Effects of beta-thujaplicin on anti-Malassezia pachydermatis remedy for canine otitis externa

The antifungal activity of beta-thujaplicin was evaluated against 51 Malassezia pachydermatis strains isolated from canine ear canals with or without otitis externa. For comparison, sensitivity tests were performed on M. pachydermatis isolates for nystatin, ketoconazole, and terbinafine HCl, all clinically available antifungal agents. The minimal inhibition concentrations over 50% of the tested isolates (MIC50) were 3.13 microg/ml for beta-thujaplicin and nystatin, 0.016 microg/ml for ketoconazole, and 1.56 microg/ml for terbinafine HCl. The antifungal effect for M. pachydermatis of beta-thujaplicin compared favorably with commercial antifungal agents. None of the 51 M. pachydermatis isolates showed resistance against any of the tested antibiotics investigated in this study. Ten representative isolates of M. pachydermatis were subcultured for 30 generations at concentrations close to the MIC levels of beta-thujaplicin, nystatin, ketoconazole, and terbinafine HCl, and examined to determine whether they had acquired resistance to each drug. As a result, M. pachydermatis was found to achieve resistance more easily for ketoconazole and terbinafine HCl than for beta-thujaplicin or nystatin. The MIC50 of beta-thujaplicin did not change during the course of subculture, and it is thought that the potential development of a resistant strain is low, even with continuous infusion for otitis externa therapy. beta-Thujaplicin is an inexpensive and safe treatment with anti-inflammatory and deodorant effects that can be recommended as an effective remedy for canine otitis externa.     

Otitis externa induced with Malassezia pachydermatis in dogs and the efficacy of pimaricin.

Eight beagles were experimentally inoculated intraotally with Malassezia pachydermatis to induce acute otitis externa. Three or 4 days after the inoculation, the animals showed the symptoms of otitis externa. All ear canals were erythematous and the dogs were shaking their heads. A large number of M. pachydermatis was noticed in exudate taken from every ear canal. Clinical signs of otitis externa were reduced after treatment with 0.1 ml (per canal) of 1% pimaricin suspension twice a day for 3 days. The amount of exudate decreased gradually and 12 of the 16 ear swabs examined, thereafter, were found to be negative for M. pachydermatis within 10 days. No side effects were observed in all the treated cases. These results suggested that M. pachydermatis could induce the canine otitis externa, and that pimaricin is effective agent for M. pachydermatis infection in ear canals.     

The pathology of the external ear canal in dogs and cats

A survey of factors which predispose the canine ear to otitis externa is presented. In resected ear specimens of 106 dogs, otitis externa without tumour was found on 58 occasions. In 46 dogs tumours were diagnosed in 15 cases with an otitis externa. In two dogs an inflammatory polyp was found. In the resected ear specimens of 48 cats, otitis externa was diagnosed 27 times, in 6 cases combined with an inflammatory polyp. In 21 cases neoplasia was present. The otitis externa was mainly a chronic proliferative inflammation characterised by hyperkeratinization, hyperplasia of the sebaceous and ceruminous glands, fibrosis and infiltration with plasma cells, lymphocytes and macrophages, often containing ceroid pigment.     

The role of Pityrosporum pachydermatis in otitis externa of dogs: evaluation of a treatment with miconazole.

The bacterial and mycotic flora were assessed in 158 ears of dogs with otitis externa and in 101 ears of healthy control dogs. Pityrosporum pachydermatis occurred in 57 per cent of ears with otitis externa and in 17 per cent of clinically healthy ears. Staphylococci and Pseudomonas aeruginosa were the predominant bacteria in otitic ears, micrococci and Bacillus spp were the most frequent isolates from clinically healthy ears. P pachydermatis, Ps aeruginosa and Candida tropicalis occurred in monoculture in a significant number of mainly chronic cases of otitis externa. A combination preparation, containing miconazole, polymyzin B and prednisolone, was highly effective in controlling the clinical signs of otitis externa and eliminating flora from the affected ears. The data presented suggest that yeasts, and especially P pachydermatis, may be significant pathogens in otitis externa and that antimycotic treatment is an essential part of the treatment of otitis externa in dogs.     

