Blood as an important tissue in dogs as mediator of nourishment and health

The mass of a dog is about 10 percent blood or around 90ml per Kg and is not in our central thoughts when your favourite companion settles down to eat. It is an important function of blood to convey the nutrients absorbed from the gut within your dog’s pet food to maintain basal requirements as well as providing for growth (protein retention and energy storage). Blood is a highly complex fluid but has numerous cells in suspension, each playing its part in the overall metabolic and physiological dynamics of this lifegiving medium.

Blood cells are manufactured and develop mostly in the bone marrow, the tissue located in the inner cavities of bones. Blood serves a variety of important functions as it circulates throughout the body. It conveys oxygen and vital nutrients (such as vitamins, minerals, lipids, essential amino acids and essential fatty acids and sugars) to all tissues and organs. It carries carbon dioxide to the lungs to be exhaled and nitrogenous waste products and metabolites to the kidneys and liver to be eliminated from the body. It transports hormones, which are chemical signalling messengers, to various parts of the body, allowing interaction and regulations with each other. Blood also includes cells (T- and B-lymphocytes) that fight infection (immune response) and clotting cascade of proteins that control bleeding. Just as there are various blood types in humans, there are several blood types in dogs, cats, horses, and other animals.

There are three cellular elements of blood: red blood cells, white blood cells, and platelets. Basically, red blood cells supply the body with oxygen, white blood cells protect against infection, and platelets start the formation of blood clots. There are occasions due to different types of stress and diseases where changes in blood chemistry can reflect these issues. Blood disorders include anaemias, but we see diabetes markers such as elevated glucose and marker enzymes associated with liver and pancreatic malfunction with obesity being the main issue. The blood offers an excellent means for diagnosis for nutritional status, and it is routine to send samples away to specialist laboratories for a range of assays.

Nutritional deficiency anaemias develop when the nutrients needed for red blood cell synthesis are insufficient. Anaemia develops slowly and may initially be regenerative, but ultimately becomes nonregenerative. Starvation may cause anaemia by a combination of vitamin and mineral deficiencies as well as a displaced energy and protein balance. The nutrient deficiencies most likely to cause anaemia are iron, copper, vitamin B12, vitamin B6, riboflavin, niacin, and vitamin E (tocopherols).

Although Iron deficiency is the most common deficiency observed in dogs, it is not often nutritional in its cause—it most often occurs after blood loss (Blood Loss Anaemia). It should be noted that young animals do not have much retained iron in the body, and milk contains very little iron to replenish. Clinical specialists like veterinarians may recommend oral iron supplements for anaemic neonates.

B-complex vitamin deficiencies are not usually common in the modern formulated dog diet but as I have discussed previously diets that may have lowered meat content and higher in plant and cereal ingredients will need revisited vitamin and mineral fortification. However, specific drugs for dogs under medication such as anticonvulsants and chemotherapeutics that can interact adversely with B vitamin metabolism, may initiate anaemia. Poor absorption of vitamin B12 has been reported in Giant Schnauzers. These dogs respond to injections of vitamin B12 quite well if extreme conditions prevail.

A deficiency of phosphorus in the blood, leading to destruction of erythrocytes, is observed in dogs with diabetes, hepatic lipidosis (a disorder of fat metabolism in the liver), and refeeding syndrome (chemical and fluid abnormalities that occur during recovery from fasting or starvation). Therefore, giving additional phosphorus, either orally or by injection subject on the severity of the illness, is the recommended course of action.

Clearly, a well-balanced pet food will provide all the major nutrients for your dog’s health and wellbeing but remember how blood undertakes its vital role powered by the heart and lungs when you next feed your loyal friend.