Often when we are in the process of investigating a patient’s illness, we may recommend to you that we perform blood tests to help us in reaching a diagnosis. In veterinary practice many of the tests that are available to us are much like the ones you would be familiar with from your own experiences with medical practitioners. One of the most common blood tests we recommend is a Pre-Anaesthetic Profile (PAP).
This gives us information on the status of the patient’s red cells, blood protein level, liver enzymes, kidney enzymes, blood glucose and electrolyte levels. These tests can provide information which can sometimes be vital to ensuring the best possible outcome from the animal’s anaesthetic procedure. We recommend a PAP for any animal undergoing anaesthesia, and particularly for any over 6 years of age. Even in young, apparently healthy, animals it is not uncommon for us to detect a significant problem when we perform a PAP, for example prior to desexing. Often such problems have a far better outcome in the long run when they are detected early by routine screening.
In some cases, especially in animals older than ten, we strongly recommend expanding the PAP to a complete blood count (CBC) and biochemistry analysis (Body Function Profile). In addition to the information gained from a PAP, this gives us more complete information about the number and type of white cells present, more detailed information on the red cells, and an expanded number of tests for the function of your pet’s internal organs. This test is also commonly performed when we are trying to establish a diagnosis in animals with a metabolic illness. In aged animals we may recommend what we call a Geriatric Profile.
This tests for any dysfunction in the most important organs which can undergo degenerative change as our pets age. We perform PAP and FBC tests on a daily basis, and the tests are run in-house, so we are in the fortunate position of having access to the results very rapidly. In addition, there are a number of other blood tests which we perform on less frequently. If, for example, when running a routine screening test we detect anaemia, we may run more detailed examinations of the red blood cells to try to determine what the underlying cause may be. If in a FBC we detect elevation of the enzymes associated with the pancreas, we may elect to run a test which is very specific for confirming or ruling out pancreatitis. In dogs we may test for the presence of heartworm infection, and in cats for the presence of feline leukaemia virus and feline immunodeficiency virus infections. Blood tests can also indicate the presence of infection with organisms such as Cryptococcus and Toxoplasma.
Cats and dogs who are diabetic need to have the degree of control achieved by their insulin injections monitored on an ongoing basis, and will frequently be admitted to hospital so we can test their glucose levels several times throughout the day. Some diabetic animals, in particular cats, may also need to have another single blood test called fructosamine, which measures the degree of control of blood glucose levels that has been achieved over the preceding weeks.
Sometimes we need to perform what are called “challenge” blood tests. This is where we measure the level of a particular chemical, eg cortisol, in the blood stream, both prior to and a given period after the injection of a substance which is designed to stimulate that chemical. This type of test is for example used in the diagnosis and monitoring of dogs with Cushing’s disease (hyperadrenocorticism). Dogs, like humans, may suffer from epilepsy, and need to go onto the same types of medications which are prescribed for epileptic people. We often take blood samples to ensure that the right dosage of the drug for that particular patient is being used. Similar blood tests are done for dogs who are on tablet supplementation for hypothyroidism (an under-active thyroid gland).
Cats, on the other hand, tend to suffer from hyperthyroidism (an over-active thyroid gland), especially when they are aged, and a blood test can determine if there is too much thyroid hormone circulating in their system.Blood tests are of course only one part of the tools we have available in our clinical pathology armoury. Along with tests on faeces, urine, cytology and histopathology, and with the aid of other diagnostic tools such as radiology, ultrasound and nuclear medicine, it’s rare that we are unable to get to the bottom of a pet’s medical problem. Our vets are always available to you to explain the importance of any particular test we recommend, and the significance of your pet’s results. With owners and veterinary staff working together, the best possible outcome can be achieved for our animal friends.