BLOOD ISSUES – PART 2 – ANAEMIA

Most trainers have had a greyhound that has had the classical signs, or been diagnosed, with anaemia.
Anaemia is not a disease as such, but an indicator of an underlying disease process that leads to a loss, depletion, or inadequate generation of red blood cells or the haemoglobin within the cells.
Common Causes
Characteristically, greyhounds are more likely to develop anaemia than horse or human athletes.
Greyhounds are more likely to be fed diets low in blood forming nutrients, are prone to chronic blood loss due to microhaemorrhages from damaged gut wall due to heavy hookworm burdens, or high numbers of blood sucking fleas.
Studies have shown that an adult hookworm can consume 0.2mL of blood each day.
A heavy infestation of 100 or more hookworms can remove 20mL or more of blood daily.
A racing greyhound only contains 2 litres of red blood cells.  A daily loss of this volume of red cells can significantly reduce numbers over an extended period in a ‘wormy’ greyhound because daily production is around 10mL of red cells per day.

Blood Count Changes
Dogs have slightly higher blood count values than bitches, and overall, a racing greyhound has 10% higher circulating red cells, haemoglobin and packed cell volume (PCV) than a resting greyhound.
A change between blood counts may be an indication of a greyhound’s overall ability to cope with training.
Blood readings can help determine whether the animal is being given adequate ‘all-out’ sprint training, such as a regular competitive trial of 200 metres or racing once a week.
Sprint exercise is important to stimulate bone marrow production of red cells to maintain red cell parameters within the ranges considered desirable for a physically fit greyhound.
If a greyhound is diagnosed with anaemia, and corrective action by worming, dietary supplementation and more sprint exercise does not improve the count, then the level of chronic stress related to duration in training, combined with bone marrow suppression that reduces the generation of cells, may need to be considered.

Dietary Influences
Dietary adequacy is an important factor in preventing the development of anaemia in racing greyhounds.
Red meats, including beef muscle and heart and horse muscle contain at least 2mg of iron per 100 gram of meat.
The popular use of white meats, including chicken, as well as tripe, pork, veal and kidneys contain between 30-45% of the iron content of red meat.
Greyhounds fed on these meats without supplements can become anaemic and lose speed and stamina within 3 weeks.
Most complete dry foods formulated for greyhounds contain an adequate amount of iron and other trace-minerals and vitamin cofactors, including vitamin A, vitamin B, B12 and folic acid to satisfy daily requirements for blood synthesis.
However, if less than the recommended daily feeding amount is given, or the major protein source is provided by chicken meat for example, then there is likely to be less blood forming nutrients available to counteract increased demands or losses in a racing greyhound.
The stress of repeated galloping with elevated levels of lactic acid, can lead to damage and a shorter lifespan of circulating red cells in racing greyhounds, or a condition often referred to as ‘sports anaemia’ in human athletes and sporting dogs.
Whilst this type of anaemia is not a common cause of red cell depletion in racing greyhounds, it can be additive to other losses and dietary deficiencies that can develop into a chronic anaemic condition.
There are a number of types of anaemia relative to the number, size and haemoglobin content of the red blood cells, that can be defined from a blood cell count.
I have summarised the symptoms, blood changes and management that may be advised in the following table.