Category Archives: laboratory

Fecal Samples – The Necessary Grossness

I’m going to be making a light post on Sunday because of the holiday, so instead of a news post today, I’ll be tackling a bigger topic.

Fecal floatations are the focus of today’s post. We always ask owners to bring a stool sample with them when their pet visits the hospital. This is an opportunity for us to check for intestinal worms and other parasites. “Worms” are a well-known concept to most owners. What’s lacking is the information about how we find the little buggers. You’ll be getting an up-close and personal look today.

I want to give some kudos where they’re due. Our veterinary technicians are the people that usually set up, run, and interpret our fecal samples. They handle poop all day long without complaint. It’s a nasty part of making sure our pets are healthy (and by extension their families, too). Thank you, Technicians!

We’re looking for evidence of worms and other parasites. Most of these nasty critters are attached to the intestinal wall in some fashion, so we don’t usually them in the pet’s stool. However, they shed eggs into the stool, and those eggs are what we’re searching for. In order to find them, we have to separate them from the fecal material. This whole process is designed to concentrate the eggs in one spot that we can sample. This gives us the best chance of finding them, and by extension, diagnosing the pet with adult intestinal worms.

Each photo is described/explained -after- the photo.

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This is part of the equipment needed to run a fecal sample. The blue pegboard thing is a test tube rack. The clear plastic tube is a test tube with a cone-shaped bottom. We use disposable dixie cups to avoid cross-contamination. The tongue depressor is used to move the stool sample from one step to the next.

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Samples need to be fresh. If they’re dried out, old, or frozen, the eggs can be hatched or damaged beyond our ability to find them. We know it’s gross to have you bring in poop, so here’s the kudos to owners for taking care of the collection part of the process. However, on that note, please notice that we don’t need a lot of stool. That’s a 50-cent-piece size, which is more than enough. We’ve had owners bring in the entire ziploc bag of stool, which is far more than we need. Just one little bit of formed stool is fine. If for the sake of not vomiting, by all means, grab the pile and run with it. 😉

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In this step, the stool is in the dixie cup. We’re adding a special liquid (Zinc Sulfate solution) to the cup.

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In this step, the stool is being broken up and mixed thoroughly with the Zinc Sulfate solution. We have to break up the stool to free the eggs from the fecal material. The end result is dissolved poop. It’s gross, yes.

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We then use a small funnel with a coarse filter in it to strain out the big chunks. We pour the liquid into the test tube.

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The test tube has to be filled right to the top of the tube, plus a tiny bit extra. We want to get a slight bulge of fluid on the top of the tube. As you can see, the cloudy brown liquid is the dissolved stool sample.

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A very thin square of glass called a cover slip is placed atop the fecal tube. The surface tension of the liquid is used to make the cover slip stick to the tube.

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The tube is placed in our centrifuge. A balance tube is put exactly opposite the fecal sample and filled with liquid to approximate the weight. We have to have the centrifuge balanced or it will self-destruct. Think about it as the same problem an unbalanced washer gets. (Whump-whump-whump-whump)

I have to explain a little bit of chemistry/physics here, so bear with me. The centrifuge spins the samples at a very high speed. (Again, just like the spin cycles on a washer.) We do this to get all of the big chunks to go to the bottom of the tube by way of gravity. The zinc sulfate solution in the tube is more dense than water (higher specific gravity). The eggs are lighter than most of the stool particles, so they will float up to the very top of the sample when the sample is spun. They concentrate right up against the cover slip. This is the critical step to getting a good result.

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As you can see in this sample, a lot of the stool particles have collected at the bottom of the tube. There are still some suspended in the liquid in this sample, but that’s a bit atypical for us to see. Usually the fluid is nearly clear.

We lift the cover slip off the top of the tube. The liquid right at the surface of the tube is pulled along with the cover slip, sticking to the bottom of it. The eggs are carried align with this small fluid sample. We place the cover slip down on a glass microscope slide.

