In the beginning, Arnold is being chased by guard dogs. Suddenly he turns around and grabs the two dogs and knocks them silly by bumping their heads together. Even without using digital pause you can see that the "dogs" are rubber dummies. They look inflated, have no hair, have floppy legs, and they aren't the same color as the real dogs.
At the end of the movie, while rolling the credits, there is a statement that says no animals were hurt while filming the production so they had to use fake dogs.
Yeah, I figured that the producers wouldn't want the ASPCA to get angry when Arnold klunked the two dogs' heads together, hence the phony dogs. But with the budget they spent on this movie, they could have gotten some rubber dogs that looked more realistic, even if they are only on screen for three seconds. That's the type of slip up that keeps this web page in business.