This happens quite often: I’ll see a sick dog or cat, run a general blood profile… and it comes back 100% normal.
Your pet could be coughing, not eating, throwing up, or just not himself. Whatever the reason, something isn’t right, and you’re disappointed that the blood tests that were ran didn’t give us a diagnosis. Now what?
I always remind owners that perfect bloodwork does not mean perfect pet. Blood panels are very good at testing for certain things, but there are many diseases that we simply cannot find by testing blood. The most common requests I get are for a blood test for cancer (doesn’t exist) or a test for toxins (only exists on TV). I wish we could do that! I know human medicine has toxicology panels and specific markers for some types of cancer – makes us vets jealous!
True story – when I was in veterinary school, one of my dogs had a seizure, and after that was not herself. The next day I ran a blood panel on her, it came back 100% normal, and she was dead 5 hours later. Turns out she had a large tumor in her brain. The only way to see that is with an MRI or a CT scan. It broke my heart that I had no way of knowing until it was too late.
Sure, blood tests are useful and a great place to start. We can check anemia, white blood cell disorders, and platelet disorders on a test called a CBC – Complete Blood Count. The chemistry panel checks kidney function, electrolytes (sodium, potassium, and chloride), liver enzymes (and sometimes liver function), calcium, phosphorus, glucose (diabetes), cholesterol, gall bladder, thyroid, and sometimes pancreas. So if a routine blood panel comes back normal, that means we have just ruled out a LOT of potential diseases – progress is being made!
This is all well and good, but if there’s a toxin or a tumor that does not affect any of those parameters, it can go completely un-noticed! I’ve had this happen with toxins that irritate the digestive tract; cancer of the intestines; tumors in the abdomen, brain, or chest; and neurological disorders. perfect blood panel, dying animal, and one very stressed out owner. When the initial blood tests are normal, we then have to dive deeper, which could mean x-rays, an ultrasound, a spinal tap, even an MRI or CT scan! If these are normal, we might even go to exploratory surgery, endoscopy, or biopsies! As you can see, the blood tests are a first step, but sometimes it’s just one step at the beginning of a very long road.
The blood tests give us a place to start, because it rules out a lot of other things. Here’s my brief rundown of what a typical blood panel shows us in a dog or cat.
Red Blood cells: Low numbers of red blood cells are classified as anemia. If an animal has a mild anemia, it can signal that there is an underlying disease process going on that we need to dig a little deeper to find. Here’s my article on mild anemia. Severe anemia can indicate an aggressive or chronic disease.
White blood cells: We check both the total number of cells, as well as the various types of cells (Abnormalities in the different types of white blood cells would indicate allergy, infection, parasites, or inflammation somewhere in the body).
Platelets: these are the cells that are responsible for clotting, or stopping bleeding. Normal numbers of these are very important, as low numbers can be life threatening and lead to bruising or even hemorrhage.
Glucose: This is blood sugar. Too high would indicate diabetes, too low can indicate a certain type of tumor.
Liver: Normal liver enzymes suggest the liver is happy and functioning well. Older dogs can see one of these numbers rise without it meaning a whole lot. Here’s my article on that.
Kidneys: We measure 3 kidney levels, which indicate various aspects of kidney function.
Electrolytes: This includes Sodium, Potassium, and Chloride. Abnormalities in any of these can indicate a serious metabolic disease.
Calcium: Increased calcium can indicate certain cancers or glandular diseases
Proteins: We check Albumin and Globulin levels, the two major proteins in the blood. Low numbers of albumin can indicate severe kidney, liver, or intestinal disease. High numbers of globulin can indicate inflammation or infection somewhere in the body.
Cholesterol: We don’t worry about cholesterol in companion animals unless it is outlandishly high, which could indicate a gland disorder.
Gall Bladder: We can check two enzymes that indirectly give us an idea of gall bladder health.
Thyroid: Dogs can experience low thyroid function, while cats commonly experience excessive thyroid function. Here are my articles on hypothyroid dogs and hyperthyroid cats.
Yes, there are other tests we can add on to a routine panel if we want to look for something specific, such as pancreatitis, hormone imbalances, diseases carried by ticks, etc. This is the basic one that we veterinarians typically start with.
So if your pet is sick and the blood tests are all normal, first be thankful they didn’t find something horrible there, but keep an open mind that there may be more steps needed to diagnose your pet correctly. It’s as frustrating for your veterinarian as it is for you when we know something is wrong and we can’t find it!