New Rabbit Owner Primer
The New Rabbit Owner Primer was written by batclock, a member of the /r/rabbits community. It has been copied and formatted here with proper external and internal links for ease of access.
Introduction
Welcome to owning a house rabbit! Rabbits are a wonderful companion pet with complex personalities. They are, however, a 10+ year commitment that require just as much work as any dog or cat. This primer will address the most common issues and direct you to the best information for care of your bunny.
Have Your Rabbit(s) Sexed
This doesn't apply if you adopted your rabbit(s) from a shelter, which you should have. If you, however, bought yours from a pet store, feed store, or out of the back of a van, have someone who is very familiar with rabbits determine the sex of yours.
Rabbits are hard to sex at a young age. Pet stores and the like are notorious for giving bad or knowingly false information. This is very important information you need to proceed. If you have multiple rabbits, separate them as soon as you can. Rabbits can become pregnant extremely early, and same sexed rabbits will begin to fight when they hit puberty. You should be ready for this and have a second home for your other rabbit.
Finding a Vet and Desexing Your Rabbit
You need to find a qualified rabbit vet. I won't go into detail on how because the House Rabbit Society has a wonderful write up on just this subject. This is extremely important as rabbits have very different needs from other animals, and having a vet that's very familiar with the ins and outs of them is vital.
When you've found a vet you should speak to him or her about spaying or neutering your rabbit(s). It can be done in males as soon as the testicles drop, and in females at or as early 4 months of age. This is not optional. Spaying or neutering your rabbit(s) will not only make a better companion but also increase their lifespan and prevent uterine cancer in females.
Food
Rabbits have very specific dietary requirements. They have fragile digestive systems and if it gets out of balance it can lead to sometimes fatal issues.
Hay
The number one and most important thing in your rabbit's diet is hay. Unlimited hay. Up until one year of age you should be giving them a mixture of timothy hay or meadow grass and alfalfa hay. The alfalfa is important as it has calcium for growing bones. You should start decreasing alfalfa hay at 7 months and take it away completely at one year as it can lead to excess calcium which causes urinary issues.
Pellets
Pellets are concentrated nutrition for rabbits. Most of the brands of pellets, however, are complete junk food. Make sure to select a good pellet for your rabbit(s). The best and most popular brand around here is Oxbow. As a new rabbit owner you can follow the House Rabbit Society feeding guidelines and be sure you're doing a good thing.
Greens
Your rabbit(s) should get daily greens. Contrary to popular culture, carrots are a treat item for rabbits and should not compromise a large portion of their green allotment. Once again I direct you to the House Rabbit Society guide on greens.
Litter Training
You can begin to introduce a litter box to your rabbit(s) right away. Find the spots they like to go to the bathroom and put a box there. Put any accidents into the box and put their hay within reach of it. Rabbits like to poop and eat at the same time. Before they are desexed it might be harder, but once their hormones start going down they will eventually get it. Make sure to clean any accidents up with vinegar, smell is a large part of how rabbits choose where to go to the bathroom and vinegar will remove that smell.
Litter
Rabbits do not need bedding and in reality it can create quite a mess. Most cat litters and cedar shavings are dangerous for rabbits. Clumping litter is also a huge no-no. Your best bet is using a litter like Yesterday's News or Carefresh.
Poop
As a rabbit owner, become intimately familiar with poop. Any changes in size or shape should be noted. Should your rabbit not be pooping normally it can be indicative of a health issue like GI stasis. Changes in shape or size can indicate a blockage. It's important to pay attention to digestive health as it doesn't take long for a bunny to go downhill. Read the House Rabbit Society's article on the rabbit digestive system.
More Poop (Cecals)
Rabbits eat their own poop. They produce a type of poop called a cecotrope or cecal that contains essential nutrients. Usually the rabbit eats these as they come out of the anus. If you see them around the cage it means that the rabbit is producing excess cecals which can indicate that their diet is too rich. Babies tend to be messy with their cecals and might leave a few lying around. They look like a bunch of grapes. These are not to be mistaken for diarrhea. If you see watery poop you should bring your rabbit to the vet immediately.
Pee
Rabbit pee can vary in color from milky yellow to orange. If your rabbit is "leaking" or straining when peeing it can indicate a urinary tract infection. If the pee has a gritty texture you should see a vet right away.
Housing
This is a controversial subject here. There are two things almost everyone agrees on here: a small cage from a pet store is not appropriate for a rabbit, and your rabbit should be kept inside . The House Rabbit Society guidelines on housing are an absolute minimum. Personally, I prefer using a puppy x-pen with indoor/outdoor carpeting underneath it over a cage. Some people use NIC cubes to build a pen. Please consider free ranging, however. Many people here have nothing but litter boxes and food dishes like any cat or dog, and with proper bunny-proofing, it works out extremely well.
Bunny Proofing
An important step to ensure your rabbit a safe environment in which to play. Once again the House Rabbit Society FAQ on bunny-proofing.