Canine and feline cognitive dysfunction syndromes are degenerative brain diseases that are often missed until the signs become so advanced that it may be too late to help the pet or owner.
"One of the greatest problems we have with cognitive dysfunction is the lack of awareness, not only on the part of the public, but on the part of the practicing veterinarians. They understand that it is out there, but they don’t appreciate how common it is,” said Jeff Nichol, DVM, a veterinary behavior practitioner at the Veterinary Emergency & Specialty Hospital in Albuquerque, N.M.
"Veterinarians assume that the owner will tell them ‘My older dog is not acting the same’ during the course of an exam,” Dr. Nichol says. "But many pet owners assume the behavior changes are a normal part of aging.”
A large 2011 study out of Australia bears this out.
Researchers found that the overall prevalence of cognitive dysfunction was a little more than 14 percent, but only about 1.9 percent of cases are diagnosed. The same study found that the chances of having cognitive dysfunction increase with age, so that by the time dogs are 15 years old, 41 percent will have at least one sign consistent with cognitive decline. Neilson and Hart estimated the prevalence in geriatric dogs at 68 percent.
In a 2011 review, Gunn-Moore estimated that one-third of cats 11 to 14 years old has age-related cognitive decline, which increased to more than 50 percent of cats 15 years old or older.
Unfortunately, less is known about the cognitive effects of aging on senior cats than on senior dogs, but their management is similar.
Just as veterinarians monitor other body systems in aging pets, they should ask pointed questions about behavior, according to Marsha Reich, DVM, Dipl. ACVB, owner of Maryland-Virginia Veterinary Behavioral Consulting in Silver Spring, Md.
"Just because he’s getting old doesn’t mean that we just stand on the sidelines and let him get old. There are things we can do to intervene and improve the dog’s ability to function and improve its quality of life,” she said.
"This is critical. Early recognition allows for early intervention,” added Gary M. Landsberg BSc, DVM, Dipl. ACVB, Dipl. ECAWBM (behavior), director of veterinary affairs at CanCog Technologies and a veterinary behaviorist at the North Toronto Animal Clinic in Ontario, Canada.
But older dogs have many co-morbidities that must be managed, so veterinarians might need help assuring that behavior issues are addressed.
" Veterinarians should not assume that the pet owner is going to walk in and make cognitive dysfunction the presenting complaint. If you wait for that, you’ve probably waited too long,” Nichol said.
Behavioral experts suggest that the intake staff give the owner a behavioral questionnaire either by email the night before or while they are sitting in the waiting room, which can be filled out before the examination. A quick look by the veterinarian will advise whether there should be a conversation about cognitive decline.
And if the forms are filled out at each visit, the veterinarian will have a history of behavior to help her decide when to intervene.
"Cognitive dysfunction is a decline in learning, memory or awareness due to the age-related changes within the brain, and they are represented clinically by a group of signs related to varying states of dementia,” Dr. Landsberg said.
"The appearance to us is psychological, but the root of the problem is physical,” Reich added.
The brains of dogs and cats undergo similar neuropathology as they age: oxidative damage, neuronal loss, atrophy and the development of ß-amyloid plaques. Although human brains with Alzheimer’s disease develop other pathology that is not seen in canine (or feline) brains, they also develop these ß-amyloid plaques. Because the brains undergo similar pathology as they develop dementia, dogs are a great research model for human dementia.
The knowledge gained from this research not only helps people, but can also help veterinarians help these pets.
"There is such a thing as normal aging,” said Nicholas Dodman, BVMS, Dipl. ACVA, Dipl. ACVB, professor and program director of animal behavior at Cummings School of Veterinary Medicine at Tufts University. He also a behavior column for Veterinary Practice News.
"Some aspects of your cognitive function do decline with age, but cognitive dysfunction in people, particularly Alzheimer’s disease, is not normal aging. It is a pathological dysfunction in the brain,” he said.
"Dogs don’t get the tau protein, which forms neurofibriliary tangles in human brains, but they do get the ß-amyloid plaques. They become confused. They don’t remember things. They can’t figure things out, and it is fairly precipitous.”
Nichol is studying these ß-amyloid plaques on high-resolution MRI. He wants to determine if there is a correlation between more and greater severity of symptoms of cognitive decline with the number of ?-amyloid plaques in the dog’s brain. His hope is that one day there will be a clinical test that can determine early onset cognitive decline.
Until then, diagnosis of cognitive dysfunction remains a diagnosis of exclusion, or as Dr. Reich likes to call it, "a process of appreciation.”
