identify bacterial virulence and antibiotic selection. Samples were collected from randomly encountered dogs with chronic otitis externa. Thirty-two strains of P. mirabilis were isolated and identified, using MALDI-TOF. The Kirby-Bauer disk diffusion method was used to assess the antibiotic susceptibility of P. mirabilis to 11 antibiotics. The isolates (n = 32) were most resistant to cefazolin (75%), trimethoprim–sulfamethoxazole (72%), chloramphenicol (72%), amoxicillin–clavulanate (63%), ampicillin (59%), cefepime (56%), ciprofloxacin (53%), aztreonam (50%), ceftazidime avibactam (50%), gentamicin (22%), and amikacin (16%). Moreover, 75% of isolates were found to be multidrug-resistant bacteria. P. mirabilis was found to have a high resistance-pattern ratio. Although the exact cause is unknown, continuous antibiotic use is thought to be a major factor. We concluded that antibiotic use must be prudent and selective to prevent antibiotic resistance.

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.

Reporting the epidemiology of aural haematoma in dogs and proposing a novel aetiopathogenetic pathway

To evaluate the incidence and risk factors for aural haematoma in dogs under primary veterinary care in the UK. A cohort study design. Dogs diagnosed with aural haematoma during 2016 were identified from the VetCompass database. Univariable and multivariable logistic regression modelling were used for risk factor analysis. There were 2,249/905,554 dogs diagnosed with aural haematoma during 2016. The estimated one-year incidence risk for aural haematoma was 0.25% (95% confidence interval 0.24–0.26). After accounting for confounding factors, 14 breeds showed increased odds and 20 breeds showed reduced odds of aural haematoma compared with crossbred dogs. Breeds with the highest odds included Bull Terrier (OR 7.42, 95% confidence interval 4.39–12.54), Saint Bernard (OR 7.28, 95% confidence interval 3.58–14.81) and French Bulldog (OR 6.95, 95% confidence interval 5.55–8.70). Increasing age, increasing bodyweight and breeds with V-shaped drop and semi-erect ear carriage also showed increased odds of aural haematoma. Associations between ear carriage within breeds and the risk of aural haematoma suggest that trauma along the line of cartilage folding within V-shaped and semi-erect ears may trigger aural haematoma. New knowledge of key breed predispositions will contribute to improved breed health control strategies.

In vitro antibacterial and antibiofilm effects of cold atmospheric microwave plasma against Pseudomonas aeruginosa causing canine skin and ear infections

BACKGROUND

Pseudomonas aeruginosa is an opportunist pathogen that causes purulent inflammation in the skin and in the ears of dogs. Among the various virulence factors of P. aeruginosa, biofilms have been reported to result in antibiotic resistance, leading to therapeutic limitations. Cold atmospheric microwave plasma (CAMP) is known to have a high antimicrobial effect, which causes physical cell wall rupture and DNA damage.

HYPOTHESIS/OBJECTIVES

The objective of this study was to evaluate the antibacterial and antibiofilm effects of CAMP against planktonic bacteria and the biofilm of P. aeruginosa.

METHODS AND MATERIALS

The antibacterial effect of CAMP against P. aeruginosa ATCC10145 and clinical isolates (n = 30) was evaluated using the colony count method. We also assessed the effect of CAMP on biofilm of P. aeruginosa ATCC strain by the colony count method, water-soluble tetrazolium salt (WST) assay and confocal laser scanning microscopy (CLSM).

RESULTS

The complete eradication of P. aeruginosa (ATCC strain and clinical isolates) was achieved within 120 s at 50 W, and clinical isolates required 60 s shorter than the ATCC strain for complete eradication at 50 W. We also confirmed the time-dependent bactericidal effect of CAMP at 50 W against ATCC strain biofilm.

CONCLUSIONS AND CLINICAL IMPORTANCE

CAMP was effective against both planktonic bacteria and biofilm formation of P. aeruginosa. However, further studies on in vivo efficacy and safety in canine skin and ears are necessary to fully validate its clinical application.

Clinical reasoning in feline vestibular syndrome: which presenting features are the most important?

OBJECTIVES

The aim of this study was to evaluate whether clinical variables from the history, clinical presentation, and physical and neurological examinations of cats with vestibular syndrome were statistically predictive of the underlying diagnosis.

METHODS

In total, 174 cats presenting with vestibular syndrome between January 2010 and May 2019 were investigated. Univariate statistical analysis of clinical variables was performed and those statistically associated with a diagnosis were retained for multivariable binary logistic regression modelling.

RESULTS

The seven most prevalent diagnoses represented 95% of vestibular presentations, which included: otitis media/interna (n = 48), idiopathic vestibular syndrome (n = 39), intracranial neoplasia (n = 24), middle ear polyp (n = 17), feline infectious peritonitis (n = 13), thiamine deficiency (n = 13) and intracranial empyema (n = 11). Idiopathic vestibular syndrome was commonly associated with non-purebred cats and had 17.8 times the odds of an improving clinical progression (95% confidence interval [CI] 1.3-250.0; P = 0.03). Intracranial neoplasia was associated with older age and chronic onset of clinical signs, and was significantly more likely to have a central vestibular neuroanatomical localisation (95% CI 8.5-344,349,142.0; P = 0.015) with postural deficits on neurological examination. Thiamine deficiency was more common in female cats, with 52.6 times the odds of a waxing and waning clinical progression (95% CI 1.2-1000; P = 0.038) and 6.8 times the odds of presenting with bilateral vestibular signs (95% CI 1.0-45.7; P = 0.047) and wide excursions of the head (95% CI 1.0-45.7; P = 0.047). Middle ear polyps were associated with 8.8 times the odds of presenting with Horner syndrome (95% CI 1.5-50.0; P = 0.015).

