Feline Hyperthyroidism Interview with Dr. Jean Hofve of Little Big Cat

Last Updated on July 15, 2021 by Jenny

A sincere thanks to Dr. Jean for taking the time to talk about hyperthyroidism in cats with us.

You can learn more about cat health by reading Dr. Jean’s book, The Complete Guide to Holistic Cat Care: An Illustrated Handbook.

You can learn more from Jean’s website as well, Little Big Cat.

We’ve now done several interviews with Dr. Jean, feel free to check any of them out:

• Cat Allergies with Dr. Jean
• Food Allergies in Cats with Dr. Jean Hofve
• Litterbox Questions with Dr. Jean
• Obesity in Cats with Dr. Jean Hofve, DVM
• Kidney Disease in Cats with Dr. Jean Hofve, DVM
• Cat Conjunctivitis and Cat Herpes with Dr. Jean Hofve
• Cat Constipation – Causes, Symptoms & Treatment of Constipation with Dr. Jean Hofve

Cat thyroid image source: Animal Emergency and Referral Center of MN

You can listen to the recorded version here: Feline Hyperthyroidism Interview with Dr. Jean Hofve or just click play below.

Here is a transcription of our conversation, if you’d prefer to read:

Feline Hyperthyroidism Interview with Dr. Jean Hofve with Floppycats

Jenny: Hello Floppycats subscribers. Today, we’re talking with Dr. Jean Hofve about feline hyperthyroidism. And Dr. Jean is a holistic vet and she runs Little Big Cat which is her website, it’s LittleBigCat.com. And she also has several books that she sells on the site and also on Amazon so I’ll link to those in the written description of this recording. Dr. Jean, thank you so much for letting us bug you again.

Dr. Jean: Oh, my pleasure.

Jenny: So today, feline hypothyroidism, can you kind of tell us what it is?

Dr. Jean: Well, the thyroid gland – in cats it’s actually a pair of glands – they sit on either side of the windpipe at the base of the throat. And the thyroid is kind of the master gland of the body in a lot of ways, and what it does, mainly, is it controls the basal metabolic rate. Well, what does that mean? That is just the speed at which your cat’s body functions. It’s kind of like a thermostat. So if you turn the thermostat down, which would be hypothyroidism which is common in dogs, they basically get sluggish and they gain weight and that sort of thing. Cats get the opposite, hyperthyroidism, so you’re cranking the thermostat up and it makes them digest food faster. So sometimes you have vomiting and diarrhea because things are just going completely bonkers through there. They become a little more active, not all cats but it increases the heart rate, it increases hyper behavior. A lot of times they’ll start howling at night. And they eat like a son of a gun but they will lose weight because they’re burning calories at a faster rate because that thermostat’s been turned up.

Jenny: Okay. So at what age do cats typically acquire hyperthyroidism?

Dr. Jean: Usually they’re older. I think the youngest I’ve heard is seven years, but it’s usually 9, 10, 11 years of age. It’s an older kitty disease.

Jenny: Okay. And you mentioned some of the signs. If you don’t mind repeating those again, the howling at night…

Dr. Jean: Yeah, that’s a really great one because I hear this from my friends all the time that my cat has started going bonkers at night. So the increased appetite, most of them eat more. They will lose weight anyways, and sometimes they lose weight pretty dramatically pretty quickly. So you get this anxiety or hyper kind of behavior, including the howling at night. Because they’re going through calories and body water so fast, they’re thirsty. So they drink a lot, they pee a lot, so everything is turned up, and vomiting and diarrhea. Now, the most difficult thing about the disease is that not all cats will have the symptoms. Some cats get sluggish. Some cats get lethargic or they eat less. But usually in 80% of cases you’ll have some of the signs of that turned up thermostat kind of behavior.

Jenny: Okay. Because I’m thinking urine output with an older cat, I’m always thinking kidney but it definitely could be a hyperthyroid thing too.

