|The effect of inadequate dietary protein on a dog's immune system can be profound. The defense system that is so crucial in maintaining health and vitality can break down if the nutrients it needs to run efficiently are lacking. |
Dogs maintained with inadequate protein reserves may appear healthy, but are more susceptible to stress from bacteria and viral infections and have more difficulty recovering from physical trauma and injury.
Besides having compromised immune functioning, protein-deficient dogs can have rough, dull haircoats and reproducing bitches produce less milk. Dogs with severe protein deficiency will not consume enough food and can develop subnormal concentrations of blood proteins, growth retardation and emaciation. In extreme cases, death can occur.
At its best, the immune system effectively protects and defends the body. The immune system responds rapidly to body changes and provides a defense against disease organisms, such as bacteria, viruses and parasites, or from malignant cells.
Many functions of the immune system involve production of proteins, such as immunoglobulins, or antibodies, and enzymes. These are made by cells of the immune system in response to a challenge, such as bacterial infection. Success in warding off the infection depends on the cells of the immune system producing defensive proteins faster than the bacteria can produce.
Having an optimum supply of amino acids, the building blocks of protein, is critical, and it depends on active protein turnover. If protein intake is inadequate, the body will reduce protein turnover, leaving the immune system at a disadvantage in protecting the body against bacteria.
Chronic intake of inadequate protein also can result in changed body composition. In a young dog diminished growth and weight gain are not uncommon. An older dog may display chronic illness and an inability to thrive. Eventually, clinical signs and symptoms develop, along with an increase in morbidity and the risk of death.
Stress in Geriatric Dogs
As dogs age, the ability of their immune system to respond to injury and illness may decline. In old age, a reduction in protein turnover - the ongoing building and breakdown of cellular protein - can lead to decreased immune competence and increased susceptibility to stress. A high-protein diet may help ease the reduced efficiency of an older dog's ability to process protein.
Changes in Lean-Body Mass
An age-related transformation that occurs in some animals and people is a reduction in lean-body mass. The depletion of lean-body mass affects skeletal muscle and reflects a reduced protein turnover, which plays an important role in the response of the immune system to trauma or infection.
Increased dietary protein intake can help maintain lean-body mass and protein reserves and promote protein turnover. Protein turnover produces the amino acids that provide energy to support cells of the immune system, including lymphocytes and those involved in tissue repair. Protein turnover also provides amino acids that are oxidized in the muscle to serve as an additional energy source. Clearly, a diminished rate of muscle protein turnover could impair these functions and compromise the ability of the body to resist stress.
Providing a dog with the correct level of protein is critical in maintaining lean-body mass and promoting protein turnover. It also is an important way of protecting a dog from susceptibility to stress and illness.