Efficacy of a Topical Ear Formulation with a Pump Delivery System for the Treatment of Infectious Otitis Externa in Dogs: a Randomized Controlled Trial Delphine Rigaut, DVM Annaele Sanquer, MSc Laurence Maynard, DVM Christophe-Alexandre Rème, DVM Virbac, 13e Rue LID, BP27, 06515 Carros, France KEY WORDS: Otitis, treatment, dog, of cases with Easotic and 69.9% of cases hydrocortisone aceponate. with Otomax on day 14. Microbial scores ABSTRACT were reduced in both groups over the study period, with a higher cytological recovery In a randomised, multicentric field clinical rate on day 14 in the Easotic group (61.3%) trial on dogs with otitis externa, the efficacy versus Otomax (37%) (odd ratio=2.7). None of an hydrocortisone aceponate-gentamicin- of the dogs with clinical recovery on day 14 miconazole otic suspension (Easotic, Virbac, presented a relapse up to day 49. Side ef- Carros, France) applied once daily for 5 days fects were minor and transient. In this study was compared to that of a betamethasone Easotic applied once daily for 5 days proved valerate-gentamicin-clotrimazole otic sus- efficient and safe for the treatment of canine pension (Otomax, Schering Plough Animal otitis externa. Health, Levallois-Perret, France) applied INTRODUCTION twice daily for 7 days. One-hundred and seventy-six dogs with bacterial and/or fun- Otitis externa is common in dogs with a gal otitis externa were included in the study reported frequency between 4% and 20% of and received one of the two ear medica- patients consulting at veterinary clinics.1,2 tions. On days 0, 5, 7 and 14 clinical signs, The condition refers to any inflammatory as well as bacteriological and fungal counts condition of the external ear canal com- at cytology from ear samples, were graded monly associated with pain and discomfort using semi-quantitative scales. Bacterial and (pruritus). It is usually classified as erythe- fungal cultures were also performed on day mato-ceruminous or suppurative depending 0. A control visit was performed on day 49 on the type of discharge material present.1,3 to check for relapses. The aggregate clinical Otitis externa is a multifactorial syn- scores were reduced by 83.2% with Easotic drome involving primary, predisposing and and 86.2% with Otomax on day 14, with secondary or perpetuating factors. Primary no significant difference between groups. factors include hypersensitivities (atopic Clinical recovery (>75% reduction of the dermatitis, adverse food reactions, contact aggregate score) was recorded in 72.2% hypersensitivity), ectoparasites (most com- Intern J Appl Res Vet Med • Vol. 9, No. 1, 2011. 15 monly Otodectes cynotis), foreign bodies, delivered through a pump delivery system keratinisation defects and idiopathic inflam- was developed recently (Easotic, Virbac). mation. Predisposing factors are related to The objective of product development was the anatomy of the ear (pendulous pinnae, to simplify first line treatment of otitis stenotic canals, hypertrichosis) and environ- externa in several ways: delivery of a preset mental conditions such as temperature and volume (1 mL) of the suspension into the humidity. Secondary bacterial and/or fungal ear canal through a flexible canula by a infections are perpetuating factors that ex- single depression of the pump on the dis- acerbate the inflammatory condition.1,3 The penser, reduced number of administrations dominant pathogens found in canine otitis (once daily dosing) and shorter duration of externa are the bacteria Staphylococcus treatment application (5 days). The suspen- intermedius (coccus) and Pseudomonas ae- sion includes gentamicin, miconazole and ruginosa (rod), and the budding yeast Mal- hydrocortisone aceponate as active ingre- assezia pachydermatitis.4,5,6,7,8 The diagnosis dients. While gentamicin and miconazole of otitis externa is achieved through clinical are respectively well known antibiotic and history, clinical examination of the ear canal antifungal agents documented for use in and cytology of ear exudates.3,9,10,11 otitis externa,4,6,17,18,19,20,21,22,23 the non-haloge- Treatment of canine otitis externa is nated diester glucocorticoid hydrocortisone usually local although systemic therapy is aceponate is only documented to date for its required in some cases (stenotic ear canal, use in a spray formulation as an anti-inflam- exacerbated expression of the disease). Long matory agent on the skin of other parts of term management of the condition can be the body in dogs.24,25 Pharmacological data challenging in case of frequent relapses or document an improved benefit/risk ratio of chronicity associated with persistence of non-halogenated diester glucocorticoids as underlying causes, which should be identi- compared to corticosteroids previously