The Shocking Reality of Misdiagnosis in Pets

Can you believe that one common dog disease is misdiagnosed 50% of the time! So then, how can we trust the accuracy of a diagnosis if our beloved pets are suffering?

1️⃣ Sensitivity and specificity are crucial in diagnostic tests but often involve a trade-off. A highly sensitive test reduces false negatives, while a highly specific one cuts down false positives.

2️⃣ Misdiagnosis can result from running inappropriate tests, lack of funds, incorrect history interpretation, and limited vet knowledge.

3️⃣ Skin allergies, heart failure, mild lameness, Cushing’s disease, and hypothyroidism are frequently misdiagnosed in dogs, often leading to unnecessary treatments.

4️⃣ The case of hypothyroidism reveals up to fifty-nine percent of dogs diagnosed might not actually need treatment according to recent studies.

💡Understanding the complexities of diagnostic accuracy and the factors contributing to misdiagnosis can save you thousands and spare your pet unnecessary discomfort. Knowing the challenges can ensure you ask the right questions and give your pet the information and tools they need to ensure your pet receives the best care possible.

Dive into more details in the full show notes - https://ourpetshealth.com/info/dog-misdiagnosis

Love the show? Sharing this episode or leaving a review helps others know it's worth a listen! - https://ourpetshealth.com/review

