An Interview with Feline Health and Nutrition Guru Dr. Lisa Pierson

Story at-a-glance -

  • Dr. Lisa Pierson, a veterinarian who specializes in feline health and species-appropriate nutrition, created the fabulous website, which is an invaluable resource for cat caregivers across the globe
  • After 25 years of practicing equine medicine exclusively, she shifted her focus to cat health and nutrition
  • Dr. Pierson’s big three take-home messages are focused on the water content of a cat’s diet, protein sources, and carbohydrates
  • Learn why even inexpensive canned food is a better choice for cats than dry food

By Dr. Becker

Today, I’m interviewing a very special guest, Dr. Lisa Pierson. Dr. Pierson graduated from the University of California, Davis School of Veterinary Medicine in 1984. Several years later, due to her own cat’s illness, Dr. Pierson became much more aware of the link between inappropriate diets and many of the diseases that kitties today suffer from. In 2003, she launched an amazing website called with the goal of educating feline caregivers about optimal nutrition for cats.

Dr. Pierson’s practice is now limited to consulting with cat caregivers worldwide. The most common health issues she deals with are kidney disease, diabetes, urinary tract issues, inflammatory bowel disease (IBD), and obesity. Since all these feline health issues tie directly to biologically inappropriate diets, Dr. Pierson is strongly opposed to feeding any dry food to cats, and today, she’ll tell us why.

From ‘Animal Doctor’ to Equine Veterinarian to Feline Health Guru

Before we dive into the topic of feline nutrition, I asked Dr. Pierson to share with us how she decided to become a veterinarian. She said it was a quick and simple decision because she loves science, medicine, and animals -- so it was a natural fit for her to become a veterinarian. As her parents remember it, Dr. Pierson decided on her career path from the first moment she realized there was a profession called “animal doctor,” and she never wavered. She loves what she does and wouldn’t dream of doing anything else.

I asked Dr. Pierson how she decided to narrow the focus of her practice to feline health issues. Interestingly, she says she spent the first 25 years of her career working exclusively with horses. But along the way, she got heavily involved in cat rescue. She’s always loved cats – cats and horses. She loves dogs as well, but has always felt especially drawn to cats and horses. So between her work in cat rescue and having cats of her own, Dr. Pierson eventually gravitated away from equine medicine into feline medicine.

In addition, horses don’t get sick all that often, probably because most are fed an herbivore-appropriate, high-fiber diet of hay and forage. In her equine practice, Dr. Pierson didn’t see a lot of kidney or urinary tract disease, or diabetes. Her keen interest in internal medicine problems meant that eventually she grew a bit bored treating only horses.

Meanwhile, she was taking note of the fact that domestic cats were getting sick quite often. And she soon realized that much of the illness in cats was secondary to the species-inappropriate diets they were fed. This led Dr. Pierson directly to her passion for nutrition and her desire to prevent disease rather than, as she puts it, “closing the barn door after the horse is galloping down the roadway.”

As she treated cats with diabetes with low-carb diets, she started asking, “Why aren’t we feeding cats low-carb diets to begin with?” And as she treated patients with feline lower urinary tract disease, she thought, “Why aren’t we feeding cats water-rich diets so we can prevent the types of health problems that are secondary to poor and species-inappropriate nutrition?”

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Dr. Pierson’s Big Three Nutrition Messages for Cat Guardians

Dr. Pierson realizes that the topic of feline nutrition can be overwhelming for cat guardians. There’s so much information out there that it’s mind-boggling.

Dr. Pierson tries to keep things very simple for cat guardians when it comes to feline nutrition. Her recommendations are based on what a cat would eat in the wild – a mouse, bird, lizard, or some other small animal. There are three main take-home messages. The first is about water. Dry food (kibble) is cooked to the point where it’s only 5 to 10 percent moisture, whereas a bird or a mouse is around 70 percent moisture. This is critical, because cats are designed to have a very low thirst drive, and when fed dry food, they don’t make up that huge deficit at the water bowl.

Now, many people say “But my cat drinks a lot of water.” Studies of cats on all-canned food diets vs. all-dry food diets show that cats eating canned food (which is very high in water content) rarely went to the water bowl, yet they consumed double the amount of moisture as the cats eating kibble. The kibble-fed cats did not demonstrate a high enough thirst drive to make up the water deficit at the water bowl. So a water-rich diet is the first take-home message.