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Here you can see the microscope slide (rectangular glass) with the cover slip stuck to it (square bit with the white edges/corners). The microscope has several different lenses that provide different levels of magnification. When we “read a fecal” we observe every single bit of the cover slip, looking for eggs.

I’ll show you the eggs we find below:

Hookworm
Hookworm

Roundworm
Roundworm

Whipworm
Whipworm

So, that’s what’s involved with “running a stool sample.” It’s a lot more involved than it seems. It’s a very important part of the twice-yearly checkups we recommend for pets. Hookworms and Roundworms are parasites that can be transmitted to human family members and other pets, so you definitely want to be sure your pet is checked twice a year.

It’s also a reminder that heartworm prevention ALSO prevents intestinal parasites. Keep your pets and you family protected with monthly prevention!

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Chronic Kidney Disease – A Case for Early Detection

Chronic kidney disease is a common diagnosis in veterinary medicine. It’s a disease for which we have no cure, only the ability to slow it down and manage the other symptoms. Ultimately, it’s fatal. The really nasty part is that we have a hard time finding it before a vast amount of irreversible damage is already done. I’ll give a little background into what’s happening with kidney disease, then talk about what we can do to treat it.

The kidney is a remarkable organ. It filters waste products out of our blood so that they can be excreted in the urine. They manage the balance of water and electrolytes (salts) in our bodies. They also make a hormone that tells the bone marrow to produce red blood cells. (Red blood cells carry oxygen throughout our bodies.) The kidneys you’re born with are the kidneys you have for the rest of your life. They don’t regrow, and “healing” is a limited ability for this important organ.

On a microscopic level, the kidney is quite complex. The illustration below shows the arrangement of blood flow and filtering in the functional unit of the kidney: the nephron (neff-ron). Tiny little arteries carry blood into a tangled ball of blood vessels called the glomerulus. Around that ball is a cup-like structure called Bowman’s Capsule. The vessels in the glomerulus are designed so that waste products and water are leaked out. Some other things the body prefers to keep are also filtered out. These wastes and other things are then collected by the Bowman’s Capsule. Bowman’s Capsule is connected to a big U-shaped tube (cut off in this illustration) that gives the kidney a chance to recollect the good things that were leaked out of the glomerulus. Those things are reabsorbed or transported back into the blood. Some new things are excreted, while others are traded out and sent into this U-shaped tube. Eventually, the U-shaped tube hooks up with a bigger tube that travels to the middle of the kidney. In the middle of the kidney, all of this waste material and whatever water the body is getting rid of is collected, then piped down to the bladder. Of course, this waste fluid is urine.
500px Physiology of Nephron svg

In chronic kidney disease, a variety of different things can go wrong, but in the end, it’s the nephrons that are destroyed. As nephrons are destroyed, the kidney begins to lose its ability to do the work it needs to do. This can be a very slow process, taking years in some cases. As with most things in the body, there’s some redundancy in the kidney to allow for a certain amount of damage without the body suffering for it. The kidneys can do their job well enough even with some loss of nephrons. Eventually, there’s a threshold after which the kidneys can’t keep up and things start to go very wrong. We can’t easily detect a problem until things start to go wrong, which is why this is such a nasty diagnosis to make.

Perfect kidneys are at 100% function. As we talk about percent damage, keep in mind that we’re referring to the grand total sum of both kidneys. It’s possible that one kidney can be damaged more than the other, or undamaged, but we aren’t distinguishing for the purposes of this post. The end result of damage to the kidneys is that the nephrons are destroyed, leaving scar tissue where functioning kidney used to be.

Chronic renal disease en

When 2/3 of the kidneys’ functional capacity is gone, leaving only 33% working, the kidneys lose their ability to manage water balance in the body. Water is allowed to leave the bloodstream at a rate that will dehydrate the animal. This is the earliest sign of chronic kidney disease. It can be subtle. The urine will seem more dilute. Pets will begin to drink more water and pass more urine. In truth, the urine production goes up because of the inappropriate loss of water, so pets drink more to remain well-hydrated. We can detect this low urine concentration when we run a urinalysis. Sometimes, we can detect protein loss in the urine, too, which is a sign of trouble. A pet may begin losing weight.

