A bodily fluid that circulates in the vascular system and supports the function of organs and tissues by supplying them with oxygen and nutrients as well as removing metabolic waste. Blood consists of a fluid component (plasma) and a cellular component (red and white blood cells, platelets).

A blood clot is the product of blood coagulation which is a mechanism whereby in case of an injury to a blood vessel, greater blood loss can be prevented. A network of fibrin, platelets and red blood cells fill the opening in the damaged vessel. Disorders of the blood clotting system can lead to an increased risk of bleeding on the one hand (reduced activity) or to the risk of a 'spontaneous' clot (thrombus) forming within an undamaged vessel (obstructive clotting or thrombosis).

Blood that is saturated with oxygen that is being carried from the lungs to tissue. As its name suggests, arterial blood is generally found in blood vessels known as arteries, between the lungs and the heart it is in the pulmonary vein. Due to its high oxygen content, it is bright red in colour.

Blood with a low oxygen content and high carbon dioxide content that is on its way back from tissue towards the heart and the lungs. Between peripheral tissue and the lungs, it is found in the veins, between the heart and the lungs in the pulmonary artery. The low oxygen content make it dark red in colour.

Venous blood is sampled for most medical blood tests. Typically, the easily accessible jugular vein is used for obtaining a blood sample.

The withdrawal of blood from the body as a form of therapy. Blood, sometimes in large quantities, is drawn through a phlenotomy incision (an opening in a vein, these days with a large gauge needle, historically with a special phlenotomy knife), with the aim of curing or preventing a disease. This was/is performed mainly in cases of acutelaminitis.

A type of horse that is of a medium build. Most riding and sport horse breeds are Warmbloods. There are over 100 breeds worldwide that can be described as a Warmblood type. The expression 'Warmbloods' originates from the Anglo-French usage of this term to differentiate the light riding horse breeds from the even lighter 'Hotbloods' (Thoroughbreds and Arabs) and the heavier 'Coldbloods' (heavy draught breeds).

Also known as leukocytes. Cells of the immune system, which are mainly present in the blood and the lymph, and originate in the blood marrow. There are several types of white blood cells (WBC) which have different functions: antibody production, recognition and destruction of pathogens, release of histamin. If a horse suffers from an infection, the number of WBCs in its blood will increase to fight the pathogen. In blood tests, the WBC count is therefore an important measure for infection and the detected types of WBC can give information about the pathogen the horse is dealing with, as some of them are very specific. Unlike red blood cells, WBCs have a cell nucleus but do not contain haemoglobin, hence the name.

A cell type which is found predominantly in blood, in bone marrow, in lymphatic tissue and to a lesser extent in all other body tissue. They are an important part of the immune system and are involved in defending the body against infectious disease and foreign substances.

Heavy draught horses are refered to as cold blooded due to their docile temperament. They are generally heavier than warmblood horses and can reach bodyweights in excess of 1000 kg.

Red blood cells are the most common cells in the body, they form the main part of the cellular component of blood. They are responsible for the transportation of oxygen around the body.

Surgical incision of a vein to remove a thrombus (blood clot) or insert a special catheter. Also used to refer to the puncturing a vein to draw blood (venipuncture) or to the process of blood letting.