− | Tryptophan is an essential amino acid for dogs and cats. Tryptophan is classified as an [[Nutrition Glossary#Aromatic Amino Acids|aromatic amino acid]] and is both gluconeogenic and ketogenic. Unlike the other aromatic amino acids such as [[Phenylalanine and Tyrosine - Nutrition|phenylalanine and tyrosine]], tryptophan has a nitrogen-containing indole side ring. Dietary tryptophan is absorbed by a neutral amino acid transporter in the [[Small Intestine Overview - Anatomy & Physiology|small intestine]] (particularly the [[Jejunum - Anatomy & Physiology|jejunum]]) and plasma tryptophan is actively reabsorbed in the [[Nephron Microscopic Anatomy#Proximal Tubule|proximal tubule]] of the kidney. | + | Tryptophan is an essential amino acid for dogs and cats. Tryptophan is classified as an [[Nutrition Glossary#Aromatic Amino Acids|aromatic amino acid]] and is both [[Amino Acids Overview - Nutrition|gluconeogenic and ketogenic]]. Unlike the other aromatic amino acids such as [[Phenylalanine and Tyrosine - Nutrition|phenylalanine and tyrosine]], tryptophan has a nitrogen-containing indole side ring. Dietary tryptophan is absorbed by a neutral amino acid transporter in the [[Small Intestine Overview - Anatomy & Physiology|small intestine]] (particularly the [[Jejunum - Anatomy & Physiology|jejunum]]) and plasma tryptophan is actively reabsorbed in the [[Nephron Microscopic Anatomy#Proximal Tubule|proximal tubule]] of the kidney. |