CONCLUSIONS AND RELEVANCE

Although it may be difficult to identify the underlying diagnosis in cats with vestibular syndrome from the presenting features alone, there are instances in which discrete clinical features may help to guide clinical reasoning when evaluating cats with vestibular presentations.

Clinical reasoning in canine vestibular syndrome: Which presenting factors are important?

BACKGROUND

Although the use of clinical reasoning has been evaluated for several neurological presentations, this approach has not yet been investigated for dogs with vestibular syndrome.

METHODS

Two hundred and thirty-nine dogs presenting with vestibular syndrome were included in this retrospective study. Univariate analysis of variables (clinical history, signalment, clinical presentation and neurological examination findings) was performed. Variables with p < 0.3 were selected for logistic regression.

RESULTS

Ninety-five percent of dogs were represented by eight conditions: idiopathic vestibular disease (n = 78 dogs), otitis media interna (n = 54), meningoencephalitis of unknown origin (n = 35), brain neoplasia (n = 26), ischaemic infarct (n = 25), intracranial empyema (n = 4), metronidazole toxicity (n = 3) and neoplasia affecting the middle ear (n = 3). Idiopathic vestibular disease was associated with higher age, higher bodyweight, improving clinical signs, pathological nystagmus, facial nerve paresis, absence of Horner's syndrome and a peripheral localisation. Otitis media interna was associated with younger age, male gender, Horner's syndrome, a peripheral localisation and a history of otitis externa. Ischaemic infarct was associated with older age, peracute onset of signs, absence of strabismus and a central localisation.

CONCLUSIONS

Discrete clinical features can be used to identify the most likely diagnosis in dogs with vestibular syndrome.

Cerumen microbial community shifts between healthy and otitis affected dogs

Otitis externa is a common multifactorial disease in dogs, characterized by broad and complex modifications of the ear microbiota. The goal of our study was to describe the ear cerumen microbiota of healthy dogs, within the same animal and between different animals, and to compare the cerumen microbiota of otitis affected dogs with that of healthy animals. The present study included 26 healthy dogs, 16 animals affected by bilateral otitis externa and 4 animals affected by monolateral otitis externa. For each animal cerumen samples from the right and left ear were separately collected with sterile swabs, and processed for DNA extraction and PCR amplification of the 16S rRNA gene. Amplicon libraries were sequenced using an Ion Torrent Personal Genome Machine (PGM), and taxonomical assignment and clustering were performed using QIIME 2 software. Our results indicate that the bacterial community of the cerumen in healthy dogs was characterized by extensive variability, with the most abundant phyla represented by Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes and Fusobacteria. The analysis of both alpha and beta diversity between pairs of left and right ear samples from the same dog within the group of affected animals displayed higher differences than between paired samples across healthy dogs. Moreover we observed reduced bacterial richness in the affected group as compared with controls and increased variability in population structure within otitis affected animals, often associated with the proliferation of a single bacterial taxon over the others. Moreover, Staphylococcus and Pseudomonas resulted to be the bacterial genera responsible for most distances between the two groups, in association with differences in the bacterial community structure. The cerumen microbiota in healthy dogs exhibits a complex bacterial population which undergoes significant modifications in otitis affected animals.

Otodectic and bacterial etiology of feline otitis externa in Tripoli, Libya

Background

Feline otitis externa is a dermatological disorder with a multifactorial complex etiology.

Aim

This study aimed to investigate the prevalence of different etiological agents, particularly the parasitic and bacterial, responsible for the cases of feline otitis externa in Tripoli, Libya, and to assess the antimicrobial susceptibility of the bacterial isolates from those cases.

Methods

Cerumen and otic discharges of the suspected cats were collected for parasite detection and bacterial culture. Kirby-Bauer's disk diffusion method was used for antimicrobial susceptibility testing.

Results

The results showed that otodectic mites and bacterial causes were equally the most prevalent in those cases, with a prevalence of 47.1% each. Otodectes cynotis infestation was more frequently bilateral and severe. Staphylococcus spp. were the most prevalent among bacterial causes (75%), followed by Proteus spp. (16.6%) and Pseudomonas spp. (8.4%). Norfloxacin and gentamicin were the most effective antimicrobials against bacterial isolates, as they were effective against 83.3% and 70.8% of isolates, respectively.

Conclusion

Otodectes cynotis infestation and staphylococcal infections constituted the most common etiology of feline otitis externa in Tripoli, Libya, and norfloxacin represented a cogent antibacterial for the treatment of otitis externa.

