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Tails of Seattle: A pets blog

Your local source for news and tips about dogs, cats and other critters, featuring fun videos, reader photos, Q&As and more.

November 29, 2011 at 6:00 AM

Veterinary Q&A: Dementia and senior dogs

Posted by Neena Pellegrini


Chen-Allencropped.jpgDr. Annie Chen-Allen, an assistant professor of neurology and neurosurgery at Washington State University's College of Veterinary Medicine, answers this week's questions about dementia in dogs. It is part of our series about the health issues facing aging dogs.

Question: What are the signs of senility?

Answer: Dogs with senility, otherwise known as canine cognitive dysfunction syndrome (CCDS), commonly have one or more of the five main symptoms: disorientation, interaction changes, sleeping-habit alterations, house soiling and activity-level alteration. This is otherwise known as DISHA.

Other behavioral changes include aggression, anxiety, sedated states, changes in eating habits and changes in sexual behavior.

Question: Are there different forms of senility? Does Alzheimer's disease exist in dogs?

Question: There are not different forms of CCDS, but just different severity or degree of CCDS.

Alzheimer's has not been proven in dogs, but there are neuropathologic lesions in dogs with CCDS that are similar to those seen in human Alzheimer's patients.

Question: Are there tests to determine if a dog has dementia?

Answer: Unfortunately, there is not a definitive test to diagnose CCDS. It is diagnosed by excluding other diseases that can produce similar symptoms ‒ metabolic disorders such as kidney or liver disease and primary neurologic disorders, such as brain tumors.

It is most helpful when the owner can provide a thorough history that includes a detailed description of the behaviors the pet is exhibiting. Many CCDS researchers have questionnaires and other tools to help define the changes the owners observe at home.

Videotape of the behavior is also helpful because the animal is more likely to show changes in cognitive function at home than in the stressful environment of a vet clinic.

Advanced imaging can be a useful (although not a definitive) diagnostic tool for identifying the brain pathology in patients with CCDS.

brainscans.jpg

Magnetic resonance imaging (MRI), in particular, is especially good at looking at brain tissues and identifying abnormalities in brain intensity, shape or symmetry.

In patients with CCDS, the brain may look smaller and asymmetric. The ventricles ‒ a normal structure in the brain that holds spinal fluid ‒ can also be enlarged. Other researchers have found the thalamus, a specific area in the middle of the brain, may be smaller in aged dogs with CCDS when compared with younger dogs.

While MRI may not be available or may be too costly for some owners, it is a necessary tool to rule out other causes of CCDS, such as brain tumors.

MRI becomes even more important for patients with presumed CCDS and concurrent abnormal neurologic examination because dogs with true CCDS should not have other neurological problem.

Therefore, having your pet evaluated neurologically would be an important step to making a diagnosis of CCDS.

Question: Is CCDS most common in senior animals, or can there be early onset cases?

Answer: Studies have shown that it is more common in patients older than 9 years, in females, neutered animals and smaller animals (weighing less than 33 pounds).

However, other studies have shown that CCDS prevalence increases with age, but sex and weight did not significantly impact the risk of developing CCDS.

Researchers have shown that the prevalence of CCDS is 14.2 percent in dogs aged 8 to 19.75 years.

Question: How do you separate the diagnoses of neuropathology and senility? Does your dog not respond to commands because it is deaf or because of a tumor or because of advancing senility? Is your dog having accidents in the house because of a physical problem or forgetfulness?

Answer: CCDS is still being researched, and there is not one definitive cause of these changes in aged dogs.

There now are several pathophysiologies that are the most supported in the literature, and some that are not yet proven to be consistent.

A protein deposit called amyloid has been found in dogs with CCDS. This protein has been pinpointed as being neurotoxic, causing brain cells to die. This similar pathology has been found in human patients with Alzheimer's disease or dementia.

Other dangerous products, such as reactive oxygen species (ROS), can also lead to brain-tissue damage causing signs of CCDS. In Alzheimer's disease and human-brain aging, ROS is also thought to play a large role in cognitive deficits.

Lastly, brain atrophy or shrinkage and larger ventricles have been implicated in causing cognitive decline in senior dogs.

The hippocampus, a part of the brain that is primarily responsible for memory, and the cerebral cortex, also responsible for memory and awareness, are the parts of the brain most severely affected by the atrophy/shrinkage.

The only way for you to tell if your dog is not responding to commands because it is deaf, has a brain tumor or has CCDS, would be to rule-out the other possible causes.

For deafness, a hearing test can be done by a neurologist. To diagnose a brain tumor, a MRI of the brain can be done. Once everything is ruled-out, then the likely diagnosis for the behavioral changes is CCDS.

If the dog is having accidents in the house, it would be important to rule out a urinary tract infection, kidney disease or brain tumor before deeming the dog as being forgetful because of senility.

bobalottoy1.jpgThirteen-year-old Louie, right, stays busy pushing an interactive toy around the kitchen floor. As the toy bobs around, it dispenses treats.

Question: Can keeping a dog mentally active or "working" help it stay more alert and less likely to become senile?

Answer: YES!!!! The least invasive method for treatment of CCDS that has been advocated by researchers is environmental or enrichment therapy.

This mode of therapy can be used alone, but the patient is more likely to show improvement when this treatment option is completed in conjunction with dietary or supplemental (nutra- or pharmaceutical) therapy.