When 3/4 of the kidneys’ functional capacity is gone, leaving only 255 working, the kidneys can no longer keep up with the removal of waste products from the blood. Byproducts of metabolism begin to build up in the bloodstream. We can detect these rising values on bloodwork, namely the serum chemistry. As these waste products rise, we begin to see effects in the animal. Appetite drops because of nausea and irritation of the stomach lining, followed by vomiting. Dehydration and weight loss occur, as well as significant loss of muscle mass. At very high levels, these wastes can directly impair brain function, too. Other effects of advancing kidney disease can include high blood pressure and anemia. Sadly, many of the pets we diagnose arrive with lots of these clinical signs.

There are lots of treatments available for renal disease, but remember that none of them are a cure. Chronic kidney disease is managed, not fixed. We lower the protein intake of a pet’s diet to decrease the waste-filtering workload of the kidney. We also keep the phosphorus low in the foods we feed to help prevent some other complex but highly damaging changes in calcium and phosphorus levels in the blood and bone. There’s an oral medicine to help with that problem as well. We can give injections of the hormone that makes red blood cells be produced. We can give fluids under the skin to help flush the wastes out through what’s left of the kidney. Some animals respond very well to these treatments. Cats tend to do better for longer periods of time than dogs. Each patient is different in terms of response to treatment and the rate the disease progresses. Some patients survive only a few months. Others can go years before we lose the fight. We manage the patient, not the numbers on the lab work, with the goal being good quality of life. The sooner we start treatment, the better most animals do!

Running lab work is the ONLY way we have to watch for the emergence of chronic kidney disease. The clinical signs that owners see are present early on, too, but they start out subtly. Most of us don’t notice a gradual change like this until it’s further along. Annual urinalysis helps us detect the changes that signal early kidney disease. Bloodwork may also show subtle signs earlier in the process, so that’s also a valuable tool.

The take home message here is this: RUN ANNUAL LABWORK ON YOUR PETS! It’s the best way we have to watch for early signs so we can begin treatment early.

Please ask questions. This is a complex disease that I could talk about for pages and pages, so I simplified the basic discussion for today. I’m happy to expand on any aspect if there’s interest!

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Cancer Diagnostics

Cancer Diagnostics

Back on August 12th, I talked a lot about cancer in veterinary patients. I didn’t cover the way we diagnose cancer, though. The process for diagnosing cancer can be quite confusing, so I’d like to take some time today to shed a little light on how we hunt for answers.

We talked about how a mass/tumor/growth is properly termed Neoplasia. Once a mass is discovered, we have to start testing the mass to find out whether it’s benign or malignant, and whether it has stayed put or has spread to other areas of the body, and how aggressive it appears to be.

Step 1 : Obtaining a Sample

In order to learn anything about a mass, we have to be able to observe the microscopic cells that make up the mass. The objective here is to discover, if possible, the tissue in which the mass started to grow. Depending on how we get a sample to observe, we may be able to accomplish the second two steps as well. We can obtain a sample in three ways.

A. Fine needle aspirate.

A needle attached to a syringe is inserted into the mass. The plunger on the syringe is pulled back to create a vacuum that sucks some cells into the needle. The cells in the needle are then gently sprayed onto a microscope slide. We use a special stain to make the cellular structures visible, then observe the sample under the microscope. This method can be performed on-site at the veterinary hospital. In some cases, a general practitioner will send the slides in for a board-certified pathologist to look at. I prefer to have a pathologist verify my observations in most cases.

