Background
As veterinarians we encounter a situation that is truly unique in the medical community. We are presented with patients that are ill, but cannot tell us about their illness. We have to rely on an owner, zookeepers, etc., that care and feed these animals for important information. As a result, diagnostic tests are crucial to our diagnosis.
Luckily for most species, diagnostic tests have been refined to the point that they allow us to get a clear picture of the inner workings of animals. This has dramatically enhanced the diagnostic process, and even allowed us to check for diseases long before symptoms become apparent. Since many pets do not live long in relation to people, the ability to diagnose problems before they become firmly entrenched is an important axiom in how we care for pets at the Long Beach animal Hospital.
This page contains a short QuickTime video of an ultrasound. You will need Quicktime from www.apple.com to view it.
Routine Diagnostic Tests
Most of these tests can be performed in our in-hospital lab. This gives immediate results, keeps the costs down, and greatly adds to convenience.
Cytology
The first of these tests is cytology. This means looking at biological material under the microscope. One of the more common cytology's is to look for ear mites in discharge from ears. They are easily seen under the microscope. Most people with pets assume their dog or cat has ear mites whenever there is an ear problem. Only if we see them under the microscope can we say for sure.
There is another test we routinely perform on ear discharge, called a DiffQik. It is a special stain placed on a microscope slide that contains a small amount of discharge from the ears. It helps us determine if an ear infection is due to bacteria or yeast. This greatly enhances our ability to control the ear problem.
One of the cytology's we perform commonly is called a fine needle aspirate (FNa). a very tiny needle is inserted into the growth and a small amount of cells are aspirated into a syringe. These cells are then put on a microscope slide and sent to pathologist for analysis.
In some cases the pathologist can tell us the source of the problem. Sometimes the pathologist can give us an idea of what the problem is, and occasionally, the pathologist cannot say for sure what the problem is. Since the test is simple to perform, relatively inexpensive, and can be performed without any anesthesia, it is well worth utilizing. In some cases, particularly if the report tells us the mass might be malignant, we know that we need to remove all of the tumor when surgery is performed.
This is a typical skin growth where a fine needle aspirate is utilized. It is from the flank of a Boston Terrier. As you can see it is small, although that does not necessarily mean it is not cancerous.
A fine needle aspirate was performed on the mass and it was found to be a mast cell tumor. This told us that we should perform surgery to remove the whole mass because of its potential for malignancy.
Skin Scraping
Skin disease is the number one problem presented to us. Even though allergies are the most common cause, pets can also get parasites (called ectoparasites) that cause skin problems. These parasites are almost always microscopic in size, and are diagnosed with a skin scraping.
In this test a small amount of skin is scraped as if shaving an area. Since some of the parasites burrow into the outer layers of the skin, the scraping has to be done deep enough to cause a minor amount of irritation. The discharge is looked at under the microscope for either the parasite itself or eggs of the parasite. We have pages on sarcoptic mange and demodectic mange, the two ectoparasites commonly diagnosed with a skin scraping.
Fecal analysis
A fecal exam for worms (internal parasites) is a test we perform many times each day. Again, the microscope comes into play. Some fresh feces is placed on a slide that already has sterile saline on it. What we are looking for is the egg of the parasite, not the actual parasite, since the parasite resides in the stomach and intestines, and usually does not come out in the feces (tapeworms and the occasional roundworm are an exception). This is called a direct smear.
To further enhance our ability to find these eggs we use a technique called fecal flotation. Taking another sample of fresh feces, we put it into a solution that causes all of the eggs (sometimes with the exception of tapeworm eggs) to float to the top. These eggs are then collected with a cover slip and placed on a slide for analysis under the microscope. In both the direct smear and fecal flotation techniques finding these eggs is a hit or miss approach, and all depends on whether or not the individual female parasite is releasing eggs at the time of the sample. This means that a negative fecal report does not guarantee our pet is free of internal parasites. If we suspect them, we will recheck the fecal sample, sometimes several times. By rechecking we increase the chance that we will be analyzing a sample in which the female parasite residing in the digestive tract is actually releasing eggs into the environment through the feces.
Blood Panel
A crucial set of tests to determine if an animal is ill is a blood panel. This panel gives us an indication of a pets internal health, and allows us to monitor disease processes and their treatments. It must be understood that each individual lab has its own set of normal values, which are based on that old bell shaped statical curve we all learned to love (and hate) in school. as a general summary, if one of your pets values falls outside of the range for this lab, it does not necessarily mean there is something wrong with your pet on that specific test. also, it is necessary to follow the blood panel over a series of time to see which direction the trends are following. Finally, we do not interpret blood panels by themselves, we use all of the information available to us in regards to the diagnostic process.
