We Start with Taking a Thorough History of Your Pet
The first step to finding a cause of a problem your animal companion is experiencing is to collect a thorough history, just as we do every time you bring your pet in for its annual checkup.
This is the part of the process when we ask you questions like when you first noticed the problem, how frequent it happens and others. It is so important to be honest.
If the problem appears neurologic, we will do a neurological examination. We watch how they walk, how they sit and stand, and their overall body condition. If they let us, we will look at your pet’s teeth and gums.
Sometime, our examination might be more focused if, for example, you bring you pet in for a possible ear infection. Our goal is to find anything that might help us find a cause for the symptoms you’ve seen. We are looking for clues.
Some medical issues will need other diagnostic tests like blood tests, cytology, or radiography (X-rays). As with humans, some problems will need referral to a specialty clinic for more specialized diagnostics like ultrasounds or a CT scan.
We will explain the tests we recommend and offer options as often as we can. Let’s look at some of the more common tests.
This is commonly one of the first diagnostic tests done with sick animals. The blood work typically done first includes a Complete Blood Count or CBC, a Chemistry panel and sometimes a urinalysis or UA. These tests are sometime referred to as “directional diagnostics” because we hope to get an idea of what direction we need to proceed.
The CBC looks at red blood cell levels as well as hemoglobin levels and overall size and condition of red blood cells. The CBC also looks at white blood cell levels (the white blood cell count or WBC). The total number of white blood cells (the white blood cell count) is evaluated, as well as the numbers of each type of white blood cell.
There are five different types of white blood cells that we look at with a CBC. These are neutrophils, lymphocytes, monocytes, eosinophils, and basophils. Each one is involved in different aspects of infection and inflammation. Some infections can cause the WBC to be above normal, while others can cause it to be below normal.
Many things influence the WBC. Infections, allergies and cancer, for example, can affect WBC levels. How long the process has been going on also can cause increases or decreases in the WBC. And, like red blood cells, the condition of the white blood cells is also evaluated.
A chemistry panel generally evaluates organ function but it can be used to evaluate possible infection as well. Liver function and kidney function are the first part of the chemistry panel we evaluate.
The chemistry panel can sometimes suggest problems with the endocrine system (Adrenal glands, thyroid, and pancreas) or the immune system. We can’t always determine the exact problem from the initial chemistry panel but we can often get an idea of the direction to go.
The meter we use to evaluate the complete blood count and the chemistry panel is called the “Reference range.” This is the range of any particular parameter that is considered normal for about 95% of animals of that species. That means that about 5% of animals can be slightly outside the reference range and still be considered normal.
We look at any levels that fall outside the normal reference range to determine if they are significant or not. To complicate the evaluation process a little more, some medical conditions can artificially increase or decrease certain chemistry values.
So, when we evaluate your pet’s blood work, we have to factor in all the things that you have told us as well as what we find when we examine your pet.
Urinalysis is used mostly to help evaluate function of the kidneys and bladder but it can be helpful in diagnosing diseases like diabetes, which is generally a problem with the pancreas, some blood issues and certain liver issues.
The amount of white blood cells, red blood cells, protein and several metabolic enzymes are looked at in a urinalysis. The specific gravity (density) of urine can give us an idea of the kidney’s ability to concentrate urine, which helps us evaluate kidney function.
A CBC, Chemistry panel and urinalysis will generally give us more information when evaluated together than they can alone.
There are literally hundreds of specialized blood tests that are used to look at more specific problems, test specific organ function or test for specific diseases.
For example, we might recommend doing a thyroid panel on your dog because a typical blood panel only evaluates a Total T4, which cannot determine if your dog truly has thyroid disease.
A typical blood panel might suggest thyroid problems but a diagnosis of thyroid disease in a dog can only be confirmed with a specific thyroid panel.
Some tests are very specific. A blood phenobarbital level only looks are the concentration of phenobarbital in the blood and is used for dogs on that medication. As with humans, it is generally recommended to not feed your pet for about 12 hours prior to taking blood.