So many conditions in an older pet mimic cognitive decline that it is important to rule out any other physical reason for the complaint.
For instance, if the pet is just standing in the middle of the room staring for a moment, it might be having a partial seizure. If it has disengaged with its owner, it could be in pain. Relieving itself in the house or outside the litter box could signal kidney disease.
Therefore, every senior pet with suspected cognitive dysfunction should receive a CBC and chemistry panel, urinalysis and a neurological examination, the experts said.
"You want to find out what is going on with the pet before you put the dog on medication because the medications for cognitive dysfunction won’t help if the dog has kidney disease,” Reich said. Nichol suggested reviewing the medications the pet is taking because sometimes the senior pet metabolizes drugs differently than younger pets. For instance, he had a patient that had been taking an anti-anxiety drug for a long time, but as it got older, it became confused.
His first thought was that the dog had cognitive dysfunction. But the aging brain produces less acetylcholine. Since the medication blocks acetylcholine development, and the dog was forming less of the chemical, it didn’t need it anymore. When Nichol took the dog off the medication, its cognitive issues resolved.
If a cat is not using the litter box, make sure that it doesn’t have trouble getting in and out of the box. Perhaps it needs a ramp or a space cut out of the side to make access easier. Older dogs that are house soiling might need to go outside more often.
Fortunately, there are treatments that can help manage the problem and delay the progression of the disease. But all the behaviorists said that eventually the disease will progress. It cannot be cured and veterinarians need to make sure that owners recognize this inevitability.
Depending on how far the cognition has declined before it is discovered, the goal is increasing quality of life for months, maybe a few years.
Teaching old pets new tricks
Changes in the diet are the first steps. The behaviorists recommend putting the dog on an anti-oxidant-rich diet, such as Hill’s Prescription Diet b/d or Purina’s One Vibrant Maturity 7+ Senior formula. Many also prescribe fish oil because omega fatty acids might be good for brain health.
Selegiline (Anipryl, Zoetis), which is used to treat human dementia, is the only medication with a veterinary indication to treat canine cognitive dysfunction. However, several dietary supplements have also been shown to improve cognitive dysfunction, including:
• Neutricks (Quincy Animal Health), which contains apoaequorin;
• Novifit (Virbac Animal Health), which contains S-adenosyl-L-methionine (SAMe); and
• Activait (Vet Plus Ltd.) and Senilife (CEVA Animal Health), which contain phosphatidylserine and a mix of antioxidants.
Some dogs seem to have more problems at night. They sleep all day and are awake all night. They pace. They make noise. They might be anxious and uncomfortable. Behaviorists recommend melatonin, which not only promotes sedation, but is also an antioxidant.
If the dog appears anxious, Reich recommends an additional nutraceutical, Anxitane (suntheanine, Virbac).
They tend to use all of the supplements together. "The scientific way is to start with one treatment, and see how it works. But dogs don’t have that much time. We use all these modalities at once,” Nichol explained.
Exercise is another important component of the program. Taking the dog for a leash walk enables it to use all of its senses, but Reich said to make sure the owner understands the dog’s limitations. Don’t turn a simple walk into an endurance contest. No one benefits if it is too strenuous or stressful.
"Exercise is helpful,” she said, "but one has to stay within the dog’s physical limits. Make sure that people don’t overdo it.”
Just as staying active helps a person with dementia, playing and working with the owner helps to mentally stimulate the pet. Puzzles and toys that require mental agility can stimulate their brains.
"Enrichment plays a key role in slowing cognitive decline,” Landsberg said. "Both physical exercise and mental activities–training, food manipulation toys and games–are beneficial. In addition, behavior counseling (and sometimes other psychotropic drugs or natural supplements for anxiety) will often be needed to improve behaviors such as night waking, house soiling and fears and phobias.”
Once a dog starts to respond to the therapies, owners can begin re-training it. The training techniques are the same ones they applied to puppy training and should be full of rewards and praise.
Training and games that involve the owner are especially important, Nichol said, because they help maintain the human-animal bond. "Owners miss that interaction with their dogs,” he said.
None of these will provide much help for a dog that is in the end-stages of cognitive decline, so it is crucial to diagnose this disease and start making changes, such as a one of the supplements or diets for brain aging, as the dog hits its senior years.
Cognitive dysfunction is a progressive problem that cannot be cured, Dr. Dodman noted, so early recognition and treatment could "buy some extra quality time.”