horseleech

[hawrs-leech] /ˈhɔrsˌlitʃ/
noun
1.
a large leech, as Haemopis marmoratis, that infests the mouth and nasal passages of horses.
Origin
1400-50; late Middle English horsleych. See horse, leech
British Dictionary definitions for horseleech

horseleech

/ˈhɔːsˌliːtʃ/
noun
1.
any of several large carnivorous freshwater leeches of the genus Haemopis, esp H. sanguisuga
2.
an archaic name for a veterinary surgeon