B. Incisional Biopsy.

A small piece of the mass is cut out and preserved in a special fluid. We send the piece into a lab, where it is sliced into micro-thin layers. These slices are observed under the microscope. This allows a board-certified pathologist to see not only the cells, but how they are arranged, which gives clues about the structure of the mass. The drawback to this technique is that a patient may need anesthesia in order to obtain this type of sample, and we leave the rest of the mass on the patient. If the pathology report comes back as malignant, the patient will need anesthesia again to take the mass off the body. The advantage to knowing what type of malignancy we’re dealing with is that it can tell us the best way to treat the mass. This includes surgical removal or other treatments such as chemo or radiation.

C. Excisional Biopsy.

In this method, the entire mass is removed at one time. Then, the whole mass (or less commonly, a part of it) is then sent in to the lab’s pathologist. As with the incisional biopsy, the pathologist can observe the type of cells and how they are arranged. The advantage here is that we can try to get the whole mass out (leaving nothing behind on the patient) with one trip under anesthesia. However, if we don’t know the tissue type or we’re unsure about the behavior of the mass, the surgery might not get the whole mass out.

When a pathologist looks at cells to determine if a mass is malignant or benign, there is a set of specific criteria to observe in the cells. If enough of these criteria are seen, a mass is called malignant. The criteria have to do with the size, shape, and contents of the cellular structures.

Step 2 : Grading

Once we have a mass identified, and we know the tissue of origin, we have to go through a process called “Grading.” The mass has come from a specific tissue. Hopefully, we know what type of tissue we started with. Looking at the cells may give us that specific answer. However, the cells in a mass are sometimes very different in appearance than the tissue type they started in. How similar the mass cells look to their tissue of origin is the criteria for grading a mass. Higher grades mean that the cells look less and less like the tissue of origin. This is important to know because it can give us clues about how aggressively a mass will behave. It may help us make treatment decisions and shed light on the longterm prognosis for a patient. In most cases, a higher grade tumor is more difficult to treat successfully and has a worse prognosis.

Step 3 : Staging

Masses that are malignant have the potential to spread to other places in the body. That spread, or metastasis, is a very important thing to find as we determine how to treat a patient. Each stage is defined by how far the mass has spread. Lower stages mean the mass has stayed in its immediate area. Higher stages mean the mass has spread to other parts of the body, such as lymph nodes or other organs.

Step 4 : Treatment Plans

Once we know the grade and stage of a mass/cancer, we can develop an individual treatment plan for a patient. Treatment with surgery, chemo, radiation, and/or a vaccine may be used to treat a cancer patient. The grade and stage provide us useful information about the longterm prognosis for cure vs. remission, and how long remission can be expected to last.

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Labwork Part 3 – Serum Chemistry

This week we’ll dive right into the larger and more complex area of the labwork that we refer to as “serum chemistry.” If you recall from the first labwork post, we draw a sample of blood from a pet and split it into two tubes. One is for the complete blood count. The other tube allows the blood to clot. We then spin it in the centrifuge so that the liquid portion is separated from the cells. This liquid portion is called serum. As a quick side note, if you spin down unclotted blood from the purple top, the liquid portion is called plasma. Plasma contains clotting proteins. Serum does not. That’s the major difference. We utilize serum for the chem.

When the results are sent back, we get a big long list of numbers. Each particular thing we look at is named, and we’re given that particular patient’s result. The lab also lists a reference range, which is what “normal” values should be. They also give you a visual slider graph for each value. I’ve cut out a small portion of my own cat’s recent bloodwork as an example.
Labworkexample

Liver Values

Alkaline phosphatase (ALKP), Alanine aminotransferase (ALT), Aspartate aminotransferase (AST), Gamma-glutamyl transferase (GGT), and bilirubin are all markers for liver health.

We pay the most attention to ALKP and ALT as a way to see if the liver is being damaged in some way. We typically start to worry when the numbers are two to three times the normal range. ALKP and ALT increases tell us that something is hurting the liver, but they don’t really tell us if the liver’s ability to do its job is compromised. Of course, if these are sky high, we start to assume that so much damage has occurred that function is compromised as well.

