death 

Ar bhord a bháis             - on his deathbed

a'saothrú bás            - dying 

Gur gearr uaidh an bás            - death was close

Is gairid go gcroithfidh sé na cosaí            - It won't be long until he passes away (slang)

Le gairid uaidh               - he hasn't got long left

Is gearr uaidh             - he hasn't got long left

Tá sé réidh            - he is finished

Mearbhall an bháis            - someone on their deathbed raving and rambling

Animals 

Tá sé a'croitheadh na gcos            - it's dying 

Chroith sé na cosaí              - it died