Gaulish "horse" words
Mandu- 'poney, little horse'
Sextan-manduus pagus 'six poney country', close to Rennes
Catu-mandus 'small war horse'
Cassica - a mare
Ueredos / paraueredos - a type of work horse
Uiro-mandui, Manduccus, Manduilla etc.
Trimarcisia = (three riders)
The sentence by Consentius "...Gallorum manni..."
The loan in Basque mando 'mule' etc. (DLG 181)

Irish "horse" words
Ech - horse
Marc - horse
Capall - horse (late, a loan from Latin)
Epa = female horse (mare)
Epona =sacred mare
Marcos = war horse => King Marc'h (Brittany)
Caballos = 'work' horse
Epos - possibly a work or war horse

British "horse" words
Mandu-essendum 'Poney chariot' Mancetter in GB
Cartimandua, queen of the Brigantes