I have heard that dogs can develop senility. Is this true?
Dogs are living longer than ever and that means they have a chance to develop diseases associated with advanced age. Cognitive dysfunction syndrome (CDS) is the name assigned to a set of symptoms associated with behavior changes that may include:
- escalating separation anxiety
- house soiling
- waking at night/disrupted sleep cycles
- excessive vocalization
- changes in interactions with people and other pets
It is important to identify the patterns of behavior that are consistent with CDS in order to provide appropriate early intervention that may improve both quality and length of life. At the moment, age is the only consistently recognized risk factor for CDS.
What happens in the brain when a dog develops CDS?
The brain is separated from the circulation by what is called the blood-brain barrier. The blood-brain barrier regulates the delivery of nutrients from the bloodstream to the cells of the brain. In aging dogs, the blood brain barrier becomes more permeable, allowing some potentially harmful molecules access to brain tissue, contributing to cognitive decline. Normal metabolism leads to oxidative damage and the production of free radicals. Free radicals can damage proteins, cellular fats, and molecules responsible for cellular health and reproduction. In the brain, damage from free radicals can lead to nerve cell dysfunction and death. Another factor in the development of CDS is that the brain atrophies (shrinks) and the tissue is replaced by cerebrospinal fluid (CSF) causing brain swelling.
Is there any way to slow or reverse the process of oxidative damage to the brain?
Antioxidants are molecules that decrease the number of oxidants and free radicals in the body's tissues. Many antioxidants are found in food and include:
- vitamin E
- vitamin C
- alpha-lipoic acid
Research has revealed that a nutrient profile could be used to decrease the production of free radicals, increasing the ability of the body to clear free radicals, and thus slowing the progression of cognitive decline by reducing oxidative damage. The studies showed significant improvement in cognitive function (learning and memory of learned tasks) in old dogs receiving an antioxidant-fortified food. Interestingly, the antioxidant-rich nutrient profile showed no beneficial effects in learning or memory in young dogs. The presumption is that the young dogs did not yet have a level of oxidative stress and damage that could be improved by such a nutrient profile.
A diet change using high levels of appropriate antioxidants has been shown to slow the rate of cognitive decline in older dogs, and the positive effects of antioxidants on cognition occur fairly rapidly when the dog is a responder to this approach.
How do I provide my dog with an appropriate nutrient profile to preserve his mental capacity?
Before nutrition can be of any benefit to cognitive function, CDS has to be confirmed as the appropriate diagnosis. There are many diseases that can cause symptoms similar to CDS. For instance, chronic pain is quite distracting and can cause a dog to behave very differently from the way he behaves when all is in balance in the body. If a systemic disease or pain is present, it is important to resolve or treat those medical issues first.
Once CDS is confirmed as the issue, look at the dog's current food and compare the levels of those key nutritional factors that have been shown to support cognitive function.
You and your veterinarian can look at all of your dog's relevant health concerns in order to choose the most appropriate nutrient profile for your dog. There are foods available, such as Hill's® Prescription Diet® b/d® and Purina® Pro Plan® Veterinary Diets NC NeuroCare™, that have been shown to help cognitive function in older dogs, which may be the best choice for your dog.
In addition to choosing an appropriate nutrient profile, research shows that dogs with CDS benefit from environmental enrichment. In one study, environmental enrichment involved increased activity via regular exercise, interactive toys, and regular interaction with other dogs. The combination of nutrition and environmental enrichment was more effective than nutrition alone.
"The combination of nutrition and environmental enrichment was more effective than nutrition alone."
Improvements in the abnormal behaviors associated with CDS are typically seen within 6-12 weeks after starting to feed a nutrient profile containing high enough levels of appropriate antioxidants. If no improvements are seen within 12 weeks, it is unlikely that nutrition alone will make a difference. These are dogs who need additional follow-up and investigation with your veterinarian. There are some medications or supplements available that can have variable results depending on the patient and these can be discussed with your veterinarian in conjunction with diet therapy.