This brings up an interesting idea.
Firstly a little about arthritis, derived from the greek arthro- for joints and -itis for inflammation, arthritis is a term used to describe any form of inflammation of the joints, from Gout to Rheumatoid Arthritis. The term is used in a wide general range by most people.
Now the arthritis being seen by your rabbit is most likely due to the wearing down, fracturing or general degradation of the cartilage that separates the bones from one another in the joints. Imagine if you will that these are like a cushion to stop the bones from rubbing together. Now in humans this wearing down is seen throughout life, all depending on the lifestyle and genetic factors of the patient.
To oversimplify the matter you can put the cause in to three categories
- Lifestyle
- Genetics
- Both
For some people their lifestyle has led to this cartilage being broken down or fractured in to tiny pieces, causing the bones to bump and grind against each other causing pain for the patient whenever they move. This is caused by repeated impact of the bones against the cartilage, such as jogging on hard surfaces, eople who walk or run with bad footwear, do a lot of moving heavy objects or who exercise regularly on surfaces that don't provide enough support are prone to this.
Naturally the body re-grows this cartilage over time, replacing it with a new fresh cushion for the bones to bump against, mind you this is specifically for lifestyle.
Genetically, there are people who are predisposed to get arthritis at earlier or younger ages, all the way to childhood. Eventually the body can not keep making the cartilage and it begins to wear away, causing the bones to yet again bump against each other and grind.
The cartilage will no longer grow back faster than it is worn away or will not grow back at all.
In some cases sufferers can be afflicted by both bad lifestyle choices and genetic problems, causing the cartilage to disappear faster.
Now mind you that arthritis isn't solely caused by the cartilage being worn away, it can also be caused by many diseases, the name means 'inflammation of the joints' and therefore is a very broad term.
Now that we know a little about arthritis it's time to apply this to rabbits and the concept of multi levelled cages.
We'll presume that at no point any rabbit will be jumping more than it's height standing up, and from our knowledge of rabbits we understand that they jump using the back legs in a pushing motion, think along the lines of a 'super hop' and when jumping down land on their front feet taking the brunt of the force to their forelegs.
Using this information, with the knowledge we have about arthritis we can see a couple of things.
- If arthritis is to occur it is most likely to form in the rabbits front feet and shoulders and also around the neck (the force is spread out through other joints nearby). Presuming that the rabbit is landing on something hard there will be a fair bit of force being applied here.
- The hind legs of the rabbit rotate the most and have the most force being pushed out of them, during a full blown hop the rabbit will rotate the hind leg a good 60-70 degrees, even up to 90 degrees. During a full blown run the rabbit will be causing a lot of wear and tear on the joints.
- Going up and down ramps will actually cause LESS of an impact on the rabbits legs than regular walking, considering the way that rabbits walk, unlike a human or a horse the rabbit moves both legs at once and then the back ones. They do not lift the leg up and then place it down dropping their weight heavily on it, instead they pull themselves forwards. This combined with less rotation when going up and down a ramp should lead to less of a wear and tear on the rabbits cartilage.
So taking these things that we can deduce, we can see that yes jumping between levels is a problem, however having a ramp between the levels will not cause a problem at all.
So this raises the question as to whether separate levels are at all healthy within a rabbits cage. My answer is Yes, they are a great idea, having a separate level really adds to the mental health of the rabbit allowing them to see farther and also come closer to level with humans. However the movement between levels presents a problem, due to the lack of well recorded statistics of the development of arthritis combined with the inclusion of multiple levels in the rabbits cage it can not be said that there is a direct correlation between the two.
The general feeling on the forums is that no one has experienced many problems with arthritis leading from multiple levels, while also taking in to account the selective breeding of many rabbits their inclination towards arthritis should be slim, however we do see it in the very old rabbits and the inbreeding and bad standards within rabbit farms can cause problems here.
If you are worried about your rabbit install a ramp, let them choose whether they wish to jump up or not, many rabbits will prefer to continue jumping and that's okay too. If you can't include a ramp and are worried try to provide some form of cushion or soft surface for the rabbit to jump on to. Anything from a simple cushion to a handful of hay will help to soften the blow.
If you are really worried and wish to try to prevent arthritis, Glucosamine supplements can be given to the rabbit daily, now these are expensive for a supplement but when your rabbit is hitting it's 11th or 12th year it can be worth it to ease the pain of walking.
Glucosamine is used by the body to create these cartilage and is integral in the creation of it, dosing for rabbits can be found elsewhere in the forums if you are interested drop me a PM.