The second is about protein sources. Cats are obligate carnivores, and must get their dietary protein from animals, not plants. When we look at a can of cat food, we want to see that the protein is coming from animals – chicken, beef, etc. – and not from plants like corn, wheat, soy, or rice.

The third take-home message is about carbohydrates. Cats aren’t designed to eat them. A bird or a mouse is a very high-protein, moderate-fat meal, with maybe a percent or two of carbs on a dry matter basis. So diets containing more carbs aren’t appropriate for cats.

It’s also very important to remember that although high-protein, low-carb dry cat foods are flooding the market these days, they are inappropriate diets for cats because they’re water depleted. It doesn’t matter how relatively high quality a dry cat food is, Dr. Pierson strongly recommends against them due to the lack-of-moisture issue.

Dr. Pierson’s favorite page on her website is her Urinary Tract Diseases page. There, you’ll see a picture of sweet Opie, a wonderful little orange tabby that was found lying in someone’s backyard, moments away from rupturing his bladder because his urethra was blocked by mucus and other debris. Most cats who endure the tremendous suffering caused by urethral obstructions got that way because they were fed a water-depleted diet. Cats on water-rich diets can and do develop blockages as well, but it’s extremely rare.

So just to recap the Big Three: water, protein source and amount, and carbohydrate content. Just imagine a cat’s natural prey of a mouse or a bird, and it’s easy to remember that canned food is much closer to one of those than what Dr. Pierson calls “cooked-to-death, overly processed dry kibble.”

Picking the Right Canned Food for Your Cat

I asked Dr. Pierson to share her expertise on how cat owners, standing in front of the cat food shelves at a pet food store, can know which canned foods (because with our new knowledge we’re avoiding all dry foods) are better than other canned foods.

Dr. Pierson explained that when she first put together her website, she listed four levels of canned cat foods. Friskies and other foods containing all byproducts were the lowest level. Above that were foods with some byproducts and a little bit of muscle meat. (By “muscle meat,” she meant meat listed as beef, chicken, perhaps deboned chicken, etc.) The third level would be a food that maybe contained no byproducts, but did contain some grain. The fourth or top level would be a canned food that was grain-free with no byproducts.

However, Dr. Pierson has really revamped her thinking since creating those four levels. Number one, she warns not to fall for the claim that a cat food is “grain-free.” It’s a misleading labeling trick, because grain-free does not mean the food is low in carbs. Many pet food manufacturers are capitalizing on the grain-free label while loading their diets up with potatoes and peas, which technically are not grains, but are certainly very high-carb, starchy ingredients. So the grain-free label is misleading for consumers who don’t realize that grains are not the only ingredients to avoid in cat food.

Dr. Pierson explains that she doesn’t necessarily have a problem with all byproducts, because some, for example, brains, eyeballs, spleens, and livers, are very nutritious. So when she decided to rewrite her Commercial Foods page, she realized Friskies is really not all that bad. In fact, her mom’s cat at 17 still runs around like a kitten, and all he’s ever eaten is Friskies canned and maybe a little Special Kitty or another low-priced brand. These days, she prefers using the term “lower priced” rather than “lower quality,” because she’s no longer convinced that some of the less expensive brands are all that low in quality.

The calories from protein, plus the calories from fat, plus the calories from carbs must add up to 100 percent. All the calories in all food, whether it’s for humans or animals, must come from protein, fat, and carbs. Protein is expensive; fat is cheap. So let’s say a pet food manufacturer has jumped on the low-carb/grain-free bandwagon and is keeping the carbs below 10 percent of calories in a given formula. That leaves 90 to 95 percent of the calories to be divvied up between proteins and fats.

Muscle meat (not from byproducts) is very expensive. So expensive cat foods end up containing maybe 30 percent protein (versus a mouse, which is about 50 to 70 percent protein), and are extremely high in fat. This isn’t really a good thing. The fact is, most diets labeled grain-free are quite high in fat, and they skimp when it comes to protein. A grain-free formula may contain, for example, 30 percent protein, whereas Friskies or 9Lives or another inexpensive brand may be 45 percent protein. Dr. Pierson says she’d rather feed 45 percent protein on a calorie basis than 30 percent, and that’s why she has come to the conclusion that, “Wait a minute, Friskies isn’t half bad.”