used, fied and corrected.1,3,12 Because of the central thanks to increased entry into, and storage role of inflammation in the pathogenesis of within, the epidermis (lipophilicity), and the condition, and frequent association with fewer local and systemic side effects (me- mixed bacterial and yeast infection, topical tabolism in skin structures).26,27,28,29 treatment is usually achieved with a prod- The objective of this study was to com- uct containing an antibiotic, an antifungal pare the efficacy and safety of the pump- agent and a corticosteroid.1,3,13,14,15,16 Ad- dosed Easotic suspension administered per ministration of the ear medication must be label (1 mL once daily for 5 days) to that of undertaken daily at home by the owner over a reference drop-dosed treatment Otomax several days until resolution of the problem. (Schering Plough Animal Health) adminis- Correct application of the ear treatment in tered per label (4 to 8 drops twice daily for 7 accordance with veterinarian’s prescription days) for the treatment of acute canine otitis may prove practically difficult however, externa. The control product was selected as especially when the auricular condition is it includes similar antibacterial (gentamicin) painful for the dog and treatment must be re- and antifungal (clotrimazole) components, peated twice daily. Achieving good restraint as well as a potent glucocorticoid agent of the dog while counting the exact number (betamethasone valerate), and it is also of drops required can be challenging, and indicated as a first line treatment of canine discouragement may thus happen before the otitis externa. end of the treatment period, leading to poor MATERIALS AND METHODS compliance and reduced therapeutic efficacy. This multicentered, controlled, randomised To improve compliance and reduce dog clinical field trial was conducted over 10 handling, an antibiotic-antifungal-corticoid months. It was performed in accordance otic suspension with a single daily dose with GCP (Good Clinical Practice) guide- 16 Vol. 9, No. 1, 2011 • Intern J Appl Res Vet Med. lines. and 1505 IU of gentamicin sulphate per mL, Study centres and animal selection was administered once daily in each ear for Dogs with otitis externa were recruited in 5 days. The daily dose of 1mL was delivered 32 veterinary clinics in France (10 sites), by one single depression of the pump on the Germany (10 sites) and Spain (12 sites). head of the dispenser. In the control group, 4 The investigators selected the animals ac- drops (dogs<15kg) or 8 drops (dogs≥15kg) cording to the following inclusion criteria: of Otomax (Schering Plough, Levallois- dogs of various breeds over 3 months, in Perret, France), a suspension containing good general health, diagnosed with bacte- 0.88mg of betamethasone valerate, 8.80 mg rial and/or fungal otitis externa based on of clotrimazole and 2640 UI of gentamicin clinical signs and cytological examination of sulphate per mL, were administered twice ear swabs. The dog could be diagnosed at daily for 7 days. Both products were used initial presentation or because of a relapse of according to label instructions. a previous episode. Otitis externa was clas- Concomitant topical or systemic ad- sified as erythemato-ceruminous (presence ministration of glucocorticoid, antibiotic, of cerumen and erythema with associated antifungal, anti-histamine or non steroidal bacterial and yeast isolates observed micro- anti-inflammatory agents, as well as cyclo- scopically) or purulent (presence of pus with sporine, were not allowed during the study bacteria detected at microscopy). In case period. The use of ear cleansers was forbid- of bilateral otitis, only the ear in the worst den as well. condition on day 0 was considered in the Schedule evaluation. Informed consent was obtained The animals were observed 4 times during from the owners of all dogs prior to their a 2-week period: day 0, day 5, day 7 and participation in the study. day 14. An additional control visit was Non-inclusion criteria included: dogs performed on day 49 to check for relapses that received any topical or systemic anti- of dogs in clinical remission on day 14. In fungal, antibiotic, corticoid or cyclosporin case of aggravation or reappearance of clini- treatment in the 15 days before the trial, or cal signs between planned visits, the owner any long-acting injectable glucocorticoid in had to bring his dog back to the veterinar- the 3 months before the trial, dogs whose ian to perform clinical and cytological ears were cleaned with an antiseptic product examinations. If the investigator decided to on day 0, dogs with a negative microbial cy- administer an additional treatment, the dog tology, dogs with a rupture of the tympanic was withdrawn from the trial and treated ap-