Surgical and Behavioral Relationships With Welfare

Veterinarians perform surgery for a number of reasons, from treating a problem to preventing future problems. There is an inextricable link between the physical and psychological aspects of an animal's health, and surgery is often a conduit to bridge that gap. Some surgical procedures can affect an animal's behavior, such as castration, and some pose an ethical dilemma, such as ear cropping and declawing. Ameliorating pain, decreasing stressful experiences for the animal, and identifying and treating concurrent problem behaviors are hallmarks of improving animal welfare. The purpose of this article is to outline some of these interrelationships and ethical dilemmas, providing evidence-based verification as applicable.

Otoscopic evaluation of epithelial remnants in the tympanic cavity after total ear canal ablation and lateral bulla osteotomy

OBJECTIVE

To determine the ability to detect the presence of epithelial remnants after total ear canal ablation (TECA) and lateral bulla osteotomy (LBO) with endoscopy and to identify the most common locations of epithelial remnants after tympanic curettage.

STUDY DESIGN

Experimental study.

ANIMALS

Five fresh canine cadavers with no gross evidence of middle ear disease.

METHODS

Ten TECA-LBO were performed by four surgeons. After tympanic curettage, a 1.9-mm rigid 30° endoscope was inserted into the rostral, caudal, dorsal, ventral, and medial sections of the tympanic cavity. Three observers evaluated otoscopic images for epithelial remnants in each compartment. The median distribution of epithelial remnants was calculated for each section of the tympanic cavity with a three-dimensional tympanic cavity model.

RESULTS

Epithelial remnants were identified in at least one of the five areas of the tympanic cavity after each TECA-LBO. The rostral section contained the most epithelial remnants (35.6%), while the medial section contained the least amount (1.8%).

CONCLUSION

Use of a 1.9-mm rigid endoscope was an effective method to evaluate all sections of the tympanic cavity after curettage in TECA-LBO. Epithelial remnants were consistently found after TECA-LBO, especially in the rostral compartment.

CLINICAL SIGNIFICANCE

Intraoperative endoscopy should be considered to improve removal of epithelium after initial TECA-LBO or revision surgeries.

Antifungal Resistance Regarding Malassezia pachydermatis: Where Are We Now?

Malassezia pachydermatis is a yeast inhabiting the skin and ear canals in healthy dogs. In the presence of various predisposing conditions it can cause otitis and dermatitis, which are treated with multiple antifungal agents, mainly azole derivatives. This manuscript aims to review the available evidence regarding the occurrence of resistance phenomena in this organism. Various findings support the capacity of M. pachydermatis for developing resistance. These include some reports of treatment failure in dogs, the reduced antifungal activity found against yeast isolates sampled from dogs with exposure to antifungal drugs and strains exposed to antifungal agents in vitro, and the description of resistance mechanisms. At the same time, the data reviewed may suggest that the development of resistance is a rare eventuality in canine practice. For example, only three publications describe confirmed cases of treatment failure due to antifungal resistance, and most claims of resistance made by past studies are based on interpretive breakpoints that lack sound support from the clinical perspective. However, it is possible that resistant cases are underreported in literature, perhaps due to the difficulty of obtaining a laboratory confirmation given that a standard procedure for susceptibility testing of M. pachydermatis is still unavailable. These considerations highlight the need for maintaining surveillance for the possible emergence of clinically relevant resistance, hopefully through a shared strategy put in place by the scientific community.

Identification of Altered miRNAs in Cerumen of Dogs Affected by Otitis Externa

Otitis externa is one of the most common diseases in dogs. It is associated with bacteria and yeast, which are regarded as secondary causes. Cerumen is a biological substance playing an important role in the protection of ear skin. The involvement of cerumen in immune defense is poorly understood. MicroRNAs can modulate the host immune response and can provide promising biomarkers for several inflammatory and infectious disorder diagnosis. The aims of this study were to profile the cerumen miRNA signature associated with otitis externa in dogs, integrate miRNAs to their target genes related to immune functions, and investigate their potential use as biomarkers. Cerumen was collected from healthy and otitis affected dogs and the expression of miRNAs was profiled by Next Generation Sequencing; the validation of the altered miRNAs was performed using RT-qPCR. The potential ability of miRNAs to modulate immune-related genes was investigated using bioinformatics tools. The results pointed out that 32 miRNAs, of which 14 were up- and 18 down-regulated, were differentially expressed in healthy vs. otitis-affected dogs. These results were verified by RT-qPCR. To assess the diagnostic value of miRNAs, ROC analysis was carried out, highlighting that 4 miRNAs are potential biomarkers to discriminate otitis-affected dogs. Bioinformatics showed that cerumen miRNAs may be involved in the modulation of host immune response. In conclusion, we have demonstrated for the first time that miRNAs can be efficiently extracted and quantified from cerumen, that their profile changes between healthy and otitis affected dogs, and that they may serve as potential biomarkers. Further studies are necessary to confirm their diagnostic value and to investigate their interaction with immune-related genes.