Transcript

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If your pet is unwell, has some tests run, and your vet reaches a diagnosis, you'd have thought that you could trust its accuracy, but one common dog disease is misdiagnosed fifty percent of the time, and that's probably just the tip of the iceberg. Welcome to the Call the Vet Show, the podcast that helps pet parents understand and optimize the health of their furry family so they can live the full and happy life you want for them. And here's your host veterinarian doctor Alex Avery. Hello, Kia ora, and welcome back to another episode of the show. Today, we're talking about accuracy of testing. Now at first at first thought, we might think, well, the vets are just rubbish. They're making misdiagnoses all the time. The situation is actually not quite as clear. And while in in some cases, I I read the the the studies that I I mentioned in this episode, and I I shake my head because this is not a new issue and and surely more and more vets should be aware of this. But equally, the situation is more complex. There are numerous reasons why a misdiagnosis might take place, which I go into in this episode. And some diseases are really just plain challenging to diagnose, including those that are frequently misdiagnosed. Now in this recording, I do reference some diagrams and you can see those diagrams over in the show notes. So tap on the link to the show notes that are in the description to this podcast episode if you want to see those diagrams just to give a visual representation of testing accuracy, the sensitivity, the specificity that I discussed before I then move into those top five misdiagnosed pet diseases. Before we get into that though, if you're not already subscribed to the show, make sure you hit that subscribe or follow button whatever app you're listening to this on just so that you, notified whenever the next episode comes out. And for now, let's jump into the episode. And now on with the show. And the first step to preventing a misdiagnosis for any disease, and I'll talk about the most commonly misdiagnosed diseases in just a minute, is to understand the issues surrounding test accuracy. Now in an ideal world, we would want a test that could give a clear yes or no for every single condition that we're trying to diagnose, and we also would want every one of these tests to be perfect. And by this, I mean that every dog with disease that we're testing for comes back with a positive result, and every dog or cat without the disease comes back with a negative result. Unfortunately, though, we don't live in this ideal world. For many conditions, we're actually putting the results of multiple different tests together to reach a specific diagnosis, kind of putting a jigsaw puzzle together. And for those tests that are more targeted, we're actually dealing with imperfect tests. Sensitivity and specificity are two important measures of any diagnostic tests. Accuracy, they help us to understand how well a test can correctly identify both those dogs and cats that do and don't have the disease being tested for. So sensitivity, that refers to a test's ability to correctly identify individuals who have the disease. A highly sensitive test means that there are few false negative results and so fewer cases of disease that are missed. For example, if a test for a certain type of cancer has a sensitivity of 95%, it means that ninety five percent ninety five out of every hundred individuals who actually have the cancer represented by the red dots will test positive for it. This also means that five percent of dogs with cancer will test negative. Specificity then refers to a test's ability to correctly identify individuals who do not have the disease. A highly specific test means that there are few false positive results. So, for example, if the same cancer test has a specificity of ninety percent, it means that nine out of every ten dogs who do not have the cancer, represented by the blue dots, will test negative for it. Conversely, one out of ten dogs who do not have cancer will actually test positive. So, ideally, a diagnostic test would be both highly sensitive and highly specific. I mean, ideally, a % sensitive and a % specific. But in reality, there is often a trade off between the two. So a test that is very sensitive will often have a lower specificity, meaning that it may produce more more false positive results. So that is a larger number of dogs that test positive do not actually have the disease, but those that test negative are likely to be identified correctly. On the other hand, a test that is very specific may have a lower sensitivity, meaning that it may miss some cases of the disease. In other words, a large number of dogs that do have the disease actually test negative with the disease, incorrectly saying the disease is not present. But those that test positive are likely to be accurately identified. So this test inaccuracy is one of the big causes of misdiagnosis, but it's certainly not the only one. Other factors that can result in misdiagnosis include actually just running inappropriate tests. So often when the symptoms of the disease being looked for are lacking or something more obvious and common is missed out. The next is a lack of funds or local test availability to investigate more fully. So a test suggests a certain problem is present, but follow-up testing to confirm the diagnosis is not possible for for whatever reason. Incorrect interpretation of history or just not asking the right information is the next reason for misdiagnosis. So clinical history is really an absolutely vital part of putting together this jigsaw puzzle of diagnosis. And if it's not accurate, it can very easily throw a vet off the right scent. Absolutely. The vet needs to be asking the right questions as well. But here, I'm thinking about appetite, thirst, toileting habits and character, energy levels, and so much more. And then a lack of knowledge, especially of more uncommon diseases, is another obvious cause of misdiagnosis. So medical knowledge is growing at a really rapid rate of knots, and it can be a real challenge. I know this personally to keep up with all the latest developments in vet medicine, being specific disease knowledge or new test availability. So with that all said, it's easy to hear this list and put the blame on the vet for making a misdiagnosis, but medical cases, they are very often not as simple as they sound on paper. Individual animals often say this, they actually don't behave as the textbooks say they should. And there are also very often limits on how many tests can be run or how complete and accurate the history is. With all that being said, here is my list of the five most commonly misdiagnosed dog diseases out there. At number five, we have skin disease. So skin allergies are really common in dogs. And while they're often diagnosed with as much accuracy as can be hoped for and very often we're talking about a diagnosis of exclusion, ruling out other things first, it's not without challenge and nuance. And one of the big diagnostic errors with these cases is a failure to diagnose secondary bacterial or fungal skin