Experimental laminitis caused by carbohydrate overload was induced in 20 healthy horses. Seventy two hours after induction, samples of the laminar tissue were obtained by biopsy from the thoracic limbs digits for histopathology. The histological findings were compared to samples from horses without laminitis. Neutrophilic infiltrate was observed in 80% of the samples, congestion in 50%, hemorrhage in 35%, and hyperplasia of the arteriolar intima layer of the primary dermal lamina in 15%. Thrombi and intravascular blood clots were observed in 15% and 20% of the samples, respectively. Apparently, these findings were due to circulatory changes that resulted in edema, congestion, and hyperemia, followed by degeneration. In 70% of analyses performed on treated horses, the histological lesions were less severe than the clinical signs of lameness. It is concluded that: (i) the biopsy technique of laminar digital tissue from horses is viable; (ii) the artifacts generated by the biopsy technique do not compromise the histological analyses; and (iii) non-steroidal anti-inflammatory drugs do not avoid laminar lesions when administered after the beginning of clinical signs of laminitis.
equine; laminitis; digital histology; non-steroidal anti-inflammatory drugs