When to Say Yes to a Diagnostic Test

by Nancy Kay, DVM 

As veterinarians we have access to so many incredible diagnostic tests. They help us uncover medical issues in our patients that, in the past, we could only guess about.

How can you know whether or not to say, “Yes” to your vet when she or he recommends a diagnostic test, whether advanced or more basic? 

Here are my suggestions:

Begin by talking with your veterinarian about all the potential risks and benefits and pros and cons associated with the recommended testing. 

What will be involved for your dog or cat (sedation, general anesthesia, time spent in the hospital) and what will be involved for you (time, expense)? Most importantly, before making a decision about whether or not to proceed with recommended testing, be sure to ask yourself the following two questions: 

  1. Will the results of the testing have the potential to change what I do next?

  2. Will the results of the testing have the potential to provide me with some necessary peace of mind?   

If your answer to one or both questions is, “Yes” then it is certainly reasonable to consider proceeding with the diagnostic testing. However, if your answer to both questions is, “No” the testing is impossible to justify. Not only will it be a waste of your money, why on earth subject your dog or cat to a needless test?

Remember, satisfying your veterinarian’s curiosity is definitely not a reason to proceed with any recommended testing! 

Here are a couple of real life examples excerpted from my practice life that illustrate how the answers to these two questions help in the decision-making process.


Shasta is a sweet as can be twelve-year-old Golden Retriever mix, brought to see me because of vomiting and anorexia (food refusal). 

When I noninvasively looked inside her belly with ultrasound I found multiple masses within the liver, stomach, and spleen. As I told Shasta’s mom I was 99% certain I’d identified cancer involving multiple organs.

Surgical removal would not be an option (disease too widespread) and the only option for potentially helping Shasta would be chemotherapy, that is, if the cancer were of the type that is responsive to chemotherapy.

We discussed performing an ultrasound guided biopsy to “name the enemy” and know whether or not chemotherapy might be of some benefit. 

Shasta’s mom was clear that, depending on the tumor type, she would wish to give chemotherapy a try. She opted for the biopsy procedure (the biopsy results are pending at the time of this writing).

In this case Shasta’s medical advocate opted for diagnostic testing because the results had the potential to change what would happen next.  


Pixel, an eight-year-old mid-sized mutt who presented for coughing. 

X-rays of his chest revealed multiple lung masses, and I told Pixel’s family that I could be 90% certain that they were malignant growths. I left the 10% door open to the slim possibility of an unusual infectious disease.

We discussed further diagnostics including a computed tomography (CT) scan of the chest cavity and aspirate or biopsy of a mass in order to “name the enemy”. With that information we could know whether or not we might be able to provide effective treatment for Pixel.

His family members felt certain that if Pixel had cancer they would not wish to treat it. 

Additionally, 90% certainty that their boy had cancer was good enough for them. Pixel’s people had all the peace of mind they needed and the results of the testing would be highly unlikely to change what they would do in terms of treating their little boy. Pixel went home on a cough suppressant and pain medication and is doing reasonably well for the time being. 

Have you ever found yourself in a decision-making dilemma concerning diagnostic tests for your pets? If so, would answers to the two questions above have helped you make your choice? 


Nancy Kay, DVM

Diplomate, American College of Veterinary Internal Medicine
Author of Speaking for Spot: Be the Advocate Your Dog Needs to Live a Happy, Healthy, Longer Life
Author of Your Dog’s Best Health: A Dozen Reasonable Things to Expect From Your Vet
Recipient, Leo K. Bustad Companion Animal Veterinarian of the Year Award
Recipient, American Animal Hospital Association Animal Welfare and Humane Ethics Award
Recipient, Dog Writers Association of America Award for Best Blog
Recipient, Eukanuba Canine Health Award
Recipient, AKC Club Publication Excellence Award
Become a Fan of Speaking for Spot on Facebook

Please visit http://www.speakingforspot.com to read excerpts from Speaking for Spot. There you will also find “Advocacy Aids”- helpful health forms you can download and use for your own dog, and a collection of published articles on advocating for your pet’s health. Speaking for Spot is available at Amazon.com, local bookstores, and your favorite online book seller.

Did you get your copy of Speaking for Spot yet?

If not, go get the book. It's likely the most important dog book you'll ever read.

What about Your Dog's Best Health? If it isn't on your bookshelf yet, you ought to add it to your must-have books. This books contains information about what is reasonable to expect from your veterinarian Such as round-the-clock care, written cost estimates and much more.

Do you know what you should be able to expect from your vet?

Articles by Dr. Kay:
Reasonable Expectations: The Ability to Discuss Your Internet Research With Your Vet
Finding Dr. Wonderful And Your Mutt's Mayo Clinic: Getting Started
Even The Best Veterinarian Can Make A Mistake
A Different Way to Spay
Making Tough Medical Decisions For Your Dog: Lily's Story
If You Don't Know What A Lick Granuloma Is, Count Your Blessings!
Anesthesia-Free Dental Cleaning 
Talking Teeth 
Urinary Accidents
I Can't Believe He Ate That! Foreign Body Ingestion 
What Caused Murphy's And Ruska'sPneumothorax?
The Whole Picture: When The Test Results Don't Match What's In Front Of You 
Stop that Scratching
Veterinarians And Vaccines: A Slow Learning Curve
What is a Veterinary Specialist? 
Veterinary Specialists: Oncologist 
Veterinary Specialists: Cardiologist 
Veterinary Specialists: Internist 
Veterinary Specialists: Neurologist
Veterinary Specialists: Surgeons
Nutritional Management of Canine Epilepsy
Have a Miniature Schnauzer? Know about Sick Sinus Syndrome (SSS)
Puddles: Potential Health Hazard for Your Dog
What Is Glomerular Disease?
Leaky Dogs: A Primer on Urinary Incontinence  
Eight Tips for Coping With Your Dog’s Age-Related Hearing Loss
Gut Feelings and Second Opinions  
Reasonable Expectations: Access to Round-the-Clock Care
Reasonable Expectations: Discussion of All Options Regardless of Cost 
Show Me the Symptom: Videotaping for Your Vet