I agree that feeding even the cheapest canned cat food is preferable to any type of dry food. I encourage my clients with cats to feed raw if they can (and if the cat will eat it), and if they can’t, then canned is the alternative. The canned food should be the best the client can afford.

So if you can afford to feed raw or high-quality canned food, that’s great. But at a minimum, you need to feed canned in order to prevent lifestyle-induced disease in your cat. Dry food is off the table. Many people say, “Boy, you are really anti-dry food.” And I am. The only time I would ever condone feeding dry food to a cat is if the owner absolutely couldn’t afford anything better, or if the cat simply refused to eat anything but dry food. Sadly, cats fed a lifetime of dry food are often very hesitant to accept a dietary change (which is why I encourage feeding raw and/or canned right from weaning), and especially in the case of sick cats, it’s much more important to keep them eating than to force a change in cat food. A cat that isn’t eating is at risk of destroying his liver.

The Scoop on Prescription Diets

Next, I asked Dr. Pierson for her thoughts on the prescription diets sold by most traditional veterinary clinics. I don’t sell the stuff and never have, but I’m in the minority.

Dr. Pierson responded that she doesn’t use them, either. She can always find healthier, more species-appropriate choices for her patients. The one exception is that she will sometimes use an acidifying canned food diet temporarily – for a week, or two, or even a month – for a cat that is suspected of having struvite stones in the bladder. She has seen Hill’s s/d dissolve stones very rapidly. But that diet isn’t for long-term use, because it is highly acidifying. As for any of the other prescription diets on the market, she has absolutely no use for them.

Dr. Pierson points out that interestingly, there’s no FDA oversight of prescription pet diets. They oversee drugs, but these diets are marketed as “prescription” when there’s nothing in them that requires a prescription. She believes anything called a “prescription” should undergo much closer scrutiny than these diets do. Clinical trials aren’t even required before prescription diets come on the market. Dr. Pierson believes they could be formulated in a far healthier manner than they are.

I think often pet owners are led to believe that if their cat has a medical issue, their only option is the prescription diet their vet recommends. But a little research can be really beneficial. For example, in the Hill’s s/d formula, there’s a high level of DL-methionine, which is an acidifying amino acid. What most pet owners don’t realize is they can get DL-methionine separately as a palatable paste or tablet, and add it to a diet that is of substantially better quality in terms of protein source, moisture, and carbohydrate content.

Of course, if a knowledgeable pet owner refuses the recommended prescription diet and instead asks her veterinarian for palatable DL-methionine to naturally acidify her cat’s urine to resolve struvite stones, she’ll likely be met with stunned silence.

Why Many Veterinarians Recommend Prescription Diets

Dr. Pierson does a wonderful job of helping cat owners formulate diets that are customized to their pet’s individual needs. I asked her if she gets much pushback… are clients hesitant to switch from prescription diets?

She replied that it’s extremely common that people are hesitant, and it’s a source of frustration for her. She has probably a half-dozen people a week email her to say things like, “My veterinarian told me if I don’t feed this prescription diet to my cat, there will be repercussions and I’ll be sorry.”

She says that unfortunately, veterinarians are extremely busy trying to keep up with their continuing education requirements, and nutrition just isn’t very sexy – it’s not very interesting to most of them. It’s much easier for a vet with a feline kidney patient to simply grab the Hill’s k/d, Purina NF, or Royal Canin Veterinary Renal LP off the shelf. There’s just not a lot of critical thought going into nutrition for pets.

The bulk of Dr. Pierson’s practice is formulating species-appropriate diets for kitties. She says it’s really not difficult, and she’s frustrated that the traditional veterinary community has made it such a big mystery. Sometimes, a small tweak is all that is needed. For example, a cat with kidney issues needs a diet lower in phosphorus.

