Aging pets, like people, can suffer mental decline that is not considered a normal part of aging. Last week we wrote about the signs and symptoms of cognitive dysfunction syndrome, or CDS. This week we're looking at how it's diagnosed. (Read all our CDS posts.)

Diagnosing cognitive dysfunction syndrome can be tricky. "There is no specific test for CDS," says Karen Johnson, DVM, of Banfield Pet Hospital in Portland, OR. "The diagnosis is made based on age, symptoms and ruling out medical issues that can cause cognitive changes."

Since CDS is a "diagnosis of exclusion," your vet will test for a variety of other conditions to see if they can be ruled out. According to Dr. Johnson, tests would typically include basic blood work, a thyroid test, urinalysis, a neurologic exam and possibly x-rays or ultrasound.

"Some types of liver disease can cause changes that could mimic CDS, as could other types of brain disease, including cancer," Dr. Johnson says. "Any illness has the potential to cause changes in mental status when normal physiologic parameters -- blood pressure, electrolytes, etc. -- are affected."

The tests can be expensive, but they're worth it -- they may identify a treatable condition. "The earlier a correct diagnosis is made and treated appropriately, the better the chance of being able to manage it," says Dr. Johnson. "Also, it's usually less expensive for the client and traumatic for everyone if a correct diagnosis can be made early."

If your vet ultimately diagnoses your pet with CDS, don't despair: "The pet owner should understand that while treatment -- medical and environmental -- doesn't change the progression of disease, it can make a difference in quality of life for both the pet and family," Dr. Johnson says.

After the jump: Questions to ask your vet.

Aging pets, like people, can suffer mental decline that is not considered a normal part of aging. Recently we wrote about cognitive dysfunction syndrome, or CDS, in senior pets. This week we're looking at its common symptoms.

Recognizing and diagnosing cognitive problems in pets can be tricky. "Many pet owners think their older dog is losing his vision or hearing when in fact the pet is having a hard time recognizing or identifying certain sights or sounds," says Calabash, NC-based veterinarian Ernie Ward.

Is your pet showing signs of CDS? Only your vet can tell you for sure, but it's important that you carefully observe any changes in your pet's behavior. According to the the Ohio State University College of Veterinary Medicine, these are the key symptoms to look out for: