Alanine

Alanine is a so-called dietary non-essential amino acid, meaning the dog’s body is able of forming it sufficiently from other substances. Alanine plays an important role in nitrogen transport, strengthens the immune system, and is needed in the metabolism of sugars, cholesterol and organic acids. Alanine is also used for energy production during negative energy balance. For example, during exercise alanine is mobilized for energy production. Catabolic states reduce circulatory alanine concentrations because of muscle catabolism. Alanine concentrations fall also in multiple forms of cancer, since the disease uses up the body’s energy stores. This condition can be treated by providing the patient sufficiently energy in the diet. Alanine is abundant in protein-rich foods such as meat, fish, eggs, beans, dairy products and peas.

 

Increased concentrations

– Post-exercise
– Compensative phase of catabolic state
– Acute liver failure

Decreased concentrations

– Decompensative phase of catabolic state
– Serious illnesses
– Cancer
– Chronic liver failure
– Necrolytic dermatitis

Additional information

de Godoy, M. R. C. et al. Acute changes in blood metabolites and amino acid profile post-exercise in Foxhound  dogs fed a high endurance formula. J. Nutr. Sci. 3, e33 (2014).
Gamble, L.-J. et al. Serum metabolomics of Alaskan sled dogs during endurance racing. Comp. Exerc. Physiol. 14, 1–12 (2018).
Strombeck, D. R. et al. Plasma amino acid, glucagon, and insulin concentrations in dogs with nitrosamine-induced hepatic disease. Am. J. Vet. Res. 44, 2028–2036 (1983).
Record, C. O. et al. Plasma and brain amino acids in fulminant hepatic failure and their relationship to hepatic encephalopathy. Eur. J. Clin. Invest. 6, 387–394 (1976).
Chan, D. L., Rozanski, E. A. & Freeman, L. M. Relationship among plasma amino acids, C-reactive protein, illness severity, and outcome in critically ill dogs. J. Vet. Intern. Med. 23, 559–563 (2009).
Outerbridge, C. A., Marks, S. L. & Rogers, Q. R. Plasma amino acid concentrations in 36 dogs with histologically confirmed superficial necrolytic dermatitis. Vet. Dermatol. 13, 177–186 (2002).

 

Glutamine

Glutamine is the most abundant amino acid in blood. Glutamine is a dietary so-called non-essential amino acid, since the dog’s body is normally able of forming it sufficiently from glutamate and ammonia. Glutamine formation occurs primarily in the muscles and liver. In catabolic states, usage of glutamine increases in the intestines, immune cells and the liver, resulting in increased muscle catabolism. If the body’s glutamine synthesis capacity cannot cover the increased use of glutamine, blood levels of glutamine decrease. Sufficient glutamine intake is necessary for immune defense cells, and in humans, low blood glutamine concentration is associated with a poorer prognosis in intensive care patients. The use of glutamine supplements has therefore been studied in people with low glutamine concentrations. Also, cancer cells consume a lot of glutamine, which is why blood levels of glutamine may decrease in different cancers. Glutamine is heat-sensitive and reduces after four days of storage in room temperature.

 

Increased concentrations

– Post-exercise
– Compensative phase of catabolic state
– Fearfulness

Decreased concentrations

– Decompensative phase of catabolic state
– Serious illnesses
– Cancer
– Infections
– Diabetes mellitus
– Intense physical exercise
– Over four days of storage in room temperature

