I’m sorry for your loss. 🙁

So, are they bonded yet? Or still in the bonding phases? If you’re currently in the process of bonding them (doing dating, side swaps, etc.) then I would pause all of that until he is healthy again. He may need a longer period of just living side by side with Squirrel as a neighbor to adjust to the change.

Bonding can be stressful for buns in any case, and as you mentioned all the routine disruption is stressful as well. If he is not eating normally you should treat as though he is going into stasis and treat accordingly. Whether the cause is depression or otherwise the treatment would be the same. If he’s still eating a bit and pooping a bit you can try syringe feeding him a bit to see if that perks him up. Sometimes a feeding or two will help stave off full stasis. If that doesn’t help you should get help from the vet.

Poor bun, they can really mourn their lost partner. My condolences to you as well, it’s awful to lose a rabbit 😥

Dana gave some excellent tips and I have little to add on the bonding part because I’m new to the experience.

I do have some tips on dealing with a depressed rabbit: use all their senses to cheer them up and reduce stress. Diminish stressful things like bright or flickering lights, unexpected noises and irritating smells. If he likes certain music, play it for him softly.

Use his senses of taste, smell and sound to keep him interested in food. Rabbits love fragrant herbs such as basil and parsley, and many love the anise scent of fennel as well. Use his sense of sound as well and give things that are crispy and fun to chew.

It’s good that he likes bananas: you can freeze slices of banana to keep feeding him little bits. Frozen and defrosted banana turns into a jelly-like substance which is also great to mix with medication.

And finally, the sense he’s missing most now: touch! Rabbits lay against each other and groom each other for a large part of the day. That touch makes the body produce happiness and comfort  hormones, and he’s missing a lot of those now.

Spend extra time on petting him, or try a light massage.

This is going to sound weird, but find out if he likes skin contact. Roll up a sleeve (or a trouser leg) and snuggle up if he wants to. Try to get skin contact by burying your arm in his fur a bit. You don’t have to do anything, but just sitting with him and having skin contact may make him very relaxed.

It’s likely that he has trouble sleeping deeply as well: rabbits need a lookout to feel safe. Choose a quiet moment in his natural sleeping hours (the afternoon or late evening) and put the phone on silent. He may fall asleep soon after touching, I expect he has some catching up to do.

Our bridge bunny Breintje couldn’t be bonded, and he really craved skin contact. I found that out when I wore short trousers: he snuggled up to the part of my leg where the skin was showing. I started to use more skin contact immediately and it really helped him to sleep and relax.

Late in the evening he often sat on the sofa cuddled up with me, so I put on my nightgown early and let him cuddle up. Sometimes I rolled up my sleeve too, and he happily purred and drifted off.

Rabbits can have very funny movements during sleep: don’t be startled if he starts to shake like he’s having a seizure. It just means that he’s so comfortable that he’s having an extra long REM sleep. This is normally a short phase, but it may last minutes for a very happy bunny.

I hope that this works for him to diminish his stress levels and to help him relax and sleep!