Enrichment therapies can consist of increased dog-human interactions, increased dog-dog interactions, frequent training sessions with owners, increased exercise, cognitive-enhancement toys or cognitive training/testing activities.

There also are toys that can improve the dog's cognitive learning, such as puzzles/mazes with food rewards available at the finish and other toys that hide the food reward that can challenge the dog to problem solve to get to the treat.

Together these activities have been shown to improve not only the dog's quality of life but improve cognitive function.

Question: What are the treatments for the various levels of senility?

Answer: Supplemental therapies for CCDS have been advocated by several research studies. Several products are available; each provides a different mix of vitamins, minerals, antioxidants and other cofactors.

Medium-chain fatty-acid supplements (composed of lauric, caproic, caprylic, capric acids) are believed to help with metabolism in the brain and improve attention, memory, spatial learning and executive function.

Phosphatidylserine has been shown to help with neurotransmitter release and receptor density in the brain for improved memory in affected animals.

Commercialized products are available for the client, such as Senilife® and Aktivait®.

Alternatively, there is also a prescription medication called selegiline (Anipryl®). This medication selectively and irreversibly inhibits certain enzymes that lead to increased levels of certain neurotransmitters (or chemicals) in the brain, which can improve cognitive function. Selegiline also can inhibit ROS in the brain, which can prevent brain damage associated with aging.

This medication does have potential side effects, such as allergic reaction, headache, restlessness, agitation, irritability, sweating, convulsions, uncontrollable or irregular movements, drowsiness, nausea, abdominal pain or diarrhea, insomnia, mild confusion, agitation or anxiety, or dry mouth.

In addition, serious side effects, such as serotonin (a neurotransmitter) sickness, could occur if given concurrently with other antidepressant medications. Signs of serotonin sickness include altered mental status, agitation, rhythmic muscle movements, stiffness, tremors, diarrhea, incoordination and fever.

Question: What about diet?

Answer: One of the easier methods of treatment available for CCDS is a strict dietary change for the pet.

Hills' Prescription Diet® b/d® (Canine Aging & Alertness Diet) is a product available through veterinary clinics that can supplement the affected pet with vitamins, minerals, antioxidants, fatty acids and other cofactors. This formulation is a balanced and complete diet for the pet that provides nutrients for the rehabilitation of brain function while offering a formula appropriate for senior pets with other potential organ dysfunction occurring simultaneously.

While this therapy may be feasible for some clients, it may be too costly for all owners.

Question: What advice do you give owners with an older animal who is becoming confused?

Answer: To have their pet evaluated by a veterinarian to rule-out other medical issues that can cause similar behavioral changes. A thorough physical exam, neurologic exam and blood work including urinalysis should be performed regularly. If neurologic abnormalities are found on the neurologic exam, a MRI of the brain may be needed to rule-out a brain tumor.

To keep animals active both physically and mentally by increasing human-dog and inter-dog interactions.

If CCDS is diagnosed once ruling out other disorders, increased environmental enrichment used in conjunction with dietary, nutraceutical, and/or pharmaceutical therapies can be useful to lessen or slow cognitive dysfunction long-term.

Dr. Annie Chen-Allen

Chen-Allen is an assistant professor of neurology and neurosurgery at Washington State University. She received her Doctorate of Veterinary Medicine from Texas A&M University and completed her internship, neurology residency and master's degree at WSU. Her research interest is in neuro-oncology, specifically in the diagnosis and treatment of brain tumors. She is now establishing a MRI compatible stereotactic brain-biopsy system for the diagnosis of brain tumors in dogs and cats. She lives in Uniontown, Whitman County, with two dogs, three cats and two horses.

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Read our past Q&As:
Veterinary Q&A: More health issues facing aging dogs
Veterinary Q&A: Eye problems in aging dogs
Veterinary Q&A: Halloween treats and pets
Veterinary Q&A: Health issues facing aging dogs
Veterinary Q&A: Why blood work is necessary
Veterinary Q&A: Are prong collars safe for your dog?
Veterinary Q&A: Birth control for pets
Veterinary Q&A: How to find a good vet
Veterinary Q&A: Neutering your dog Part 2
Veterinary Q&A: Neutering your dog Part 1
Veterinary Q&A: Hyperthyroidism in cats
Veterinary Q&A: Incontinence in dogs
Veterinary Q&A: Hanging tongue syndrome
Veterinary Q&A: Bad breath in dogs
Veterinary Q&A: How much is too much exercise for my dog? Part 2
Veterinary Q&A: How much exercise does my dog need? Part I
Veterinary Q&A: A killer called bloat
Veterinary Q&A: Initial care for new puppies
Veterinary Q&A: Knee problems in dogs
Veterinary Q&A: Flea-control treatment
Veterinary Q&A: Bearded dragon lizards
Veterinary Q&A: Vaccinations for indoor cats
Veterinary Q&A: Lumps and bumps
Veterinary Q&A: More on aging dogs and arthritis
Veterinary Q&A: Aging dogs and arthritis
Veterinary Q&A: Puppy and geriatric exams
Veterinary QA: What dogs can safely chew
Veterinary QA: Why does it cost so much to clean a dog's teeth?
Veterinary QA follow-up: More on cleaning a dog's teeth
Veterinary QA: When to spay or neuter

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Do you have a question about pet health? Ask now! We'll pose some of your questions to a local vet in an upcoming post.

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