heartworms : Parasites that live in dogs’ hearts and cause heart failure. They’re transferred through mosquito bites.

heat: The period when a female dog is fertile.

heel : A command and position in which a dog walks at your left side staying with you as you change direction or pace.

hip dysplasia: A painful malformation of a dog’s hip socket. Some breeds are genetically predisposed to the condition.

hot spot : A localized area of skin infection. It’s usually round, red, and warm to the touch.