Management of otitis externa with an led-illuminated gel: a randomized controlled clinical trial in dogs

BACKGROUND

Canine otitis externa is a painful condition which can be challenging to treat due to difficulties in the administration of otic medication. This can be due to lack of owner compliance in the application of ear drops or due to the resentment that some dogs demonstrate when attempts are made to administer topical medication into a sensitive ear canal. The aim of the study was to assess the efficacy of a topical LED-illuminated gel (LIG) in canine otitis externa in comparison to standard of care therapy. Dogs with spontaneous otitis externa were randomly allocated in three groups: groups QW received LIG once weekly; BW received LIG twice weekly; group C received enrofloxacin and silver sulfadiazine twice daily. LIG consists of a topical application of a gel containing chromophores that, when illuminated by a LED lamp, re-emit fluorescent light which can stimulate physiological responses, promoting healing and controlling bacteria. The evaluation protocol (T0 to T5) considered clinical assessment (OTIS-3-index-scoring-system; pruritus-severity-scale; pain-severity-score; aural temperature), cytological scoring system, quali-quantitative bacteriologic assessment.

RESULTS

All groups (QW, n = 21; BW, n = 23; C, n = 20) showed improvement during the study (QW: P < 0.02 for cytological and pain scores, P < 0.003 for bacteriologic assessment, P < 10- 4 for pruritus, total OTIS-3 and temperature assessments; BW: P < 10- 4 for all clinical, cytological and bacteriologic assessments; C: P < 0.02 for all clinical and cytological assessments, P < 10- 4 for bacteriologic assessment). The highest clinical score reduction occurred in Group BW (P < 0.014 in T3; P < 0.001 in T4 and P < 10- 4 in T5). BW reached the clinically relevant effect level at T3 (- 3.26 ± 1.21 levels), QW reached it at T4 (- 3.24 ± 0.99), C did not reach it. No differences between groups were seen in the reduction of CFU/mL (T0-T5).

CONCLUSIONS

All treatment groups showed a positive clinical effect. LIG administered twice-a-week was the most favourable protocol of the study. LIG may be considered beneficial in the management of canine otitis externa; it seems to be effective in controlling the clinical condition, including the signs of inflammation and local pain, the bacterial growth, and it may help increasing treatment compliance.

Occult otitis media in dogs with chronic otitis externa - magnetic resonance imaging and association with otoscopic and cytological findings

BACKGROUND

Identification of perpetuating factors, such as otitis media (OM), is important for the successful management of canine chronic otitis externa (OE).

HYPOTHESIS/OBJECTIVES

Occult OM can occur in cases of chronic OE; a focused magnetic resonance imaging (MRI) examination is a useful tool in their management.

ANIMALS

One hundred twenty one client-owned dogs presented for investigation and treatment of chronic OE between 2009 and 2018.

METHODS AND MATERIALS

Mixed retrospective (74 dogs) and prospective (47 dogs) study of chronic OE cases without neurological signs, describing the MRI, otoscopic and cytological findings; comparing cases with and without MRI evidence of OM.

RESULTS

A total of 123 MRI studies were analysed (two dogs scanned twice). A short, focused MRI scan allowed detection of inflammation of the mucosal bulla lining as well as excellent discrimination between avascular material and vascularised soft tissue in the tympanic cavity. OM was found in 41 of 197 (21%) ears with chronic otitis externa. On otoscopy, the tympanic membrane was intact in six of 41 ears (15%), ruptured in 16 of 41 (39%) and not visible in 14 of 41 (34%) [no data in five of 41 (12%)]. Analysis of cytological findings showed that the presence of rods was only associated with an increased likelihood of OM when found together with inflammatory cells.

CONCLUSIONS AND CLINICAL IMPORTANCE

Occult OM is a not uncommon finding on MRI of dogs with chronic OE. A targeted MRI study ("bulla mini-scan") may be useful as part of the clinical investigations.

Biofilm production by pathogens associated with canine otitis externa, and the antibiofilm activity of ionophores and antimicrobial adjuvants

Otitis externa (OE) is a frequently reported disorder in dogs associated with secondary infections by Staphylococcus, Pseudomonas and yeast pathogens. The presence of biofilms may play an important role in the resistance of otic pathogens to antimicrobial agents. Biofilm production of twenty Staphylococcus pseudintermedius and twenty Pseudomonas aeruginosa canine otic isolates was determined quantitatively using a microtiter plate assay, and each isolate was classified as a strong, moderate, weak or nonbiofilm producer. Minimum biofilm eradication concentration (MBEC) of two ionophores (narasin and monensin) and three adjuvants (N-acetylcysteine (NAC), Tris-EDTA and disodium EDTA) were investigated spectrophotometrically (OD_570nm ) and quantitatively (CFU/ml) against selected Staphylococcus and Pseudomonas biofilm cultures. Concurrently, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of planktonic cultures were assessed. 16/20 of the S. pseudintermedius clinical isolates were weak biofilm producers. 19/20 P. aeruginosa clinical isolates produced biofilms and were distributed almost equally as weak, moderate and strong biofilm producers. While significant antibiofilm activity was observed, no MBEC was achieved with narasin or monensin. The MBEC for NAC ranged from 5,000-10,000 µg/ml and from 20,000-80,000 µg/ml against S. pseudintermedius and P. aeruginosa, respectively. Tris-EDTA eradicated P. aeruginosa biofilms at concentrations ranging from 6,000/1,900 to 12,000/3,800 µg/ml. The MBEC was up to 16-fold and eightfold higher than the MIC/MBC of NAC and Tris-EDTA, respectively. Disodium EDTA reduced biofilm growth of both strains at concentrations of 470 µg/ml and higher. It can be concluded that biofilm production is common in pathogens associated with canine OE. NAC and Tris-EDTA are effective antibiofilm agents in vitro that could be considered for the treatment of biofilm-associated OE in dogs.