Bilirubin to tells us more about the liver’s functional ability. Bilirubin is found in red blood cells, bile, and urine. The liver is responsible for recycling and excreting the bilirubin. When this value goes up, it can mean that the liver isn’t able to recycle the bilirubin the way it’s supposed to. That’s a more direct measure of liver -function-.

Because the liver does so many things, there are a LOT of reasons for liver damage. Infection, cancer, toxins, dental disease, hormone disorders, and trauma can all make these values go up.

Kidney Values

The kidneys are monitored with two main values: Blood Urea Nitrogen (BUN) and Creatinine. BUN is a waste product of the body’s use of protein. Creatinine is actually something that is formed in our muscles as a waste product. The kidney is responsible for filtering these two waste products out of the blood so they can excreted in urine.

Calcium and Phosphorus are two elements found in bone and other areas of the body. They are ingested with food and utilized in many areas. The kidneys play a part in helping the body maintain a balance of calcium and phosphorus in the blood, bone, and tissues. When the kidney isn’t functioning normally, these values can go up in the bloodstream.

The kidneys are a complex system, with lots of special rules and considerations for deciding if high BUN and Creatinine are due to a problem within or outside of the kidneys. The bottom line is that if the BUN and Creat results are high, I’m going to be looking for dehydration, kidney failure, or urinary blockage.

Protein Levels

We measure two protein levels in the serum. One is the Total Protein (TP), which looks at a combined value for many different proteins in the blood. TP is the sum of the albumin and the globulins. Albumin is a specific protein in the blood. We usually get a direct measured value for that protein. We subtract the albumin from the TP and that leaves just the globulins. Globulins are basically antibodies circulating in the bloodstream. If the TP and the Albumin are low, it means that protein is being lost from the body in some fashion. Massive wounds, kidney failure, and gastrointestinal disease are the most common reasons for low albumin. We don’t usually worry too much if albumin is a bit high. Very high globulins can be a concern, however, for things like chronic inflammation or cancer.

Electrolytes

Electrolytes are salts, chemically speaking. When these salts dissolve in the blood, the individual elements are freed to circulate on their own. We look at Sodium (Na), Potassium (K), and Chloride (Cl). These electrolytes are important for nerve impulse conduction, water balance, and muscle contraction (including the heart!). Their levels can be altered by dehydration, kidney damage, urinary blockage, hormone/endocrine diseases, and damage to muscle or blood cells. We pay attention to values that are too high or too low.

Miscellaneous Values

Glucose is more commonly known as blood sugar. Diabetes and blood infections are some of the main reasons we see glucose levels change. Head trauma, insulin overdoses, and tiny puppies/kittens that aren’t eating are some other reasons glucose can be outside the normal range.

Cholesterol

Thankfully, pets don’t have to worry about coronary artery disease the way people do. We don’t generally distinguish between ‘good’ and ‘bad’ cholesterol in pets. Sometimes, we do have to measure the serum triglycerides, but only in a small specific set of cases/diseases. That being said, if cholesterol is high, we may suspect a problem with a pet’s GI tract or thyroid gland.

Amylase and Lipase

These two values were once used as the main ways to check the pancreas for damage. They’re unreliable as indicators for pancreatic disease, though, and we have a far better test now for pancreatic damage/inflammation. Amylase may go up if the kidneys are failing but it’s far less important than the other kidney values.

A Note on Cancer Testing

One of the most common questions I get is whether we have a blood test for cancer. While we are able to sometimes detect lymphoma on the CBC, there really aren’t widely-used or well-studied blood tests for various cancers. There is a company that is offering testing to help detect cancer. The test does not specify which TYPE of cancer is present. Most of the veterinary oncologists aren’t a big fan of this test because it doesn’t tell you which type, nor where to find it in the patient. It could lead to radiographs, other bloodwork, ultrasounds, organ biopsy… and if all of that comes back normal, then what? There just hasn’t been enough work done on the effectiveness of the test for me to fully promote it. The idea has promise and merit for the future. For the time being, regular examination every 6-12 months is the best tool we have to detect changes.

