Common Diagnostic Tests in Small Animal Veterinary Medicine


Common Diagnostic Tests in Small Animal Veterinary Medicine

In veterinary medicine, we use many different tests to help us care for our patients. Some of these tests are used for screening healthy patients, and others are used to help diagnose sick patients. Oftentimes, the same test can be used for multiple purposes. Your veterinarian may suggest one or more of these tests at different times for your pet. Below are explanations of common diagnostic tests we run in small animal medicine, what they involve, and some examples of why your veterinarian may recommend them. This is not a comprehensive list of tests or rationale, but rather an overview of some of the most common diagnostics. Each patient is unique, and will require a unique approach. However, with a clear understanding of recommended diagnostics, you will best be able to partner with your veterinarian in decision-making and care for your pet.


Most of the blood tests we run require only a fairly small blood sample. Blood draws are usually quick, and can be performed with minimal stress to an awake patient. Depending on your pet’s needs, blood tests may be run in the hospital (“in-house”), or sent out to a reference laboratory.

Image result for blood test imagesComplete Blood Cell Count (CBC)

The CBC is a blood test which gives us information about the blood cells circulating in your pet’s body. The results tell us about the number, size, and character of red blood cells in the body, which can alert us to things like blood loss or decreased production. We also get information about white blood cells, which help us identify things like infection or inflammation. A platelet count gives information about clotting activity. A CBC may be run as a screening test on a healthy pet (such as before surgery or as an annual check on an older animal). It may also be run on a sick patient to help diagnose disease or injury, or to monitor progress. Pets who

Figure Annual blood tests are recommended for dogs and cats who are in their senior years. Early indicators of disease can often be detected in the blood. When detected early, your pet can begin medication or treatment which can enhance their quality of life.

are being treated with certain medications may require regular CBC checks. A CBC can help a veterinarian assess the status of a pet with a chronic disease, as well. In some cases, a pet will require multiple CBCs. This allows the veterinarian to evaluate changes or trends.

General Chemistry Profile (or General Health Profile or Internal Organ Function Screen)

This blood panel may also be run in-house or at a reference laboratory. It gives us important information about the health and function of several organs in the body. Among other things, the chemistry profile will help your veterinarian evaluate your pet’s liver and kidney function, as well as blood sugar level and blood calcium level. Like the CBC, this panel may be run to screen a healthy pet, or before surgery or beginning certain medications. It can be used to help diagnose diseases (such as organ disease or diabetes) and provide clues to help diagnose hormonal diseases or certain cancers. Pets with certain diseases or on specific medications may require regular chemistry panels in order to monitor their progress.

Thyroid Panel

Some animals have inappropriate levels of thyroid hormone circulating in their body, which can affect their metabolism and other body functions. In dogs, we worry about this value being too low. In cats, we worry about it being too high. With a simple blood test, we can determine whether or not an animal’s values fall within normal range. If your pet has abnormal levels accompanied by clinical signs, your veterinarian will discuss treatment options.

Image result for 4dx blood test image

The 4DX test is another tool which helps your veterinarian screen for infections such as Lyme and Heartworm which are transmitted by ticks and mosquitoes. By keeping your pet on preventatives YEAR ROUND, you can avoid potentially deadly infections such as these.


This simple blood test checks for 3 different diseases carried by ticks (Lyme, Ehrlichia, and Anaplasma), as well as heartworm disease. It only requires a few drops of blood, and can be run quickly in-house. It may be run as screening for a healthy pet, or to help diagnose a pet showing clinical signs such as lameness or lethargy.


Imaging tests allow us to visualize internal parts of the body. They are not at all painful to the patient, though in some cases the pet may be sedated in order to minimize anxiety and to allow us to capture the best (and most helpful) images. There are many potential reasons to perform imaging; a few of the most common are discussed here.

Image result for positioning a dog for thoracic x ray

Thoracic Radiographs (Chest X-Rays)

Radiographs use x-ray beams to obtain images of structures inside your pet’s body. Thoracic radiographs, or chest x-rays, are most often used to evaluate the heart and lungs. This is particularly important in cases of heart disease and respiratory disease. Your veterinarian will look for fluid in or around the heart or lungs. These images may be taken if there is a concern regarding pneumonia, or if your veterinarian needs to rule out or monitor tumors in the lungs. These radiographs also provide important information regarding bony structures in the upper part of the body, such as the spine and ribs.

Image result for positioning a dog for chest x ray


Abdominal Radiographs

This test reveals images of the structures inside the belly, such as the stomach, intestines, liver, kidneys, spleen, and urinary bladder. This test may be recommended if your vet is concerned about a foreign body (when your pet has ingested an object it shouldn’t). It is also helpful in evaluating the size of these organs, and evaluating for masses that should not be there. Stones in the urinary tract may be revealed by radiographs. These images also include important information about the hips and lower spine.

