Assessment of the neurologic effects of dietary deficiencies of phenylalanine and tyrosine in cats.
OBJECTIVE
To determine the neurologic effects of reduced intake of phenylalanine and tyrosine in black-haired cats.


METHODS
53 specific pathogen-free black domestic shorthair cats.


METHODS
Cats were fed purified diets containing various concentrations of phenylalanine and tyrosine for < or = 9 months. Blood samples were obtained every 2 months for evaluation of serum aromatic amino acid concentrations. Cats were monitored for changes in hair color and neurologic or behavioral abnormalities. Three cats with neurologic deficits underwent clinical and electrophysiologic investigation; muscle and nerve biopsy specimens were also obtained from these cats.


RESULTS
After 6 months, neurologic and behavioral abnormalities including vocalization and abnormal posture and gait were observed in cats that had received diets containing < 16 g of total aromatic amino acid/kg of diet. Electrophysiologic data and results of microscopic examination of muscle and nerve biopsy specimens from 3 cats with neurologic signs were consistent with sensory neuropathy with primary axonal degeneration. Changes in hair color were detected in cats from all groups receiving < 16 g of phenylalanine plus tyrosine/kg of diet.


CONCLUSIONS
Findings suggested that chronic dietary restriction of phenylalanine and tyrosine in cats may result in a predominantly sensory neuropathy. In cats, the long-term nutritional requirement for phenylalanine and tyrosine appears to be greater for normal neurologic function than that required in short-term growth experiments. Official present-day recommendations for dietary phenylalanine and tyrosine in cats may be insufficient to support normal long-term neurologic function.
Dickinson
Peter J
PJ
Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
Anderson
Peter J B
PJ
Williams
Diane C
DC
Powell
Henry C
HC
Shelton
G Diane
GD
Morris
James G
JG
LeCouteur
Richard A
RA
D000601:Amino Acids, Essential / Q000097:blood; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002371:Cat Diseases / Q000378:metabolism* / Q000473:pathology; D002415:Cats; D004576:Electromyography; D006200:Hair Color / Q000502:physiology; D008855:Microscopy, Electron, Scanning; D018482:Muscle, Skeletal / Q000648:ultrastructure; D009431:Neural Conduction / Q000502:physiology; D019636:Neurodegenerative Diseases / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*; D009751:Nutritional Requirements; D010543:Peroneal Nerve / Q000648:ultrastructure; D010649:Phenylalanine / Q000172:deficiency*; D014443:Tyrosine / Q000172:deficiency*
D000601:Amino Acids, Essential; D014443:Tyrosine; D010649:Phenylalanine