Additional information

de Godoy, M. R. C. et al. Acute changes in blood metabolites and amino acid profile post-exercise in Foxhound  dogs fed a high endurance formula. J. Nutr. Sci. 3, e33 (2014).
Gamble, L.-J. et al. Serum metabolomics of Alaskan sled dogs during endurance racing. Comp. Exerc. Physiol. 14, 1–12 (2018).
Azuma, K. et al. Plasma free amino acid profiles of canine mammary gland tumors. J. Vet. Sci. 13, 433–436 (2012).
Cruzat, V., Macedo Rogero, M., Noel Keane, K., Curi, R. & Newsholme, P. Glutamine: Metabolism and Immune Function, Supplementation and Clinical Translation. Nutrients 10, (2018).
Puurunen, J. et al. Fearful dogs have increased plasma glutamine and γ-glutamyl glutamine. Sci. Rep. 8, 15976 (2018).
O’Kell, A. L., Garrett, T. J., Wasserfall, C. & Atkinson, M. A. Untargeted metabolomic analysis in naturally occurring canine diabetes mellitus identifies similarities to human Type 1 Diabetes. Sci. Rep. 7, 9467 (2017).
Guasch-Ferre, M. et al. Metabolomics in Prediabetes and Diabetes: A Systematic Review and Meta-analysis. Diabetes Care 39, 833–846 (2016).

 

Glycine

Glycine is a so-called dietary non-essential amino acid, meaning the dog’s body is able of forming it sufficiently from other substances. Glycine has many important functions. Glycine is a constituent of the most abundant protein, collagen, in mammals. Collagen acts as a structural protein in many tissues such as bones, tendons and cartilage. Glycine is also needed for nucleotide formation, bile acid metabolism, and as a neurotransmitter in the central nervous system. Diet has been found to have an effect on blood glycine levels in dogs. Glycine is not quantifiable from EDTA-plasma samples.

 

Increased concentrations

– Post-exercise
– Acute hepatitis

Decreased concentrations

– Serious illnesses
– Necrolytic dermatitis
– Intense physical exercise

Additional information

de Godoy, M. R. C. et al. Acute changes in blood metabolites and amino acid profile post-exercise in Foxhound  dogs fed a high endurance formula. J. Nutr. Sci. 3, e33 (2014).
Gamble, L.-J. et al. Serum metabolomics of Alaskan sled dogs during endurance racing. Comp. Exerc. Physiol. 14, 1–12 (2018).
Strombeck, D. R. et al. Plasma amino acid, glucagon, and insulin concentrations in dogs with nitrosamine-induced hepatic disease. Am. J. Vet. Res. 44, 2028–2036 (1983).
Record, C. O. et al. Plasma and brain amino acids in fulminant hepatic failure and their relationship to hepatic encephalopathy. Eur. J. Clin. Invest. 6, 387–394 (1976).
Chan, D. L., Rozanski, E. A. & Freeman, L. M. Relationship among plasma amino acids, C-reactive protein, illness severity, and outcome in critically ill dogs. J. Vet. Intern. Med. 23, 559–563 (2009).
Outerbridge, C. A., Marks, S. L. & Rogers, Q. R. Plasma amino acid concentrations in 36 dogs with histologically confirmed superficial necrolytic dermatitis. Vet. Dermatol. 13, 177–186 (2002).

 

Leucine

Leucine is a so-called dietary essential amino acid. This means that the dog’s body is unable to form it from other substances and needs to be adequately supplied in the diet. Leucine is needed for protein formation and for many important metabolic functions. For example, leucine is needed in the regulation the body’s sugar balance, for muscle and bone growth and repair, hemoglobin formation, growth hormone formation, and wound healing. Leucine also prevents muscle breakdown due to injuries and severe stress.

 

Increased concentrations

– Diabetes mellitus
– Intermittent fasting
– Post-exercise
– Eating before blood sampling

Decreased concentrations

– Renal failure
– Chronic liver failure
– Malnutrition
– Low protein diet

Additional information

de Godoy, M. R. C. et al. Acute changes in blood metabolites and amino acid profile post-exercise in Foxhound  dogs fed a high endurance formula. J. Nutr. Sci. 3, e33 (2014).
Gamble, L.-J. et al. Serum metabolomics of Alaskan sled dogs during endurance racing. Comp. Exerc. Physiol. 14, 1–12 (2018).
Strombeck, D. R. et al. Plasma amino acid, glucagon, and insulin concentrations in dogs with nitrosamine-induced hepatic disease. Am. J. Vet. Res. 44, 2028–2036 (1983).
Guasch-Ferre, M. et al. Metabolomics in Prediabetes and Diabetes: A Systematic Review and Meta-analysis. Diabetes Care 39, 833–846 (2016).
Holecek, M. Branched-chain amino acids in health and disease: metabolism, alterations in blood plasma, and as supplements. Nutr. Metab. (Lond). 15, 33 (2018).
Ivy, J. H., Svec, M. & Freeman, S. Free plasma levels and urinary excretion of eighteen amino acids in normal and diabetic dogs. Am. J. Physiol. 167, 182–192 (1951).
Parker, V. J., Fascetti, A. J. & Klamer, B. G. Amino acid status in dogs with protein-losing nephropathy. J. Vet. Intern. Med. 33, 680–685 (2019).