Dr. Jean: It could and often they go together. Older cats, they get old and their functions start to decline. One thing that’s real tricky about thyroid disease is because it does increase blood pressure and heart rate, that actually increases the blood flow to the kidneys. So if you have kidneys that are kind of marginal or starting to go, the function is starting to really decline, being hyperthyroid can actually mask that so the cat will act normal longer than it would have otherwise. So when we talk about treatment, there are some real serious implications about treating that. But there are a lot of things that can cause the drink a lot, pee a lot syndrome – kidneys was the most common, but diabetes, thyroid disease, liver disease, a whole bunch of things can cause that. So if you have a cat who suddenly increases drinking and urine output, you really want to have your vet do some blood work. And in a cat over seven or eight years of age, all the veterinary labs have a test panel that include thyroid. Always get the thyroid checked if you’re doing blood work on an older cat. That’s just simple and you may be able to catch things in the early stages where damage has not really been done.

Jenny: Okay. So the only test that you can do is a blood test to figure out?

Dr. Jean: That’s the first screening test. There are some other tests that can confirm. There are radioactive CAT scans or bone scans, or you can shoot radioactivity in. That’s got iodine and iodine collects in the thyroid so you can actually see on the scan results, you can see the thyroid. That maybe an indicator for some cats because one thing about the thyroid is you can have thyroid tissue kind of scattered all over the place. In the embryo, when the thyroid gland kind of starts to form, it has to migrate up to where it’s going to be at the base of the throat. Well, sometimes thyroid cells get shed along the way and you can have no signs of an enlarged thyroid or anything, but there will be a thyroid nodule in the chest where you can’t see it or feel it or anything. That can be a real problem for these guys when you’re trying to treat them.

Jenny: Wow, yeah. I didn’t know about that. Wow. That makes it very complicated.

Dr. Jean: Yeah. I had one kitty who had actually had her thyroid glands removed and the surgeon originally put this cat on thyroid supplementation because there’s often thyroid tissue somewhere else. That is almost never necessary. But this person felt that she wanted to keep the cat on that medication. Well, the cat became hyperthyroid again and it turned out that she had a massive thyroid tumor in her chest. So it was really shocking. I mean, the thing was a couple inches across. This is a strange disease and it’s something that you really want to stay on top of if you’ve got it going on.

Jenny: Wow. That is fascinating. I didn’t share this with you but I was hyperthyroid for eight years. So, I know a lot about hyperthyroidism in humans. But, wow, that’s fascinating.

Dr. Jean: It’s like living on a caffeine drip, isn’t it?

Jenny: Yeah. Yes, and it is a beast to manage. Okay, so what are some of the causes of hyperthyroidism in kitties?

Dr. Jean: Well, that’s the most curious question of all and we don’t really know exactly but there have been a lot of theories put forth. One theory is that there’s too much thyroid. If you have chronically elevated iodine intake, that can actually cause hyperthyroidism. So it’s kind of a circular thing. Well there’s too much iodine so the thyroid gets more active so it eats more iodine but then it makes more iodine. It’s just a ridiculous thing. The thing about iodine in commercial pet food is that iodine is very difficult and extremely expensive to measure. So when pet food companies buy a vitamin mineral premix and put it in the food, often many things in that premix will be at elevated levels and it’s possible that iodine is kind of chronically elevated in the food. So is that causing the thyroid disease? Well, at least one pet food company thinks so because their treatment for it is to feed an iodine deficient diet from evidence that BPA, you know, our favorite little biphenyl A that’s in plastic bottles and all that stuff…

Jenny: Yeah.

