Glutamine is a dietary non-essential amino acid in dogs and the most abundant circulatory amino acid. The utilization of glutamine increases during catabolic states and cancer, resulting in the breakdown of muscles. If the body’s glutamine needs cannot be filled by glutamine synthesis, the blood levels of glutamine fall. Glutamine is also an important molecule in mental function, and increased glutamine concentrations have been observed in fearful dogs. Glutamine cannot be measured from samples from oligofin oligomer gel tubes. It is also a heat-sensitive molecule, and its concentration falls after 4 days of sample storage at room temperature.