Why Does My Vet Want To Xray My Dog?

by Dr. Greg Magnusson, DVM

This post is going to be part science, part philosophy.

Xrays are one of a veterinarians primary diagnostic tools. 

Side view of a dog’s knee looking for evidence of cruciate ligament ACL tear

Especially with general practice veterinarians, besides our hands, our eyes and our ears, we mostly have blood tests, urine tests, and xrays to guide our diagnostic and therapeutic plans.

That’s why nine times out of ten, if you bring your sick pet to me, I’m going to recommend all three of blood tests, urine tests, and xrays right off the bat. We vets call that our “minimum database” of baseline diagnostic tests, ie: the very least we can do in most cases to come to a proper diagnosis.

If I were a dog, I’d hate having xrays done. 

Laying on a cold hard table, with strange people restraining all my limbs, mom and dad not allowed anywhere nearby, usually holding me in awkward positions, even on my back, and doing it in complete darkness? Nuh uh, I’m not at all surprised my patients hate having xrays taken! But what’s gotta be done, has gotta be done.

Which is why, taking xrays is about my least favorite thing. 

Not because it’s technically difficult, but because for the most part, my patients hate it. I’m so glad I have outstanding technicians who patiently, gently guide my patients through the xray process. The downside, of course, is that it takes at least two technicians to take xrays, which takes up a lot of my staff’s time.

What information can xrays of my dog give a veterinarian?

Like I enjoy telling my clients, xrays are great at taking pictures of bones, really lousy with soft tissues like muscles, ligaments and tendons.

Observe the knee xray above. A trained eye can distinguish between the femur at the top, the tibia/fibula on the bottom, and the kneecap floating around in the upper middle. Can I see the tissue that connects the kneecap to those bones? Not really. Can I see the cruciate ligament between the femur and the tibia? Nope. I can see a vacancy where there should be fluid, and I can see a little cotton ball looking thing that suggests fat around the ligament, called the “fat pad”, but I can’t see the ligament itself. Many times, veterinarians aren’t looking for the ‘thing’ itself on xrays, we’re looking for surrounding evidence of the ‘thing’.

In the case of a cruciate ligament (ACL) injury in a dog, then, I’m not looking for the ligament itself, I’m looking for inflammation within the joint that suggests, but does not conclusively prove, that the ligament might be injured.

Most of the time, reading xrays is part gut feeling, part anatomy training, part art form. 

That’s why many veterinarians send all their xrays to a radiologist for “interpretation”. Radiologists spend their whole career looking at these pictures and trying to infer usable conclusions from lines and shadows. It takes a lot of practice to do it correctly.

Why might my veterinarian recommend against taking xrays of my dog?

Now we’re getting into the philosophy component of this blog post.

There are basically two reasons to ever take an xray. Either to discover what might be causing your pet’s problem (diagnostic) or to direct a treatment plan (therapeutic).

The flip side?

If I don’t think I’ll see anything on an xray that will explain a pet’s symptoms, I may not recommend an xray.

If I don’t think taking an xray will change my therapeutic plan, I may not recommend an xray.

Many times, for instance, I will not recommend xrays on an old, arthritic dog to prove they have arthritis. What’s the point? To show you a picture of your poor dog’s painful joints? Either way, I’m going to recommend glucosamine for every old limping dog just because they’re old and limping. And if your dog is visibly in pain, I don’t care what the pictures look like, I’m going to listen to the dog and treat the pain.

On the other hand, if your dog is vomiting, I will take xrays, because my other two tests (blood and urine) will probably be useless. 

Visit our blog on vomiting to learn why that is.

Xrays are hard to take, hard to interpret, hard on the pet, hard on my people, time consuming, staff consuming, and generally a pain in my butt. 

Let alone the cost of the machinery, the time, effort and challenge involved is the primary reason vets charge so much to take xrays. Yet often, there is no other test that will so clearly define your pet’s problem, and direct your veterinarian’s medical or surgical plan as a well taken xray.


Reprinted with permission from Leo's Pet Care, 10598 N College Ave # 200, Indianapolis, IN 46280 | www.leospetcare.com | indianapolisvet@gmail.com

Greg Magnusson, DVM describes himself as Leo's daddy. Public educator, mender of wounded bodies, healer of troubled souls, veterinarian in Indianapolis at Leo's Pet Care - out to change the world for one little boy...
Contact Dr. Magnusson via his Leo's Pet Care Facebook Fan Page or @IndianapolisVet on twitter.

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