ABSTRACT. Silva R.C.C., Campos D. R., Oliveira P., Laguna A.G.V., Magalhães V.S., Cid Y.P., Almeida M.B., Scott F.B. & Fernandes J.I. [Efficacy of Chitosan gel mucoadhesive containing Doxycycline associated or not to Meloxicam as adjuvant to treatment of gingivitis in dogs with periodontal disease.] Eficácia de um gel de Quitosano Mucoadesivo contendo Doxiciclina associada ou não ao Meloxicam como coadjuvante ao tratamento da gengivite em cães portadores de doença periodontal. Revista Brasileira de Medicina Veterinária, 38(Supl.2):40-44, 2016. Programa de Pós-Graduação em Medicina Veterinária, Universidade Federal Rural do Rio de Janeiro, BR 465 Km 7, Seropédica, RJ 23897-000, Brasil. E-mail: firstname.lastname@example.org Periodontal disease is the highest occurrence condition in the pet clinic, affecting mainly older animals because of its characteristic of chronicity. Among the clinical signs observed in afflicted animals, gingivitis is the first to be observed. The goal of this study was to develop a mucoadhesive gel, containing doxycycline and meloxicam, and evaluate its efficacy as an adjuvant in the treatment of gingivitis induced by periodontal disease, with a clinical and histopathological rating. Eighteen Beagle dogs presenting gingivitis secondary to periodontal disease were divided into three experimental groups. Group I – animals treated with placebo formulation. Group II – Animals treated with a chitosan gel formulation containing doxycycline. Group III - Animals treated with a chitosan gel formulation containing doxycycline and meloxicam. All animals were treated for seven days, every twelve hours, in the gingival margin of the right maxilla. During the clinic evaluation, only the animals treated with the product containing doxycycline had improved. Contrasting, in the histopathologic evaluation, only animals treated with association of doxycycline and meloxicam presented improvements in their clinical score, although no statistic significance was observed between the groups. The developed formulations were not effective as adjuvants in the treatment of gingivitis induced by periodontal disease treatment.