Traces of HCN in Guinea grass are reported as well as small amounts of oxalic acid (0.28%) (Ndyanabo, 1974 cited by FAO, 2009). Continuous feeding of oxalates has been implicated in hyperparathyroidism ("big head") in horses, and occasionally nephrosis or hypocalcaemia in ruminants (Miyazaki et al., 2003).
In South Africa, it is suspected to cause photodermatitis in sheep ("dikoor", literally "thick ear"), perhaps in conjunction with the smut fungus Ustilago (Botha et al., 2002). The plant is also said to cause fatal colic if eaten too wet or in excess, particularly in Equidae (Duke, 1983; Cerqueira et al., 2009).