Cognitive Dysfunction in Cats
Many people have known old cats that have matured to the point of minimal activity, and who have lost most of their kittenish joie de vivre. That’s normal aging. Feline cognitive dysfunction (FCD), however, is a truly pathological condition represented by a constellation of behavioral signs that are abnormal, seem out of character, or are performed out of context. No one sign is absolutely diagnostic, but the insidious onset of a cluster of signs suspicious of the syndrome in an elderly cat is suggestive of the disorder.
What to Watch For
- Loss of control of bladder or bowels
- Decreased activity/playfulness
- Increased sleeping time
- Loss of coordination
- Increased irritability/aggression
- Hypervocalization (excessive crying)
- Nocturnal separation distressIn addition, there may be other changes in normal behavior pattern, such as lack of grooming, altered sound behavior and loss of appetite.
Even if two or three of the typical clinical signs appear in an elderly cat (more than 12 years old), cognitive dysfunction cannot be definitively confirmed as the most likely explanation to the problems unless thorough examination and medical tests are performed. The diagnosis of FCD is made by ruling out other conditions that could cause similar signs:
- If house soiling is a feature, your veterinarian will perform a detailed examination. This may involve laboratory tests.
- Brain tumors need to be ruled out. This requires neurological examination, sometimes along with a computed tomography scan (CT scan) or magnetic resonance imaging (MRI).
- Inflammatory conditions of the brain and its surrounding membranes (encephalomyelitis) as a result of viral, bacterial, or parasitic diseases. Conditions like rabies, toxoplasmosis, and brain abscesses should be ruled out by appropriate tests.
- Hyperthyroidism must be ruled out by measuring blood thyroid hormone (T4), especially if there is increased irritability and aggression.
- Dietary problems, especially thiamine deficiency caused by excessive raw fish in diet, may mimic the condition.
- Kidney and liver failure must be ruled out by means of appropriate blood tests.
- Toxicological problems, such as lead poisoning, should be considered and investigated, if necessary.
If cognitive dysfunction is the only logical explanation for the behavioral change, the next step is to implement therapy. The only treatment likely to be of any benefit is deprenyl (Anipryl®). This drug is currently only licensed for the use of cognitive dysfunction in dogs but its extra label use by veterinarians is permissible according to the Animal Medical Drug Use Clarification Act (AMDUCA) of 1984.
Organized studies to evaluate the efficacy of deprenyl for the treatment of FCD in cats have yet to be performed but if the results turn out to be similar to those in dogs, treatment with deprenyl would be well worth a try. Typically, a low dose of deprenyl would be given by mouth once a day and the cat’s response evaluated after 2-4 weeks. If no effect is apparent and no side effects have been seen, the dose should be gradually increased until treatment success or side effects dictate against further dose increments.
A positive response to treatment – a full or partial return to earlier vigor and more typical behavior – provides justification of the clinical diagnosis, but it should be remembered that deprenyl treatment is a symptomatic treatment and will not arrest the inexorable disease process. All we do by treating elderly cats this way is to buy them and us additional quality time together – a worthwhile goal.