As always, thanks for reading!

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Labwork Part 2 – The Complete Blood Count

Labwork Part 2 – The Complete Blood Count

This week I’m going to cover the complete blood count. The post will be divided into pages, so just click the numbers at the bottom to move to the next page!

We need to start out with an explanation of the components of blood so that we can understand what is being counted. I’m going to try to draw an imperfect analogy to cooking (or at least to a recipe) to help.

Blood is soup. It’s composed of a liquid portion — the broth — which contains water, salts (electrolytes), small proteins, and antibodies. The chunks in this particular soup are cells of various types. These cells are produced in the bone marrow from larger, more complex progenitor cells. Through a series of divisions, these larger cells are transformed into red blood cells, white blood cells, and platelets. I suppose you could consider these the vegetables in the soup. Each cell type has a specific function in the body. The forms of the cells are specialized to handle these functions. The donut-cell on the left is a Red Blood Cell. The little spiny thing in the middle is a Platelet. And the fuzzy ball on the right is a White Blood Cell. This is a scanning electron microscope picture.

Bloodcells

When we draw blood, part of the sample is put into the purple top tube. This tube prevents the blood from clotting. When we send this sample to the lab, they do two types of analysis on it.

The first is to run the blood through a special counting machine. Usually, this machine uses a laser to shine light through the cells as they pass through a very tiny tube. The effect the cells have on the light is recorded by the machine. Because the composition of the cell types differs, the machine is able to tell which type of cell has just gone through the tube. It keeps track of this and gives us a count of each type of cell. Before we had the technology to count cells with a machine, a trained individual had to look at the sample through a microscope and count the different cell types by hand. This is a picture of the laser cell concept:
Lasercytediagram

The next test that’s done on the blood is to take a drop of blood and spread it in a very thin layer on a microscope slide. This is called a blood smear. The smear is dipped in special stains to color the cells. This staining allows us to distinguish parts of the cells as well as the types of the cells more readily. In some cases, we can also identify abnormalities with the structure of the cells. This visual pathology review is still done by humans. Here is a picture of how to make a blood smear, and then a picture of what it looks like under the microscope. Notice the different types of cells that can be seen there — they differ in size, shape, and color.
Smeartechnique
Smearpicture

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Introduction to Labwork Part 1

Whether you’ve heard it called “bloodwork” or “Labwork” or “Annual Blood Screening,” it all means the same thing. We’re drawing blood from a pet and submitting it to a laboratory for analysis. I field lots of questions about labwork: what are we looking for, what does it check for, why is it important. I’d like to start a series of posts today that introduce you to the contents and interpretation of labwork in the veterinary field.

Drawing a Sample

Most everyone is familiar with a needle and syringe used to give vaccinations or other injections. This is also the most common way that we draw blood from an animal, as well. There are other ways to draw blood, but we find for veterinary patients that the needle-syringe combination works the best. (On the Human side, they use that odd little needle and sleeve thing, and the blood collection tube gets pushed up into the sleeve to fill with blood. It’s called a vacutainer.)

When we draw blood, we utilize one of a number of different sites where it’s easy to hit a vein. For people, the inside edge of the elbow is often used. In pets, depending on species, we aim for a vein that’s close enough to the surface for us to feel it. All of the fur on pets can make it very difficult to -see- the vein, so much of what we do is by touch.

The sites we prefer are: jugular vein (dogs and cats), inside of the thigh (cats), outside of the hock joint (dogs), and the vein on the lower front leg (dogs and cats). My preferred place overall is the jugular vein. It allows us to draw the required amount of blood very quickly, which means the patients don’t have to hold still for very long. This vein is also generally quite close to the surface, which means it’s easier to get the needle in the right spot. Most animals tolerate the small pick from the needle very very well. However, for patients that are too frightened to hold still this way or object to the small pick of the needle, we select a different spot.

