Why Did the Family Cat Suddenly Attack the Family Dog?

Play Gone Wrong

• If Fluffy and Rover were playing with each other before the aggression occurred, it's possible their game went too far. Many cats and dogs enjoy companionable games of chase, wrestling or stalking. It might look like they're fighting, but if neither animal is attempting to escape, their bodies are not stiff and their facial expressions are neutral, Fluffy and Rover are just having a bout of spirited play. But if Rover accidentally hurt Fluffy, continued the game past her signals she wanted to stop or became a little too exuberant, Fluffy might cross the line from play into aggression. If you suspect this is the case, keep an eye on them next time they play. Separate them if Rover gets rough or Fluffy acts annoyed. Ears flat to her head, tail low and lashing, and puffed-up fur are all signs the cat has had enough.

Protecting Territory

• Cats and dogs can both be protective of their territory, including sleeping areas, food, toys and even people. Fluffy's sudden attack on Rover might have resulted from the dog overstepping the cat's boundaries. If Fluffy is eating and fears Rover wants her food, she'll protect her bowl. Jealousy over Rover receiving human attention can trigger aggression. A sleeping cat stepped on or bothered by the family dog can wake up ready to attack. Fluffy might also feel threatened by Rover crowding her while she's using the litter box. If you think any of these situations triggered Fluffy's aggression, keep a close eye on your pets and make sure Rover respects the cat's turf. Put her food bowl out of his reach, make sure both animals receive plenty of human interaction and give Fluffy a high perch for sleeping and a private spot for her litter box.

Redirected Aggression

• Redirected aggression occurs when a cat, usually an indoor pet, spots something outside the window or door that makes her feel threatened. Another cat roaming on what Fluffy considers her territory is a frequent cause. Unable to get at the target outside, but upset and threatened, Fluffy lashes out at whomever is unlucky enough to be nearby. In this case, Rover was the victim, but it could just as easily have been you. Redirected aggression can be quite violent and may result in injury. Separate the animals, and keep them apart while Fluffy calms down. You will need to slowly reintroduce them to each other, because Fluffy might remain aggressive toward Rover long after the triggering incident. Be patient and don't force the cat near the dog. Most cats get over the upset, but if Fluffy remains aggressive toward Rover, talk to your veterinarian about behavioral intervention.

Physical Causes

• If Fluffy wasn't feeling well or had pain, she might have taken her discomfort out on Rover. Check the cat for signs of injury, including abscesses, sore joints or skin abrasions. Consider Fluffy's health. Has she shown signs of illness such as lethargy, lack of appetite, changes in litter box habits or just not being herself? If you see any signs of illness or injury, or if Fluffy has a chronic condition like arthritis, thyroid disorder or diabetes, a visit to the vet is in order to treat her discomfort. Some feline illnesses, particularly hyperthyroidism, neurological or adrenal disorders, orthopedic problems or cognitive changes from aging can cause a previously calm cat to become aggressive. Your vet can test for these conditions and provide treatment to help Fluffy feel like herself again.