Otitis externa in eight horses - clinical signs, treatment and prognosis

BACKGROUND

Otitis externa is rare in horses and the condition is poorly described in the literature.

OBJECTIVE

To describe clinical signs, treatment regimens and prognosis of otitis externa in horses.

ANIMALS

Eight horses diagnosed with otitis externa during 2011-2018.

METHODS

Retrospective review of medical records and follow-up contact with owners.

RESULTS

Common clinical signs seen in affected horses were pruritus, ear discharge and ear droop of affected ears. The most common cytological findings were neutrophils, bacteria and yeast. All horses responded well to treatment; two horses were reported to have recurrent problems.

CONCLUSION AND CLINICAL IMPORTANCE

Otitis externa in horses is a rare and treatable condition. The condition may be present for prolonged periods before owners become aware, compromising the welfare of affected horses. Untreated otitis externa is a suggested cause of otitis media and temporohyoid osteoarthropathy, emphasizing the importance of identifying and treating this condition at an early stage. For this reason, clinicians should include a brief inspection of the pinnae and external ear canal in the clinical examination of horses.

An unusual case of feline otitis externa due to sporotrichosis

Case summary

It is described a case of a 10-month-old female mixed-breed cat with left ear discharge of approximately 6 days’ duration prior to the admission. Secretions were collected from both ears using a sterile swab for cytological and mycological analysis. A pyogranulomatous inflammatory infiltrate (predominantly characterized by the presence of neutrophils and macrophages) with the presence of cocci, rods and many yeast-like structures were seen on cytological analysis; the fungal culture confirmed the presence of the Sporothrix schenckii complex. Upon diagnosis of fungal otitis due to the S schenckii complex, treatment with oral itraconazole was administered. After 4 weeks of treatment, no S schenckii complex colonies were isolated, and clinical recovery had occurred.

Relevance and novel information

Although rare, clinicians must be aware of atypical presentations of sporotrichosis, as in this case of external otitis. This is of clinical relevance because this infection has been reported in several countries and is defined as a zoonotic disease.

Determination of minimum inhibitory concentrations for silver sulfadiazine and other topical antimicrobial agents against strains of Pseudomonas aeruginosa isolated from canine otitis externa

BACKGROUND

Otitis externa is a common presenting complaint in practice. Ear infections by Pseudomonas aeruginosa are particularly problematic due to the organism's high level of resistance and ability to damage the tympanum. Treatment should be based on susceptibility testing although minimum inhibitory concentrations (MICs) are not available for all treatment options. Silver sulfadiazine has been used in cases of recurrent P. aeruginosa otitis, although a MIC for silver sulfadiazine as a single agent has not been established.

OBJECTIVES

To describe susceptibility patterns of P. aeruginosa isolated from canine otitis externa and determine the MIC for silver sulfadiazine and other topical antimicrobials.

ANIMALS

Thirty-six P. aeruginosa isolates were collected from client-owned dogs, suffering from otitis externa.

METHODS AND MATERIALS

Susceptibility patterns were established using disc diffusion susceptibility testing against 17 antimicrobial agents. For determination of the MIC, selected strains were tested against increasing concentrations of marbofloxacin, enrofloxacin, gentamicin, polymyxin B and silver sulfadiazine using broth microdilution.

RESULTS

For nine of 17 antimicrobial agents, complete resistance was seen in all isolates tested via disk diffusion susceptibility testing. Approximately 94% and 96% of isolates were susceptible to gentamicin and imipenem, respectively. These findings were consistent with broth dilution, where all strains were susceptible to gentamicin. Resistance was higher against polymyxin B and the fluoroquinolones. Silver sulfadiazine was effective in vitro with a MIC ranging from 1 to 64 μg/mL.

CONCLUSIONS AND CLINICAL SIGNIFICANCE

As the MIC of silver sulfadiazine was lower than the concentration in a 1% preparation, such a product potentially represents a treatment option for dogs with P. aeruginosa otitis.