 

Isoleucine

Isoleucine is a dietary essential amino acid. This means that the dog’s body cannot synthesize it from other molecules and it must be sufficiently supplied in the diet. Protein-rich food like eggs, meat, beans, nuts, and soybean are good sources of isoleucine. Isoleucine is important in regulation of blood sugar and energy levels and participates in hemoglobin synthesis. This amino acid is also needed for stimulating immune function, regulating hormone secretion, wound healing and detoxification of waste products. Isoleucine is heat-sensitive and its concentration increases already after 24 hours of storage in room temperature.

 

Increased concentrations

– Diabetes mellitus
– Post-exercise
– Intermittent fasting
– Eating before blood sampling

Decreased concentrations

– Chronic liver failure
– Malnutrition
– Low protein diet

Additional information

de Godoy, M. R. C. et al. Acute changes in blood metabolites and amino acid profile post-exercise in Foxhound  dogs fed a high endurance formula. J. Nutr. Sci. 3, e33 (2014).
Strombeck, D. R. et al. Plasma amino acid, glucagon, and insulin concentrations in dogs with nitrosamine-induced hepatic disease. Am. J. Vet. Res. 44, 2028–2036 (1983).
O’Kell, A. L., Garrett, T. J., Wasserfall, C. & Atkinson, M. A. Untargeted metabolomic analysis in naturally occurring canine diabetes mellitus  identifies similarities to human Type 1 Diabetes. Sci. Rep. 7, 9467 (2017).
Guasch-Ferre, M. et al. Metabolomics in Prediabetes and Diabetes: A Systematic Review and Meta-analysis. Diabetes Care 39, 833–846 (2016).
Holecek, M. Branched-chain amino acids in health and disease: metabolism, alterations in blood plasma, and as supplements. Nutr. Metab. (Lond). 15, 33 (2018).
Ivy, J. H., Svec, M. & Freeman, S. Free plasma levels and urinary excretion of eighteen amino acids in normal and diabetic dogs. Am. J. Physiol. 167, 182–192 (1951).

 

Valine

Valine is a dietary so-called essential amino acid. This means that the dog’s body is unable to form it from other substances and needs to be adequately supplied in the diet. The diet also influences the blood valine concentrations. Valine is known for its functions in muscle growth and tissue repair. Valine is also needed in maintaining mental function and muscle coordination. Valine is abundant in soybean, fish, meat and vegetables.

 

Increased concentrations

– Diabetes mellitus
– Post-exercise
– Intermittent fasting
– Eating before blood sampling

Decreased concentrations

– Chronic liver failure
– Malnutrition
– Low protein diet

Additional information

de Godoy, M. R. C. et al. Acute changes in blood metabolites and amino acid profile post-exercise in Foxhound  dogs fed a high endurance formula. J. Nutr. Sci. 3, e33 (2014).
Strombeck, D. R. et al. Plasma amino acid, glucagon, and insulin concentrations in dogs with nitrosamine-induced hepatic disease. Am. J. Vet. Res. 44, 2028–2036 (1983).
O’Kell, A. L., Garrett, T. J., Wasserfall, C. & Atkinson, M. A. Untargeted metabolomic analysis in naturally occurring canine diabetes mellitus  identifies similarities to human Type 1 Diabetes. Sci. Rep. 7, 9467 (2017).
Guasch-Ferre, M. et al. Metabolomics in Prediabetes and Diabetes: A Systematic Review and Meta-analysis. Diabetes Care 39, 833–846 (2016).
Holecek, M. Branched-chain amino acids in health and disease: metabolism, alterations in blood plasma, and as supplements. Nutr. Metab. (Lond). 15, 33 (2018).
Ivy, J. H., Svec, M. & Freeman, S. Free plasma levels and urinary excretion of eighteen amino acids in normal and diabetic dogs. Am. J. Physiol. 167, 182–192 (1951).

