Serum markers of lamellar basement membrane degradation and lamellar histopathological changes in horses affected with laminitis

In order better to evaluate the extent to which degradation of the lamellar basement membrane (LBM) by matrix metalloproteinases (MMP) occurs in equin e laminitis, we determined the concentration of type IV collagen and Lamini n in normal and laminitic horses, using specific immunoassays. Blood sample s were obtained from both the jugular and the cephalic veins of horses (n = 10) before and after the induction of acute alimentary, laminitis by carbo hydrate overload. Jugular and cephalic venous blood samples were also obtai ned from horses affected with naturally occurring laminitis (n = 16) and no nlaminitic controls (n = 8). The serum collagen IV concentration was not ch anged following the induction of laminitis in the experimental group. Serum collagen IV concentration was increased in jugular venous blood obtai ned from cases of naturally occurring laminitis (mean +/- s.e. 218.04 +/- 1 8.59 ng/ml) compared with nonlaminitic controls (157.50 +/- 10.93 ng/ml) (P <0.05). Serum collagen IV concentration was also increased in jugular venou s blood obtained from severely laminitic horses (219.50 +/- 18.18 ng/ml) co mpared with nonlaminitic controls (157.50 +/- 10.93 ng/ml) (P<0.05). A diff erence in serum concentration of collagen IV was not identified based on ch ronicity of naturally occurring laminitis. Serum laminin concentration did not differ between laminitic and nonlaminit ic horses. Differences in serum laminin concentration were not identified b ased on sampling location (jugular or cephalic vein), severity of laminitic pain, or chronicity of spontaneous laminitis. In conclusion, the circulati ng concentration of collagen IV was increased in horses affected with natur ally occurring laminitis. The potential role far serum collagen IV assay fo r characterisation of equine laminitis warrants further investigation.