quoted from the article:
TESTING AND RETESTING
In order to check out our suspicions, we removed the pine shavings for a period of time and did the blood tests again. Nothing else in the rabbits’ environment was changed. Results were consistent when we began retesting a month later. Liver enzymes were back in the normal range. Meanwhile, opportunity allowed us to conduct an informal survey. As HRS members in various parts of the country reported deaths of their rabbits due to liver disease, we asked what type of litter was being used. It has been invariably some kind of softwood shavings.
Although our data do not qualify as a truly scientific experiment, there is enough evidence to suggest using caution. Documented scientific research has already shown that aromatic softwood beddings are potent enough to alter biological functions of the liver.*
What is it in the wood that’s doing damage? Apparently it’s not a result of ingesting but rather inhaling the fumes, which contain phenols, or toxins which pass in the fumes from the lungs to the blood and are finally filtered through the liver.
The fact that a large number of indoor house rabbits live in an environment of pine or cedar may account for the large number of deaths due to liver damage and anesthesia fatalities.
A CAUTIOUS APPROACH
For a safer use of shavings, keep them in large, open, ventilated areas only, and get your bunny’s blood checked every few months. Blood panels are now inexpensive since basic lab work is done in most veterinary offices.
New organic litters have been developed by several companies, and include CareFresh, Cat Country, Critter Country and Yesterday's News.
Here are a few that we have tried:
Carefresh - is dust free, lightweight, super-absorbent, non abrasive, and non-toxic, this is currently in use in many foster homes.
Cat Country - an organic grass-based pellet.
Straw alone can be used as litter in a large litterbox on the floor. It’s too untidy to use in small boxes inside the cage. Absorbency is similar to rice hulls, and the boxes must be rinsed with every litter change.
Peat moss - interesting, if you don’t mind having your house smell like a freshly plowed field. I find it a little too "dirty" for litterboxes, but it's fine for trays under cages. The manure/peat moss mixture is gold for your own garden, or you might sell it to a local rose grower.
Shredded paper popular with veterinarians and animal shelters where animals are kept in kennels with solid (sterile). However, we found that it tempted some of our rabbits to excessive chewing.
Aspen pellets - inexpensive, highly absorbent litters used in many foster homes.They are made from hardwood and they are not toxic because the phenolic compoundsare removed during their manufacture. Their wood composition helps control bacterial growth and odors. Wood stove fuel pellets and Feline Pine are two examples of this product.
They included a chart in the article that showed a good comparison between types of bedding. Go check it out. It was worth the read.
Care for your bunnies well!