Guest Blog: Why we recommend bloodwork

Posted in Medical, Why We Recommend at 7:11 am by ACR&S

We have a new guest blogger joining us: Dr. Jhondra Funk-Keenan holds a PhD in genetics and is a rising 3rd year vet student at UW-Madison. She is also the recipient of Oxbow’s 2008 Veterinary Student Scholarship, and has owned rabbits and been involved in animal rescue for well over 10 years. Jhondra is able to mesh the perspectives of an owner and an educated medical specialist, and will be contributing a regular column called Why we recommend, which will provide owners with understandable clinical information on the reasons behind vets’ recommendations.

If you have a specific question you’d like investigated or explained by Dr. Jhondra (for exotics or traditional small animals like dogs or cats), please email us!

Why we recommend….performing bloodwork on pets

I have a lot of people ask me “Why should I do bloodwork on my pets?” Admittedly, only one of these people owned an exotic animal. However, I think this will change in the next decade. More higher-end exotics specialists and emergency clinics regularly recommend bloodwork to exotics owners. And, within 5-10 years, I believe more vets (including ones seeing exotics) will routinely recommend bloodwork to exotics owners, both for “wellness” checks and for medical problems requiring vet care.

So, here are some of the basics of bloodwork you should know as a client. Few vets perform bloodwork in-house. Typically, orders for bloodwork are sent out to the nearest medical laboratory. There will be a few days lag time before results are back. The exceptions are veterinary schools and higher-end emergency veterinary clinics, which typically have in-house labs. These clinics have faster lab results, but may charge more for both a physical exam lab work. Most vets will recommend two types of different but complementary bloodwork to the average client: a biochemistry panel and a Complete Blood Count with Differential (CBC/Diff).

A CBC/Diff is very similar regardless of where the bloodwork is analyzed. Information about your pet learned from the CBC/Diff include:

  1. The number of red blood cells (RBC). RBC carry oxygen in all mammalian species and almost all vertebrates (except in the icefish, who has clear, whitish blood—totally awesome). Low RBC may mean anemia and be cause for concern, but this depends on why the animal is anemic. Was the animal hit by a car. If so, anemia may reflect blood loss from the trauma. A good CBC/Diff will tell us if the anemia is regenerative, which it should be. If not, that leads us down a different diagnostic path and may warrant more tests.
  2. The number of white blood cells (WBC). High number of white blood cells (called leukocytosis) may indicate an infection, especially if certain types of white blood cells are high (neutrophils, maybe monocytes). However, this isn’t straightforward, as stress can increase WBC, including the stress of traveling to the vet.
  3. Total protein. A increased total protein can mean an animal is dehydrated; decreased can mean blood loss.

Chemistry panels are a little less straightforward. Most labs (and vet clinics) offer numerous panels, which differ by which tests are on the panel. More complete panels will include more of the boldfaced tests:

  1. Liver function: via AST, ALT values; these are enzymes produced in the liver cells. Liver cells also produce albumin and cholesterol; these markers can tell us how well the liver is producing proteins. Bilirubin can be a indicator of liver clearance and also if red blood cells are being destroyed within the body.
  2. Kidney function: via BUN and Creatinine values. Cholesterol and albumin can also be informative about kidney function.
  3. Gull bladder function: via ALP and GGT
  4. Muscle health: via AST and CK.
  5. Electrolytes (Sodium, Chloride, Potassium, and Bicarbonate): All four tell us about Acid/Base balance within the animal, about the GI tract’s state and a little about the kidney function.
  6. Strong ions (Calcium, Potassium, Magnesium): Tell us about the kidney and about GI tract health). Calcium imbalance can be a sign of other issues, like pancreatitis, GI tract, milk fever in lactating females, among other illnesses.
  7. Glucose: tells us about food consumption and also about the pancreas’ secretion (the pancreas regulates blood glucose). Is blood sugar low? If so, is the animal flat on the ground? For example, we can see really low blood glucose in ferrets due to insulinomas.
  8. Several exotics panels will also offer uric acid, which can tell us about kidney function (and possible vitamin imbalance) in birds.

So, now that you know the basics of bloodwork, which tests should you consider doing on your pets?

For my pets, I get a complete chemistry panel (the most complete available) performed while the animal is fairly young and healthy. Suppose you have a sick pet, you come to see me and I perform bloodwork for the first time during that illness. We can only compare this animal’s tests to the “officially reference interval” but these intervals include only 95% of animals (2 standard deviations from the statistical mean). Statistically speaking, as the number of tests on a panel increases, we have an increased risk of getting a high or low values of one or more tests due to either artifact or a value that appears abnormal but is normal FOR YOUR ANIMAL. How would we know what is normal FOR YOUR ANIMAL? Only via previous routine bloodwork, performed when your pet is healthy.

If you have already performed the routine bloodwork and your vet asks about routine bloodwork on subsequent visits, I would ask the vet “What problems do we want to look for?” Some vets want to monitor liver and kidney values in animals (especially pre-anesthesia); if that’s the rationale, can we avoid the complete panel and perform a pre-anesthesia panel? I also perform regular geriatric panels on my older animals; these panels allow me to watch for changes in the liver, kidney, and electrolytes. As my pets age, I perform bloodwork more regularly (every 6 months).

Your vet may recommend a urinalysis, based on physical exam findings or symptoms. Is your pet drinking more water or urinating more? Is he urinating red-tinged urine? This may be normal or abnormal in some small mammals, depending on diet. A urinalysis also complements any kidney values from your chemistry.

If your animal is ill, I would definitely consent to a CBC/Diff and a chemistry panel. A CBC/Diff will tell your vet if your animal is sick due to an infectious disease. Depending on symptoms, your vet may suggest a complete chemistry panel; is the animal suddenly ill, with no signs 12 hours ago, meaning we have few clues as to where to start? For the reappearance of a re-occurring problem, a less-complete panel may give your vet all the needed info.

Be ye warned: bloodwork is not all diagnostic and will never replace a good physical exam by a vet (exotics-specialist for exotics pets). I had a (beloved) rabbit with a very normal geriatric panel 4 months before she was euthanized due to advanced pulmonary neoplasia. She had little to no normal lung tissue at the time of her death and yet her chemistry panel was normal.

Also, don’t try to interpret bloodwork on your own. Vet schools typically have one entire semester-long class on interpreting bloodwork; students learn how to understand ALL the tests performed and ALWAYS in the light of physical exam findings. Don’t be afraid to ask your vet to spend time explaining what the bloodwork means and how it should guide your management of your pet’s health.

1 Comment

  1. diandlerne said,

    August 2, 2008 at 6:31 pm

    Thanks !