Equine Matters Spring 2019

03 Blood tests have formed part of the investigation of a large number of illnesses, diseases and injuries for a long time. The number of tests available is continuously expanding and their accuracy improving, making analysis of blood a very useful diagnostic tool. Sometimes blood results will yield a diagnosis and in other situations the information they provide helps to build an overall picture of what may be going on. Equine Matters Spring 2019 Blood tests What can we learn from a blood test? Taking blood is well tolerated by most horses and is generally a safe procedure. Alistair Todd BVSc MRCVS Kernow Farm & Equine Taking blood is well tolerated by most horses and is generally a safe procedure (Figure 1). Common uses of blood testing 1. Investigating illness Many conditions will affect red and white blood cells, or circulating chemicals and enzymes. Blood tests can help differentiate diseases with similar clinical signs, thus ruling problems in or out, and, help reach a diagnosis. 2. Monitoring response to treatment After diagnosing an illness, the response to treatment can be monitored by repeating the tests, to ensure that the condition is being treated effectively. 3. Screening normal animals Healthy animals can be screened to pick up early signs of a problem. This is particularly useful in older animals or those which may have been exposed to a contagious disease but might not yet have developed any clinical signs. 4. Pre-purchase examination (PPE) Blood samples are collected at the time of the PPE then posted and stored in a special facility for six months. If a problem such as lameness arises after purchase then the sample can be tested for a wide range of substances including pain-killing drugs and sedatives. In certain circumstances these tests may be performed immediately following the examination and it’s important to tell the vet if the results are required quickly. 5. Confirming exposure to infectious diseases Exposure to diseases such as Equine Influenza and Streptococcus equi (Strangles) can be confirmed or ruled out. Some yards will request this for new liveries prior to their arrival. Also, prior to breeding, blood tests may be necessary as certain infectious diseases are sexually transmitted and can affect mare and stallion fertility, as well as causing illness. 6. Confirming the health status of an animal before export/import Entry into many countries is dependent upon a clear disease screen. Blood tests are used to rule out serious infectious diseases and maintain the disease-free status of a country. The requirements will vary dependent on the countries involved. 7. Monitoring a patient prior to and during a general anaesthetic Bloods are often taken preoperatively as a screen to pick up any underlying disease. Blood samples can also be used to monitor parameters relating to patient safety such as oxygen and carbon dioxide levels whilst under anaesthetic. 8. Identification of banned substances. Professional equestrian competitions, including racing, monitor equine athletes for the presence of prohibited, performance enhancing drugs in the urine and blood to ensure a level playing field. Figure 1: Blood taken from a horse