August 14, 2024 – 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.
At the Foundation, we love those sugar muzzles too. Senior dog health and aging is the topic of our current call for proposals, and there are several active studies devoted to finding answers for some of the critical health problems affecting senior dogs. Our focus in this area is in direct response to calls for more research by our donors and supporters.
One of the most important senior dog health concerns voiced by senior pet parents is a decline in mentation and behavior in older dogs. Owners will describe their dogs as “senile” or having “dementia.” In fact, a recent Morris Animal Foundation pet owner survey showed that 36% of respondents listed senior dog health as an area 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 syndrome (CDS).
Before we take a closer look at CDS, it’s important to learn more about what is considered normal aging.
When Normal Aging Isn’t Normal
It’s not unusual for us (and our pets) 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 CDS.
Veterinary neurologists, behaviorists and CDS experts report that the three most common misconceptions about canine aging are:
• Cognitive impairment reflects normal aging and is inevitable
• CDS 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 CDS. The earlier that signs of CDS are detected, the sooner owners can intervene to reverse or slow disease progression.
Now that we know a bit more about normal and abnormal aging, we can take a deeper dive into CDS.
What We Know About CDS
CDS is a neurodegenerative disease like Alzheimer’s disease in people. Studies in dogs with CDS 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 CDS can be reversed while this is generally not the case with Alzheimer’s.
The estimated prevalence rates of CDS range from 14% to 35% in the pet dog population, with the prevalence dramatically increasing as dogs age. One study found the prevalence of CDS 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 CDS in the same time frame.
The bottom line from all these studies is that CDS is more common than originally suspected, and owners and veterinarians need to be on the lookout for changes consistent with CDS.
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 acronym DISHAA summarizes the most commone ones:
• D – Disorientation
• I – Change in social interactions, such as increased fear, withdrawal, aggression
• S – Change in sleep/wake cycle, such as pacing, vocalization, restlessness
• H – House soiling, learning and memory changes
• A – Change in activity (loss of interest in some activities, restlessness, pacing)
• A – Increased anxiety
If you notice any of these signs, even if they’re infrequent, consult with your veterinary care team. Other diseases of aging, such as osteoarthritis, kidney and heart disease, can have signs that overlap with CDS. It’s important to treat any concurrent diseases, since some experts have suggested other diseases can exacerbate or accelerate cognitive decline.
Most experts don’t recommend that additional diagnostic testing, such as MRI or CT, be performed on dogs diagnosed with CDS unless there is a strong suspicion that other diseases, such as cancer or inflammatory disease, are contributing to the signs. That said, there are reports of brain changes detected on MRI that can be helpful in making the diagnosis. More work needs to be done to learn if advanced testing is beneficial in these patients.
Risk Factors
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 CDS
Other risk factors, such as sex, reproductive status and anxiety disorders haven’t been shown to be consistently associated with CDS. Some controversy remains about the potential relationship between body size and CDS 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 CDS. These may include:
• Omega-3 fatty acids
• SAM-e
• 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. However, to date, there are no large studies looking at the efficacy of these diets.
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.
Active Minds
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 CDS 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 CDS
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 CDS.
In addition, the Neuropathology Initiative, launched in 2022, is collecting brain tissue samples from dogs in the Golden Retriever Lifetime Study to learn more about CDS as well as Alzheimer’s disease. The team continues to collect samples and the project should be completed in the next 3-4 years.
Moving Forward
The Foundation recognizes that there is a need for more studies focused on the issues affecting our senior dogs. Because of this need, our scientific programs team chose senior dog health and welfare as the topic for this year’s canine grant proposal selection. Grant submission is in progress, with our expert team of reviewer’s scheduled to meet in October to select the best proposals for funding.
We can’t do this work without the support of the thousands of donors who help fund the innovative science that’s made us a leader in canine health studies. The sad fact is that each year there are worthy studies we simply can’t fund due to a lack of resources.
Science to Save Animals Starts with YOU!
Innovative animal health research takes vision as well as financial investment. That’s why Morris Animal Foundation, with the generous support of our donors, continues to fund this important work to change the odds for animals suffering from diseases and painful health conditions. DONATE TODAY and support critical science to save the animals you love!
Resources
TEDxMileHigh webinar – Cognitive Health in Dogs and Cats