Dr. Jean: Well, did you know that steel cans are lined with plastic? It turns out stainless steel isn’t stainless, and it will rust. And what causes it to rest? Water. Oh brilliant. Okay, so if you buy a stainless steel, BPA free water bottle, or aluminum one and you think there’s no plastic in this, they’re all lined with plastic, every one of them. And so cat food cans are lined with plastic and BPA is found in the plastic in a lot of foods. A few foods have taken it out. A few foods have substituted a different kind of plastic that’s probably even worse. But the thing about BPA, it is an endocrine disruptor. Endocrine means the hormones like thyroid hormone or insulin or those kinds of hormones that run around in the body and do many important things. That can be disrupted by these chemicals. So that’s a thought. Another idea that has been tested and shown to have some merit is fire retardant chemicals. They’re called PBDEs (Polybrominated diphenyl ethers) and I’m not going to even try to tell you what that is. It’s interesting that thyroid disease was first documented, first found at UC Davis near Sacramento, California. And it was a few years after California started mandating the addition of fire retardant chemicals through things like carpet, furniture, clothing, baby toys and things like that. And so when these fire retardants all of a sudden became extremely common and everything was saturated in them, all of a sudden now our cats are getting this weird disease. So, there is some thought that that’s part of what’s going on. And the thing about the PBDEs is they’re kind of ubiquitous in the carpet and the furniture. So they’re present in dust. Well, cats like to sleep on warm things like stereos and TVs where dust collects, static collects, and then they groom it off and they are ingesting these chemicals, and they’re walking across your fire retardant carpet and licking it off their feet and it’s being taken up by the dust mites and they’re grooming those off. So that’s a very good thought, and the other thing about PBDEs is they are also found in food. A lot of cat foods have been tested and the two ingredients that are fish and chicken byproducts, well, those are also the flavors of foods that are the most implicated with possibly the lining, possibly with the ingredients. I think what we can say for sure is that there are many factors and probably no one thing that does it. But if you have a cat that’s susceptible and their thyroid function may be a little bit off, their regulation is a little bit off and they’re more susceptible to develop these diseases, you start getting one or two or three of these triggers and they’re going to develop the disease. It’s become so rampant. It’s not yet half of older cats, but I think it’s close to a third of older cats you can kind of bet that they’re going to develop this disease.

Jenny: I’m just going to knock on wood that it doesn’t happen to my two little guys.

Dr. Jean: Yeah. I had a cat that did develop it. It was 20 something years ago. She was born and raised in California. Is that the problem? She didn’t eat that much fish, I didn’t feed her fish. She got homemade food, but at some point in her life, she did get a lot of Fancy Feast. So is that what it was or was it the can liners, now they’ve all changed? It used to be when the first study came out about the BPA in the plastic, the most common can liners were the white ones. Well, that’s not true anymore and it can be in any of them. Some of the white ones are fine now, and some of the silver ones are worse. It’s very difficult. It’s very difficult to figure out.

Jenny: Another reason why I need to switch my guys to raw.

Dr. Jean: Exactly, or homemade. Every day I find out something new about the food supply and the Roundup in the food. Every day I find new evidence as to why you really have to make your own cat food. And I know that’s not practical for a lot of people so we’ve got to deal the hand we’ve been dealt. We’ve got to play those cards, so we do the best we can.

Jenny: Right. Well, so once you’ve got a hyperthyroid kitty, what are your treatment options?

Dr. Jean: Well, it used to be, back when I started practicing, there were only two. There’s a drug called Methimazole and that binds up the iodine and prevents the thyroid from making active thyroid hormone or surgery to remove the thyroid. The surgery is a little tricky and there can be some pretty serious complications. It’s not that difficult of a surgery but there are other glands involved and you’re operating in an area that has a lot of really important things like your carotid arteries and your veins and your nerves and things. But then a number of years ago, it’s probably been close to 20 years now, I’m dating myself, but now you can have your cat irradiated with radioactive iodine. Iodine collects in the thyroid and the radioactivity destroys thyroid tissue. The advantage of that is it destroys the thyroid tissue wherever in the body it is. So even if you do have one of those oddball interstolastic tumors, the iodine will get that too. The downside, it’s kind of expensive. It can be anywhere from $1000 to $2000. A cat has to be hospitalized because for a number of days, through a week or so, its pee and poo are radioactive and they are a walking, brewing biohazard. And the government does not let you have one of those in your house so they have to be hospitalized. That is a definitive treatment. It works really, really well. It’s almost the ideal treatment except for the whole radioactive thing. And some cats don’t really do well away from home that long. These are little old cats, they’re old cats and they’re fragile. And there is a distinct problem as we talked about a little earlier about the kidney and thyroid disease if you have both, if your cat has both. You may not know about kidney disease. But if you suddenly shut off the thyroid hormone, that kidney disease is going to become overt very, very fast. And it is recommended use the drug to bring the thyroid levels down to normal first so you know that your cat’s kidneys are okay on that lower amount of thyroid circulating in the body and that it’s not going to go into catastrophic kidney failure the next day which happened in a number of cases early on.

