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Kitty litter: does it really matter what type I buy? The difference between clay, clumping, and crystals

Dr. Justine Lee, DVM, DAVCECC, DABT

Posted March 08, 2013 in Cat Health

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Who knew there was so much to kitty litter? Dr. Justine Lee provides some valuable litter box advice. For more from Dr. Lee, find her on Facebook!

We’re bombarded by pet store advertising when it comes to what type of litter to use. Basically, it all comes down to personal preference. While living with my vet school housemate, I asked her why she used clay (“Hellooo! Old school!”). She said that’s what she has always used (my roomie was from the 1960s generation, when clay was hip). After being fed up with the smell and mess, I decided to change her litter to clumping one day. She was wowed, dumbfounded, an instant convert, and she hasn’t gone back since. Crystal, her cat, loved it too.

Clay litter was first introduced in 1947 by Edward Lowe, who used to sell clay to garage owners to soak up oil and gasoline spills. When he realized it worked well in kitty litter boxes, it became an instant success. Since then, kitty litter has become a multimillion dollar business. (Why, oh why, didn’t I think of this first?) Clay is still a great absorber and cheap as dirt (well, clay), but it’s more environmentally unfriendly as you have to dump out the whole litter box once it’s full (in other words, once a week). Like its name suggests, clay doesn’t clump, so you can’t just scoop out nice, neat clumps of urine to clean the box. Notice how those large forty pound bags of clay litter are cheaper than the twenty-five pound bucket of clumping litter? You get what you pay for.

Since the early-1980s, cat lover (and, oh yeah, biochemist) Thomas Nelson discovered that a particular type of clay, bentonite, formed clumps in the presence of moisture, and voila… clumping kitty litter. Because bentonite can absorb up to ten times its own weight, it is able to bind and hold water (or urine) firmly in place, resulting in that tight clump. Bentonite is dug up from the ground and processed into either granules or a powder form, and apparently we cat lovers are using a lot of it. According to a U.S. Geological Survey, approximately 987,000 metric tons of this clumping clay was mined in 2003 for cat litter. Popular stuff, right? Remarkably, the Bureau of Waste Management estimates that approximately 8 billion pounds of kitty litter fills landfills each year.

This clumping litter is much better than the clay stuff, in my opinion. First of all, it’s more pet owner friendly – it’s less cleaning and work than clay litter. Second, clumping litter is more environmentally friendly than the clay stuff. With clumping litter, you don’t have to completely dump out the whole litter box of clumping litter (ever) – just lift out the nice, scoopable urine and fecal ball clumps, and voila, all done. I only harp on this because when owners bring in their cat to the ER for urinary problems, I quiz them on their kitty litter habits. That’s when I learn that most cat owners don’t really know about kitty litter husbandry – in other words, how to take care of their kitty litter box in the easiest, most efficient, most environmentally-friendly, least dirty way (e.g., have enough boxes, scoop daily, and pick the right type of litter your cat likes – not you).  

Since I’m on my environmental soap box: Even if clumping litter marketers say you can flush litter down the toilet, I’m not an advocate of this practice as I don’t feel that it’s safe to have our water supply contaminated with cat feces. There’s a lot of controversy on this topic, especially when it comes to people toilet training their cats. That said, many sea otter deaths reported in the northwestern United States recently have been linked to toxoplasmosis, a bacterial infection shed in cat feces. While there’s no definitive, scientific proof that cats caused this, save the world and all the other fuzzy creatures and please don’t flush.

Finally, the $20 bottle of crystals. Is it worth it? Being that you likely have to buy it monthly (depending on how many cats you have), it’s the most expensive option when it comes to kitty litter. That said, some people love crystals because they absorb odor very well and allow you to scoop out the feces. Keep in mind that crystals will never clump, so you can’t expect to remove large piles of urine. Rather, the crystals work by absorption. Once the crystals have turned yellow, they will no longer absorb and the whole litter box has to be dumped and cleaned
(approximately one to two weeks, depending on how many cats use the litter box). Also, having accidentally stepped on these crystals before…ouch! I can’t imagine that it is fun to urinate on dull shards of silica gel; it reminds me of walking on a nice sandy beach (clumping) versus a pebbled beach… and I prefer the former.

Other options include using silica gel pearls, recycled newspaper, pine or cedar sawdust, corncob litter, or even wheat husks. It’s all personal preference, and priority should go to what your cat wants, not what you want. Just keep in mind that these other options are expensive, slightly less effective (they don’t form a tight clump, making it harder to scoop and clean), but are more environmentally friendly. That said, I’d rather not have my cats pee all over my house owing to behavior problems just to save the earth (Trust me, I make a difference in other ways – I promise!). Also, animal behaviorists find that cats prefer clumping litter to any other type, so I’d trust them. If you’re thinking of switching and experimenting with new litters, remember that cats do not do well with acute change. They are creatures of habit and want gradual changes; otherwise, they may inappropriately urinate around the house just to spite you.

The contents of this blog are modified from Dr. Lee’s book It’s a Cat’s World… You Just Live In It (Crown Rivers Press, 2008). Copyright Justine Lee Veterinary Consulting, LLC.

If you have any questions or concerns, you should always visit or call your veterinarian – they are your best resource to ensure the health and well-being of your pets.

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