Do rabbits need sunlight?

[ThorBunny]

Hi all! 

A question came up in June chat that has got me thinking: do rabbits need sunlight? Ellie’s vet told her that rabbits need sunlight for vitamin D, so they can properly build strong bones. 

It is making me feel a bit bad, we don’t get a lot of direct light in our apartment (although a generous amount of indirect light through trees). But I could make a greater effort to get Thor outside a few times a week! We have a small lawn outside our apartment, it is not treated and on a fairly quiet street. I’d held off on taking her outside up until now because of risk of disease and exposure, etc. 

If it matters, we live on the East coast of the US and I don’t think there are any raccoons about. In the US there are no vaccinations routinely given to rabbits. 

Thoughts on pluses and minuses of outside time? Do rabbits need sunlight?

[Gina.Jenny]

Ours all go out most days, each run is always given a mix of sun and shade, so buns can choose. A common sight is a bun with their head in the shade and their rear soaking up the sun. I don’t know if buns need sun to make vitamin D in the way we do, they can make their own vitamin C which we can’t (a trait we share with guinea pigs!) I can’t see hair absorbing sun in the way human skin can, so I would wonder if it is necessary for vitamin D, but mine all say it is nice to have the choice, and it doesn’t do any harm to give the sun a chance to top up vitamin D levels ‘just in case’!

[sarahthegemini]

This is an interesting topic – I wouldn’t have thought they need sunlight as indoor rabbits are generally healthier than their outdoor counterparts. But I’m curious now! My rabbits can’t go outside as I don’t have a garden yet :-/

[Luna]

My vet said the same thing about sunlight and vitamin D, but buns also get vitamin D from other sources (ie. foods, supplements). I try to take Luna outside when I can and when the temperature is safe, not for vitamin D reasons, but so she can get fresh air and exercise/mental stimulation . She hops around in the sun but lays in the shade – she gets warm easily because of her lop ears and black coat. I don’t worry about disease as much as I do about stray cats and hawks. And I always scan the grass for bird droppings and other things before I let her roam about (supervised of course).

[Deleted User]

Great question, I would love to know as well, as I am on the east coast! I live in an apartment and I try to get the blinds open for her every now and then but she doesn’t like that…we have glass sliding doors in the room that she primarily resides in and when I open the blinds up she just runs around scared. I think she likes hiding behind the blinds so it bothers her when they are open. But I do live in FL, right smack in the middle of a college town so I don’t think she would have a good experience outside at all. Plus, it is VERY hot here in the summer, which I think would also be a disadvantage. I’m sorry for a reply that doesn’t answer your questions XD

I found this article, which you may also find helpful:

http://www.medirabbit.com/Safe_medication/Vitamins/VitD_results_en.pdf

[Deleted User]

The role of sunlight in vitamin D production is that it actually works by transforming a precursor molecule that is present in our bodies into vitamin D. Learned that in a nutrition class! I think the mechanism is the same for rabbits, but it is via the fur since it covers their skin completely. It was explained in the article link I posted above. I stumbled across the article and it seems to be legitimate, although I cannot vouch for it’s validity because I don’t know that source all that well.

[Bam]

BunNoobs, cholesterol in the skin gets converted to vitamin D by sunlight.

Rabbits do have a calcium metabolism that differs quite a lot from ours though. In humans and most mammals, calcium from the food can’t get absorbed by the body from the small intestine without vitamin D. Calcium that doesn’t get absorbed through the intestinal wall come out with the poop. Vitamin D deficiency is for this reason implicated in osteoporosis.

In rabbits, all dietary calcium is absorbed. Excess calcium then is excreted with the urine.

And here’s where the debate starts.

Frances Harcourt-Brown says vitamin D is not needed if the rabbit’s diet contain enough calcium. Here’s an article by her on this subject:
https://www.harcourt-brown.co.uk/articles/free-food-for-rabbits/calcium-and-rabbit-food
(Frances harcourt-Brown is the author of the first edition of the Textbook of Rabbit Medecine).

Then other experts claim that the high prevalence of dental problems in domestic rabbits is due to a lack of sunshine-derived vitamin D that cause them to not get enough calcium for their skull- and jaw bones and their continously growing teeth. here’s an article suggesting this:
http://healthypets.mercola.com/sites/healthypets/archive/2014/06/20/vitamin-d-deficiency-rabbits.aspx

It’s very rare to find dental disease among wild rabbits. This could however, at least to some extent, be explained by the fact that a wild rabbit rarely lives to see its second birthday.