EFFECTIVENESS OF TOBRAMYCIN AND CIPROFLOXACIN AGAINST BACTERIAL ISOLATES IN CANINE OTITIS EXTERNA IN UBERABA, MINAS GERAIS

Abstract Canine otitis externa is a common and recurrent disease in domestic dogs. Although not being life threatening, it can result in the overuse of antibiotics, increased bacterial resistance and reduction of options for treatment. This study aimed to determine: the principal characteristics (age, race, and gender) of dogs affected by otitis externa; the most frequently bacteria identified as being associated with it and their antimicrobial resistance profiles. A total of 221 bacterial isolates were identified by morphological staining and biochemical processes and tested against eleven antibiotics. Among the 148 dogs diagnosed with otitis externa, 51.4% (76/148) were males and 48.6% (72/148) females. The cases were detected mainly in dogs with age above 7 years (54.7%; 81/148. Among the races examined, poodles were the most numerous (14.84%; 22/148). The most common bacteria found were: coagulase-negative Staphylococcus (StCN), 33.9% (75/221); coagulase-positive Staphylococcus (StCP), 19% (42/221); Proteus spp., 17.2% (38/221) and Pseudomonas aeruginosa, 9.5% (21/221). Simultaneous resistance to more than three classes of antimicrobials were most frequently detected in P. aeruginosa (61.9%; 13/21) and Proteus spp (39.47%; 15/38). According to data obtained from this study, two veterinary medications found to be most effective for topical treatment were tobramycin and ciprofloxacin.

Microbiological and antibacterial resistance profile in canine otitis externa – a comparative analysis

The aim of the present study was to compare the prevalence of microbial agents involved in canine otitis externa and their sensitivity to antibacterial drugs in two periods: 2007–2011 and 2013–2017. For 2013–2017, coagulase-positive staphylococci were the dominating bacterial species (186 isolates), followed by Pseudomonas aeruginosa (82 strains). The rate of isolated yeasts (mainly Malassezia pachydermatis) was substantially high (152 isolates). Compared to the earlier period (2007–2011) a tendency to more frequent occurrence of co-infections was noted – 61.7% and more than 80% of co-infections involved yeasts. Antibacterial resistance patterns showed a clear trend to increased resistance of coagulase-positive staphylococci and β-haemolytic streptococci to amoxicillin/clavulanic acid (42% and 50% respectively) and gentamicin (29%, 40%). Increased resistance of P. aeruginosa was established to gentamicin (16%) and amikacin (18%). The prevalence of pseudomonads resistant to enrofloxacin was lower (27%).

Efficacy and safety of fluocinolone acetonide 0.025% otic solution in patients with otic eczema: a randomized, double-blind, placebo-controlled clinical trial

Objectives

To assess the efficacy and safety of fluocinolone acetonide 0.025% otic solution versus placebo in treating patients with otic eczema.

Methods

In this multicentre, randomized, double-blind, parallel-group phase 3 clinical trial, conducted at 12 Spanish centres between March 2012 and March 2013, patients received fluocinolone acetonide 0.025% or placebo otic solution twice daily for 7 days (days 1–7) with an 8-day follow-up (days 9–15). Outcome measures included change in itching from baseline (day 1) to study days 4–8 and 9–15, and change in otoscopic signs (erythema, oedema, and scaling) from baseline to the end of treatment (day 8) and end of follow-up (day 15).

Results

Patients treated with fluocinolone acetonide 0.025% (n = 66), as compared with placebo-treated patients (n = 69), showed significantly higher reductions in itching from baseline to study days 4–8 and 9–15, and in individual and global otoscopic signs from baseline to the end of treatment (day 8) and end of follow-up (day 15). Incidence and severity of adverse events was similar between the fluocinolone and placebo groups.

Conclusions

Fluocinolone acetonide 0.025% otic solution, administered twice daily for 7 days, is an effective and safe treatment for otic eczema.

Impact of synthetic canine cerumen on in vitro penetration of auricular skin of dogs by florfenicol, terbinafine, and betamethasone acetate

OBJECTIVE To determine the pharmacokinetics of florfenicol, terbinafine, and betamethasone acetate after topical application to canine auricular skin and the influence of synthetic canine cerumen on pharmacokinetics. SAMPLE Auricular skin from 6 euthanized shelter dogs (3 females and 3 neutered males with no visible signs of otitis externa). PROCEDURES Skin adjacent to the external opening of the ear canal was collected and prepared for use in a 2-compartment flow-through diffusion cell system to evaluate penetration of an otic gel containing florfenicol, terbinafine, and betamethasone acetate over a 24-hour period. Radiolabeled ¹⁴C-terbinafine hydrochloride and ³H-betamethasone acetate were added to the gel to determine dermal penetration and distribution. Florfenicol absorption was determined by use of high-performance liquid chromatography-UV detection. Additionally, the effect of synthetic canine cerumen on the pharmacokinetics of all compounds was evaluated. RESULTS During the 24-hour experiment, mean ± SD percentage absorption without the presence of synthetic canine cerumen was 0.28 ± 0.09% for 3H-betamethasone acetate, 0.06 ± 0.06% for florfenicol, and 0.06 ± 0.02% for 14C-terbinafine hydrochloride. Absorption profiles revealed no impact of synthetic canine cerumen on skin absorption for all 3 active compounds in the gel or on skin distribution of ³H-betamethasone acetate and ¹⁴C-terbinafine hydrochloride. CONCLUSIONS AND CLINICAL RELEVANCE ³H-betamethasone acetate, ¹⁴C-terbinafine hydrochloride, and florfenicol were all absorbed in vitro through healthy auricular skin specimens within the first 24 hours after topical application. Synthetic canine cerumen had no impact on dermal absorption in vitro, but it may serve as a temporary reservoir that prolongs the release of topical drugs.

