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October 22, 2017 |0 min read |Veterinarian Reviewed

The Truth About Clay Litter

Written by

Sharilyn Vera

Here at PrettyLitter, we care about your cat's health first and foremost. So we did some digging into the real reasons why pet parents tend to be leaning away from traditional clay litter and toward healthier alternatives.

Like many medical professionals on the pet and human sides of the aisle, we plundered the depths of scientific research databases and came up with nothing. While no scientific research studies have been done yet on the effects of clay litter on cat or human health, we found a staggering number of stories from physicians, veterinarians, and pet parents about the hazards of clay litter.

Here's what we found.

How It’s Made

Clay cat litter was invented in 1947 by H. Edward Lowe, a successful businessman in the building supply industry. First, wet clay is gathered from below the earth's surface (about 30-40 feet down) and carried away to processing plants for drying. The clay is then broken into smaller pieces and loaded into a 2000-degree F kiln, which bakes away any moisture.

Next, the clay is crushed, sifted, crushed again, and ground up. Clay clumping litters go through an extra step where sodium bentonite, another type of natural clay that swells when it contacts moisture, is added to the mix. Some companies then add dust-reducers and scents to their litter before sending it off for packaging.

Since clay can be found in the natural world, pet parents and manufacturers assumed it'd be a safe potty-box medium. However, the aluminum silicates and minerals clay is made of have some problematic traits.

Cat Health Problems

Feline Asthma

One of the most common issues clay litter causes is feline asthma, also known as feline allergic bronchitis (FAB). Despite the fact that many clay litter manufacturers add dust reducers to their products, the issue remains. If your cat is using a clay litter, those airborne particles can be inhaled and cause irritation, an allergic reaction, and even an asthma attack.

According to vets at Cornell University's College of Veterinary Medicine, repeat exposure to allergens like clay dust cause the immune system to go into hyperdrive. Cats who develop this allergy suffer from inflammation, irritation, swelling, and constricted airways.

Symptoms of feline asthma include:

  • Coughing
  • Difficulty breathing
  • Hacking
  • Open-mouthed breathing
  • Rapid breathing
  • Vomiting
  • Wheezing

Like allergies in humans, feline asthma gets progressively worse the more your cat is exposed to the allergen. If your cat uses a clay litter box, his condition could worsen every time he needs to go.

Feline asthma is difficult to treat and can be fatal. So most vets recommend using a dust free cat litter, unscented litter. Unfortunately, no clay litter is completely dust-free.


Another serious medical concern associated with clay litter is the potential for an internal blockage. Kittens are particularly at risk. Naturally curious, kittens will often lick their litter.

The problem is that the granules in clay clumping litter can expand up to fifteen times their size once they come in contact with moisture. If your cat ingests these granules, they can cause a life-threatening internal blockage. 

Adult cats are also at risk as these granules often stick to your cat's paws and can be ingested during your cat's many daily grooming sessions. If you're a multi-species household, dogs that get into the cat box (litter box) or lick up tracked litter are also at risk.

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Bacterial Breeding Ground

Unlike cat/kitty litters that encourage moisture to evaporate, clay cat litter holds onto moisture. While this is necessary to maintain the convenient clumps, it also means bacteria are encouraged to reproduce.

Cat waste can contain bacteria that are extremely dangerous to cats and humans alike.

Human Health Problems

In addition to being a natural irritant for people with asthma and other respiratory issues, clay cat litter can lead to toxoplasmosis infection, which is particularly hazardous to pregnant women.

Most people have heard the rumor that pregnant women shouldn't be around cat litter. While the kitty litter itself isn't the problem, there is a foundation of truth to the rumor.

The problem with clay cat litter for pregnant women is that it can transmit harmful bacteria. Toxoplasma gondii is a one-celled parasite often found in the feces or cat waste that eat raw meat. Indoor cats who are given raw meat or outdoor cats who catch and eat mice, birds, and other critters can bring Toxoplasma gondii into the home when they deposit waste in the cat litter box or in the soil around the home.

Cat feces containing Toxoplasma gondii dries out in the litter box. When the litter in the cat litter box is changed, contaminated clay litter dust in the air can be inhaled and can transmit the parasite to you.

Toxoplasma gondii causes toxoplasmosis. If a pregnant woman is infected, it can lead to birth defects and problems later in life, like blindness or mental disability,
according to the CDC.

However, while clay litter dust is one form of toxoplasma transmission, you're more likely to contract the bacteria gardening in contaminated soil, eating unwashed fruits or vegetables, eating raw meat, or coming in contact with cat feces in a sand box, says Lorie Huston, DVM.

While dust-free alternatives to clay litter, would help avoid aerosolization, the fecal contamination is the biggest threat and that is present in clay or in silica litter boxes.

To prevent health problems for you and your cat, it's recommended to replace any type of cat litter at least twice a week. Keeping your cat's litter box clean can help odor control and prevent urinary or kidney problems with your pet. Whether you are using a clumping cat litter, corn cat litter, silica gel litter, wheat litter or any biodegradable litter, regular maintenance is necessary to avoid the toxic smell and bacteria build up from your cat’s urine and feces, especially if you own multiple cats.

Like to know more which one is best for your furry friend? Check out our blog about clumping vs non clumping litter.

Have questions about alternatives to clay litter or PrettyLitter’s own health-indicating litter? Post in the comments below!




Written by

Sharilyn Vera

Sharilyn is a proud cat owner, long time storyteller and researcher. Her work spans beloved podcasts, television shows, media outlets, and independent documentaries. She likes to strike a balance between education and comedy, which you can hopefully tell when you read her articles!

Veterinarian-Reviewed by

Geoff DeWire

PrettyLitter's Veterinarian in Chief Dr. Geoff DeWire graduated UC Davis School of Veterinary Medicine in 2007 where he earned the Pfizer Clinical Achievement Award for Excellence in Veterinary Medicine.

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