Abdominal X Ray offers an inside view of key organs in the abdominal cavity.

Image result for dental x ray animals

Dental Radiographs

Radiographs are an important part of your pet’s annual dental exam and cleaning, as much of the disease in a pet’s mouth occurs below the gum line, where we cannot see it with the naked eye. These types of radiographs are taken when the pet is under anesthesia (usually during a dental procedure), and help a veterinarian determine the best course of action for each particular tooth. They are also used to evaluate the health of the jaws.


Image result for positioning a dog for chest x ray

Limb or Joint Radiographs

These images give us information about bony structures in the body, and allow us to draw conclusions about certain soft tissue structures such as ligaments. They may be used to identify fractures, arthritic changes, and tumors.

Canine Pelvic X Ray

Abdominal Ultrasound

Related imageUltrasounds use sound waves to obtain images. An abdominal ultrasound allows us to visualize organs in the belly, as well as lymph nodes and blood vessels. It is much more sensitive than a radiograph in evaluating certain changes in these organs (meaning we can see more, and therefore gather more information). It is often used in cases of chronic or nonresponsive gastrointestinal signs, to rule out or monitor certain types of cancer, and to better diagnose organ disease.

Ultrasound is a non-invasive imaging tool used to diagnose organ disease among other things. Ultrasound provides the veterinarian with a more detailed image of what’s happening inside the animal’s body. Ultrasound can be performed on various parts of the body.


The evaluation of cells under a microscope is called a cytology. These tests are extremely helpful in characterizing tissue and fluid from a pet’s body.

Fine Needle Aspirate (FNA) with Cytology

Image result for cytology If there is a lump on your pet’s body, your veterinarian may recommend an FNA and cytology to better characterize what types of cells make up the mass. Your veterinarian will use a needle to aspirate (suck up) some cells, and they will be put on a microscope slide for evaluation. This test may be used to help determine if a mass is benign, cancerous, or related to infection or inflammation.

Malignant cancer cell

Urinalysis (UA)

A simple urine sample can help tell us a lot about your pet’s body. A urinalysis reveals how concentrated a pet’s urine is, which gives information about kidney function. We also look for the presence of red blood cells, white blood cells, cells that line the urinary bladder, bacteria, and crystals. These cells may tell us if there is an infection in the urinary tract. A pet exhibiting abnormal urination behavior will likely need a urinalysis. This test will also be recommended as screening for pets who are particularly susceptible to urinary tract infections, such as those with kidney disease or dogs with Cushing’s disease. Urine samples can be collected via various methods. A free catch (non-sterile) sample can be easily collected in a clean container at home or in the hospital. In the hospital, we can obtain sterile samples via urinary catheterization or cystocentesis. A cystocentesis refers to the procedure of using a needle and syringe to collect urine directly from the bladder. This procedure is actually quite quick and only minimally uncomfortable to the patient.

Ear or Skin Cytology

Related image If your veterinarian suspects an ear or skin infection, a cytology may be advised. A sample is collected from the affected area, and evaluated under the microscope for the presence of yeast, bacteria, or inflammatory cells. This will help guide treatment. It may also be used to recheck the site of a previous infection to evaluate progress. A skin cytology may also be used to evaluate for cancerous cells.

Ear swabs can be examined for the presence of mites, yeast or bacterial infection.


Related imageUrine Culture and Sensitivity: A urine culture involves a sterile urine sample being sent to a reference laboratory. This test identifies exactly which strains of bacteria are present in the urine, and which antibiotics are most likely to be effective against them. This test is usually performed in patients with recurrent urinary tract infections or underlying disease processes.

Fecal Float: A small sample of your pet’s stool is evaluated for the presence of intestinal parasite eggs. Intestinal parasites may cause signs like diarrhea, vomiting, or inability to gain weight appropriately. In other pets, these parasites may be present but undetected until they are identified on a fecal float. Some parasites are transmissible to humans, which makes it particularly important that they be identified and treated. Fecal floats are recommended as screening for dogs and cats, and may also be recommended in cases where a pet is exhibiting GI signs.

Ear or skin culture:

Similarly, this test involves a sample from infected skin or ears and is sent to a reference laboratory, where exact strains of bacteria are identified.

This can be very important in choosing effective treatment for recurrent or non-responsive infections.

As veterinarians, we are passionate not just about our patients’ care, but also about our clients! We want to be sure that you fully understand and are on board with the recommendations we make.

We love to educate clients about all aspects of animal health, and why we do what we do. If you have questions about your veterinarian’s recommendations, please ask! We are happy to explain each step of your pet’s care.