My cat is suddenly aggressive, yowling, and eating less. What to do?

A sudden change in behavior may have, at its root, injury or infection. Ideally, Rostom should be physically examined by your veterinarian to diagnose and treat any medical causes for his sudden aggression. Neutering him should be strongly considered as testosterone can be a driving force behind aggressive behaviors. Once medical causes have been ruled out, you can address behavioral concerns such as stress or anxiety. A pheromone product, such as Feliway Spray or plug in diffusers, may help decrease any aggression or anxiety. A gradual desensitization to loud noises can also be done to lessen Rostom's response to them.

Sorry you are having some troubles with Monster! I recommend that you take him to your vet for a senior blood panel. They can check his thyroid as well. Hyperthyroidism (an overactive thyroid gland) is not uncommon in older cats and can lead to behavioral changes, more vocalization, eating more, acting odd. Get him in for bloodwork when you can! Thanks for asking Petco Pet Education Center, formerly Petcoach!

These sudden changes in temperament and the weight loss are commonly due to an endocrine problem called hyperthyroidism. The thyroid starts working more than normal increasing the metabolism (that is the cause of the weight loss) and causing behavioural changes similar to what you described. A clinical examination at your local veterinarian is essential to confirm this clinical suspicion and treat appropriately. A blood test and urine analysis are needed. Hope this answer was helpful, but please do not hesitate to contact us again on the forum or by requesting a consultation if you have any more questions or to discuss it any further. If this answer was helpful please let us know, this will be used to improve our service!

Stress and illness can be two factors in sudden behavior changes in cats, so getting Kosinus checked out by your vet is a good first step. Cats that are in pain or sick may suddenly lash out at friends or other pets when they were normally friends. If Kosinus checks out healthy, then looking for stress factors is the next step. Do the two cats have to share one food or water bowl? One litter box? One bed or perch? These can be things that may become contested, and if one cat is pushing the other out may lead to aggressive behavior. Making sure there are multiple litter boxes, beds, and food and water dishes may help. Pheromone diffusers that can be plugged into walls of shared rooms or used as a collar can also be useful for decreasing stress and aggression among cats, and may help Kosinus calm down some and get along again.

Have him examined by your veterinarian to diagnose illness or injury. Either are common culprits of a sudden behavioral change. Being an intact male may also be playing a role in the behavior. Consider having him neutered. In the meantime, provide additional food/water bowls, beds, toys and litterboxes to prevent food aggression or resource protection. Consider a pheromone product, such as Feliway Spray or plug in diffusers, to decrease any anxiety or aggression in the home.

That is very unusual and sounds scary! There could be a few reasons for this behavior. Sometimes there could be pain or a medical condition causing a change in behavior. Since Oscar can't talk and tell you what is happening, I recommend to have him examined by the veterinarian to be safe. Sometimes this behavior is related to the stress of seeing another cat outside. For some cats, this causes frustration and they can then exhibit bullying type behavior to other pets or people within the house. If the veterinarian thinks this is behavioral, there are a few things you can do. Try enriching the environment. Here is a great article about cat's instinctual needs: https://www.petcoach.co/article/why-every-cat-needs-a-place-to-climb/ Use a Feliway diffuser, set aside 30 minutes a day for vigorous play (really get him moving) and/or switch the food to Royal Canin Calm. If he is the only cat in the household, you may try feeding him out of a food puzzle. Hide food for him to find. Do not use these last two mentioned options if you have other cats. Provide a stand or resting place by a window so he can look outside. You may also try clicker training him for positive behavior. Here is a link about training cats: https://www.petcoach.co/article/can-i-train-my-cat/ Wash all windows and doorway exteriors where a cat may be spraying outside. Try to drive out the cat if possible. You may also need to block the window where you think Oscar may be viewing the cat most frequently. Most cats response best to combination therapy. The veterinarian can also prescribe medications which can help with aggression/stress. I hope this helps and please feel free to post any additional questions.

Sudden aggression and behavioral changes in cats can indicate pain or illness, so if you haven't already, a veterinary check up is best. If your cat checks out healthy, it may be there is a lot of stress causing your cat's behavioral issues. Making sure she has her own access to food, water, toys, treats, hiding spots etc from other pets or people is best. She is also still very young, and may just have a lot of energy/is still learning what appropriate behavior is. Ignoring bad behavior, increasing play and activity times, and rewarding calm, quiet behavior is best to teach her the right way to interact and to get out that excess energy. If the behavior continues even with this, speaking with a veterinary behaviorist is the best next step.