My neutered male sibling cats fight. How to help them get along?

Hi there! Behavioral issues in cats can definitely be frustrating. Obsessive mounting can often be attributed to underlying anxiety. I would recommend trying an anxiety reducing pheromone product called Feliway. It comes in diffusers, sprays, and collars and often helps multi-cat household behavior problems. If there is no improvement with Feliway, I would recommend talking to your vet about putting Max on a trial of anti-anxiety medication to see if that helps.

I am sorry to hear about your kitties! It is possible there is a change in dynamics if one cat has now reached sexual maturity. If he is not already neutered this may help. You can also get a Feliway multicat diffuser for your house which can help reduce intercat aggression, but it may also take some time and training to get them to get along again. You can read about methods for training the cats to get along again at https://drsophiayin.com/blog/entry/feuding_felines/

I would recommend getting them neutered as soon as possible. As they have gotten older they are becoming more aggressive and controlling of there territory. I would recommend neuter, increase number litter boxes, increase food and water dishes to start. Hopefully once all the added hormones are gone they will settle down

Do not separate them. let them figure it out themselves. Cats will have tiffs no matter how much they like each other. The fact that they are grooming each other and lie with each other is a good sign that they like each other. Think of their tiffs as brothers having sibling tiffs. It is normal. Let them have their once a day fights. This will eventually subside.

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!

Such behavior can be a dominance issue and in older pets may be a sign of changing social dynamics and i would schedule a vet check to rule out any medical causes. The comfort zone diffusers for multicat household or the original feliway pheromone diffuser may help but i would not introduce a new kitten until things settle down

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.