Tibetan Terrier Club of America Voluntary open list for
CCL (Canine Ceroid Lipofuscinosis) or NCL (Neuronal Ceroid Lipofuscinosis)

Canine Ceroid Lipofuscinosis is an inherited neurological disorder affecting Tibetan Terrier for which there is no known cure. It is a multisystemic storage disease thought to be caused by an inborn error of metabolism. This metabolic error results in the accumulation of storage bodies thought to affect the ability of nerve cells to function.

CCL (NCL) in Tibetan Terrier has been characterized by manifestation of at least some of the following symptoms and diagnostic observations:
- decrease in or loss of vision, particularly in dim light, changes in dark adaptation
- ataxia, a loss of normal muscular coordination and movement, often associated with an irregular gait, loss of balance, and a roaching of the back
- a progressive Alzheimer-like dementia, which can include difficulty adapting to changes in environment, confusion, aggressive behaviour
- seizures in the advanced stages of the disease
- magnetic resonance Imaging (MRI) changes and accumulation of storage bodies within the brain retina and other tissues, observable with fluorescence and electron microscopy.
It is considered to be a simple autosomal recessive disorder.

A diagnosis of NCL has been confirmed for the Tibetan Terrier by Martin L Katz, Ph.D., of the University of Missouri using fluorescence microscopy and EM (electron microscopy) to confirm inclusions in neural and retinal tissue obtained at necropsy. This list includes only dogs whose owners or breeder have voluntarily agreed to release this health information.