The first part of the blood panel is called a CBC, which stands for complete blood count. It is a measure of an animals white blood cells (WBC's) and red blood cells (RBC's). In measuring the RBC's we are looking for a low count, called anemia, and a high count, called polycythemia. Of the two, anemia is much more common, so we will base our explanation on this problem only. also, anemia is not a disease, it is a potential sign of a disease.
The RBC's are measured with 3 different tests. These are the RBC count, hematocrit, and hemoglobin. The RBC's are counted with a machine that gives us an actual number, usually in the millions per cc. Hematocrit is a percent of the red blood cells in the serum, usually near 45% (this varies tremendously with the species). Finally the amount of hemoglobin is determined. all 3 numbers are used in a determination of anemia. If anemia is present, other tests are used to determine if the anemia is regenerative or non-regenerative. In regenerative anemia's the body is making more red blood cells to make up for the anemia, in non-regenerative it is not. This is an important point from the diagnostic point of view because certain diseases tend to be one or the other.
The other part of the CBC is the analysis of the white blood cells, and is closely tied to the immune system. The total number of WBC's are noted, giving us an overall indication if a problem might exist. an elevated WBC count can be caused by inflammation, infection, or cancer. A low WBC count can be caused by a virus, an immunosuppressive disease, or a problem with the bone marrow. After the total WBC is determined the WBC's are broken down into their different types. These different types all have unique functions in the normal processes of the body. Changes in the amounts of these different types, whether or not the WBC count is normal, high, or low, also gives us important information.
The next part of the blood panel is called the chemistry panel (chem panel), also called the biochemistry panel (bcp). It tends to leave the white and red blood cells alone, and focuses more on the internal organs (although the two are closely related and not easily distinguished in this way-but that's the art of medicine). It is an automated test that checks many biological functions whether they are helpful in diagnosis or not. In some species, even though the tests are included in the chem panel, they might be useless in determining whether a pet has a disease or not. a good example of this is the kidney function test called BUN (blood urea nitrogen). This test is critical in diagnosing kidney problems in mammals (including humanoids), but is useless in birds and reptiles.
In general, the chem panel checks internal organs like the liver and kidneys. It also checks the general health of the body by measuring parameters like protein, glucose, and calcium. Interpretation of problems in the chem panel is very complex, and must be interpreted in conjunction with the other parameters of the diagnostic process.
Some of the tests in the chem panel measure internal organs directly, while others measure them indirectly. These tests are interpreted in conjunction with the CBC since the two are so closely related. For example, if a pet has anemia, and the liver tests are significantly elevated, all other things being equal, it is probable that the anemia is caused by a liver problem. It is not this simple though, because an anemic pet with normal liver tests can still have a liver problem as the cause of the anemia. Obviously, a normal chem panel is highly advantageous, although it is no guarantee that a pet is disease free.
We routinely perform 2 different blood panels. The first, called the pre anesthetic blood panel, is performed in our hospital. The second, called the Standard Blood Panel, is sent to our outside lab:
In House Pre anesthetic Blood Sample
This blood sample is performed in our own hospital's laboratory. From the time we take the sample until we get results is less than 30 minutes. It is used for young pets, apparently healthy pets, and for routine surgeries like spays, neuters, and declaws.
Organs that are important for the metabolism of the anesthesia we will be administering are targeted. Five specific areas are monitored:
Red blood cells (RBC's) to check for anemia, proper oxygen carrying capacity of the red blood cells, and adequate clotting.
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White blood cells (WBC's) to look for signs of infection, inflammation, or cancer
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A protein test to check for dehydration, overall health status, and to help assess the liver
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A specific kidney test to check for proper kidney function
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A specific liver test to check for proper liver function
To run these tests we take less than a teaspoonful of blood from your pet. This blood is put into 2 separate test tubes for analysis. The first set of tests is performed with our QBC machine, the second set with our serum chemistry analyzer.
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This is the first tube we put some of your pets blood into. It contains 1 ml of whole blood, the equivalent to 1/5th of a teaspoon.
It is called a lavender top tube because it has chemicals (Ca EDTa) in it to prevent clotting of the RBC's. If the RBC's clot, we cannot count them.