This doesn’t make things easier for us rabbit owners.

[Hanz]

I strongly feel that all mammals need some sun.

[ThorBunny]

Hmmm interesting points from everyone. I think I will try taking her outside in her x-pen, 100% supervised, next time it is nice enough and not too hot If she likes it we will try to make it a regular thing, but if she gets really stressed out I will probably not push it.

[Azerane]

I also believe that vitamin D from sunlight acts slightly differently to vitamin D obtained via diet/supplements.

While I also believe sunlight is important, even if to a slightly lesser degree for rabbits than other animals, I don’t take my pair outside for disease prevention reasons.

[Luna]

Posted By Azerane on 6/16/2017 4:06 PM

I also believe that vitamin D from sunlight acts slightly differently to vitamin D obtained via diet/supplements.

While I also believe sunlight is important, even if to a slightly lesser degree for rabbits than other animals, I don’t take my pair outside for disease prevention reasons.

I’ve read here that RVHD is a serious issue in countries other than the U.S., but are there other diseases in the U.S. that buns have a high risk of contracting from being outdoors? Have I been going on a misconception that I didn’t have to worry about viruses because Luna is a U.S. bun? 

[Bam]

Luna, Azerane is in Australia where they have the dreaded “European” rabbit viruses, but they’re only allowed to vaccinate against one of them.

In the USA a rabbit can get raccoon roundworm from grazing where raccoons av defecated, they can get tularemia in areas where there’s tularemia (spread by mosquitos and ticks).

But there’s nothing you should vaccinate against.

ETA: I see now you probably know Az is in Aussie, but I’ll let it stand in case other readers of this thread don’t.

[Azerane]

Yes, I suppose I should have clarified that  Between RHDV, RHDV2, the K5 strain and Myxomatosis, I don’t have a whole lot of desire to let my buns out and about. Councils her are allowed to release the viruses (usually RHDV, recently K5 as well) as a means of population control of the wild rabbits so it always has the potential of being recently in an area. I’ve previously had an outdoor rabbit for years in a rural area with no issues, but I go lucky and wouldn’t risk it now. I would love to take them out in the yard, but if they contracted one of the diseases as a result I would never forgive myself.

There are very rare outbreaks of myxomatosis in the US sometimes every few years I think but there is never any recommendation for vaccines and I think you’d be hard pressed to find a vet that stocked them. I think I read something recently about a couple of cases in california, but it usually doesn’t spread terribly far because the wild cottontail rabbit population can’t carry it like the wild European rabbits do here.

[ThorBunny]

Interesting about viruses! I live far from CA, so myxo is probably not an issue. Certainly disease is something to worry about!

If I do take her oustide, are there any toxic lawn plants I should look out for? Mostly it is grass, but I do believe I saw some creeping charlie…

[Boston's Mama]

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[Q8bunny]

I feel too lazy to retype so am copying and pasting my 2c from June discussion on this topic.

“But my bunny guru vet (before she retired… booo) emphasized the same thing. Unlike wild buns, most domestic buns, despite love and pampering and enriched pellets, don’t get the D3 they require because like humans, they don’t necessarily absorb oral D well (it’s best absorbed in conjunction with fat, on top of it all). So from her years of bunny treatment in the UK and other countries, domestic buns are more prone to soft/spongy bones, and the accompanying tooth problems, breaks, and bone damage from abscesses than their wild or outdoors counterparts. This is one of the biggest reasons I moved up my relocation by a year: Chewie is no longer able to go outside for months at a time due to weather, and because he’s developed a mortal fear of the local stray cats. So I need to be somewhere where I can safely expose him to a few hours of sunshine each week. Please don’t get me wrong: plenty of buns are just fine without significant exposure to sunlight. But it is a risk factor (however small) worth considering. My vet said that even letting the bun bask in a puddle of sunshine from an open window for 10-15 minutes a day is enough. Sadly, my apartment has loads of windows but no direct sunshine from any of them.”

[jerseygirl]

They do seem to like those puddles of sunshine.  I’d like my rabbits to get that, for enjoyment alone. Currently, TimTim gets some in the bedroom, Ailis and Rumball get a little at certain time of the day and do go sleep in that spot where the sun is streaming in. No sunbeams reach Potamus and Goosey’s side of the room. : (

Im thinking about popping them in a pen occasionally in another room when the sun is coming in..

