There’s no way around it. Some people will appreciate this post. Some will hate it. But I promise the content is honest and meant to be helpful. If you bring your pet to a board-certified veterinary specialist, there is a reasonable chance a test your pet previously had performed with your family veterinarian will be repeated. No, this isn’t because we want to spend your money frivolously. No, this isn’t because we want to perform unneeded tests. We repeat tests because we always want to provide optimal care for your pet, and achieving this goal requires using the best possible data to make treatment recommendations. While pet parents may exclaim, “My vet already ran that test”, I’ve come up with three main reasons we, as specialists, may recommend repeating a test for your pet.
Because things change…
This is, perhaps, the most common reason I recommend repeating a blood test. But l should also say it’s uncommon to need to repeat a test that has been performed within the previous 48 hours. So let’s say a primary care doctor performed a test called a complete blood count (CBC) in his/her in-hospital laboratory – this test evaluates red blood cells, white blood cells and platelets (cells that help form a proper blood clot). And let’s say the test showed a patient had low platelets. If this patient is referred to me a week later for this low platelet problem, I will almost certainly repeat a CBC. Why? There are several reasons for a platelet count to be decreased – bleeding, a problem with the bone marrow, and destruction by the immune system. I will send a fresh blood sample to a reference veterinary laboratory (not an in-hospital machine) to see if the previously documented abnormality is persistent, has improved or worsened, and to have a board-certified clinical pathologist review the sample. This reevaluation is of paramount importance because a patient who is bleeding requires different treatment than a patient with a problem with its immune system or bone marrow.
Because experience counts…
Let’s consider a patient in need of an abdominal ultrasound. Any veterinarian can purchase ultrasound equipment. But having the equipment and having the expertise to use it are two entirely different things. It is true that a veterinarian can attend continuing education seminars to gain experience with ultrasonography. But if one doesn’t use these skills regularly, these abilities are not honed. The need to perform a complete abdominal ultrasound on a daily basis is not common in a primary care hospital. Contrast this experience with that of a board-certified veterinary radiologist or internal medicine specialist. These doctors have completed at least three years of advanced clinical training, including the frequent use of ultrasonography. In clinical practice they often perform 5-10 abdominal ultrasound examinations every day!
It is also important to understand that ultrasonography is a “real time” imaging modality – seeing internal organs in such a manner is much more powerful and valuable compared to reviewing still images. If I’m provided with pictures from another clinician’s ultrasound examination of a pet, I can only evaluate what is captured in those pictures. And that means I’m left to consider if there are abnormalities not captured in the provided images.
Because quality makes a difference…
Probably the best way to illustrate this point is to consider a pet’s need for radiographs. During veterinary school, all veterinary students are taught proper radiographic techniques. We are taught to use appropriate exposure and to focus the x-ray beam only on the site of interest. These are just two of the basic principles of radiology, but unfortunately these rudimentary doctrines are too commonly disregarded. What do I mean? Let’s consider an example of a cat that is having trouble breathing. For this patient we want to look at radiographs of the lungs. We want the x-ray beam to be focused only on the chest cavity so we see as much detail as possible (see image on the left below). Unfortunately this type of image isn’t what typically comes across my desk. I most commonly get what we affectionately call a “cat-o-gram”, a radiograph of a cat’s entire body (see image of the right below). This type of radiograph isn’t recommended because it doesn’t provide the best detail to make optimally informed recommendations for your pet.
We also need discuss the exposure of a radiograph – that is, how light or dark an image is when developed. We want the clearest pictures (not too dark and not too light) with best detail. So think about a warm gooey chocolate chip cookie (because who doesn’t like a warm, gooey chocolate chip cookie?!). And we want a radiograph to be that warm gooey perfect cookie. But a radiograph can be under-exposed (cookie dough) or over-exposed (burned crispy cookie). And in the world of useful radiography, cookie dough and burned cookies aren’t helpful and should be avoided!
Often I need to obtain additional radiographic images for completeness. A easy example to consider is a patient suspected to be living with cancer. As in people, many cancers metastasize or spread to the lungs, and for this reason we recommend taking chest radiographs for these patients (called a metastatic screening). Three radiographic views of the chest cavity are recommended for a proper metastatic screening. However I commonly only receive two. Thus to be complete and to be able to provide families with the most accurate data, I recommend completing the imaging study by obtaining the missing image(s).
I hope this post has provided some insight into why we, as specialists, sometimes recommend repeating a test. If you ever have questions about why a test has been recommended by a veterinary specialist, please don’t hesitate to ask. We will gladly explain our rationale because we always want pet parents to be as informed as possible!
Wishing you wet nose kisses,