How to stop my old cat from being aggressive to my new male cat?

As a starting point, make sure that both of your cats have been neutered, as intact male cats will often spray urine due to hormone influences. If both cats have been neutered, the spraying behavior is likely a sign of stress and anxiety, but medical causes of inappropriate urination should be ruled out by a visit to the veterinarian. Separating the newly adopted cat and only allowing the cats to interact under direct supervision may minimize fighting behavior. Also, utilizing calming pheromone products for both cats, such as the Comfort Zone® Multi-Cat Diffuser, may decrease the stress level for both cats. If the aggression continues, consultation with a specialist in [veterinary behavior](http://www.dacvb.org/) to get to the root of the aggression, coupled with prescription anti-anxiety medication may be helpful for both cats.

Here is an article on introducing new cats to the home. https://www.petcoach.co/article/5-steps-to-introducing-your-cat-to-a-new-feline/ In addition, I recommend a calming pheromone such as Feliway that can help with anxiety. It is available as a plug-in room diffuser for large areas, and as a spray for small areas like a mat or bed. https://www.drsfostersmith.com/product/prod_display.cfm?pcatid=8906 https://www.drsfostersmith.com/product/prod_display.cfm?pcatid=37241 Another product I like is Composure, which is available as a little treat. https://www.petco.com/shop/en/petcostore/product/vetri-science-composure-feline-bite-sized-chews I hope this helps. Thanks for using PetCoach.

I would try a Feliway spray, diffuser or collar. It is a pheromone that helps with relaxation and anxiety. There are also supplements for anxiety. Set up separate areas for feeding and two litter boxes so they each have their own space with an area that they both have access to. Usually over time they will adjust if left alone. If she’s still aggressive there are prescription medications to give her for a little while to help her adjust so please discuss this with your veterinarian. Thanks for using Petco Pet Education Center, formerly Petcoach to help you care for Kaji.

You may ned to just keep them separated. If it has been 2 years, there is a chance she will never get along with them. You could try some Feliway spray and see if that helps or talk to your vet about trying an anti-anxiety drug, like Prozac or Trazodone. http://www.feliway.com/us/#redirected

Moving can be very stressful on any species. Cats will sometimes display signs of mis-directed aggression when they are stressed. I would recommend getting Feliway pheromones started asap. These come as plug in diffusers or even collars if the cats will tolerate them. They release calming hormones into the air that people won't smell, but do help relax agitate pets. Give the cats a safe place to retreat to - a room or hideout where they can get away from each other, the dog and people. If possible try to have items from their last home there (a bed or toys). Try to feed the same food, switching it over gradually. I would recommend having several litter boxes in different areas of the house while they are acclimating. If the fights are serious enough you may need to separate the cats into separate areas of the house and gradually reintroduce them to each other. If the behaviours continue or worsen, I would recommend consulting with their veterinarian. There are medications that can help in conjunction with training to decrease behavior problems. The following website has some great information about cat behavior by one of best behavior veterinarians there ever was. You may want to search for articles on aggression and anxiety in cats for some more ideas. https://drsophiayin.com/resources/cat_behavior/

He may be experiencing some stress and anxiety from having another cat in the house. You could try Feliway Spray or a diffuser and see if that helps. You could also try Solliquin and see if that helps. If he is still having issues than your vet could prescribe an anti-anxiety medication, like Prozac. http://www.feliway.com/us/#redirected http://www.solliquin.com/

Both of them are really cute! I would get the male neutered once his turns 5 months to prevent this behavior from getting worse. The female could go into heat at anytime so I would advise to get her spayed as well. This behavior may never go completely away as it is their personalities. You may try to put some feliway diffusers throughout the house to help calm them. Feliway is a cat pheromone that doesn't work on all but can help with this behavior. They even have a multicat household version now. I would always meal feed and feed them separately as food aggression is really hard to control. I would also make sure you have at least 2, preferably 3, litterboxes to decrease competition. If the feliway and neutering doesn't help, I would talk to your vet about giving the more dominant one something to help mellow him out like an antianxiety medicine. Hopefully this is just a behavior he has since he is young and boisterous and he will grow out of it. I hope this helps!