Extraocular lymphoma in the horse.

OBJECTIVE: To describe the clinical findings and prognosis for extraocular lymphoma in the horse. PROCEDURES: Retrospective medical records study of horses diagnosed with third eyelid, corneoscleral, conjunctival, and/or eyelid lymphoma from multiple academic and private veterinary institutions. Data collected from the medical records included signalment, clinical descriptions of the extraocular lesions, treatment, and treatment outcomes. Nonparametric statistical analysis was performed with Fischer's exact tests. RESULTS: Extraocular lymphoma involving the eyelid, third eyelid, cornea, sclera, and/or conjunctiva was diagnosed in 26 horses. Differences in signalment, unilateral vs. bilateral extraocular involvement, and single vs. multiple extraocular lesion locations held no significance in terms of outcome. ANIMALS STUDIED: Horses with lesions localized to the eyelid or other nonextraocular cutaneous locations had a significantly higher chance of negative outcome when compared to the horses with no eyelid or cutaneous involvement (P = 0.019). Lesions to the third eyelid, corneosclera, and conjunctiva were either nodular or diffuse in nature. Nodular lesions when compared to diffuse lesions were associated with a higher chance of a positive outcome (P = 0.007). Surgical resection of the extraocular lesions as part of the treatment produced a statistically higher chance of a positive outcome when compared to horses where resection was not performed (P = 0.03). CONCLUSIONS: The prognosis for clinical remission in horses with extraocular lymphoma is generally fair to good, as long as the affected tissues are completely excised, and there is no eyelid or cutaneous involvement. Horses diagnosed with the nodular form of extraocular lymphoma seem to have the best prognosis with complete excision.

Correction of a large animal model of type I Glanzmann's thrombasthenia by nonmyeloablative bone marrow transplantation.

OBJECTIVE: The purpose of this study was to determine if nonmyeloablative bone marrow transplantation would induce stable hematopoietic chimerism that would correct the bleeding diathesis associated with type I Glanzmann's thrombasthenia (GT). METHODS: Three young dogs (less than 12 weeks of age) with GT were transplanted with DLA-matched bone marrow from littermates. Recipients received a sublethal dose (200 cGy) of total-body irradiation (TBI) prior to infusion with bone marrow (1-4 x 10(8) cells/kg). Recipient dogs were immunosuppressed with cyclosporine (15 mg/kg) and mycophenolate mofetil (10 mg/kg). Chimerism was determined by quantitation of donor microsatellite repeat polymorphisms in peripheral blood DNA and by flow cytometry to detect the presence of glycoproteins IIb and IIIa on platelets. Platelet function was assessed by a clot retraction test. RESULTS: One dog died one week posttransplant due to hemorrhage. Another dog died four weeks posttransplant from an unrecognized congenital heart defect and complications due to canine distemper virus infection. At the time of death, microsatellite analysis indicated 35 to 50% chimerism. Flow cytometry showed 20% of circulating platelets positive for glycoproteins IIb and IIIa. The third dog is alive and doing well approximately two years posttransplant. Hematopoietic chimerism has been sustained at 35 to 60% with approximately 30% of the platelets positive for glycoproteins IIb and IIIa. Platelet function is normal based on clot retraction. The animal does not have clinical signs of bleeding. CONCLUSIONS: These observations suggest that GT and perhaps other severe inherited platelet disorders can be corrected using nonmyeloablative bone marrow transplantation to establish partial chimerism with normal platelets in the platelet compartment.