WESTBROOK, Maine, Apr 17, 2001 /PRNewswire via COMTEX/ -- Ah, spring! For many Americans, the season brings warm weather, green grass, blooming flowers -- and ticks carrying bacteria that cause disease, including Lyme disease. As the fastest growing tick-transmitted disease in the United States, Lyme disease may threaten the health of twice as many dogs as it does humans.

"According to experts with the Centers for Disease Control and Prevention (CDC), more than 16,000 cases of Lyme disease in people were reported during both 1998 and 1999 -- and CDC experts believe the disease is underreported," says Jan K. Strother, DVM, a companion animal veterinarian in Harselle, Ala.

"Studies conducted in Connecticut and Maryland found an estimated seven to 12 unreported cases for each reported case.(1,2) Unfortunately, dogs are at much greater risk for Lyme disease than are people living in the same geographic area and the ratio of unreported cases could be even higher."

Tick season typically starts the last week of March and is at its highest level for the next six to eight weeks, putting millions of dogs and people at risk for Lyme disease and several other tick-transmitted diseases. Human Lyme disease has been reported in all 50 states except Alaska.

"The vast majority of Lyme disease cases in people -- more than 90 percent -- have occurred in eight Northeastern and mid-Atlantic states and two upper Midwestern states," Strother explains. "But Lyme disease cases also are common in some areas on the Pacific Coast, specifically in California and Oregon. And since ticks may move with people and dogs, this disease could appear anywhere."

According to CDC reports, human Lyme disease is most prevalent in these 10 states (ranked in descending order based on the number of reported cases in 1999): New York, Connecticut, Pennsylvania, New Jersey, Maryland, Massachusetts, Rhode Island, Wisconsin, Minnesota and Delaware. California and Virginia are not far behind Delaware in number of cases reported each year.

Lyme disease is caused by a corkscrew-shaped bacterium, Borrelia burgdorferi, that is found in certain species of ticks, including the black-legged (deer) tick (Ixodes scapularis) and the Western black-legged tick (Ixodes pacificus). The disease is transmitted when an infected tick bites a dog, person or other mammal. If not removed, the tick may feed for as long as four days. Ticks must be attached for at least 24 hours before the bacterium is transmitted through saliva to the bite wound.

"In many areas of the country, people and their pets are at moderate to high risk of exposure from April to November," Strother states. "Ticks are most active at this time when people and their pets are spending more time enjoying outdoor activities.

"A number of factors have contributed to increased risk of Lyme disease," she continues. "These include a large black-legged tick population, resulting from an exponential increase in the U.S. deer population; increased recreation; extended forest cover, especially in the Northeast; reduced hunting in some areas; and continued suburban sprawl. Suburban living has brought more dogs into areas frequented by ticks and the animals that serve as hosts or reservoirs of disease."

The most common signs of Lyme disease in dogs are recurrent arthritis and lameness that lasts for only three to four days, sometimes with a loss of appetite and depression. Dog owners should be aware of these warning signs: Sudden occurrence of lameness, reluctance to move or a stiff, painful gait; warm, swollen joints; pain in the legs or throughout the body; fever; fatigue; loss of appetite; and swollen lymph nodes. The signs may come and go, vary in intensity from mild to severe, and can mimic many other conditions. If Lyme disease is suspected, a dog owner should contact his or her veterinarian as soon as possible to have the dog tested.

Fortunately, there's a new blood test available that screens dogs simultaneously for Lyme disease, heartworm disease and ehrlichiosis, another rapidly emerging tick-transmitted disease. The new in-clinic diagnostic test -- SNAP(R) 3Dx(TM), available from IDEXX Laboratories, Inc. -- takes only eight minutes and provides an accurate result, even if a dog has been vaccinated against Lyme disease. With this quick, inexpensive test, the dog owners has the benefit of knowing if the dog has been exposed even before leaving the clinic.

"The American Veterinary Medical Association recommends testing for Lyme disease in the spring and fall, whether or not a tick has been found on your dog," Strother says. "Knowing if your best friend has been exposed to the bacterium that causes Lyme disease provides peace of mind. A dog with a positive test result may not develop the disease, but at least you and your veterinarian will know to watch for possible signs. That bit of knowledge is really the greatest benefit of the new in-clinic test."

Strother encourages dog owners to ask their veterinarians about having their dogs tested for Lyme disease during their next visit.