Conjunctivitis can have a number of causes from a scratch caused by ferreting about in the undergrowth to a bacteriological infection. Another cause of inflamed eyes, thankfully not usual in Labradors is Glaucoma. There are a number of home remedies which CAN be used but I hesitate to post them just in case there is something more serious wrong. Eyes are too delicate to take chances with! The safest thing is a trip to the vet’s. If you cannot get there immediately then bath in cold weak tea.