New Hope for Senior Dogs
'Senile' dogs may get a second chance.
Susan Bertram, DVM |
Posted: Mon Oct 14 00:00:00 PDT 2002
In the autumn of 1996, Sasha's family noticed the 12-year-old Dachshund behaving oddly. Minutes after eating a full meal, Sasha waited at her food dish as if she had forgotten she had eaten. She went outside to relieve herself, and as soon as she was back in the house, she sat by the door expecting to be let out again. She often got lost in her own back yard until someone went looking for her. Sasha also started having housetraining accidents.
Jeffery Richman, DVM, faced a dilemma. He examined Sasha and ran lab tests but found no health problems. The dog's memory loss and confusion were symptoms of her aging brain. Dr. Richman began to think Sasha would have to be put to sleep. That decision would be all the more difficult because Dr. Richman is also Sasha's owner. "Owners had been telling me for years how their old dogs seemed to be 'losing their marbles,' and I'd say, yes, I call it 'Dogsheimer's disease,'" said Dr. Richman, owner of Richman Animal Clinic in Richmond Heights, Ohio. "They'd ask 'Is there anything we can do?' and I would have to tell them no."
But that "no" has since changed to a "yes." Richman learned about a new drug called l-deprenyl, normally used to treat dogs with Cushing's disease, a hormone imbalance. After two months on the medication, Sasha was a different dog. "It was as if she was young again," Dr. Richman said. "She realized when she ate, when she went to the bathroom; she didn't get lost anymore or have accidents in the house. [The drug] gave us our dog back."
Sasha and perhaps millions of other old dogs suffer from canine cognitive dysfunction syndrome, also known as canine cognitive disorder or "old dog syndrome." Experts maintain that this is not Alzheimer's disease in dogs, although there are similarities. CDS describes a cluster of behavioral changes in older dogs that occur as cognitive abilities (mental functions such as memory, learning, awareness and perception) decline.
Some dogs remain sharp throughout their golden years, but dogs affected by CDS may experience disorientation, decreased interaction with owners, sleep disturbances and house-training problems.
Dogs as young as 8 years old may show signs of CDS; it can affect any breed and worsens with age. "Dogs are living longer because of better health care," said Debra Horwitz, DVM, diplomate of the American College of Veterinary Behaviorists in specialty practice in Bridgeton, Mo. "So we are seeing proportionately higher numbers of dogs being affected by this disease."
As the body ages, so do all the major organs, including the brain. Some changes may reduce "brain power." An accumulation of beta amyloid, a protein that is toxic to neurons (active brain cells), creates "plaques," which are believed to diminish cognitive function.
With aging, neurotransmitters - the brain's chemical messengers - don't function as well. Dopamine, one of the most important neurotransmitters, is less effective in dogs with cognitive dysfunction. This is one area where treatment can help. In the early 1990s, researchers studying the similarities between aging dogs' and humans' brains discovered that a drug used to treat Parkinson's disease in humans improved the memory of some geriatric dogs. The drug l-deprenyl (also called selegiline) is now offered to veterinarians under the trade name Anipryl, manufactured and marketed by Pfizer Inc. It works by inhibiting the enzyme that breaks down dopamine. As a result, the transmission of chemical messages required for cognitive function is enhanced.
The FDA approved use of l-deprenyl for treating CDS in the United States in December 1998; it has been used in Canada since 1996. L-deprenyl was first approved in the United States in 1997, but only for treating a form of Cushing's disease in dogs. Until the availability of Anipryl, veterinarians could offer owners of CDS-affected dogs little more than sympathy. " Owners and their dogs often just lived with the problem," said Gary Landsberg, DVM, diplomate of the American College of Veterinary Behaviorists, of Doncaster Animal Clinic in Thornhill, Ontario. "Many dogs were probably put to sleep earlier, not because of medical problems but because of the behavior changes." Anipryl doesn't cure CDS, but it can help improve quality of life and even extend the life of many dogs.
