The Combination Therapy of Ethylene Diamine Tetra Acetic Acid Tris (EDTA-Tris) and Antibiotics in Chronic Otitis Externa: A Case Report
Skin and Allergy Clinic, Thonglor Pet Hospital, Sukhumvit Street Bangkok, Thailand
Ethylene diamine tetra acetic acid tris (EDTA-tris) has been used as a cleaning product currently to veterinary dermatologist. Although not a licensed veterinary drug but has been found that it can be harnessed in the topical management of bacterial otitis. EDTA-tris has three principal functions, which are an antibacterial flush, alkalinising solution, and antibiotic potentiating agent. The cell surface of gram-negative bacteria is damaged by exposure of cells to EDTA. Tris buffer enhances the effect of the EDTA. Soaking of the ear canal in a solution of EDTA-tris can thus damage bacterial cell walls and also has been shown to be particularly active against Pseudomonas aeruginosa. The fact that EDTA-tris is water based means it is well tolerated even in ulcerated ears of chronic otitis externa. Otitis externa is inflammation of external ear canal distal to the tympanic membrane; the ear pinna may or may not be involved. Clinical signs can include any combination of headshaking, odor and pain on ears. The treatment and management are complex in chronic cases. This experiment has shown 8 chronic otitis externa dogs that have had this problem for more than 6 months to 3 years by differences of underlying cause; atopic dermatitis, food allergy, insect bite hypersensitivity and contact allergic dermatitis. All 8 dogs have been on antibiotic for at least 4 weeks and controlled by flushing EDTA-tris once a week as maintenance shown a good response of less otitis signs and reduced the recurrence of symptoms after off all antibiotics.