Canine cognitive dysfunction syndrome (CDS) is a neurodegenerative condition that is common in older dogs. The disorder is analogous to Alzheimer’s Disease (AD) in humans. Prevalence of CDS in the pet dog population is estimated between 14% to 35%. Dogs with CDS often display slowly progressive signs of behavioral change and dementia. This may include confusion, anxiety, changes in sleep pattern as well as a decrease in interaction with owners. Early in the course of the disease, pet owners may attribute subtle clinical signs to normal aging. However, as the disease progresses, severe cognitive impairment can impact quality of life.
Any dog above the age of 8 years may develop CDS. Although some studies suggest that female, spayed/neutered dogs, and patients with smaller body size are at higher risk of developing CDS, other studies have found no association between the aforementioned factors. Idiopathic epilepsy (a group of seizure disorders that come about from abnormal activity in the brain) is thought to be associated with an earlier age of onset of CDS in dogs.
There are many clinical signs associated with CDS that may present throughout the course of the disease. The acronym DISHAA groups these signs based on changes in behavior as well as interactions. The DISHAA scoring table is a helpful tool for veterinarians and owners to determine the mental sharpness of their pet.
Although there are many clinical signs associated with CDS, disturbance of the sleep-wake cycle is most prevalent in the early stages of the disease. It is worth noting that every patient’s case is different; clinical signs as well as progression of signs may vary between individuals.
A diagnosis of CDS is typically made based on a patient’s signalment, history and clinical signs. Your veterinarian will perform a complete physical and neurological examination as well as routine blood tests to rule out other diseases. As described in the previous section, the use of the DISHAA checklist can be helpful in making an initial diagnosis. Patients with CDS can show age-related changes on magnetic resonance imaging (MRI) of the brain. It should be known that these MRI changes may also be found in older patients without evidence of CDS. More objective measures of CDS include tests such as delayed nonmatching to position (DNMP) memory task (a test of working memory in animals) and the attention task. These are, however, not routinely performed in clinical practice.
The goal of CDS treatment is to slow down progression of the disease. Although there is no cure for CDS, early intervention can ensure a patient maintains good quality of life. Broadly, treatment options can be divided into 3 categories which include 1) diet, 2) drug therapies and 3) environmental & behavioral enrichment.
Diet: In AD, a correlation has been found between diet and cognitive decline. Similarly, in CDS, dogs should be maintained on an appropriate diet to slow down progression of the disease. Recommended diets are typically rich in antioxidants, vitamin B, vitamin C, vitamin E, certain types of fats (medium-chain triglycerides and omega-3s) and other supplements such as mitochondrial cofactors & carotenoids. At present, there are several commercial diets that specifically cater to geriatric patients. These include Purina Bright Mind & Hill’s Brain Aging Care.
Drug therapies: There are multiple drugs used to delay the progression of CDS. Selegiline hydrochloride (Anipryl) is an approved medication for the control of CDS. The drug assists in restoring the dopamine balance in the brain. Studies have shown that dogs with CDS can respond to Selegiline hydrochloride after a month of treatment. Improvements in activity levels, sleep cycle and house training were observed. A list of other drugs used in the treatment of CDS is listed below.Other drugs used to treat CDS: Anti Inflammatory drugs (eg. Carprofen), Levetiracetam, Pregabalin/Gabapentin, S-adenosylmethionine (SAMe), Apoequorin)
Environmental & behavioral enrichment: Environmental & behavioral enrichment is an important factor in slowing the progression of CDS. In humans with AD, intellectual stimulation has been shown to slow the rate of mental decline. Social interaction, exercise and “thinking” games should be part of the daily routine of any patient with CDS. Regular exercise is particularly helpful in giving dogs a sense of routine, it can also improve sleeping habits in dogs with disturbances in the sleep-wake cycle. “Thinking” games include puzzle feeders, playing hide and seek as well as teaching them tricks. There are many pet rehabilitation facilities which provide enrichment activities.
Household modifications may be required to assist pets with CDS. This could include placing more potty pads around the house to help with inappropriate house soiling. It may be helpful to provide more surfaces with traction (i.e., rubber mats or carpets) to allow pets with CDS to move around more comfortably. Providing your veterinarian with more information on your household will allow them to make more specific improvements/ changes.
As described earlier, many owners may attribute the first signs of CDS as part of normal aging. However, as the disease progresses, clinical signs may increase and/or worsen, ultimately affecting the daily life of both pets and owners. It is therefore helpful to consult with your veterinarian should you notice any changes in your pet consistent with CDS. The key to CDS is early intervention and to assist a pet in the process of healthy aging. Dogs with CDS that are diagnosed early in the course of the disease can have a good long-term quality of life.