In previous projects, Embrapa Dairy cattle developed nanostructured intramammary formulations of mastitis, which show potential therapeutic use in the treatment of bovine keratoconjunctivitis. Infectious bovine keratoconjunctivitis is a contagious disease that affects the eyes of cattle of all age groups, mainly calves, caused by Moraxella bovis. The disease is rarely fatal, but production losses are high. The costs caused by this disease involve weight loss, falling milk production and treatment expenses. The animals clinically affected present discomfort and depression, and this is considered the eighth disease that most causes economic losses to livestock in South American Southern Cone region. The initial symptoms are excessive tearing and photophobia, and within 24 hours the conjunctival infection occurs. An area of opacification and edema in the cornea is observed. Several factors may predispose to the occurrence of this ocular infection, such as sunlight, which is capable of injuring the corneal epithelium and favoring the access of bacteria. Other contributing factors are: dust, seeds, hay and other irritants. The disease can be transmitted by direct contact, aerosol or nasal and ocular secretions. The main obstacle to the therapy of such ocular infection is the difficulty in handling topical treatment. Subconjunctival injections are often recommended for keeping drug concentrations in the affected region elevated for longer periods than topical applications of ointments or solutions. The most commonly used drugs are gentamicin, erythromycin, oxytetracycline and cloxacillin. To overcome the limitations, facilitate the treatment and accelerate the healing process, nanoparticles were developed with the potential to favor the penetration of the antibiotics through the eyeball, a strategy capable of reducing the number of applications and improving the healing rates. Thus, the aim of this project was to improve the production process and to evaluate the efficacy of nanoencapsulated cloxacillin applied in conjunction with nanostructured antimicrobials compared to the same antimicrobials conventionally administered in the treatment of bovine keratoconjunctivitis. The sensitivity to the main antimicrobials used in the treatment of bovine keratoconjunctivitis was investigated in susceptibility tests and the minimum inhibitory concentration determined for cloxacillin. The animals were evaluated according to the following scores: 1) normal eye; 2) epiphora with tearing; 3) opacity <0.3cm; 4) opacity 0.3-0.6 cm; 5) opacity>0.6 cm; and 6) corneal perforation. The study allowed obtaining a formulation with benzathine cloxacillin nanoparticles effective in the treatment of keratoconjunctivitis in cattle and the inactivation of M. bovis by the antimicrobial, favoring the posology of the treatment of bovine keratoconjunctivitis.