Prevalence of external ear disorders in Belgian stray cats

Objectives Feline otitis externa is a multifactorial dermatological disorder about which very little is known. The objective of this study was to map the prevalence of external ear canal disorders and the pathogens causing otitis externa in stray cats roaming around the region of Ghent, Belgium. Methods One hundred and thirty stray cats were randomly selected during a local trap-neuter-return programme. All cats were European Shorthairs. This study included clinical, otoscopic and cytological evaluation of both external ears of each cat. Prospective data used as parameters in this study included the sex, age and body condition score of each cat, as well as the presence of nasal and/or ocular discharge, and the results of feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV) Snap tests. Results Remarkably, very few (sub)clinical problems of the external ear canal were found in the stray cat population. Malassezia species was by far the most common organism found in the external ear canals of the 130 stray cats. A total of 96/130 (74%) cats were found to have Malassezia species organisms present in one or both ears based on the cytological examination. No correlation was found between the parameters of sex, age, body condition score, the presence of nasal and/or ocular discharge and FIV and FeLV status, and the presence of parasites, bacteria or yeasts. Conclusions and relevance This study provides more information about the normal state of the external ear canal of stray cats. The ears of most stray cats are relatively healthy. The presence of Malassezia species organisms in the external ear canal is not rare among stray cats.

Assessment of in vitro inhibitory activity of hydrogen peroxide on the growth of Malassezia pachydermatis and to compare its efficacy with commercial ear cleaners

Otitis caused by Malassezia pachydermatis is generally a common and recurrent disease in canine clinical pathology. The increased incidence of fungal resistant to antifungal in both humans and pets is a cause for concern and is associated with the indiscriminate use of antifungals. Finding the most effective disinfectants and antifungals has become essential. To evaluate the in vitro inhibitory activity of hydrogen peroxide on the growth of M. pachydermatis and compare its efficacy with commercial ear cleaners. The test for sensitivity to antimicrobials was carried out following the indications of the CLSI document M44-A2. The comparative results demonstrated that hydrogen peroxide 1.5% showed excellent results for growth inhibition of M. pachydermatis, followed by Epiotic^® and MalAcetic^® , the lowest result was for Otoclean^® .

Survey of otitis externa in American Cocker Spaniels in Finland

Background

American Cocker Spaniels are overrepresented among breeds that require surgery as a treatment of end-stage otitis externa. However, the prevalence of otitis externa (OE) in this breed remains unknown. We reviewed the year 2010 medical records of 55 private veterinary clinics in Finland to determine the prevalence of OE in American Cocker Spaniels compared with English Cocker and English and Welsh Springer Spaniels. An American Cocker Spaniel owner questionnaire was designed to identify potential risk factors for end-stage OE.

Results

From the medical records of 98,736 dogs, the prevalence of OE was highest in Welsh Springer Spaniels (149 out of 468, 31.8%, [95% confidence interval 27.6–36.0]), followed by American Cocker (89/329, 27.0%, [22.2–31.7]), English Springer (96/491, 19.6%, [16.1–23.1]) and English Cocker Spaniels (231/1467, 15.7%, [13.8–17.6]). The mean number of OE episodes in ear-diseased dogs and the number of ear surgeries were highest in American Cocker Spaniels. Owner questionnaires were received for 151 American Cocker Spaniels, 85 (56%) of which had suffered from OE. In 47% (40/85) of these dogs, OE occurred without concurrent skin lesions, 46% (33/72) displayed the first signs of OE before 1 year of age. In 24% (20/85) of the dogs, the signs of OE recurred within 1 month or continued despite treatment, 16% (14/85) required surgery (n = 11) or were euthanized (n = 5; 2 of the operated dogs and 3 others) due to severe OE. The onset of OE before the age of 1 year significantly increased the risk (OR 3.8, 95% CI 1.1–13.6) of end-stage OE.

Conclusions

The prevalence of OE in American Cocker Spaniels in Finland was higher than previously reported in Cocker Spaniels, but the highest prevalence of OE was found in Welsh Springer Spaniels. Compared to the other Spaniels, OE was more often recurrent and more frequently surgically managed in American Cocker Spaniels. Based on the questionnaire, early onset (<1 year) of OE increased the risk of end-stage OE. In American Cocker Spaniels, OE requires an intensive approach from the first treatment, and prevention of recurrence should be emphasised. The causes and treatment of OE in this breed warrant further study.

Efficacy of medical grade honey in the management of canine otitis externa - a pilot study

BACKGROUND

The high prevalence of antimicrobial resistance within otic pathogens has created a need for alternative therapies of otitis externa (OE). Evidence suggests that medical grade honey (MGH) may be effective against drug-resistant pathogens.

HYPOTHESIS/OBJECTIVES

The efficacy of a commercial MGH compound was assessed in an open clinical trial. We hypothesized that it would be an effective alternative to conventional treatments.

ANIMALS

Client-owned dogs (n = 15) with a confirmed diagnosis of infectious OE were enrolled in this pilot study.

METHODS

Dogs were prescribed MGH (1 mL daily per ear) until cure was achieved or for a maximum of 21 d. Evaluation was based on weekly clinical scores, cytological progression and owner assessments of pruritus. Swab samples were submitted for culture and susceptibility testing. MGH was tested for biocidal activity against the bacterial isolates.