Once the sample is drawn, we put the blood into one or more special test tubes. These tubes may contain a chemical to prevent the blood from clotting, or a special gel that helps the blood clot and then separates the various parts of the blood when the tube is spun in a centrifuge. The type of tubes that we use are determined by what which tests we need to run. The tubes have simple ‘common’ names that we use simply because they’re easy to remember. “Purple Top,” “Tiger Top,” “Serum Sep,” “Blue Top.” The colors refer to the color of the rubber stopper in the tube. Here’s a look at a couple of the tubes we use most commonly.
PurpletopTigertop

Sample Processing

All of our blood is sent to an outside lab. This lab is a veterinary-only company that processes hundreds of different types of tests. They’re able to run blood tests, bacterial cultures, urine samples, histopathology, and more. We use a special web site to log each pet into the lab system so that each patient has a unique barcode for their sample. The barcode tells the lab which tests to run for that patient’s sample. A printed form is also generated as a backup for the barcode. Samples are packaged individually in special ziplock bags with the identifying paperwork. Each tube is labeled with the patient’s name. Samples are kept at the hospital in the refrigerator until we’re finished for the day. Then, a courier comes to pick up the blood. The blood may go by car or plane to the outside lab. I believe that the closest lab to us with the company we use is Elmhurst, IL.

The lab runs the tests overnight. Most types of blood tests have results completed that night. We get the results faxed to us by about 11am the following morning. Sometimes it’s a bit earlier, sometimes it’s later. The really great part, though, is that we almost always have results within 24 hours. Certain tests take longer than that, but the routine stuff is back the next day like clockwork. This allows us to call you the following day with results. I’m very proud of the fact that we’re able to provide such quick service in our profession. I’ve waited anywhere from a week to a month to get results from my own doctor!

Interpretation

Once the results are back, they’re placed in the patient’s file and returned to the doctor for interpretation. We read over the results and investigate anything that’s out of the normal range of results. In some cases, the bloodwork is providing confirmation of a diagnosis that was made during the examination the day before. In some cases, we’re able to detect a problem that wasn’t found on the physical exam. Most importantly for healthy pets, we’re able to detect trends. For example, if an otherwise healthy dog is having a steady increase in kidney values over a 3 or 4 year period, we know that kidney health is declining for that patient. We’re able to start treatment much sooner, which leads to a better quality of life over a longer period of time. We really rely on bloodwork to help us find out the things that our patients can’t tell us because they don’t speak.

The vets (sometimes techs) call clients directly to discuss the results of any tests that were sent out. This is something that I’m also very proud of. We feel it’s important to be able to speak directly with a client, especially when results are abnormal. We’re able to explain the information gained, discuss treatment options, and schedule any necessary follow-up visits. I hope that clients feel that this is something special that sets us apart from our human medical counterparts. We’re certainly trying to provide individual, focused attention to each patient and client. We’re also happy to call to deliver good news! Normal bloodwork is a -good- thing!

Next week, I’ll start talking about the different tests and what they all mean. I hope everyone enjoy the holiday weekend!

Fireworks2010 53
I took this photo in Bay City last year for the fireworks festival. I didn’t make it up this year, unfortunately. If you ever have a chance to go to Bay City for the 4th, it’s well worth it. Easily one of the best fireworks shows I’ve seen anywhere.

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Stool Samples and Heartworm Tests

There are two topics I want to cover tonight — neither one in great depth, but more to give you an idea about what to expect when you bring your pet in for a routine visit. The staff spends quite a bit of time clearing up confusion on these topics, which tells me we’re not being particularly clear about what we’re doing. I hope the post helps clear up the confusion.

