Equine allogeneic umbilical cord blood derived mesenchymal stromal cells reduce synovial fluid nucleated cell count and induce mild self-limiting inflammation when evaluated in an lipopolysaccharide induced synovitis model.

REASONS FOR PERFORMING STUDY: Improvement has been reported following intra-articular (i.a.) injection of mesenchymal stromal cells (MSCs) in several species. These observations have led to the use of i.a. MSCs in equine practice with little understanding of the mechanisms by which perceived improvement occurs. OBJECTIVES: To evaluate the effect of i.a. allogeneic umbilical cord blood (CB-) derived MSCs using a lipopolysaccharide (LPS) induced synovitis model. We hypothesised that i.a. CB-MSCs would reduce the inflammatory response associated with LPS injection. STUDY DESIGN: Randomised, blinded experimental study. METHODS: Feasibility studies evaluated i.a. LPS or CB-MSCs alone into the tarsocrural joint. In the principal study, middle carpal joint synovitis was induced bilaterally with LPS and then CB-MSCs were injected into one middle carpal joint. Lameness, routine synovial fluid analysis, and synovial fluid biomarkers were evaluated at 0, 8, 24, 48 and 72 h. RESULTS: LPS injection alone resulted in transient lameness and signs of inflammation. In joints untreated with LPS, injection of 30 million CB-MSCs resulted in mild synovitis that resolved without treatment. Mild (grade 1-2) lameness in the CB-MSC-treated limb was observed in 2 horses and severe lameness (grade 4) in the 3rd, 24 h post injection. Lameness did not correlate with synovitis induced by CB-MSC injection. Simultaneous injection of LPS and CB-MSCs resulted in significant reduction in synovial fluid total nucleated, neutrophil and mononuclear cell numbers compared with contralateral LPS-only joints. No difference was detected in other parameters associated with synovial fluid analysis or in synovial fluid biomarkers. The incidence of lameness was only different from baseline at 8 h, where horses were lame in CB-MSC limbs. CONCLUSIONS: Allogeneic CB-MSCs reduced synovial fluid cell populations and stimulated mild self-limiting inflammation in the synovitis model. Continued evaluation of the effects of i.a. CB-MSC therapy on synovitis in horses is needed to evaluate anti- and proinflammatory properties of CB-MSCs. Immediate interests are dose, timing of treatment, and treatment frequency.

Otitis media in a llama.

A 7-month-old female llama was examined because of chronic otitis media and externa of 7 months' duration. Radiographically, the tympanic bullae appeared thicker than normal, and the ventral borders were poorly defined; the left external acoustic meatus (ear canal) appeared to be narrower than the right. The llama was treated with penicillin, and the ear canals were lavaged daily. Contrast radiography was performed on day 15 to determine the shape and size of the ear canals and evaluate the integrity of the tympanic membranes. Contrast medium was visible radiographically in the left tympanic bulla, indicating that the left tympanic membrane was ruptured, but the right tympanic membrane appeared to be intact. The left ear canal was narrower than the right, and the bony ear canals had a well-defined sigmoid shape. The right ear improved with medial treatment alone, but the left ear did not. Therefore, lateral ear canal resection was performed. After surgery, however, exudate was still evident in the left ear canal, and the llama became more lethargic and more reluctant to eat. Lateral bulla osteotomy was attempted, but no purulent material was obtained, and curettage of the bulla resulted in hemorrhage. Because of this and because of the llama's poor physical condition, a decision was made to euthanatize the llama. The sigmoid shape of the bony ear canal and the multicompartmental nature of the tympanic bulla make surgical treatment of otitis media and externa in llamas difficult. Further study of surgical treatments for otitis media in llamas is needed.

A combined frontal and maxillary sinus approach for repulsion of the third maxillary molar in a horse.

The 3rd maxillary molar is a difficult tooth to remove by extraction or repulsion. A combined frontal and maxillary approach provides good exposure for repulsion of this tooth, debridement of the sinuses, and placement of an alveolar seal. The improved exposure should minimize operative difficulties and postoperative complications.