Jenny: Okay.

Dr. Jean: You remove the thyroid hormone completely and all of a sudden the cat is thrown into severe kidney failure just overnight because you’re massively reducing the blood flow to the kidneys and kidneys, they don’t like that. There’s a newer treatment. It’s made by Hill’s Prescription Diet and it’s called YD. It’s an iodine deficient diet. Now Hill’s likes to say oh just feed YD and only feed YD because animal products tend to have a lot of iodine in them so this, their dry food, is pretty much a vegetarian food which is not great for cats. But if that food is fed exclusively, Hill’s claims that the thyroid levels will come down to normal within a few weeks. Now here’s the problem. Most of us have more than one cat, right. If you have one hyperthyroid cat, you cannot feed this diet to the other cats in the house. It will hurt them because it is so deficient in iodine, way below the known minimum healthy concentration of iodine. So it’s tricky to feed if you’ve got multiple cats. For animals that you don’t want to do any of the other treatments, it’s an option. But there are problems with it. It’s a terrible food in terms of nutrition. It’s got soy and corn in it which are both genetically modified. So now you have a roundup factory in your cat’s gut.

Jenny: Well, and as someone who has hyperthyroid, my thirst was out of control. Having a kidney cat or any older cat and dry food, ugh, that doesn’t make any sense to me.

Dr. Jean: Yeah. Dry food is terrible for cats anyway and it’s especially terrible for older cats. And older cats really need more and better protein. They do better on a higher quality protein because old cats tend to lose weight no matter what is going whether they have kidney or any other disease. They just tend to get skinny when they get older. So you really want to make sure you’re feeding a very high quality food. Well this ain’t it. But I was just reading a case on the veterinarian boards. A100 year old lady couldn’t kill her cat and didn’t have $1000 or $1500 laying around to do the iodine. So it was very limited what she could do. So the diet might be a good choice for someone in that situation. I just don’t have a good feeling about it and none of the experts are recommending it. It’s something to try if you’re kind of stuck. With the drug, it is a pill but it can be made into a gel that you apply to the inside of the cat’s ear every day and that works pretty well. The problem with the drug is that cats tend to develop an allergy to it and when they do that then you can’t use it anymore and now you’re left with very little or no way of options. It’s complicated. Life is getting so complicated. Have you noticed that, Jenny?

Jenny: Yes. And the gel thing too, I remember a few years back, Methimazole is what I took. So a few years back, one of my readers contacted me and said had her cat has hyperthyroidism and I asked her what they were doing and she said, oh, I apply the gel. And I said, gel? I was like do you wear gloves or something? Is that not transported to you, you’re going to hurt your thyroid?

Dr. Jean: Yeah, it sure is. So either you have to wash your hands immediately or usually the vet will give you a bunch of rubber gloves and you just cut off the tips and stick it on your finger and use that to rub it in. But yes, you will become hyperthyroid if you apply that every day to your cat and you don’t protect yourself.

Jenny: And the other cats. Yes.

Dr. Jean: That’s a good point, and it’s also through any other topical hormone like topical testosterone, topical estrogen, topical progesterone that people use for themselves and then pet the cat or the dog. You put it on, and then you put lotion on, and then the dog licks it off. And now all of a sudden your spade dog comes in to eat. Hormones are not something to treat lightly. Just a little teeny tiny bit can really mess you up.

Jenny: Oh, man. I didn’t even think about the consequences of that testosterone and estrogen gel for animals. Oh, my gosh…

Dr. Jean: You put it on your upper arm, then your cat sleeps next to you and it’s like oh my goodness. Life is complicated.

