INDOCYANINE GREEN-DYE AS A MARKER FOR MEASUREMENT OF PLASMA-VOLUME INGOATS

Evans blue dye disappears slowly from blood plasma and is not ideal fo r repeated measurements of plasma volume in the same goat because of i ncreasing turbulence of the plasma. Therefore, indocyanine green (ICG) was evaluated as an alternative to Evans blue in goats. The plasma vo lume was 40 +/- 6 ml kg(-1) and 41 +/- 3 ml kg(-1) measured with ICG a nd Evans blue, respectively, in six non-pregnant, non-lactating goats. In three other goats plasma volume was measured during late lactation (7-8 months after parturition; milk production 1.0 +/- 0.6 l). It was 52 +/- 1 ml kg(-1) (ICG) and 51 +/- 5 ml kg(-1) (Evans blue), respect ively. Thus, values of plasma volume measured by ICG corresponded well to these achieved with Evans blue. In a second series ICG was used re peatedly in the same goats to measure plasma volumes during late pregn ancy and early lactation. A group of non-pregnant, non-lactating goats was used as control. Plasma volume was 39 +/- 3 ml kg(-1) (N = 7) and 44 +/- 8 ml kg(-1) (N = 6) at 23 +/- 7 days and 2.5 +/- 1 days before parturition, respectively. During early lactation it was 70 +/- 12 ml kg(-1) (23 +/- 5 days after parturition; milk production 2.4 +/- 0.5 l N = 7). No side effects were observed after several injections of IC G in any of the goats. In the control group, plasma volume was 40 +/- 7 ml kg(-1), which was the same value as that observed in the first se ries. We conclude that ICG is a good alternative to Evans blue for det ermination of plasma volume in goats.