My sibling recently bought two mini lop bunnies in late December 2017 and we are both looking after them. They were 8 weeks old brothers, happy and healthy. They are very close to each other (brothers in fact) and they love each other’s company. They are very friendly and always come up to me when I sit down and they follow me quite a bit. They are sheltered outside and living in Australia. I really want them to live inside but my parents would never let me I noticed there were lots of mosquitoes and I was a little worried because I heard they released a virus in Australia through mosquitoes to wipe out the fast growing population of rabbits. I was really scared when I heard about this. I bought a mosquito net and I place it over the hutch all day whether the lops are in there or not. There was also a wheel burrow full of water which I had no idea about until a few days after we got the bunnies (one of my family members put it there a while ago but we tipped it out when we saw it as mozzies breed in there). Unfortunately about a week ago, I noticed a behavioural change in one bunny. He became a little less active than usual and I was a little alarmed. Because it’s my first time owning bunnies, I wasn’t sure if it was normal or not. The next day I noticed the bunny’s poo a little dark and soft. I converted him to an all hay diet (oaten hay) but it didn’t seem to fix the problem and his poo just became a more liquid form. He also wasn’t able to use the litter box properly and started peeing in places he doesn’t usually. He was drinking A LOT of water and I give a lot of hay and all of it is pretty much eaten and I refilled it more frequently than usual. However, I’m not quite sure which bunny was eating the hay. The sick one normally eats everything and the other one can control himself. The well looking bunny also seemed fine in terms of behaviour while the one seemed to be getting less active by the day. He lost a lot of weight too and my thumb and middle finger were able to circle around his body, indicating how much weight he’d actually lost. It was hard to tell with all the fur. I decided to book an appointment to see the vet as I was previously planning to vaccinate both bunnies anyway, but the bunny (that wasn’t behaving normally) wasn’t moving the next day. Every time he stood up, he fell back down and was lying on his side (according to my sibling as I wasn’t at home). He was rushed to the vet and they said they couldn’t do anything about it as he was already suffering so they had to put him asleep . The vet working that day wasn’t specialised with rabbits but he said it was most likely due to RHD or the calicivirus. I felt horrible for the other bunny that was still doing okay, but I was scared because the vet said the virus was highly contagious and the other bunny was with his sick brother for the past week. I cleaned the cage and everything but it’s pretty much impossible to kill the virus in our backyard if the rabbit died because of it. They were sharing water, food bowls, blankets etc. and they both played outside on the concrete and grass. We took the other bunny to the specialised rabbit vet the next day and he said that he seemed healthy. He also doesn’t seem like he’s been losing weight but we have to keep a close eye. He said that the other bunny may have passed away due to the virus but he wasn’t actually quite sure. However, ever since the bunny’s brother passed away, he seems really sad! Also, when we took him for his vaccination, the next day he seems a lot more inactive and not jumpy like usual. He just sits in one place. Time to time he’ll move. He did jump only a little bit when he saw me bringing some food but otherwise, his behaviour is quite different than usual. Usually he jumps around a lot very happily when he comes outside his hutch but not in the past 2 days since the bunny’s death and vaccine. The vet said we have to keep a close eye on him just in case he does develop the virus or some other sickness. I’m not sure what to do? 

My main concern is:

1) Is it normal for my bunny to act like this following the death of a close bunny brother?

2) Is it normal for him be inactive like this after a vaccine?

3) Is he lonely? Should we get him another bunny friend in a few weeks/months?

4) Do you really think my other bunny passed away due to the virus? If so, why hasn’t my other bunny passed away as well? They were in the cage together sharing everything and it’s highly contagious apparently. 

5) Are there any good mosquito and fly repellents that are bunny safe or to put on the bunny?

I really just want my other bunny to be happy Please help!