Measurement of body temperature by use of auricular thermometers versus rectal thermometers in dogs with otitis externa

OBJECTIVE: To compare measurements of body temperature obtained with auricular thermometers versus rectal thermometers in dogs with otitis externa. DESIGN: Prospective study. ANIMALS: 100 client-owned dogs: 50 with and 50 without clinical evidence of otitis externa. PROCEDURE: Dogs were evaluated for the presence of otitis externa on the basis of clinical signs, otoscopic examination, and cytologic evaluation of ear exudate. Auricular and rectal temperatures were obtained simultaneously in all dogs prior to and following ear examination. RESULTS: There was a high correlation between auricular and rectal temperatures in dogs with otitis externa both prior to and after ear manipulation. Significant differences were not detected in temperature measurements among dogs with different degrees of otitis externa. CONCLUSIONS AND CLINICAL RELEVANCE: Auricular temperature readings obtained by use of an auricular thermometer in dogs with otitis externa are accurate measurements of body temperature, compared with rectal temperature measurements. Temperature measurements are reliable before and after examination of the ear canal.     

The pathology of the external ear canal in dogs and cats

Summary

A survey of factors which predispose the canine ear to otitis externa is presented In restected ear specimens of 106 dogs, otitis externa without tumour was found on 58 occasions. In 46 dogs tumours were diagnosed in 15 cases with an ototis externa. In two dogs an inflammatory polyp was found.

In the resected ear specimens of 48 cats, otitis externa was diagnosed 27 times, in 6 cases combined with an inflammatory polyp. In 21 cases neoplasia was present.

The otitis externa was mainly a chronic proliferative inflammation characterised by hyperkeratinisation, hyperplasia of the sebaceous and ceruminous glands, fibrosis and infiltration with plasma cells, lymphocytes and macrophages, often containing ceroid pigment.     

Morphologic measurements of the external horizontal ear canal of dogs

Microscopic anatomy of the horizontal part of the external ear canal was evaluated in 24 dogs. Sixteen dogs were from breeds known to have a predisposition to otitis externa. The remaining 8 dogs were from breeds that do not have a predisposition to otitis externa. Dogs were separated into groups according to predisposition to otitis externa: group 1-predisposed dogs without otic inflammation, group 2-predisposed dogs with otic inflammation, and group 3-nonpredisposed dogs without otic inflammation. Qualitative microscopic evaluation of distribution of hair follicles revealed hair within proximal, middle, and distal regions of the horizontal ear canal in all breeds. The degree of keratinization was directly proportional to the presence of otic inflammation and was excessive in group-2 dogs. Quality of sebaceous glands within the horizontal ear canal was similar among dogs with and without otitis externa, whereas the quantity of apocrine tubular glands was significantly increased (P less than 0.05) in dogs with otitis. Quantity of apocrine tubular glands was also greater in group-1 dogs than in group-3 dogs. Thickness of the soft tissue in the external ear canal increased in direct proportion to the progression of disease and was greatest in the proximal region of the affected ear canal. Soft tissue located caudally between nonopposing ends of the annular cartilage, within the proximal region of the horizontal ear canal, contained few glands and hair follicles in dogs without otitis externa. In dogs with otitis externa, this region was infiltrated by distended apocrine tubular glands.     

Evaluation of an ear cleanser for the treatment of infectious otitis externa in dogs

Thirty-one ears (16 dogs) with otitis externa originating from bacterial or yeast infections were enrolled in a study to evaluate the in vivo efficacy of an ear cleanser containing 2.5% lactic acid and 0.1% salicylic acid for the treatment of infectious otitis externa. The affected ears were treated with the ear cleanser twice daily for 2 weeks and evaluated after 1 and 2 weeks of treatment. The ear cleanser was effective in resolution of infection in 67.7% of the ears, and clinical signs of infectious otitis externa were significantly reduced within 2 weeks.     