Jenny: So more on the radioactive iodine, a few years back, the Cat Writer’s Association sent out an email about a company, I think it was in Chicago. I interviewed them on the site but I haven’t looked at it for a few years. They were selling a cleanup kit for radioactive iodine because I guess there were some vets that were letting the cat go home the same day or the next day. So that should be a warning sign, right, if the vet’s willing to let you take the cat home the next day?

Dr. Jean: I think so. Now, I haven’t looked at the protocol lately but it used to be the cat had to stay in the hospital for two or three weeks. They’ve done it down to five or seven days, but I think they still need to stay in the hospital. It is radioactive waste and it has to be treated. You can’t just send that out into the community.

Jenny: Right. That was one of my problems as a human with that risk factor. So to avoid radioactive iodine exposure in the home, as far as you know it’s like a seven day period?

Dr. Jean: Yeah, I believe that’s what it is. I could look into it or you could. Radiocat is the name of the company that has kind of made a career out of doing that. They have centers all over the place. In any big city, you probably have a facility there.

Jenny: Okay. In a human, the radioactive iodine usually kills enough and then you end up having to take a thyroid supplement for the rest of your life. But cats don’t need that?

Dr. Jean: Usually, they do not need thyroid supplementation. Weird. I don’t know why. But usually they don’t. It should never be prescribed just without thinking about it for long-term because the body will make up for that somehow. Cats are really interesting animals and they have ways of dealing with things that are just beyond comprehension sometimes. But it’s very, very rare for a cat to me that would supplementation even if you destroy the glands. I don’t know why.

Jenny: Yes, that is very curious but nice at the same time.

Dr. Jean: Yeah because you’re trading one pill for another pill and while Methimazole is really well absorbed through the gel through the ear, the same is not true of the thyroid hormones. Now you have a pill that you have to give. Let me just say this because it’s just triggered a thought not exactly on topic but a compounding pharmacy will put anything into a gel that you ask it to do. However, they do not guarantee whether the drug will be absorbed by that gel. For example, Amitriptyline which is an anti-depressant and it’s used for anxiety and aggression, and compounding pharmacies will put Amitriptyline in a gel for you. It is not absorbed at all through that route. So you are paying for something that is not going to work. But they will not tell you it’s not going to work. So you’ve got to make sure your vet has researched it and understands that they’re going to put a steroid or some other kind of thing into a gel, make sure that they have done the studies that show that it’s actually absorbed that way. Hormones tend to be absorbed pretty well through that route because it’s a natural substance. But it’s not always the case. So if your cat or your dog has to be on some kind of medication and you think, oh, hey we could put it in a gel. Well, you can, but whether it’s going to work or not is a whole different topic.

Jenny: Yeah. Interesting. Okay. Well, I guess we sort of covered this a little bit but I figured I’d just ask it again, are there any ways to lessen the chance of a cat developing it?

Dr. Jean: Well, possibly. I mean, dust a lot, make sure if you’ve got carpets and furniture with fire retardants in them, think about getting a hardwood floor or really keep your dust low so that your cat’s not ingesting that kind of stuff. I would stay away from foods that contain fish and byproducts just because those particular ingredients have been associated with more thyroid disease than other ingredients, and they do contain higher levels of BPAs than other, rather the PBDEs, the fire retardants. This stuff is ubiquitous in the environment but the ocean is really a wonderful sponge for soaking up pollution and there’s a lot of it floating around there for the fish to eat. And if you’re not going to home make food, I do recommend canned food. But maybe you can find a manufacturer, they change all the time so you’re going to want to call, ask them if they’ve taken BPA out of their cans and if they have make sure they haven’t put BPB or BPF or BP any other kind of thing in there instead. It’s real tricky. I would say feed a homemade diet as much as possible. Go organic if you can. It’s kind of a disease as just hanging around on planet earth for long enough some of these kitties. And there’s not a whole lot of prevention that you can do. But if you can do the diet and keep things – if you know that the BPA is a problem and you know that the fire retardants are a problem, try and get rid of them as much as you can in your house.