In relation to Vitamin D, I just read this which is interesting. Keep in mind, this is done from studies to formulate feed for farmed rabbits. I supposed there is funding for research to maximise production where as there is little study done on house rabbit rabbits in comparison. It’s from a paper published 2010 but does cite info from the 70’s 80’s.

Vitamin D Vitamin D is synthesized by the animal when exposed to sunlight. The two major natural sources are cholecalciferol (vitamin D3 of animal origin) and ergocalciferol (vitamin D2 of plant origin). Vitamin D3 is preferred to vitamin D2 by rabbit tissues. Vitamin D, after dihydroxylation in the liver and kidney, acts as a hormone and plays a central role in the metabolism of calcium and phosphorus, as in other mammalian species, influencing bone mineralization and mobilization. The classic symptoms of deficiency are rickets in growing animals and osteomalacia in adults. Under normal circumstances (calcium levels in excess of requirements) rabbits are very efficient in absorbing calcium, a process that seems to be quite independent of vitamin D status. Bourdeau et al. (1986) showed that the net intestinal absorption of calcium and phosphorus in adult rabbits is similar for rabbits deficient in vitamin D and those with vitamin D-supplemented diets. Fébel and Huszar (2000) found that the injection of a large dose of 100,000 IU cholecalciferol did not affect calcium and phosphorus excretion via the faeces. In addition, excess vitamin D3 increased renal tubular reabsorption of calcium, but did not affect that of inorganic phosphorus. Levels of vitamin D3 as low as 2300 IU kg−1 are detrimental to rabbit productivity, with increased fetal mortality, depressed appetite, diarrhoea, ataxia, paralysis and death (Ringler and Abrams, 1970; Kubota et al., 1982; Lebas, 1987; Zimmerman et al., 1990). Excess vitamin D, rather than deficiency, is more likely to be a problem under practical conditions. The excess causes resorption of bones and calcification of soft tissues such as the arteries, liver and kidneys (Löliger and Vogt, 1980; Kamphues, 1991). The incidence of problems because of excess dietary vitamin D3 is more acute when calcium is fed in excess of requirements. Consequently, the recommended level of vitamin D3 for rabbits is low and should not, under practical conditions, exceed 1000–1300 IU (Table 7.7). Most of the commercial premixes surveyed (Table 7.8) were within this range, but >0.3 (ten out of 29) appeared to have an excess of this vitamin.

Source: http://wabbitwiki.com/images/7/7d/Nutrition.of.the.Rabbit.2ed-deBlas.Wiseman.pdf

Sunlight also affects cicardian rhthyms, the parathyroid hormone and perhaps moulting (??)  A friend of mine who has some rabbits housed outdoors (under cover) and some indoors said her rabbits outside seem to moult less. It could be that temperature variations outdoor affect this too. I really couldn’t say!!

@BunNoob, the medirabbit site is pretty good imo. We tend to quote info from there a lot here on BB. Definitely one worth bookmarking. : )

[jerseygirl]

Re Myxomatosis, I saw an alert of HRS fb page yesterday of some very recent cases occuring in Northern California.

[Azerane]

Unfortunately none of our rooms have good sunny spots, which is a real shame. Must have been on Facebook that I saw the info regarding the myxo in california.

[Bam]

I’d like to comment on my own link about possible D deficiency in rabbits – it was about laboratory animals. Lab rabbits don’t get play time, and exercise is important for bone renewal. Plus I dont think lab rabbits get hay. Hay would interfere with the demand for scientific reproducibility.

I do think Bam likes his outdoors run though. Just the other day he discovered the two runs are connected, and ran through them at full speed over and over

I have mosquito netting over the runs. It keeps mosquitos and the dreaded flies out. But I of course also check the little butt closely every day.

[Q8bunny]

One of the benefits of taking the wookie home to the grandparents will be easier butt checks
If he sees me holding the biscuits bag, he’ll run. Away! Knowing that’s often what precedes an abduction. I adore him and have no doubt he loves me, but despite never having given him a reason to, he remains the most skittish bun.

[Boston's Mama]

I would love to be able to take mine out but it is not safe – we have wild rabbits in our section at times
We do have good sunny spots though where the sun comes in a lot so we are going to move the boys Houses and playpens to a sunnier spot in a couple of days where they will get loads of sun through the windows
Very cool thread!

[Q8bunny]

Make sure you open the windows. Glass kills the wavelengths they require

[Luna]

Az & OBM – Wow, I didn’t realize that the viruses are still being released today. I incorrectly assumed that once the viruses were in the environment they didn’t go away so there was no need to keep adding to it.

[Author]

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