RESULTS

Medical grade honey promoted rapid clinical progress, with 70% of dogs achieving clinical cure between days 7 and 14 and over 90% having resolved by Day 21. There was a decrease in clinical scores throughout the duration of the trial (P < 0.001) and owner-assessed pruritus also decreased significantly (P < 0.05). In vitro assays of the biocidal activity of MGH showed activity against all bacterial isolates, including meticillin-resistant strains of Staphylococcus pseudintermedius (MRSP) and other species of drug-resistant bacteria.

CONCLUSION AND CLINICAL IMPORTANCE

Medical grade honey was successful in both clinical and laboratory settings, thus demonstrating its potential of becoming an alternative treatment for canine OE.

Clinical evaluation of an antiinflammatory and antioxidant diet effect in 30 dogs affected by chronic otitis externa: preliminary results

The aim of this evaluation study was to assess the possible role of a specific nutraceutical diet in relieving main clinical symptoms of chronic bilateral otitis externa (occlusion of ear canal, erythema, discharge quantity, and odor) in 30 adult dogs. Thirty dogs of different breeds (mean age ± SEM; 6.03 ± 0.15 years and mean weight ± SEM; 32.01 ± 1.17 Kg; 53.3% males, 46.6% females) with evident chronic clinical otitis symptoms were equally divided and randomly assigned to receive either the nutraceutical diet (ND group) or a standard diet (SD group) over a period of 90 days. In all cases a topical pharmacological treatment was given. The nutraceutical diet, also endowed with anti-inflammatory and antioxidant activities, significantly decreased the mean score intensity of all symptoms after 90 days of intervention (P < 0.0001) with the exception of Malassezia pachydermatis infection which was only slightly reduced. Our investigation is one of the few evidence-based results where a commercial nutraceutical diet has been proven effective, in combination with drugs, in relieving otitis externa-related symptoms. This study opens new insights into otitis externa clinical management providing evidence of efficacy of a combined therapy with drugs and a specific nutraceutical diet.

Is transmission electron microscopy (TEM) a promising approach for qualitative and quantitative investigations of polymyxin B and miconazole interactions with cellular and subcellular structures of Staphylococcus pseudintermedius, Escherichia coli, Pseudomonas aeruginosa and Malassezia pachydermatis?

Antimicrobial therapy using a combination of polymyxin B and miconazole is effective against the main bacterial pathogens associated with otitis externa in dogs, and a synergistic effect of both drugs has been shown previously. The objective of the present investigation was to visualize ultrastructural changes after exposure of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus pseudintermedius and Malassezia pachydermatis to polymyxin B and miconazole by transmission electron microscopic (TEM). For this, cultures of E. coli, P. aeruginosa, S. pseudintermedius and M. pachydermatis were exposed to polymyxin B and miconazole, alone or in combination for 24 h. Ultrastructural changes were observed most frequently in the cell envelope of the four microorganisms. Exposure to polymyxin B seemed to cause more damage than miconazole within the range of concentrations applied. Treatment resulted in changes of the cell size: in E. coli, cell size increased significantly after treatment with either compound alone; in P. aeruginosa, cell size decreased significantly after treatment with polymyxin B and with miconazole; exposure of S. pseudintermedius to miconazole caused a decrease in cell size; in M. pachydermatis, cell size increased significantly after treatment with polymyxin B.; in E.coli, S. pseudintermedius and M. pachydermatis, cell size changed highly significant, in P. aeruginosa significantly after exposure to the combination of both compounds. In conclusion, by using a different approach than previous investigations, this study confirmed a clear combinatory effect of polymyxin B and miconazole against the tested microorganisms involved in canine otitis externa. It is the first time that visualization technologies were applied to compare the effect of single drugs to their combinatory effects on cellular and subcellular entities of selected bacterial and yeast species.

Prevalence of otitis externa in stray cats in northern Italy

Feline otitis externa is a dermatological disorder that has not been evaluated much in stray cats. One hundred and eighty-seven stray cats were randomly selected during a trap-neuter-release programme to investigate the prevalence of otitis externa in stray cat colonies in northern Italy. Swabs for cytological examination were obtained from the external ear canal of each cat. A direct otoscopic assessment of the external ear canal was made in 86/187 cats. Cytological evidence of otitis externa was present in 55.1% of cats. The influence on otitis of age, gender, habitat and season of sampling was tested, but no risk factors were found. Otodectes cynotis (as a sole agent or in combination) was the primary cause of otitis in 53.3% of cats. Cocci and rods, either alone or in combination with other agents, were perpetuating factors in 71.8% and 29.1% of cats, respectively. Pregnancy status was a risk factor for otitis caused by coccal infections. Malassezia species, alone or in combination, was the perpetuating factor in 50.5% of cats with otitis. Urban habitat and winter season were risk factors for otitis associated with Malassezia species. Demodex cati was identified as an incidental finding in two cats. There was good agreement between otoscopy and cytology with regard to the diagnosis of otitis externa. The results of this study show a high prevalence of otitis externa in stray colony cats and provide information on causal factors for feline otitis externa.

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.