DEAR DR. FOX: I just read your article about the safety of clumping litter. You said you had "no evidence that cats get blocked or impacted internally after grooming themselves and swallowing the clumping litter." I wanted to share with you my recent experience.
Like you, I have been using the World's Best brand of cat litter for my two cats (both less than 2 years old), one of whom, Benga, has a habit of using the box and jumping up on the bed, getting litter dust all over my pillow. In early February, I decided I would switch over to a clay-based clumping litter to see if that would mitigate the problem.
I did some research on Amazon and saw that Precious Cat Ultra Premium Clumping Cat Litter got great reviews, so I picked up a bag at my local pet store. I have two litter boxes and wasn't sure how the cats would react to the new litter, so I put it in only one of the boxes. They both took to it immediately.
The next day, however, I noticed that Benga had thrown up. It was a small amount of clear vomit with a bit of foam. I did not think this was particularly remarkable, but did make a note of it.
Over the course of the next week, I found little bits of this clear vomit all over the house daily, and sometimes twice on a single day. On two occasions, I found vomit that contained part of a meal's worth of food. The interesting thing about those instances was that the vomit had clumped -- I could literally pick it off the carpet with my thumb and index finger. This was my first clue that the new litter was contributing to my cat's upset stomach.
Near the end of that first week, I also noticed that Benga's stools were getting smaller in size and less frequent -- normally he goes once a day, but it was down to every two or three days. And when he did have a bowel movement, it was no longer brown but gray, the color of the litter. At this point -- day 13 of the new litter -- all the clues were leading me to believe that the new litter was at fault. That day I replaced the new litter with the old brand, and right away Benga stopped vomiting. His stools returned to normal within a few days.
I did some Internet searching and was surprised to see that this doesn't seem to happen that often. Cats, largely, are not affected by the clumping agents used in these litters. But it got me wondering what, exactly, are these chemicals that they add to clay (or wheat, or corn, or whatever) to give the material the clumping properties? And am I better off using a low-strength clumping litter, rather than a "multi-cat" clumping litter?
My other cat was fine throughout this whole ordeal, but he barely digs and is never covered from nose to tail in litter dust like Benga.
Anyway, I wanted to raise this to your attention because I have to imagine other cats might react this way to certain litters. -- A.B., Washington, D.C.
DEAR A.B.: Your observations concerning the possible harms of clumping clay litter raise a host of questions. Manufacturers of cat litter rarely reveal chemical additives in the ingredient list for reasons of protecting proprietary interests. But this disclosure should be mandatory.
I am opposed to clay litters, especially the clumping kind, for a variety of reasons. The most important is the possible risk of clay particles adhering to cats' paws and being ingested when the cat grooms himself. Sodium bentonite is the most often used clumping agent.
Constipation and bowel obstruction may be a rare occurrence, but I've never read about it in any veterinary literature. I am concerned about potentially toxic mineral compounds in some types of clay litter as well as inhaled dust laden with silica particles. I say no to all litters containing synthetic fragrances, since I have reports of cats getting better after being provided dust-free and fragrance-free litter material. According to consumersearch.com, you were using one of the better, low-dust clay litters, but it is apparently not biodegradable and should not be composted or flushed down the toilet. No cat litter of any kind should be put down the toilet, especially in coastal areas; toxoplasma parasites in cats' feces are responsible for the deaths of marine mammals, notably sea otters in California.
I would like to hear from other readers who have found that changing to another kind of litter either improved their cats' health or caused health issues.
(Send all mail to firstname.lastname@example.org or to Dr. Michael Fox in care of Universal Uclick, 1130 Walnut St., Kansas City, MO 64106. The volume of mail received prohibits personal replies, but questions and comments of general interest will be discussed in future columns.)