Yes and no

Most dogs are perfectly capable of swimming. There are a few exceptions in the heavy short nosed breeds. But, even though a dog should be capable does not mean he can. Some dogs panic in the water and cannot hold themselves above water with their frantic paddling. 

Most dogs can learn to swim and we are careful to encourage them slowly and safely. Puppies almost immediately adapt to swimming and learn to like at quickly. Older dogs can swim be are neutral to negativeon the idea of it.