Efficacy of boric-complexed zinc and acetic-complexed zinc otic preparations for canine yeast otitis externa

The purpose of this 2-week, double-blinded, controlled clinical trial was to evaluate the efficacy of topical amino acid-complexed zinc gluconate formulated with boric acid (ZGB) or acetic acid (ZGA) versus a topical placebo in the treatment of yeast otitis externa in dogs. Included in the study were dogs with otitis externa and a cytopathological finding of yeast organisms in the affected ear. Ears were treated with the placebo, ZGA, or ZGB medications. Yeast counts as well as clinical appearance of the ears were monitored. Results revealed that ZGB significantly reduced the number of yeast organisms in cases of otitis externa.     

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

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

Ulcerative otitis externa responsive to immunosuppressive therapy in two dogs

Two middle-aged dogs were presented with bilateral severe ulcerative otitis externa without previous history of disease or evidence of other skin disease. Based on the exclusion of microbial infection and other primary causes, histopathological findings and response to immunomodulatory treatment, a diagnosis of presumed immune-mediated ulcerative otitis externa was made in both cases. However, the two cases differed with regard to their histopathological characteristics and the course of the disease. This report indicates that primary ulcerative disease needs to be considered in cases of ulcerative otitis externa which are unresponsive to appropriate antimicrobial therapy.     

Diagnosis and medical treatment of otitis externa in dogs and cats

A review of otitis externa in dogs and cats is presented. Aetiology, includes primary causes: ectoparasitoses, allergic diseases, endocrine disorders, pyodermas, trauma and irritation, contact dermatitis, auto-immune skin diseases, drug eruption, keratoseborrhoeic skin disease, tumours and pseudoneoplastic lesions, as well as secondary causes: bacteria and yeasts. Clinical aspects are variable but a practical classification distinguishes two forms: erythematoceruminous otitis externa and suppurative otitis externa. Diagnosis is made in five steps which are clinical examination, direct examination of cerumen (erythematoceruminous otitis externa) or bacterial culture and sensitivity testing (suppurative otitis externa), direct impression smears, cleaning and otoscopy, and diagnosis of underlying skin disease. Medical therapy includes cleaning of the external ear canal and local therapy (acaricides, antifungal agents, antibiotics, corticosteroids, other topical agents, the appropriate selection of an optic preparation being essential). Treatment of underlying skin disease is always necessary. Otitis externa is in fact a dermatological disease complex (like pododermatitis). Although local secondary infections (bacterial and fungal) must be managed in every case, there are grounds for including otitis externa in a larger frame.     

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.     

Antimicrobial susceptibility of Pseudomonas aeruginosa isolates from dogs with otitis externa

Pseudomonas aeruginosa is a common cause of otitis externa in dogs, and treatment of these infections is becoming problematic because of the increasing number of multiresistant strains. The aim of the present study was to compare the in vitro activities of cefepime, ceftazidime, enrofloxacin, ciprofloxacin, gentamicin and ticarcillin/clavulanic acid against 104 strains of P aeruginosa isolated from dogs with otitis externa. Antimicrobial susceptibility and minimum inhibitory concentrations, in μg/ml, were evaluated by the E test (bioMérieux). The most active compound was ceftazidime, with 100 per cent efficiency. The majority of tested strains were susceptible to ticarcillin/clavulanic acid (89.4 per cent), followed by ciprofloxacin (88.5 per cent) and cefepime (60.6 per cent). The highest resistance was observed to enrofloxacin (51.9 per cent) and gentamicin (43.3 per cent). Large numbers of strains were intermediately susceptible to antibiotics registered for use in veterinary medicine in Croatia--enrofloxacin (47.1 per cent) and gentamicin (41.3 per cent).     

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

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

Total ear canal ablation combining bulla osteotomy and curettage in dogs with chronic otitis externa and media

Ear canal ablation combining bulla osteotomy and curettage was performed on 44 dogs (n = 72 ears). Indications for the procedure included one or more of the following: chronic nonresponsive otitis externa and/or media (n = 71), tumor in the horizontal portion of the ear canal (n = 1), failed lateral ear resection (n = 11), ossified auricular cartilages secondary to chronic otitis externa (n = 22), failed previous total ear canal ablation (n = 1), and otitis interna (n = 1). In 40 dogs, the surgery was successful in alleviating all clinical signs of otitis externa and media. During the immediate postoperative period, 2 dogs died of causes unrelated to otitis. Complications related to the surgery developed in 9 of the surviving 42 dogs. Ultimately, 95% (40 of the surviving 42) of the dogs were cured by use of this procedure. Surgery successfully resolved the original problems in 97% (66 of 68) of the surgically treated ears of these dogs.     

