Is Phenylalanine Toxic to Dogs?

Your dog's health depends on receiving adequate essential amino acids that are necessary for growth and repair of his body. Among these, phenylalanine naturally exists in foods such as meat, eggs, cheese, fish and milk. Phenylalanine in various forms to treat pain, depression and other maladies and is one of the components that makes up the sweetener aspartame.

Phenylalanine sold over the counter in health food stores is used in humans to treat arthritis pain, depression and attention deficit hyperactivity disorder. Anecdotal evidence for its use in dogs shows potential benefits for pain with no adverse side effects. The substance combined with aspartic acid -- another amino acid -- forms the sweetener aspartame. Studies in laboratory animals show safe levels of 50 milligrams of aspartame per day per kilogram of body weight. Although phenylalanine is readily available in health food stores as DLPA supplements, you should first consult your veterinarian before using it for your dog.

Dogs with a rare genetic disorder known as PKU or phenylketonuria can't process phenylalanine normally, causing toxic levels to build up in the blood stream. Phenylalanine must be strictly limited in the diet to prevent the amino acid from blocking other necessary chemicals from entering the brain, resulting in abnormal brain development.