 

Branched-chain amino acids

This biomarker represents the total concentration of the branched-chain amino acids (BCAA) leucine, isoleucine and valine. The concentrations of these amino acids is tightly connected with muscle mass. The blood concentration of BCAAs increases in conditions, where muscle catabolism is active. The blood concentration of these amino acids is typically low in chronic catabolic conditions, when the amount of muscle mass is already reduced. Elevated concentrations of BCAAs in diabetes are caused by impaired BCAA uptake into cells and simultaneously increased BCAA synthesis in the liver.

 

Increased concentrations

– Diabetes mellitus
– Intermittent fasting
– Post-exercise
– Eating before blood sampling

Decreased concentrations

– Renal failure
– Chronic liver failure
– Malnutrition
– Low protein diet

Additional information

de Godoy, M. R. C. et al. Acute changes in blood metabolites and amino acid profile post-exercise in Foxhound  dogs fed a high endurance formula. J. Nutr. Sci. 3, e33 (2014).
Gamble, L.-J. et al. Serum metabolomics of Alaskan sled dogs during endurance racing. Comp. Exerc. Physiol. 14, 1–12 (2018).
Strombeck, D. R. et al. Plasma amino acid, glucagon, and insulin concentrations in dogs with nitrosamine-induced hepatic disease. Am. J. Vet. Res. 44, 2028–2036 (1983).
Guasch-Ferre, M. et al. Metabolomics in Prediabetes and Diabetes: A Systematic Review and Meta-analysis. Diabetes Care 39, 833–846 (2016).
Holecek, M. Branched-chain amino acids in health and disease: metabolism, alterations in blood plasma, and as supplements. Nutr. Metab. (Lond). 15, 33 (2018).
Ivy, J. H., Svec, M. & Freeman, S. Free plasma levels and urinary excretion of eighteen amino acids in normal and diabetic dogs. Am. J. Physiol. 167, 182–192 (1951).
Parker, V. J., Fascetti, A. J. & Klamer, B. G. Amino acid status in dogs with protein-losing nephropathy. J. Vet. Intern. Med. 33, 680–685 (2019).

 

Phenylalanine

Phenylalanine is a so-called dietary essential amino acid. This means that the dog’s body is unable of forming it from other substances and needs to be adequately supplied in the diet. Thus, feeding affects the phenylalanine blood concentrations. Phenylalanine is found richly in e.g. eggs, chicken, liver, beef, milk and soybeans. Phenylalanine acts as a precursor for many important proteins and enzymes. These include the thyroid hormone thyroxine, neurotransmitters dopamine and noradrenaline, and skin pigment melanin. The D-form of phenylalanine also has analgesic effects. The breakdown of phenylalanine, as well as tyrosine, occurs in the liver. In liver diseases, their catabolism is impaired, causing the blood levels of phenylalanine and tyrosine to rise.

Phenylalanine is heat-sensitive and it’s concentration rises after three days of storage in room temperature.

 

Increased concentrations

– Post-exercise
– Liver failure
– Renal insufficiency
– Serious illnesses
– Over three days of storage in room temperature

