there is a similar thread elsewhere runing parallel to this one, but, as I said on the other one, you need to introduce them through a barrier that neither can pass but which allows smelling and vision. A screen door with a strong grille is best. Keep the cat on one side, the dog on the other and stroke the cat, while talking calmly and continually to the dog. Repeat as often as is necessary. Our dog who hated cats with a passion, finally learnt that there were our cats, and other cats. She still chased other cats, but shared food with our cats. It takes time, patience and a level head.