ASCERTAINMENT OF AURIN EAR DROPS ANTIMICROBIAL AND HEALING EFFECT IN DOG OTITIS

Microbiological and clinical examinations have been made, related to the effect of Aurin ear drops the solution „Primavet Sofia” on dogs with acute and chronic conditions of external and media otitis. The pharmaceutical compatibility of the active substances and solution stability were examined. The inhibitory effects in vitro of Acidum boricum, Acidwn salicylicum, Ethanolum and Aurin solution on laboratory referents and clinically isolated strains of microorganisms were studied. The dosage and manner of application were specified and was considered the effect on different clinical forms of otitis were specified. In the course of the one-year examination period, it was ascertained that Aurin-solution possesses the necessary stability. The active Aurin-solution substances (Acidum boricum, Acidum salicylicum, Novocainum) secure optimal composition of supporting substances, and high inhibitory activity in vitro on microbial strains in the examined agents of dog otitis. A dosage of 10 to 20 drops and touching the earconch with 5-10 drops twice a day, in the course of 5-7 days, has local antiseptic, anti-inflammatory, antimycotic and pain soothing effects. The healing effect of Aurin is due to selective antibacterial and antimycotic effects of the active substances used. The effectiveness against otitis is due to synergism of the effects of active and supporting substances. The obtained clinical results present grounds for recommending Aurin ear drops as an effective method of healing dog otitis.

Inflammations of the external and middle ear are frequent and widespread in dogs Š14, 15¹.Depending on their way of life, dogs are most susceptible to inflammatory diseases of the ears ŠRenneth, 1983; 2, 11¹.The development of the disease depends mainly on the breed, the age and the microbial agent Š2, 6, 11¹.Most susceptible are poodles, because of their rich coat in the ear canal, and cocker spaniels, because of the anatomical peculiarities of their ears.There is a risk of inflammation of the ears as a result of primary diseases -allergies, seborrhea, foreign bodies in the ear canal, etc. Š16¹.
The most important factor for the development of the disease is the microbial agent.The predominant opinion is that the acute forms are caused by gram-positive microorganisms where leading roles play S. aureus, Coagulasa neg.Staphylococci (CNS), Corynebacterium spp., Streptococcus spp., and in the chronic otitis -Pseudomonas aeruginosa and Proteus spp.Š4, 7, 18, 17, 8¹.
Antibiotics applied locally or parenterally are used most frequently to treat the disease.A number of authors recommend for that purpose the use of Gentamicin and Amoxycillin in the form of ear drops or general antibacterial therapy Š5, 11, 19, 8¹.
During the recent years, the tendency both in human and veterinary medicine is to limit the use of antibiotics and to apply other antibacterial and antiinflammatory drugs Š13¹.
Antibiotics should not be used for prevention as ingredients of ear drops.
The objective of this study is to create ear drops with antibacterial and anti-inflammatory action for treatment of external and middle otitis in dogs and cats as well as to carry out microbiological and clinical investigations of the antibacterial, anti-inflammatory and curative effects of these drops.
Aurin ear drops are developed by the firm "Primavet -Sofia" OOD.The composition of the drops is: ods were used for initial isolation and identification of the microbial strains Š9, 10¹.To prove the antimicrobial action of the Aurin ear drops, in vitro investigations of 4 reference strains (E. coli ATTC 25922, P. aeruginosa ATTC 27853, S. aureus ATTC 25923, S. aureus ATTC 29213) as well as of strains of the most frequently isolated microbial species (S. aureus, P. vulgaris, P. mirabilis, Streptococcus spp., Coagulase-negative Staphylococci (CNS), K. pneumoniae, Candida, Corynebacterium spp.) were carried out.Solid nutrient media were used -Müller-Hinton agar and Müller-Hinton agar with 5% sheep blood.From each strain, we prepared suspensions in sterile physiological solution with a density of 0.5 McFarland and inoculated petri dishes with agar.After drying, we pipetted with an Eppendorf pipette 50 ml of the tested substances: Aurin, working solution Ac. borici 2% and working solution Ac. salicylici 1% in 96 o ethanol, and only ethanol for control.We dried the material at room temperature up to drying of the drops and after that incubated for 24 hours at 37 o C.
Clinical investigations of the curative effect of Aurin ear drops were carried out during the period from 2001-2002, on 76 dogs with eczematous, pustular and purulent external otitis.
We based diagnoses on the basis of the clinical symptoms and otoscopic examinations.
We examined the ear canal with an otoscope in order to establish the presence and degree of the inflammatory process.If a foreign body (awn, tick, etc.) was found in the ear canal, it was removed in time, and after that, we cleaned and dried the ear canal and concha.
We performed the local treatment with Aurin ear drops as follows: after lifting the head and opening the concha, we put 5-10 drops of the preparation and shadowed the affected concha with another 5-10 drops, two times per day.
The results in Table 1 show that in a total of 76 dogs with otitis that entered the Surgical Clinic at the Veterinary Medical Faculty during the mentioned 2year period, pustular otitis of the external ear is the most frequent and represents 47.37% of all the forms of disease.Almost always, it affects both conchae at the same time.We observed inflammation of the middle ear quite rarely.
The results of the microbiological investigation of Aurin ear drops showed a strong inhibition of bacterial growth in all tested reference and patientisolated bacterial strains.Exceptions are one strain, Proteus vulgaris, which showed stability, and two strains, Proteus mirabilis and coagulase-negative Staphylococcus, which showed low sensitivity (Table 4).The curative effect of Aurin is due to the selective antibacterial antimycotic action of the active substances used.The efficiency of the tested drug combination is due to the combination of the different mechanisms of antimicrobial action of the active and auxiliary ingredients.It is seen most clearly in strains No. 1, 3, 6, 8 and 12.