Additional information

de Godoy, M. R. C. et al. Acute changes in blood metabolites and amino acid profile post-exercise in Foxhound  dogs fed a high endurance formula. J. Nutr. Sci. 3, e33 (2014).
Strombeck, D. R. et al. Plasma amino acid, glucagon, and insulin concentrations in dogs with nitrosamine-induced hepatic disease. Am. J. Vet. Res. 44, 2028–2036 (1983).
Record, C. O. et al. Plasma and brain amino acids in fulminant hepatic failure and their relationship to hepatic encephalopathy. Eur. J. Clin. Invest. 6, 387–394 (1976).
Chan, D. L., Rozanski, E. A. & Freeman, L. M. Relationship among plasma amino acids, C-reactive protein, illness severity, and outcome in critically ill dogs. J. Vet. Intern. Med. 23, 559–563 (2009).
Fischer, J. E. et al. The role of plasma amino acids in hepatic encephalopathy. Surgery 78, 276–290 (1975).
Hashimoto, N., Ishikawa, Y. & Utsunomiya, J. Effects of portacaval shunt, transposition, and dimethylnitrosamine-induced chronic liver injury on pancreatic hormones and amino acids in dog. J. Surg. Res. 46, 35–40 (1989).
Barrios, C. et al. Circulating metabolic biomarkers of renal function in diabetic and non-diabetic populations. Sci. Rep. 8, 15249 (2018).
Kopple, J. D. Phenylalanine and tyrosine metabolism in chronic kidney failure. J. Nutr. 137, 1586S–1590S; discussion 1597S–1598S (2007).

 

Phenylalanine/tyrosine ratio

The catabolism of both phenylalanine and tyrosine occurs in the liver. However, tyrosine is removed from plasma faster than phenylalanine. Thus, in catabolic states, the ratio of phenylalanine to tyrosine increases. The ratio may also increase in renal failure, in which tyrosine formation from phenylalanine is disturbed. The relationship between phenylalanine and tyrosine has been studied mainly in other animal species than in dogs.

 

Increased ratio

– Catabolic state
– Renal failure

Additional information

Parker, V. J., Fascetti, A. J. & Klamer, B. G. Amino acid status in dogs with protein-losing nephropathy. J. Vet. Intern. Med. 33, 680–685 (2019).
Kopple, J. D. Phenylalanine and tyrosine metabolism in chronic kidney failure. J. Nutr. 137, 1586S–1590S; discussion 1597S–1598S (2007).
Wannemacher, R. W. J., Klainer, A. S., Dinterman, R. E. & Beisel, W. R. The significance and mechanism of an increased serum phenylalanine-tyrosine ratio during infection. Am. J. Clin. Nutr. 29, 997–1006 (1976).

 

Tyrosine

Tyrosine is a so-called dietary non-essential amino acid because the dog’s body is normally able of forming it sufficiently from phenylalanine. However, the diet does affect the circulatory tyrosine concentration. Tyrosine is a precursor of many important proteins and enzymes. These include: adrenaline, thyroid hormones and skin pigment melanin. Tyrosine is heat-sensitive and it’s concentration increases after four days of storage in room temperature.

 

Increased concentrations

– Liver failure
– Over four days of storage in room temperature

Decreased concentrations

– Renal insufficiency
– Necrolytic dermatitis

Additional information

Strombeck, D. R. et al. Plasma amino acid, glucagon, and insulin concentrations in dogs with nitrosamine-induced hepatic disease. Am. J. Vet. Res. 44, 2028–2036 (1983).
Record, C. O. et al. Plasma and brain amino acids in fulminant hepatic failure and their relationship to hepatic encephalopathy. Eur. J. Clin. Invest. 6, 387–394 (1976).
Outerbridge, C. A., Marks, S. L. & Rogers, Q. R. Plasma amino acid concentrations in 36 dogs with histologically confirmed superficial necrolytic dermatitis. Vet. Dermatol. 13, 177–186 (2002).
Parker, V. J., Fascetti, A. J. & Klamer, B. G. Amino acid status in dogs with protein-losing nephropathy. J. Vet. Intern. Med. 33, 680–685 (2019).
Hashimoto, N., Ishikawa, Y. & Utsunomiya, J. Effects of portacaval shunt, transposition, and dimethylnitrosamine-induced chronic liver injury on pancreatic hormones and amino acids in dog. J. Surg. Res. 46, 35–40 (1989).
Fischer, J. E. et al. The role of plasma amino acids in hepatic encephalopathy. Surgery 78, 276–290 (1975).
Kopple, J. D. Phenylalanine and tyrosine metabolism in chronic kidney failure. J. Nutr. 137, 1586S–1590S; discussion 1597S–1598S (2007).