A review of techniques for the investigation of otitis externa and otitis media

Otitis externa, inflammation of the externa ear canal, is relatively easy to diagnose based on the history and physical examination findings. The diagnosis of otitis media, inflammation of the middle ear cavity, is more challenging, with the work-up being both costly and, at times, invasive. The pathogenesis of otitis externa has been classified into predisposing, primary, and perpetuating factors. It is critical to the management of ear disease that the clinician recognize and investigate which factors are contributing to each individual patient's ear disease. Failure to identify and address the primary and/or predisposing factors is the most common cause of chronic recurrent otitis externa. Chronic inflammation of the ear canal leads to the development of the perpetuating factors, which may be the major reason for treatment failure, regardless of the primary cause of the ear disease. In this article, the predisposing, primary, and perpetuating factors involved in ear disease will be presented, along with a review of the techniques used in the diagnosis of otitis externa and otitis media.     

Subtotal ear canal ablation in 18 dogs and one cat with minimal distal ear canal pathology

A modified technique for performing total ear canal ablations is described. This technique requires less dissection than the standard technique and maintains a portion of the distal vertical ear canal. Subtotal ear canal ablations were performed in 18 dogs and one cat for the treatment of otitis externa or masses of the horizontal ear canal. Animals with otitis externa had minimal involvement of the distal ear canal. Dermatological problems associated with the remaining ear canal and pinnae occurred in eight animals and resolved with medical management. Normal ear carriage was maintained in all animals with erect ears. Further investigation is required before the procedure can be recommended as a treatment for otitis externa not caused by masses or anatomical abnormalities of the horizontal ear canal in dogs with pendulous ears.     

Surgical Management of Rabbit Ear Disease

Clinical signs associated with otic disease in rabbits (Oryctolagus cuniculus) are very similar to those demonstrated in dogs and cats. The surgical treatment options to resolve diseases involving the rabbit ear are also comparable with those used for canine and feline species. However, there are key anatomic and physiologic differences that must be accounted for to perform proper surgical treatment on a rabbit that has been diagnosed with ear disease. This article describes the diagnostic and treatment options for otitis externa, otitis media, and otitis interna, with an emphasis on surgical procedures and the important distinctive otic features of the rabbit patient. The ventral bulla osteotomy procedure is recommended for management of otitis media in rabbits without otitis externa. In rabbits with pathology in the external ear canal and the middle ear, total ear canal ablation and lateral bulla osteotomy should be performed. This combined procedure will allow the surgeon to address pathology in both sites, with the ultimate goal of resolution of the underlying disease etiology. Lateral ear canal resection is only appropriate in rabbits with otitis externa without otitis media; however, this surgical procedure may not resolve the otitis externa. If this is a concern, a total ear canal ablation should be done because it offers a greater chance of success.     

Identification and antimicrobial susceptibility of coagulase positive staphylococci isolated from healthy dogs and dogs suffering from otitis externa

A total of 67 strains of coagulase positive staphylococci isolated from healthy dogs and dogs suffering from otitis externa were studied. Twenty-two isolates were from healthy dogs (five from hound dogs and 17 from companion dogs) and 45 from dogs suffering otitis externa (14 from hound dogs and 31 from companion dogs). Presumptive identification was attempted using the following tests: production of acetoin, anaerobic utilization of mannitol, acid production from mannitol, presence of beta-galactosidase, and growth on P agar supplemented with different concentrations of acriflavine. Susceptibility of staphylococci to 16 antibiotics was determined. Most effective antibiotics were imipenem, amoxycillin/clavulanic acid, ciprofloxacin, tobramycin, gentamicin and marbofloxacin. Penicillin, ampicillin and polymyxin B showed the lowest activity. There were no significant differences in antimicrobial susceptibility among isolates from healthy dogs and dogs suffering from otitis externa.