Older cat bites new cats throat

Question
I have a 3 cat household - up until recently I had a 10 year old neutered male, Velcro, who was friendly, laid back but independent; a 5 year old neutered female, Tiger, shy, timid yet loyal enough to sit at our feet and just beginning to trust us enough to enjoy being picked up and cuddled occasionally. And lastly the 4 year old male, Roddy, who was neutered at 2 years. He's a big boy, very people oriented (loves sitting on my shoulders) but also he played well with Velcro; the two of them would invent all kinds of games. Any time Roddy got too rough or started biting, Velcro would just push him away or lie on the ground and act disinterested, which worked well. Roddy on the other hand loves terrorising Tiger. He's not overly aggressive with her, since all he needs to do is get close to her or poke her with his paw and she screams like she's being murdered. Sometimes they do come to blows if Tiger can't get away. The last side of the cat relationship triangle was between Tiger and Velcro - she adored him and would sniff him when he wasn't looking, but he was largely indifferent towards her. If he ever tried to lick or wash her she'd panic and run away.

Anyway Velcro died suddenly recently, which was apparently due to an undetected heart condition - it was all over in 30 minutes. I checked with the vets the next day in case there was any chance that my other cats were at risk of some illness and they confirmed that it was most likely his heart if it wasn't a snake bite (it definitely wasn't, it happened inside my house). Aside from my grief, my immediate concern was for Tiger's wellbeing. I did not believe Roddy would grieve even though he was friends with Velcro, because he is also so strongly people oriented. Tiger on the other hand, would now have to bear the brunt of Roddy's interest and "playfulness". I decided to give it some time to see how the new 2 cat dynamic settled down before deciding whether to get another cat or not.

However in the first 24 hours after Velcro died, Roddy turned his attention to Tiger 5 or more times, causing much screaming growling and distress. He also started wandering the house, bobbing his head and apparently looking for Velcro.

This made my mind up straight away so I started asking around at the shelters whether they had a cat available who gets along well with other cats. Enter Toby - an 11 month old neutered male who loves other cats. After visiting him at the shelter he seemed ideal. He was a little bit timid, which was to be expected, but he showed both affection towards us visiting him, and apparent concern for the wellbeing of the other cat in his enclosure (who was terrified). He seemed to keep going back as if to check on the other cat - I realise this is probably me anthropomorphizing, but Toby was quite obviously very good with other cats.

I kept him separate in his own room for a week and this already took the pressure off Tiger since Roddy was very interested in seeing what was behind the closed door. Toby had been at the shelter for months looking to be rehomed. He's affectionate towards people, comes when he's called or fingers are clicked and purrs and rubs his face on our hands or the floor. However he hates being picked up; he struggles and jumps but he's got to the stage where he doesn't run away and hide. Interestingly, he's still uncertain around people but as soon as he sees another cat, his tail goes up, he greets them and becomes totally confident. He's very cat-oriented, which is what we were hoping would be good for Roddy.

It did not take long for Roddy to accept him, and Toby seems to be quite smitten with him. They play with each other, they chase and wrestle, and Toby trots along shoulder to shoulder with Roddy. The other good thing is while Toby is interested in Tiger, he respects her and leaves her alone. She's wary of him but not too scared because he is around the same size as her (maybe slightly smaller). The conflicts between Tiger and Roddy are back to an acceptable intensity and frequency and Tiger seems much happier.

Toby has been here 3 weeks now and is settling in very well. My problem is that as Toby has been getting more confident with us, Roddy seems to be getting more jealous of him. I have tried very hard to make sure Roddy gets more attention; that he gets the first cuddle when I come home from work and so on. But I do also want to include Toby and try to build some trust with him so I also try to interact with him every day.

What I've noticed is, at first when Roddy would wrestle with Toby, they'd bite each other but if Toby cried out, Roddy would stop biting. I understand that wrestling and nipping is normal cat play behaviour. In the last few days however, Roddy has started pinning Toby on the ground by the throat. Toby can cry or struggle but Roddy doesn't let go and sometimes I feel that I have to break it up. I don't know how hard Roddy's actually biting but the visual similarity to the killing choke hold of a tiger is disturbing. Roddy used to try to do this with Velcro but as they were of a similar size, and Velcro's coat was very long, Velcro could easily repel him or Roddy would have to give up with a mouthful of fur. Toby isn't big enough yet to be able to push Roddy away, and his fur isn't as long. If he was simply biting the back of Toby's neck, it would be clearly a dominance thing and I wouldn't be worried because Toby seems quite happy for Roddy to be the top cat. But biting the front of the throat seems more dangerous, especially since Roddy seems to want to hold it for a long time. Toby still loves Roddy and isn't scared of him since this has started. Roddy tends to do it more if I show Toby attention.

If this behaviour of Roddy's could become a problem I would like to stop it early. However I don't know whether I should stay out of it so that Roddy doesn't think I am defending Toby, or if I should intervene to prevent harm to Toby. Or if I should just believe Toby's body language that he really doesn't seem to be bothered by Roddy's rough behaviour.

Roddy often sleeps on the bed with me and my partner. Toby has slept at the foot of the bed, and successfully slept on the bed a couple of nights. Roddy seemed ok with this at first but he's decided to start biting Toby on the throat when he gets up on the bed now too, which is what led me to think this could be a jealousy issue as well as, or instead of, a dominance issue.

I'd love to know if you have any advice for me on whether I should do anything, and if so, what steps should I take to ensure Toby's wellbeing without upsetting Roddy's top cat status too much.

I really don't want this situation escalating and getting out of hand.

Thanks!

Answer
Bron,

Let me first tell you how sorry I am that you recently lost a much loved member of your family. I think that your situation is fairly common. The one point I would like to make starting out is that humans are not the only animals that grieve. Cats are capable of missing their housemates and even trusted humans that they have lost. I would suggest isolating Toby again for 1-2 weeks. Then you need to do what I like to call the scent exchange. Using a damp washcloth rub Toby so that his scent ends up on the cloth, then rub down Roddy and Tiger with the same cloth and go back to where you started. This will help familiarize each of the cats with the other's scents. Once you have done this for about a week or so you can start a litterbox rotation. As I am sure that you are aware you need one litterbox per cat plus one. Allow Toby to use a litterbox exclusively for a day or two, then swap it with the most frequently used litterbox without removing all of the waste. I usually leave one or two pee and poop pucks to help them use scent to identify their new housemate's presence in the litterbox. In the meantime you can go to most natural health stores and find a Bach flower essence by the name of Rescue Remedy. Make sure that you put this in fresh water daily for all of your cats. This will help to calm the situation down a little. At the health food store there are usually charts to indicate what each remedy is for, you could try one for grieving as well as one for jealousy. Homeopathy can sometimes be like peeling an onion, solve one layer to get to the next. If you are patient and willing to work with your household things should work out. This last part kind of goes as a common sense bit of advice, but I would have everyone vet checked again just to be sure that no contagious illness is going through your house. Good luck with your new family! Please feel free to contact me with any further questions or concerns.