When veterinarians use the term "retardation" in reference to animals, they're usually talking about impaired physical development, not mental disability. In fact, the human concept of "mental retardation" doesn't really apply to cats: We can neither test their intelligence nor even clearly understand their thought processes, veterinary researchers Michael Rand and Paula Johnson of the University of Arizona have written.
Impaired Brain Function in Cats
When a cat appears to be confused, disoriented or unable to process information as quickly as other cats, the reason isn't necessarily substandard intelligence. Since cats and people suffer from many of the same maladies, such symptoms might suggest almost as many possible causes. Among them are brain damage or other neurological problems, strokes, seizure disorders, genetic abnormalities and a wide range of viral, infectious and immunological diseases. Only a vet can narrow down the potential causes with hope of arriving at an accurate diagnosis.
Genetic Mutations, Facial Deformities and Inbreeding
All cats can inherit diseases if both parents have the same gene mutation, but the likelihood is greater among pedigree cats bred from a restricted gene pool.. Some breeds have been created by exploiting existing genetic mutations, which can leave generations more vulnerable to other mutations. Siamese cats, for example, all carry a mutated gene responsible for partial albinism, which is why they're born white and have blue eyes. That breed is susceptible to the feline version of a genetically transmitted disease that affects humans and causes multiple abnormalities, including facial deformity, in both: Maroteaux-Lamy syndrome, or mucopolysaccharidosis. Even though some people associate facial deformities with mental retardation, low intelligence isn't a symptom of that disease.
The Case of Kenny the White Tiger
What can happen when cats are inbred for qualities desirable to their owners came vividly to public attention in 2000, after a white tiger named Kenny was rescued by the Turpentine Creek Wildlife Reserve in Eureka Springs, Arkansas. At the time, white tigers fetched exorbitant prices in zoos and among private collectors. But Kenny, who had a severely deformed face and couldn't fully close his mouth, was worthless. After pictures went viral on the Internet, Kenny started being known as the world's first "retarded" tiger with Down syndrome. He and his brother Willie, who had orange coloring but crossed eyes, were the offspring of white tiger siblings forced to mate. Kenny died of cancer in 2008 at the age of 10. Whether he was actually afflicted with Down syndrome or any other kind of so-called retardation has never been confirmed.
Cognitive Dysfunction Syndrome
Cats age 9 or older sometimes start to experience a decline in cognitive function called cognitive dysfunction syndrome. According to Manhattan Cat Specialists, CDS is a default diagnosis that vets make when no other disorder can be found to account for behavioral changes such as litter box accidents, uncharacteristic displays of anxiety and general disorientation, and failure to recognize familiar people and places. Like the brains of people with Alzheimer's disease, the brains of cats afflicted with CDS often show accumulations of a waxy substance called amyloid plaque. Other problems common in aging cats, such as declining heart function causing oxygen deprivation and high blood pressure, can aggravate CDS symptoms.
Retarded Physical Development in Cats
Intestinal parasites such as roundworms and tapeworms can be debilitating enough to stunt the growth of kittens. Abnormalities of the endocrine system such as an underactive thyroid gland -- hypothyroidism -- can also retard a cat's development. If a pregnant female cat contracts the virus responsible for feline distemper, her kittens are likely to be born with severe brain damage. Another viral disease, feline leukemia, can cause neurological disorders in adult cats and stunt the growth of kittens. Oregon's Creswell Animal Clinic advises that all cats be tested for intestinal parasites at least once a year and vaccinated against viral diseases as appropriate based on age.