Letha Melton of Bend, Ore., thinks her 15-year-old Australian Cattle Dog mix, Ashes, may have cognitive dysfunction. "For the last few months, she has stood in the kitchen, staring at nothing, or she has whined for no apparent reason," Melton said. Ashes has trouble recognizing familiar people: "She has even growled at my parents, who she thinks the world of." She has to encourage Ashes to eat by tapping on the food dish, reminding her to take another bite. Melton plans to take Ashes to her veterinarian to confirm the diagnosis.
Veterinarians can't tell by looking at a dog if it has cognitive dysfunction, nor can they order a "cognitive dysfunction test." Older dogs often have more than one body system showing signs of wear that mimic CDS. Housetraining accidents may be related to kidney disease, diabetes or hormone imbalances, for example. A dog that paces restlessly, unable to lie down comfortably, may suffer from arthritis. Loss of interest in food may be a sign of a dental or metabolic disease, or cancer. A dog that seems to ignore its owner's commands may be losing its hearing.Proper diagnosis requires:
- A geriatric checkup, including a neurologic exam to check brain and nerve functions.
- Blood and urine tests to rule out medical causes for behavior changes.
- A behavioral history to rule out purely behavioral causes.
"Old dogs can be affected as much as younger dogs by changes such as a move to a new home, the addition of a family member or a change in the owner's work schedule," Landsberg said. Dogs may whine, pace, or house-soil because of stress or anxiety.
Experts suggest many cognitive dysfunction cases go undiagnosed because people assume old age, not a medical condition, is the culprit. A recent survey of veterinarians estimated fewer than 7 percent of owners volunteer such information. Yet a study conducted at the University of California-Davis School of Veterinary Medicine indicates the prevalence of cognitive dysfunction may be high. Thirty-two percent of the 11-year-old dogs and 100 percent of 16-year-old dogs showed one or more signs.
Sparky, a 14-year-old Terrier/Cocker Spaniel mix, was brought to his veterinarian, Dr. Anthony Braithwaite at the Kingsville Animal Clinic in Kingsville, Ontario, to be put to sleep. Dr. Braithwaite could see gray in Sparky's whiskers, but otherwise the dog looked good for his age. "He was bouncing around the room and certainly didn't look like a dog that had come to the end," Dr. Braithwaite said. "Yet I could see that his owner was close to tears, so I had to ask why are we doing this?"
Sparky's owner said he couldn't live with the dog's behavior anymore: Sparky had been defecating indoors, usually in the middle of the night, next to the owner's bed. "That very morning, the man had stepped from his bed, right into the odorous pile, and it as just the last straw," Dr. Braithwaite said. Sparky's owner described other signs of disorientation. After lab work and a checkup ruled out medical problems, the owner tried Anipryl. "About two weeks later, the family sent a lovely thank-you card. Not only had Sparky's nighttime soiling stopped, but he was sleeping through the night and acting more playful than he had for several years. The availability of Anipryl has changed the way we handle geriatric checkups."
L-deprenyl isn't a cure-all and won't help every patient, but experienced veterinarians agree it's worth trying for a month. If no improvement is seen, a second month of increa sed dosage is recommended. If it helps, the medication continues once a day for the remainder of the dog's life. Free of serious side effects, the medication's only drawback is its expense, which can be more than $2 per day, depending on the dog's size.
No other medications are approved for treating cognitive dysfunction in the United States. As research progresses on cognitive dysfunction in dogs and Alzheimer's disease and other forms of dementia in humans, other CDS treatments should become available. Nicergoline, a drug that increases cerebral blood flow, is available in the United Kingdom for treating dogs' age-related behavioral disorders - and one day may be available here. Gingko, antioxidants and other compounds purported to help maintain brain function have yet to be proven.
Meanwhile, owners can help prevent mental deterioration in older dogs through ongoing activities. "People can engage their dog in activities that stimulate mental function." said Dr. Horwitz. She suggests taking the dog for exploratory walks where it can use all its five senses. Daily play sessions and continuous training also help keep older dogs vital and active. "The concept of use-it-or-lose-it applies here," she said.
So why not teach that old dog some new tricks? It's for his own good.
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