The War Against Fleas in Goats and Sheep: Impacts and Control Strategies Fleas are blood-sucking external parasites that can cause significant harm to sheep and goat herds. The most common species is the cat flea (Ctenocephalides felis), but in goat herds, you may also encounter the sticktight flea (Echidnophaga gallinacea), which attaches to the skin, especially around the head and ears. Sometimes, due to their tiny size, people mistakenly believe that the damage they cause is insignificant – b