Results / Rezultati
The clinical symptoms of the dogs that entered the clinic for treatment of external otitis depended mostly on the etiologic causes and on the development of the inflammatory process.A typical symptom is the itch expressed in restlessness, rubbing of the ears against neighbouring objects and frequent shaking of the head and ears.Usually one or both affected ears were burning red and sore.The results obtained from the conducted treatment of dogs with the different clinical forms of otitis are shown in Table 4.The curative effect attained for dogs with otitis externa eczematosa and for dogs with otitis externa pustulosa is 88.9%, and for dogs with otitis externa purulenta is 78.6%.The curative effect attained for all clinical forms of otitis is 86.4%.
For the dogs, whose treatment started in due time, we achieved a positive curative effect in 5 to 7 days after the start of the treatment.Nevertheless, we recommend the curative procedures to continue for another 2 or 3 days following clinical recovery.
The results of the conducted complex microbiological and clinical investigations of Aurin ear drops created conditions for technological development based on a screening technological approach, by elaboration of an optimum formulation and technology of production.The active substances of the Aurin preparation, incorporated into a suitable base, ensure a high inhibitory activity in vitro on the investigated microbial strains.The tested drug Aurin had the necessary stability within the observed one-year period.
The results obtained in this study for the frequency of the etiologic agents of external otitis in dogs are confirmed by other authors Š7, 2, 19, 8¹.In the acute cases, gram-positive microorganisms, such as S. aureus, have a leading role, and in chronic cases, gram-negative microorganisms, such as Pseudomonas spp., are usually isolated Š2, 3, 17¹.
We consider that the efficiency of the microbiological and clinical action of Aurin ear drops is due to the good combination of the antimicrobial and antimycotic action of the active ingredients, as well as to the local anesthetic and neurotrophic action of Novocain on the inflamed tissues, the keratoplastic action of the salicylic acid and the suitable formulation base.
The curative effect of 86.4% obtained for external otitis gives us reason to recommend the preparation Aurin as a prospective drug for therapy of inflammatory diseases of the ears of dogs.