Are dogs allergic to seafood such as squid shrimp octopus etc If so what would be the signs of an allergic reaction?

Like people, different dogs have different Allergies. Also, as with people, allergic reactions can range from mild to life-threatening and can progress quickly. Dogs often show a rapid swelling in the face, hives, itching, but can progress to difficulty breathing and shock (both life-threatening), collapse and death if they have a severe allergic reaction.