The unclotted RBC's are siphoned from the lavender top tube and placed into a special tube that is used by our QBC machine. |
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The tube filled with blood is spun down in a special centrifuge to reveal these bands. These bands are used by the QBC machine to count the RBC's and WBC's. |
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The special tube is placed in our QBC machine. The process of analyzing your pets RBC's and WBC's is automated by this machine. The end result is greater accuracy and speed. The report is printed out, analyzed by the surgeon, and placed in the medical record. |
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This is an actual report from our QBC machine.
The 48.3 is a measurement of the percent of RBC's in the blood stream.
The 345 is a measurement of the platelets.
The 10.1 is a measurement of how many WBC's are present in the bloodstream.
The other numbers break down the WBC's into different components and gives us information on the duration of infection (if there is an infection), the type of infection, and if there are any other problems besides infection or inflammation. |
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This is the other tube the original blood sample is placed in. This blood clots, allowing us to analyze the serum. This tube is called a serum separator tube because it separates the serum from the RBC's when placed in a high speed centrifuge. |
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This is what the serum separator tube looks like after 5 minutes in the high speed centrifuge. There are 3 distinct bands visible. at the very bottom are the clotted RBC's, above that is the separator between the RBC's and the serum, and the fluid that remains on the top is the serum. |
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The serum that remains is placed into a special pipette and put into our VetTest machine. The VetTest checks what are called "serum chemistries". These are specific compounds in your pets serum that gives us a clue to the function of internal organs. They are similar to the chem panel described above. |
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For our pre anesthetic blood samples we check the aLT (alanyl amino transferase) for liver problems, and CREaT (creatinine) for kidney problems. We picked these two tests because of the importance of the kidney and liver in the metabolism of the anesthetic we will be giving. |
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This is the report that is printed out. as you can see, this pet passed with flying colors. Its ALT was 33 (the normal range for this species is 0-77) and its CREAT is .97 (normal is .4-1.5). |
Standard Blood Panel
The standard blood panel, made up of a CBC (complete blood count) and BCP (biochemical profile), is a thorough test of many of your pet's internal functions. It is much more thorough than the in house pre anesthetic blood panel, and consists of over 40 different parameters of internal health. Our standard blood panel routines includes a thyroid test, along with a heartworm test in dogs, and FeLV and FIV tests in cats.
This blood panel is used for pets that seem ill, for older (geriatric) pets, for pets that have a problem discovered during an exam, or when your doctor feels he or she needs a blood panel that is more thorough than the in house pre anesthetic blood panel. In general, this test is one of the most important ones your doctor can order because it gives us a large amount of information regarding your pet's internal status.
It is sent to one of our outside laboratories that maintain a high level of quality control by using highly automated and advanced laboratory equipment. The results of any blood panel submitted to this lab are faxed to us within 12-24 hours in most cases.
Urinalysis
This test is used in conjunction with the standard blood panel. Its main goal is to assess the urinary tract (kidneys, ureters, and urinary bladder).
It checks for inflammation, infection, specific diseases (sugar diabetes), and kidney function. It is obtained in our hospital and sent to the same lab that does our standard blood panel. The results are also available within 12-24 hours.
EKG
An electrocardiogram monitors the minute electrical activity within the heart. This sequenced electrical activity is what allows the heart to beat in a rhythmic way and continuously pump blood to all cells in the body. The electrocardiogram can help diagnose a heart that is having a problem but appears normal during a physical exam. We have substantial more information on EKG's in our heart page.
It is a painless procedure (the pain is for us trying to keep wiggly pets still for the 5 minutes it takes to obtain a reading) that is obtained with our EKG machine. The results are read by a veterinary cardiologist and are available within 24 hours. We are able to get a consultation with a cardiologist for the price of a routine EKG!
We use a special instrument that converts the electrical activity into sounds that are transmitted over the telephone to a cardiologist.
It is printed out for a permanent record and for analysis by a cardiologist. For routine pre anesthetic EKG's, the cardiologist faxes the report back within 1 hour, therefore the test can be performed just prior to anesthesia to increase its relevancy.
X-rays
The people that developed radiology many years ago are true geniuses. The ability to take a peak into the internal anatomy of a living organism using x-rays was a watershed in the diagnostic process. Over the years this has been refined to the point that it is a normal part of diagnostic testing. Simply put, x-rays are able to penetrate the body cavity to varying degrees. This depends on how strong the x-ray is, how much time it is given to penetrate the body, how sensitive the x-ray film is, and how dense the body part being x-rayed.
