Keen Hearing and Smell. The zombie hound has advantage on Wisdom (Perception) checks that rely on hearing or smell.

Bite. Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 4 (1d6 + 1) piercing damage. If the target is a creature, it must succeed on a DC 11 Strength saving throw or be knocked prone.

If a target is reduced to 0 Hit Points by this attack, it must succeed on a DC 8 Constitution Saving Throw or turn into a Zombie in 1d4 hours. This saving throw is made is disadvantage if the target was under the Frightened when it was reduced to 0 Hit Points.

Rotting Roar. The Zombie Hound unleashes a terrifying, snarling roar. All living humanoids within 30 feet of the Zombie Hound must make a DC 8 Wisdom saving throw or be Frightened for 1 minute. The DC for this saving throw increases by 1 for every 3 Undead within 30 feet of a creature making the saving throw. A targeted frightened in this way can repeat the saving throw at the end of each of their turns, ending the effect on a success. If a target succeeds on the saving throw, they are immune to this effect for 24 hours.