Glaucoma is a multifactorial disease that leads to apoptosis of retinal ganglion cells and the development of glaucomatous ocular neuropathy and is the leading cause of blindness in middle-aged dogs. The most significant clinical symptom of glaucoma is an increase in intraocular pressure. During the ophthalmologic examination, it is necessary to determine whether the glaucoma is of primary or secondary nature with various diagnostic tests. The approach and choice of therapy for the patient should be individual because it depends on the type of glaucoma, the stage of the disease and the severity of clinical signs. Proper and timely medical and surgical therapy and constant ophthalmological recheck examinations can slow down the development of glaucomatous ocular neuropathy. It is important to improve the quality of life of irreversibly blind patients in the chronic phase of the disease with the help of end-stage surgical therapy. This paper describes the pathophysiological mechanisms that lead to the development of glaucoma, describes the classification of glaucoma, the necessary diagnostics, medical and surgical treatment options to improve clinical approach to a glaucomatous patient.