Digital Starling forces and hemodynamics during early laminitis induced by an aqueous extract of black walnut (Juglans nigra) in horses

• Published in: American journal of veterinary research Vol. 56; no. 10; p. 1338
• Main Authors: Eaton, S.A. (University of Georgia, Athens, GA.), Allen, D, Eades, S.C, Schneider, D.A
• Format: Journal Article
• Language: English
• Published: United States 01.10.1995
• Subjects: AFFECTION PODALE; Animals; CABALLOS; Capillary Permeability - physiology; CHEVAL; CIRCULACION SANGUINEA; CIRCULATION SANGUINE; CONTEO DE CELULAS; DEBIT; ENDOTOXINAS; ENDOTOXINE; ENFERMEDADES DE LOS PIES; EXTRACTOS DE MADERA; EXTRAIT DE BOIS; FACTEUR IMMUNOLOGIQUE; FACTORES INMUNOLOGICOS; Foot Diseases - etiology; Foot Diseases - physiopathology; Foot Diseases - veterinary; Forelimb; FREQUENCE DU POULS; GASTO; Hemodynamics - physiology; HEMOGLOBINA; HEMOGLOBINE; Hindlimb; Hoof and Claw - physiopathology; Horse Diseases - etiology; Horse Diseases - physiopathology; Horses; INSTRUMENT DE MESURE; INSTRUMENTOS DE MEDICION; JUGLANS NIGRA; Lameness, Animal - etiology; Lameness, Animal - physiopathology; LEUCOCITOS; LEUCOCYTE; LINFA; LYMPHE; METHODE D'APPLICATION; METODOS DE APLICACION; MODELE; MODELOS; NUMERATION CELLULAIRE; PESO; PIED; PIES; Pilot Projects; Plant Extracts - toxicity; POIDS; PRESION SANGUINEA; PRESSION SANGUINE; PROTEINAS SANGUINEAS; PROTEINE SANGUINE; PULSACIONES; RESPIRACION; RESPIRATION; TEMPERATURA DEL CUERPO; TEMPERATURE CORPORELLE; TRASTORNOS DE LA LOCOMOCION; TROUBLE LOCOMOTEUR
• ISSN: 0002-9645; 1943-5681
• DOI: 10.2460/ajvr.1995.56.10.1338

Starling forces and hemodynamics in the digits of 5 horses were studied during early laminitis induced by oral administration of an aqueous extract of black walnut (Juglans nigra). The black walnut extract was prepared from heartwood shavings and was administered by nasogastric tube. Heart and respiratory rates, rectal temperature, central venous and arterial pressures, digital pulses, and signs of lameness were monitored. Blood samples were collected for determination of WBC count, hemoglobin concentration, and PCV and for endotoxin and tumor necrosis factor assays. Total WBC count and central venous pressure were monitored until they decreased by 30 or 20%, respectively. These decreases in WBC count and central venous pressure were observed 2 to 3 hours after dosing with black walnut extract. Respiratory and heart rates, body temperature, systolic and diastolic blood pressures, PCV, and hemoglobin concentration did not change significantly. Anesthesia was induced, heparin (500 IU/kg of body weight) was administered IV, and a pump-perfused extracorporeal digital preparation was established. Digital arterial and venous pressures were maintained at 100 and 30 mm of Hg, respectively. Blood flow, capillary pressure, lymph and plasma protein concentrations, and weight of the isolated digit during rapid increase in venous pressure were measured. Isogravimetric capillary filtration coefficient, vascular compliance, vascular and tissue oncotic pressures, tissue pressure, osmotic reflection coefficient, and precapillary and postcapillary resistances were calculated. Mean digital blood flow was 14 ml/min/100 g, capillary pressure was 52 mm of Hg, and vascular compliance was 0.06 ml/mm of Hg. The vascular and tissue oncotic pressures were 21.49 and 4.93 mm of Hg, respectively. The osmotic reflection coefficient was 0.71, and tissue pressure was 41 mm of Hg. The precapillary and postcapillary resistances were 7 and 2 mm of Hg/ml, respectively