Be aware that 'Gaelic' is actually two separate languages: Scottish Gaelic (called 'Gaelic' in Scotland) and Irish Gaelic (called 'Irish' in Ireland).
In Irish: gadhar rua or madra rua (the latter can also mean 'fox')
In (Scottish) Gaelic: cu ruadh.
Irish: Madra beag dubh
Scottish Gaelic: Cù beag dubh
It depends on which Gaelic you mean: Irish could be madadh dubh/madra dubh while Scottish Gaelic is cu dubh (grave accent on u).
The Scottish Gaelic word for 'little' is beag, pronounced beg.
Irish Gaelic would be bocairín.In Scottish Gaelic it is foileag.
beag
madra álainn
Bláithín Éireannach in IRISH Gaelic.
In Irish: garpháiste beag In Scottish Gaelic: ogha beag
Mo stoirín.
Cailín beag Éireannach
coileáinín faolchú / coileáinín mactíre
piosa beag de glas
In Irish it's "A Aodhán, mo lasóg"
perrito