Radiographs are taken in our Radiology Department. Radiographs are a very safe test that will cause no discomfort or harm to your pet. This is because you cannot feel an x-ray, along with the fact that negligible radiation is used because of the precision of our x-ray machine and the sensitivity of the x-ray film. all radiation is continuously monitored.
Our machine is inspected every 3 years and certified by the state of California be safe. all staff members wear lead shields and gloves, along with badges that monitor their exposure levels. Even after years of this exposure there is negligible radiation due to the minor amount of x-ray power needed with today's highly sensitive x-ray film.
There are 5 different radiographic densities. With the exception of air, these densities appear as different shades of white:
1. Air- this appears black on a radiograph, and is commonly seen in the lungs and as gas in the intestines.
2. Fat- this appears white, and is usually found in the abdomen and under the skin.
3. Soft tissue- this also appears white, and consists of internal organs like the liver, kidney, and intestines.
4. Bone- it appears whiter than the above radiographic densities.
5. Metal - it appears a vivid white. a typical example is lead.
One of the densities, called soft tissue, can be difficult to visualize if not surrounded by fat. This occurs in young animals due to a lack of abdominal fat, and in older animals that are emaciated by a chronic disease like cancer that has caused them to lose their abdominal fat stores. It is also difficult to see soft tissue densities in an animal that has fluid in the abdomen, since the fluid obscures the distinct margins between organs.
This chest radiograph shows four of the densities described above. Can you visualize all four of them? The only missing density is metallic.
Metallic density is easy to spot in this dog that was shot in the front legs with a bullet. In this case the metallic density is lead.
Many diseases are diagnosed using radiology. a common one that we are all familiar with is broken bones. These are relatively easy to diagnose and are easy to show clients. Many other diseases are diagnosed with radiology, although some of the radiographic changes can be subtle and are open to interpretation. also, some organs can only be accurately diagnosed if dye is injected into them. This dye radiograph is called a myelogram for the spinal cord, and an intravenous pyelogram for the kidneys. In these cases we enlist the aid of a specialist, called a radiologist. These are veterinarians that have graduated from veterinary school and continued their education in just this one area for an additional 5 years. If they pass a special test they are board certified, and truly specialists in radiography.
Results are usually available the day the radiograph is taken. On occasion, due to unusual findings or complex situations, we request the opinion of a veterinary radiologist. Depending on the circumstances, these results are usually available within several days
Here is our radiologist, Dr. Craychee, interpreting one of our radiographs during rounds.
If you would like to learn how to read an x-ray follow the link.
For specialized radiographs and dental radiographs we have a dental x-ray machine.
Ultrasound
When a significant disease process is present we occasionally need the help of an ultrasound. This is the use of sound waves instead of x-rays to look at the internal organs. It is used only when one of our doctors deems it is necessary. It allows us to look at an internal organ in ways x-rays cannot, and even allows us to biopsy these organs using a small biopsy needle during the ultrasound process. We have a page that shows how ultrasound is used and how this biopsy is obtained.
Most of us would probably agree that a poke with a needle like this in our abdomen is preferable to the long incision needed during an exploratory surgery.
This test must be arranged in advance since we call in a specialist to perform the test in our hospital.
Ultrasounds are especially important in some heart diseases. an ultrasound of the heart is called an echocardiogram. It is very useful for pets that have significant dental disease because it assesses the heart valves that are commonly injured due to bacterial infection. Our heart page has more information on echocardiograms.
In this ultrasound picture of a small dog, we are looking at the liver and the heart. The abbreviations of the heart are:
LV-left ventricle RV-right ventricle La-Left atrium aOR-aorta
Here is a short movie showing an echocardiogram of the heart of a dog. You can see the valves moving towards the top of the picture. Below the valves, towards the middle of the picture, is a color rendition of how the blood is flowing through the heart chambers. You need Quicktime on your computer to view this movie. Double click on the movie to get it to play.
MRI (Magnetic Resonance Imaging)
A relatively new diagnostic modality of increasing importance in veterinary medicine is MRI. It involves the use of magnetic fields to look at the internal organs. It is particularly useful in neurologic diseases and for the diagnosis of problems in the brain.
An MRI takes small "slices" of the brain and looks at them individually. By doing this in a sequential fashion it is able to view the whole brain from front to back.
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