Concept:
Liability for injuries caused by animals is governed by the "Scienter Rule" and the law of Negligence.
• Scienter Rule: If an owner knows their animal has a "vicious propensity," they are strictly liable for injuries it causes.
• Negligence: Failure to exercise reasonable care to control an animal in a public place.
Step 1: Evaluating the knowledge of the owners (Scienter).
The question explicitly states that
Y's dog is ferocious.
There is no mention of X's dog having a dangerous history or nature.
Under the law, an owner of a known dangerous animal (Ferae Naturae or a domestic animal with known vicious traits) is under a strict duty to ensure it does not harm others, regardless of whether the dog actually bites or just causes a frightful situation.
Step 2: Determining the Liability for Z's injury.
Y is liable because he brought a
known ferocious dog into a public space.
His failure to restrain his ferocious dog led to the fight that frightened Z.
Even though Z was not bitten but injured while trying to escape, the "Chain of Causation" starts with Y's negligence in controlling a dangerous animal. Thus, Z has a valid claim against Y.