Equine sampling

- Blood diagnostic tests

1-     Hematology

                 This type of test examines the cells in the blood which are divided into red blood cells, white blood cells and platelets. Information on how many cells, their size and any apparent abnormalities in the cells. Additionally, the different subtypes of white blood cells are counted including neutrophils, lymphocytes, monocytes eosinophils and basophils.  

2-     Biochemistry

                    There are many chemical substances that circulate in the blood stream that can be used to indicate damage or disease in various organs as follow:

a)     When we see higher concentrations of certain biochemical markers in the blood, it may indicate that the liver cells for example have been damaged and have released their contents into the blood stream (such as ALT, AST and ALP).

b)     Some enzymes such as CK should be located within muscle cells and therefore a high level in the blood stream indicates damage to muscle cells.  

c)      Chemicals if found in the blood can imply that certain organs are not functioning correctly.  For example, the kidneys should remove creatinine and urea from the blood stream and therefore higher levels suggest that kidney function is impaired.

d)      The higher levels of bilirubin and bile acids indicate that the liver is not fully functional.  

3-     Serology

-        Serology is the measurement of antibody levels in the blood stream.   Serology testing can be confusing as it is one type of test where a positive result doesn’t necessarily mean that the horse has the disease, and a negative result does not rule out the disease!

-        It is perfectly possible to have a positive result (a high antibody level) due to exposure to a disease several years previously from which the horse has now recovered. Additionally, it takes a couple of weeks or so to develop an antibody response and so a horse that has been exposed to an infectious disease within the last week may well still test negative.   

4-     Endocrinology

                 This refers to measurement of hormone levels in the blood, for example Equine Metabolic Syndrome is a further condition making horses and ponies prone to laminitis. often in association with being overweight and inactive. This is usually diagnosed and investigated via measurement of the hormones for example insulin and adiponectin which both indicate increased laminitis risk.

5-     Blood parasites

 Infected horses can be identified by demonstrating the parasites in stained blood or organ smears during the acute phase of the disease. Romanovsky-type staining methods, such as Giemsa, give the best results. In carrier animals, low parasitaemias make it extremely difficult to detect parasites, especially in the case of B. caballi infections, although they

may sometimes be demonstrated by using a thick blood smear technique.

Procedure of blood collection:

1.     Personal Protective Equipment (PPE) and Hygiene. Ensure appropriate PPE is used to protect handler from accidental injury or exposure to blood and other body fluids.

2.     Restrain animal

3.     Clip (optional) and swipe with antiseptic gauze to remove superficial dirt and debris. This may also assist in visualizing raised vein.

4.     Occlude jugular vein by applying pressure in the jugular groove 2-3 inches below venipuncture site and visualize raised vein.

5.     With bevel up, insert needle firmly and smoothly (don’t jab) through the skin and into the vein at 20°angle.

6.      When using needle and syringe, break the seal on the syringe by gently pulling back before use.

7.     If using vacutainer, once needle inserted, stabilize needle and push the vacutainer tube into hub. If you have hit the vein, blood will flow freely into tube. Multiple tubes can be filled by removing filled tube and replacing with fresh tube.

8.     Serial samples can be taken by alternating sides, and by moving insertion sites cranially, as long as there is no hematoma formation.

Potential Adverse Effects of blood collection

a. Hematoma or thrombus

b. Pain at blood collection site

 c. Infection at blood collection site Ch. by:

1.     Heat, pain, swelling first noted at the insertion site of the blood draw, purulent material draining from the insertion site.

2.     Induration (hardening) of the vessel.

3.     Pyrexia, local or systemic infections, septic shock.