Dr. Pierson agrees with me about the DL-methionine add-in vs. getting it in Hill’s s/d. She explained that often she uses the prescription diet because it’s temporary – anywhere from a week to a month, tops. In the meantime, she’s helping the cat’s owner wrap his head around making his own cat food and transitioning his pet to homemade. The Hill’s diet is only a stopgap measure. It can be used with some added water while the cat is being switched over gradually to a healthier homemade diet that is formulated appropriately for the medical problem in question.

Switching Your Cat to a Better Diet

Next, I asked Dr. Pierson to talk a little about transitioning cats to a different diet – especially cats that have eaten dry food for most of their lives and are addicted to it. The transition can be surprisingly difficult, so I’m hoping she has some words of encouragement for people who want or need to switch their kitty to a better diet.

Dr. Pierson replied, “Oh boy. Patience, patience, patience, and more patience!” (Dr. Pierson and I are Skyping, and while we’re chatting, she happens to have in her lap one of her worst die-hard kibble-addicted cats!)

Back in the day, Dr. Pierson had several cats and she never fed canned food because she was, as she puts it, “a typically uneducated veterinarian” who thought dry food was best. At that time, she fed her cats a 100 percent kibble diet, which of course wasn’t a good thing.

She refers clients (and all of you listening and reading here today) to the page of her website called Transitioning Dry Food Addicts to Canned Food. It took her three months to get her own kibble addicts on canned food. A month or so after everyone was eating canned, she began introducing them to homemade. She reiterates that we must be patient, but she’s not met a cat yet that she hasn’t been able to transition to a species-appropriate diet.

Dr. Pierson says she’d be quite wealthy if she had a dime for every time someone told her that their cat would never eat anything but kibble. She tells them, “No offense, but you haven’t tried hard enough. Roll up your sleeves. Get busy. Prepare to sit in the middle of the room and cry. You’re allowed to use four-letter words like I did.” A couple of times, she just had to leave the house because her cats were grumpy. They were crabby at her. So she just left for a few hours, and when she returned, no one had died from hunger.

Hunger is the key word here, by the way. Hunger – not starvation. Cats can withstand 12 to 18 hours of hunger with no food. Cats in the wild sometimes get to eat only once a day (though on a typical day, they eat about 8 to 10 small meals). But feral cat caregivers typically only feed their colonies once a day, and the kitties do just fine. So treat your cat’s hunger as your friend. Don’t give in after 20 minutes to plaintive cries or a pair of pleading eyes staring up at you, or you’ll never get the job done.

Dr. Pierson says to read her transition tips linked above and just stick with it. Some people have spent six months transitioning their cats away from dry food. She doesn’t think it should take that long – but do what works best for your individual situation. In hindsight, she says it probably shouldn’t have taken her three months to transition her own cats, but she had some serious kibble addicts on her hands, one of whom was 10 years old and had never taken even a bite of canned food.

A word about the texture of cat food. Dr. Pierson says during the transition, it’s all about texture, texture, texture. Kibble-addicted cats are so accustomed to dry, crunchy stuff that getting them used to soft wet stuff takes a lot of work. She also says it’s okay to use some smelly fishy food at the beginning of the transition, though generally speaking, she recommends avoiding fish altogether. (So do I.) Fish-based cat food can contain fire-retardant chemicals linked to feline hyperthyroidism. There’s mercury in fish, and it also tends to be high in phosphorus. So there are a lot of reasons to stay away from fish – except during the transition if your cat seems to go for it.

Make Sure to Visit Dr. Pierson at

In addition to the pages we’ve talked about today, Dr. Pierson’s website is loaded with great information about all things feline-related. I recommend it all the time to clients who want to learn more about specific illnesses or diseases, or who are looking for helpful tips. If you haven’t visited yet, I encourage you to do so. And bookmark it for future reference because it’s a site you’ll want to go back to whenever you have cat-related questions or concerns.

Another fantastic page I should mention is Dr. Pierson’s Protein/Fat/Carbs Chart, which gives the protein, fat and carbohydrate content of a huge list of commercial cat foods – every variety but kibble. It’s an invaluable resource, as is her entire site.

I so appreciate Dr. Pierson’s hard work and commitment to feline health in general, and species-appropriate nutrition in particular. I’m thrilled she was able to chat with us today and I look forward to talking with her again on more kitty-related topics.