Cognitive Dysfunction Syndrome Hounds Senior Beagles

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Twelve-year-old “Penny,” a tricolor 13-inch Beagle, was slipping away bit by bit, as she struggled to remember her routine, her family and her housetraining skills. The independent, self-confident female had become anxious when left home alone, shredding magazines into confetti and trying to squeeze her 25-pound body into the safe, tight space under the recliner.

Unbeknown to owners Terri Grimm Walter and her husband of Germantown, Wisconsin, Penny had canine cognitive dysfunction syndrome (CDS), an irreversible degeneration of the brain similar to Alzheimer’s disease. The slow onset of behavioral changes caused by the progressive disorder makes CDS challenging for owners to recognize until dogs are well into their senior years.

Thanks to advances in nutrition and preventive veterinary care combined with greater awareness of canine health and well-being, dogs in general live longer today. Senior dogs that age successfully have lives that are rich in physical and cognitive exercises and behavioral stimulation. The changes seen in dogs with CDS are beyond what is expected to occur in aging.

 “As dogs age, eventually end-of-life health problems, such as failing organ systems and/or degenerative brain changes, occur. To diagnose potential health problems as soon as possible so that treatment can begin sooner, dogs over 8 years old should be scheduled for twice annual veterinary visits. During these visits, dogs should be screened with a cognitive assessment questionnaire,” advises veterinary behaviorist Gary Landsberg, DVM, DECAWBM, of Fergus, Ontario, Canada.  

An Accurate Diagnosis
An accurate diagnosis of CDS involves first ruling out medical, physical and motor dysfunction disorders with similar clinical signs. To help owners and their veterinarians evaluate the mental sharpness of senior dogs, and to help veterinarians diagnose CDS, Dr. Landsberg recommends using a screening questionnaire known by the acronym DISHAA. The DISHAA Assessment Tool, which was developed by the Purina Institute, provides a rating system in which owners score their dogs’ behavior related to signs of advancing brain pathology.

CDS upsets many basic behaviors due to the degenerative changes that impair memory and learning. Behaviors commonly reported by owners include dogs becoming disoriented in their homes and yards, losing housetraining skills, and sleeping more during the day and staying awake more at night. “Fortunately, there are ways to promote brain health and enrich the life of a dog with CDS,” Dr. Landsberg says.

Oxidative stress is the main culprit causing a senior dog to have a mixed-up, changed personality. “The cumulative burden of oxidative stress over time affects brain aging,” Dr. Landsberg says. “Physical atrophy occurs in certain areas of the brain due to oxidative damage and decreased energy metabolism. The brain is particularly susceptible to free radicals because it has a high rate of oxidative metabolism, a high content of lipids, or fats, and a limited ability to regenerate.”

Purina Principal Research Scientist Yuanlong Pan, PhD, who studies healthy aging in dogs, says, “Reduced brain-glucose metabolism is a common feature of aging, which at least partially contributes to the decline in brain function in middle-aged and older people and dogs. One of the strategies is to provide the brain with an alternative energy source called ketone bodies. This natural energy source, which is mainly produced in the liver from body fat, is used by the tissues such as the brain, heart, kidney, and muscle.”

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