A 1-year-old-female Yorkshire Terrier was referred to the Veterinary Teaching Hospital of the Autonomous University of Barcelona (VTH-UAB) (Spain) with a 6-month history of unilateral chronic proliferative conjunctivitis and intermittent vomiting and cough. Several medical and surgical treatment efforts to manage conjunctival lesions had resulted in no improvement of the clinical signs. Complete general and ophthalmic examinations revealed several proliferative ‘wood-like’ masses in the conjunctiva, oral cavity and an interscapular subcutaneous nodule. Conjunctival and buccal biopsies were performed as diagnostic procedures. A diagnosis of ligneous conjunctivitis was made on the basis of histopathology findings and clinical presentation. The only biochemical abnormalities found were severe proteinuria and low plasminogen activity in plasma. No other analytical abnormalities were observed. Topical treatment with heparin and anti-inflammatory and immunosuppressive drugs have controlled the ophthalmological clinical signs. To our knowledge, this is the first case report of a dog with plasminogen deficiency and ligneous conjunctivitis with a long survival period and 2-year follow-up.