Have you ever seen an otter attack a dog? I went down to the beach today (I live on water-front property). A neighbor dog came with me. When we got there, a family of otters (mother and three babies), was hanging around on the float, eating a big flat-fish (a sole maybe). Bosco, the dog, immediately started swimming to them. The mother was not accommodating. Bosco turned back after only like 5 feet. The mother chased him all the way to shore and then actually came on shore and bit him. He squealed and ran off. He's a big dog too, a chocolate lab, but he was terrified of this creature (river, not sea, otter). Usually they're playful, but not when they have babies.