Stool Samples

When you make an appointment for a routine healthy examination (with vaccines or bloodwork), the reception staff probably reminded you to bring in a stool sample. We use the stool sample to check for intestinal parasites (primarily worms, but some other protozoan critters, too). Stool samples do not check for heartworm!

We mix the stool sample up with a very dense solution of zinc sulfate, then transfer it through a screen into a large test tube. The solution fills the tube right up to the very top. We then lay a very thin square of glass atop the tube (a cover slip). It’s held in place by the surface tension of the liquid.

Then, we spin the sample tube in the centrifuge. What this does is cause the worm eggs and some parasites to float up to the top of the tube. Centrifugation increases the success rate of detecting worms from a particular patient.

When we lift off that glass square, the eggs are pulled along with some of the solution. The square is placed on a microscope slide and then visually inspected for eggs or organisms.

We are readily able to find hookworm, roundworm, and whipworm. Some of the protozoans we see commonly are giardia (diarrhea!) and coccidia. Tapeworm eggs are generally heavier than the solution, so they sink to the bottom and are rarely collected.

Sometimes, we have to look at the bacterial population in a stool sample. In this case, only a very tiny amount of the sample is mixed with plain saline (0.9% NaCl) and observed under the microscope. This is called a direct fecal. We usually do this for patients having diarrhea or some other GI problem.

Heartworm Testing

Heartworm is a parasite that can affect many different mammals. Dogs and cats are both at risk in Michigan, no matter how little or how much time they spend outside. ( Indoor-only cats get heartworm just as often as outdoor cats! I’ll save the many other details of heartworm disease in dogs and cats for another post. )

Heartworm is transmitted to pets by the bite of a mosquito. The mosquito has heartworm larvae (babies) in its body. When it bites a pet, the larva are transferred to the pet. The larva go through some changes as they migrate from the bite to the heart and the major blood vessels going to the lungs. It can take 5-7 months for the worms to develop into full adults in the pet’s body.

We take a blood sample to look for heartworm. The heartworm test does not tell us anything about intestinal worms! We usually send samples out to the lab for testing, but in special cases we can run a test right at the hospital.

When we test for heartworm in dogs, we’re looking for signs of adult female worms. A special chemistry test is done on blood to look for a part of the female worm’s outer coat that is released into the bloodstream. Male worms will NOT cause a test to be positive. For dogs, the test is very sensitive. It’s also very accurate — there are very few false positives or false negatives. The only catch with dogs is that if the dog has been bitten in the past few days to 7 months, the test might be negative on that day, but positive later. This happens because the larva have not yet developed into adults that can be picked up by the test.

Cats have special rules, as usual. 🙂 They handle heartworm very differently than dogs. There are usually very few worms (1-3 in general), so there is a much higher possibility that there are all males, or not enough females to make a standard test turn positive. Because of the complexity of testing cats, I’ll save that for another post. Suffice to say for now that it requires more than one test and even then, you can’t always be sure.

So, just to summarize:

Poop is used to look for gastrointestinal parasites — intestinal worms and protozoans.
Blood is used to test for heartworm disease.

If you’re interested in learning more about intestinal worms — including which are transmissible to people and how that works — please check out the Companion Animal Parasite Council pages. The CDC has a ton of great information for pet owners. It’s well worth checking out.

If you’re interested in the fine details of heartworm disease, check out the American Heartworm Society web page. All of our guidelines for testing, treating, and preventing heartworm come from the AHS. They’re the leading authority on heartworm. Don’t miss the prevalence maps! Here’s a video to get you started, too.

Later this week, I’ll explain all of the different options for prevention.
IF YOU HAVEN’T STARTED YOUR PET ON HEARTWORM PREVENTION YET, YOU’RE LATE! Call us right away to set up an appointment so we can get your pet protected! Dogs will require a test before starting prevention. Cats only need to be current on their examinations to get prevention. Heartworm disease isn’t something you want to mess around with.

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Filed under infectious diseases, laboratory, preventive care