Mastitis is defined as inflammation of the parenchymal tissue of the mammary gland, regardless of its cause. Mastitis cases with unidentified etiology have drawn attention to the possible role of viruses. Viruses whose activity has been detected directly or indirectly in cattle with clinical mastitis have also been reported to play an important role in subclinical mastitis, causing significant economic losses in milk production. In sheep and goats, maedi-visna virus and caprine arthritis-encephalitis virus have been reported as important viral mastitis agents. In this review, the results of studies conducted on mastitis in cattle, sheep, and goats are evaluated. The reviewed studies reveal that viral agents can replicate in mammary tissue and cause lesions, lead to mastitis associated with secondary infections due to virus-induced immunosuppression, and result in physical and chemical changes in milk. Consequently, there is a need to develop rapid diagnostic methods and antiviral agents to identify viral causes of mastitis, as well as to conduct studies to determine viral agents involved in mastitis in our country.