Jenny: Okay. Well that is all that I had for today unless you had something else that I should have brought up that I didn’t.

Dr. Jean: No, I don’t have any brilliant ideas but it’s a tough disease. It’s not fatal. Oh, yes, we do have something else we have to talk about. We have to talk about the heart.

Jenny: Yes. I’m laughing because I’m three years into remission so it’s not as obvious in my head anymore. Yes.

Dr. Jean: Yes, well because thyroid hormone increases the heart rate. In kitties, that’s not a good thing. The heart is a muscle and if you exercise a muscle you get big musclebound muscles and in cats you can get heart failure with that. It’s a particular type of heart disease called hypertrophic cardiomyopathy. The heart is in a sack and for some reason in these kitties the sack doesn’t expand as well or for some reason the muscle grows inward. So you’ve got a fairly normal sized heart but the walls have gotten thicker. Well that means that the chambers have gotten smaller and eventually the blood can actually clot right in the heart and when the heart pumps, it’ll fly out and cause a serious thrombus. Usually that happens where the aorta splits to go down the hind legs. It’s incredibly painful. It’s called a saddle thrombus. And if your cat throws one, he’s going to scream bloody murder and they’re going to drop in the hind end like they’ve been shot. They’re completely paralyzed in the hind end. It is possible for them to recover but usually if the heart is that bad and you have that kind of thing, that’s usually fatal. You could get embolizer go elsewhere but we don’t see that as much. You have to treat this because they look fine, they’re eating good, they really feel pretty good because there on caffeine all the time and they feel pretty awesome. So you might think, well, I guess I won’t do much of anything about it. Well, if you don’t do anything about it, the cat’s going to die a really, really horrible death. So you don’t want to do that either.

Jenny: Right. Do they get a goiter?

Dr. Jean: In cats, it is a benign thyroid tumor. And because it’s benign, that means the cells are pretty normal which means they’re pumping out a lot of thyroid hormone. So yeah. There has not been a link to vaccinations elucidated except for in dogs. Most hypothyroid in dogs probably is related to vaccine induced antibodies attacking the thyroid. So we don’t know, and cats don’t over vaccinate. That’s going to save your kidneys, that’s going to save a whole lot of other… So just in general, the best diet you can and the minimal vaccines, once your cat is an adult, rabies is required by law almost everywhere. But nothing else is really necessary. So they don’t need annual boosters or even every three years or even every five years. The kitten vaccinations are so effective, they’re essentially set for life. So don’t keep doing that.

Jenny: Okay. It’s always something I have a little fight with my vet with and I say I’m not budging so are we done?

Dr. Jean: Yeah. You’ve got to do rabies. That’s required by law. If you choose not to – I had a client who is also a really good friend and she had a cat named Spike and he was the cat from you know where, a very hot place. And I even went and did a house call and tried and still couldn’t get near him. So he didn’t get his rabies vaccine. A couple of weeks later he shredded the brother in law or the neighbor’s brother in law or something and she got cited for not having him vaccinated. And I wrote a letter to the judge on her behalf. I said your honor, I would be happy to give you this shot and you go do it because this cat cannot be vaccinated. Okay, case dismissed. And most likely, cats that have had the first few rabies vaccines, they’re probably also protected. But because it’s a public health hazard and it will kill you, the law does take very dim view of not keeping up with those vaccines.

Jenny: Alright. Well thank you very, very much for the hyperthyroidism talk. I’ve totally forgotten about the heart rate thing and that heart failure thing would be a horrible way to lose your cat.

Dr. Jean: We talked about the increased heart rate but then I forgot to explain why that’s a problem.

Jenny: Yes. Yes. It’s so crucial.

Dr. Jean: We got it.

Jenny: Yeah. Thank you very, very much and please continue to let me know about your new projects and that sort of thing so that I can share them on Floppycats.

Dr. Jean: Okay, will do.

Jenny: I know everybody loves hearing from you.

Dr. Jean: Well, thanks. It’s so much fun to work with you. I really enjoy it.

Jenny: Thanks.

Dr. Jean: Okay, bye bye.