infection. These are very common when a dog is suffering a flare from a long term untreated skin disease, And actually failing to make this diagnosis can lead to the treatment with more and more anti allergy medication, starting different costly supplements and various other treatments when actually some form of antibacterial or antifungal treatment, perhaps just a simple medicated shampoo is actually all that is needed. Heart failure is next at number four. This one is a little bit more gray in the sense that over the last decade or so, it's actually been shown to be beneficial to start treatment for dogs with structural heart disease before they go into actual heart failure proper. It used to be that we didn't think that that was the case. Treatment is then ramped up with additional treatments as the disease progresses, as heart failure develops, and it is a progressive disease. It is, though, very easy to start a dog with a murmur, for example, on all of the late stage drugs at the early stage, misdiagnosing the level of disease actually present. And clearly, a discussion also needs to be had if a medication is being started early as for some, this will end up spending so much money that by the time the disease actually progresses, there is nothing left in the kitty to further adjust treatment. And one huge negative impact I see with the misdiagnosis of overt heart failure is that an owner may elect not to treat a condition requiring anesthesia. Severe dental disease causing chronic pain is the most common one here because they feel the risk is too great when in fact they have a murmur only and the heart is otherwise functioning well, making any crease in risk fairly negligible. The next misdiagnosis is different in the sense that it's actually a failure to make a diagnosis of chronic disease that would benefit from long term treatment. So cases of mild lameness, especially in our younger dogs, they're very frequently passed off as just knocks, bumps, and bruises, when in fact we know that around forty percent of dogs under the age of four have arthritic changes in one joint that can be seen on X-ray, and twenty four percent show signs of pain associated with this disease. But how many young dogs are we actually X raying when they become lame? How many are given short term anti inflammatory painkillers rather than started on a holistic multimodal treatment plan? Not very many. Next and the second most commonly misdiagnosed dog disease, we have Cushing's disease or hyperadrenocorticism to give it its proper name. So this is a hormonal disorder caused by an overproduction of the stressed hormone cortisol, and it leads to symptoms such as an increased thirst, more frequent urination, excessive appetite, panting, pot bellied experience a pot bellied appearance, thinning of the skin, and hair loss as well. And one recent study actually involving a survey of over 2,000 vets from nine countries revealed that sixty percent of vets will conduct testing for this disease even when the dog is not showing clear clinical signs of suffering from it. And this is very significant because the tests for Cushing's disease are actually not that fantastic. In terms of sensitivity, so, again, the proportion of dogs with the disease that test positive, the sensitivity for one test, the ACTH stimulation test, is only sixty to eighty percent. The other test, the low dose dexamethasone suppression test, they're all a bit of a mouthful, is much better, around ninety five percent. So most dogs with the disease will test positive, but its specificity is really low with about fifty six percent of dogs, so half of dogs with nonadrenal illness, so with not not with Cushing's disease, falsely testing as positive. With the ACTH stimulation test, this figure is fourteen percent. So it's better, but it's still not fantastic. And while this study didn't suggest just how many dogs were diagnosed or were misdiagnosed, the figure is likely significant, especially when a dog isn't actually showing the normal symptoms associated with this disease, which makes what we call the positive predictive value of these tests even worse. And then we've got the most commonly misdiagnosed dog disease, at least in my opinion. And at number one, we have hypothyroidism. So hypothyroidism in dogs is a condition where the thyroid gland, it doesn't produce enough thyroid hormone, and that leads to, slowing down of metabolism and various health issues such as weight gain, lethargy, and skin problems. The challenge with diagnosing an underactive thyroid in dogs is that any other disease in the body can also naturally reduce the amount of thyroid hormone being produced. This is something that we call euthyroid sick syndrome. And it's and that's a normal protective response to severe illness or physiological stress because it helps the body to conserve energy by lowering its metabolic rate. So then how often is hypothyroidism misdiagnosed? Well, another recent study examined the accuracy of hypothyroidism diagnosis in dogs, and researchers looked at a hundred and two dogs being treated for hypothyroidism. We had three veterinary specialists that reviewed the case notes for each of this dog. They were they reviewed the history, the clinical findings, the the laboratory testing, and they came to the conclusion that between forty five and fifty nine percent of these dogs did not require treatment for underactive thyroid. In other words, about half of these dogs have been completely misdiagnosed. This finding suggests that not only should thyroid testing be done on dogs showing clear signs of the disease, but also that further testing is likely to be highly valuable in confirming this diagnosis. And with all of these misdiagnosis, the end result can be an unnecessary financial burden on you, the pet parent. It can include a potential reduction in the quality of life and actually deterioration in health of our pets or just an increased risk of drug side effects. Helping your pet live the happy, healthy life they deserve. So I hope that gives you some some tools and some awareness around this issue of misdiagnosis. It's not clear cut, but there are definite steps that you can take to to help prevent it. We can be asking, are there any more tests that we need to run to confirm this? Are we sure that this is the right diagnosis? Even something as simple as making sure that you've got a really accurate history, you know what your pet is doing with regards to their appetite, with their thirst, with their activity levels, any other changes that you might have noticed because they might be the key to unlocking this puzzle of whatever is going on with your pet, whatever's caused that concern that you originally have. So that's it from me for this episode. Remember to hit that subscribe or follow button, and I will see you in the next episode. But until then, I'm veterinarian doctor Alex. This is the Call the Vet Show because they're family. That's it for this episode of the Call the Vet Show. Be sure to visit callthevet.org to join the conversation, access the show notes, and discover our fantastic bonus content. We'll see you next time. Free audio post production by alphonic.com.