Radiography, commonly referred to as “doing X-rays,” uses X-rays to give us an image of what is going on inside your pet. We take chest X-rays to evaluate your pet’s heart, lungs and surrounding structures. We take abdominal X-rays to evaluate your pet’s abdominal organs and surrounding structures. Although we do use X-rays to look for broken bones, we also commonly use them to evaluate other internal organs. X-rays cannot be used to look at the brain.
When we evaluate abdominal X-rays, for example, we look at the size, density and position of the organs of the abdomen. X-rays cannot tell us what is going on inside of organs but they can tell us if the size and position is normal or if organs appear more or less dense than usual.
We also look for signs or foreign material in the abdomen. Metal and stone are very obvious on radiographs because they are very dense. Less dense material (fabric, wood or plastic) are not dense enough to easily be seen on radiographs but sometimes we can see other things that can suggest that there might be something there.
Sometimes, we need to do what is commonly called a “Barium series,” which uses liquid barium sulfate given by mouth and a series of radiographs over several hours, to look for foreign material in the intestines or other obstructions.
If, for example, your 90 pound retriever starts vomiting and you think there might be a sock missing, we might do a barium series to help us determine if he might have eaten it. And dogs are not the only ones to swallow crazy things. Cats are known to swallow string, thread, ribbon or even Christmas tree tinsel, where ferrets have a reputation for swallowing rubber.
Ultrasound, CT scans and MRI scans generally full under the “Special imaging” category because they are not used as commonly as X-rays, though a CT scan uses X-rays and a computer to capture its image. Because the equipment to do these procedures are expensive and need specialized training to operate, they are not commonly found in general practice.
Specialty centers more commonly have and operate this type of equipment because they use them enough to justify the expense and training. If we feel this type of diagnostics would benefit your pet, we will suggest places that can do them.
An ultrasound can be used to evaluate soft tissue like abdominal organs or the heart. Ultrasound is not good at evaluating lungs or hard tissue like bone because ultrasound does not penetrate bone or air very well. A CT (computerized tomography) scan uses X-rays and a computer to create a sort of 3D image, where an MRI (magnetic resonance imaging) machine uses a strong magnetic field and a computer to generate a sort of 3D image. Although there is some overlap between a CT and MRI scan they look at the body differently.
Cytology and Biopsy
Cytology looks at the types of cells that may be involved in a problem to try to determine a cause and is generally done with a very small sample. Ear cytology, for example, looks at what might be causing an ear infection.
Urine cytology, part of a urinalysis, looks at the various cells, crystals or bacteria in a urine sample to try to determine the cause of urinary issues.
Some cytology samples are looked at in house while others are sent for a pathologist to read.
Biopsy is generally done on a larger sample than cytology. When we surgically remove a growth, lump or bump and send it to the pathologist, they process the sample to look at very thin slices of them using a microscope, looking at the cells that make up the growth to determine what the growth is. Biopsy samples are sent to the lab to be processed and evaluated by a pathologist.
An electrocardiogram, or ECG, is used to evaluate the electrical activity of the heart. It is sometimes called an EKG because it was originally developed in Germany where Cardiac is spelled with a K.
Similarly to use in people, small clips are attached to an animal’s limbs and a tracing is made, which looks very much like an ECG in people. We evaluate the size and shape of each little blip on the ECG strip and compare it to all the others.
With an ECG we can get an idea of the size and function of the upper and lower parts of the heart, see how well the electrical impulses are traveling through the heart and get an idea of any abnormalities in the rhythm. It does not tell us how efficiently the heart is beating but, like other tests, it is one piece of the puzzle when we are evaluating the heart.
An ultrasound of the heart, also called an echocardiogram, is used to “look” at the inside of the heart. With it the thickness of the walls of the heart can be evaluated, as well as all four heat valves. Heart murmurs can be evaluated and how efficiently the heart is pumping blood.
Having an echocardiogram done for animals that have heart disease is often recommended because of the amount of information it can give about the heart. As mentioned above, this would need to be done by a specialist.