January 7, 2021 – We all love a nuzzle from a graying nose, or a cuddle with a four-legged friend who’s been with us through good and bad times. Advances in veterinary care are helping our dogs live longer lives and dog owners want to make sure those extra years are filled with special moments. A growing awareness of the challenges of aging is leading dog owners and veterinarians to learn more about diseases affecting older dogs and develop strategies to keep dogs healthy and happy in their golden years.
Many dog owners are concerned about behavior and personality changes they see in their aging pets. In a recent Morris Animal Foundation pet owner survey, 36% of respondents listed senior dogs as an area of canine health of greatest interest to them, followed by 31% of respondents who listed behavior. Mental sharpness can decline over time in both people and dogs, but some dogs suffer from a more serious condition called canine cognitive dysfunction (CCD). We are learning more every day about CCD and what owners and veterinarians can do to maintain quality of life in our dogs’ senior years.
When normal aging isn’t normal
It’s not unusual for us (including those with four legs!) to have slight declines in memory over time. In people, it’s estimated that 40% of people over the age of 65 will experience mild memory loss. However, other than the frustration that comes from grasping for a word or trying to remember where you put your car keys, mild memory loss doesn’t affect day-to-day functioning. Most people retain many strong memories and can learn new information and tasks into advanced age.
It turns out, the same pattern of age-related mental changes occurs in older dogs. Slight lapses in attention and memory are normal and not cause for concern.
What is important for dog owners and veterinary professionals is to recognize changes that aren’t part of normal aging. This includes understanding more about normal aging signs and signs related to CCD.
Veterinary neurologists, behaviorists and CCD experts report that the three most common misconceptions about canine aging are:
- Cognitive impairment reflects normal aging and is inevitable
- CCD is not a common disease
- There are no effective preventives or treatments
These misconceptions can keep owners from seeking care, and veterinarians from recommending treatments that can help dogs with CCD. The earlier that signs of CCD are detected, the sooner owners can intervene to reverse or slow disease progression.
What we know about CCD
CCD is a neurodegenerative disease similar to Alzheimer’s disease in people. Studies in dogs with CCD reveal that changes in brain tissue appear to be similar to those noted in people with Alzheimer’s. However, disease progression differs between the two diseases, and there is evidence that some signs of CCD can be reversed while this is generally not the case with Alzheimer’s.
The estimated prevalence rates of CCD range from 14% to 35% in the pet dog population, with the prevalence dramatically increasing as dogs age. One study found the prevalence of CCD was 28% in dogs aged 11 to 12 years old but jumped to 68% in dogs 15 to 16 years old. Unfortunately, because many owners and veterinarians tend to accept some cognitive decline as normal, the true incidence of the disease is probably higher than what is reported.
Another prevalence study followed cognitive abilities in a group of dogs more than 8 years old over a two-year period. They found that 33% of dogs with normal cognitive behavior at the beginning of the study progressed to having mild impairment during the study period. In addition, 22% of the study dogs with mild impairment developed CCD in the same time frame.
The bottom line from all these studies is that CCD is more common than originally suspected, and owners and veterinarians need to be on the lookout for changes consistent with CCD.
Making the diagnosis
Diagnosis of CCD begins with a complete physical examination to look for other conditions that can either mimic CCD or impact the diagnosis.
Signs of CCD can develop in mature dogs (defined as 50-75% of expected lifespan) most people might not consider elderly. Veterinarians should include an assessment of behavior and cognition in annual exams for dogs reaching middle age, while dog owners need to pay special attention to their dog’s mental sharpness, too.
Many signs are associated with CCD, but the most common include:
- Sleep/wake cycle disturbances
- Decreased interaction with owners
- Loss of housetraining
- Aimless wandering/pacing/restlessness
If an owner notices any of these signs, even if infrequent, they should consult with their veterinarian. Many concurrent diseases can be ruled in or out with a complete physical examination and routine bloodwork.
Some common aging-related diseases associated with aging can complicate the diagnosis of CCD. These include:
- Loss of hearing or sight – either partial or complete
- Painful orthopedic diseases such as osteoarthritis that can lead to behavior changes (for example, house soiling)
- Systemic diseases such as chronic kidney disease that can make a dog feel ill and less likely to engage with their owner
For the majority of dogs with CCD, the diagnosis is made after other possibilities are excluded since there are no specific tests for CCD.
That said, there are reports of brain changes detected on MRI that can be helpful in making the diagnosis. MRI also can be considered if other diseases, such as brain cancer, are strong possibilities and further confirmation is needed.
Known risk factors include:
- Age – having been objectively demonstrated in many studies
- Epilepsy – dogs with this disease have a higher likelihood of developing CCD at an early age, and dogs with a history of cluster seizures or high seizure frequency are at the highest risk
- Activity level – dogs engaged in training activities were less likely to develop CCD
Other risk factors, such as sex, reproductive status and anxiety disorders haven’t been shown to be consistently associated with CCD. Some controversy remains about the potential relationship between body size and CCD as well. Many of these questions can be addressed with comprehensive studies such as the Golden Retriever Lifetime Study and the Dog Aging Project that will use standardized assessment tools on large numbers of dogs.
What You Can Do
Keeping your dog fit and trim has many positive effects, such as a greater capacity for exercise, that could indirectly benefit brain health. Dietary supplements and diet may have a role to play, too.
Although still under investigation, increasing evidence shows dietary supplements may slow progression of CCD. These may include:
- Omega-3 fatty acids
- Melatonin (for dogs suffering from sleep/wake cycle disruption)
- B vitamins
Supplements can have negative interactions with medications, so be sure to check with your veterinarian first.
Commercial diets are available that follow many of the dietary recommendations for improving brain health as suggested by research studies.
It’s also possible to formulate a home-prepared diet that combines many brain protective recommendations, but care needs to be taken to make sure the diet supplies adequate overall nutrition. Consult with a veterinary nutritionist, who can help create special diets, and your veterinarian, who can help coordinate this collaboration.
While dogs can’t do crossword puzzles or sudoku, the idea of use it or lose it applies to them, too. Exercise and play remain important, especially as dogs age. Play time that incorporates aerobic exercise (with modifications to account for underlying conditions) is recommended. Introducing new toys and new tricks (yup, you can teach an old dog new tricks) can help keep an older dog’s mental function sharp.
Finding unique ways to stimulate your pet also can provide mental benefits. Many canine rehabilitation facilities are starting to offer programs for senior dogs that include swimming, massage and social interaction in a novel environment. Dogs use their noses to help make sense of their environment, so taking walks and allowing dogs to take their time sniffing is an easy way for older dogs to get additional stimulation.
Adhering to a firm schedule for walking, feeding and bedtime can help older dogs with CCD as well. If a dog is struggling with breaks in house training, owners should think of treating their dog as a puppy, taking the pet out more frequently and rewarding them when they are successful.
The Golden Retriever Lifetime Study and CCD
Each year, our Golden Retriever Lifetime Study participants fill out an extensive questionnaire that includes 100 behavior questions. We know this can get pretty tedious for the participants, but this data serves an important purpose when it comes to capturing subtle behavior changes over time.
As the Study cohort ages, we will be watching and then analyzing these changes. The answers to these important questions, coupled with all the other environmental, nutritional and lifestyle data we’re collecting, will provide a valuable source of information for future researchers interested in normal aging and CCD.