Climate change among factors that influence tick season, geographic spread of ticks
By Kim Campbell Thornton
Tick season is between May and September, right? That has been the conventional wisdom -- until recently.
Two recently published studies found that deer, or black-legged, ticks -- the ones that spread Lyme disease -- are emerging earlier and expanding their range, thanks to warmer spring temperatures and milder fall weather. Based on data collected over 19 years, researchers concluded that milder weather allowed nymphs -- immature ticks -- to feed as much as three weeks earlier in spring. The change in activity may presage a spread of tick-borne diseases, one that's already being seen in some areas.
Tick populations have moved northward into Canada, making Lyme disease endemic in southern Ontario, says Susan E. Little, DVM, who teaches veterinary parasitology at Oklahoma State University and is president of the Companion Animal Parasite Council. Ticks have also moved up in altitude and are now found at higher elevations in Appalachia than in the past.
"It used to be that ticks weren't at 3,000 or 4,000 feet, and now they are," Dr. Little says. "That's a change that we think is due to warming trends."
Ticks are also moving farther south. From its origins in the Northeast, Lyme disease is now established down the Virginia coast and into North Carolina. In the Midwest, ticks are moving southward across Iowa, through the northern half of Illinois and most of Indiana, and into the lower peninsula of Michigan. One or more species of tick can now be found in every state, including Alaska.
Climate isn't the only culprit. Ticks piggyback on wildlife such as white-tailed deer and coyotes, which spread them to new habitats; they can also be carried away by migratory birds. Habitat modification, such as increasing development in formerly rural areas, also contributes to the expansion of tick territory.
"We're seeing a general expansion of range," Dr. Little says. "It's probably facilitated by longer, warmer periods in most of the country."
If you're still digging out from the snow that buried much of the Northeast this winter, you may have your doubts about that. But even if ticks aren't active all 365 days of the year, they are active every month of the year. There will always be a few days that are warm enough for them to make an appearance.
A tick begins the disease transmission cycle when it inserts its sharp mouthpiece into a rodent or deer and feeds on its blood. In the process, the tick takes in bacteria, protozoa and viruses that it later passes on to cats, dogs and humans.
Yes, cats, too. They don't appear to get Lyme disease -- yet -- but ticks can transmit a deadly disease called cytauxzoonosis to cats, as well as ehrlichia and anaplasmosis.
What can you do to ward off the beastly bloodsuckers?
-- Start thinking about tick prevention before May. Dr. Little recommends year-round protection, no matter where you live.
-- Talk to your veterinarian about the best tick preventive measures for your pet's lifestyle, as well as about the species of ticks found in your area. Products include oral preventives that kill both ticks and fleas on dogs, and long-lasting anti-tick collars for use on dogs and cats.
-- Keep grass short and foliage trimmed back to reduce tick habitat.
-- Discourage deer from grazing near your yard.
-- Indoor pets can be at risk, too. You can bring ticks in on your clothing or body -- it's happened at my house -- and the brown dog tick (Rhipicephalus sanguineus) prefers to live indoors.
Pets don't directly spread tick-borne diseases, but they can bring you into contact with ticks -- and vice versa. If your cat goes outdoors or your dog hikes or hunts with you on a regular basis, tick prevention can help protect all of you from disease.
Canine liver disease
affects several breeds
Q: My Labrador retriever has been diagnosed with chronic hepatitis. He's being treated, but do I need to worry that he could pass on the disease to family members or friends? What can you tell me about this disease?
A: First things first: The good news for you is that canine chronic hepatitis is not a disease that can be transmitted to people.
Canine chronic hepatitis is a weird disease. It's not actually a single disease, but a group of liver diseases, none of which we understand very well. Some forms appear to be autoimmune-related, while others are associated with high levels of copper in the liver. Sometimes, cases are associated with infection or drug toxicity. When the cause is unknown, the disease is referred to as idiopathic chronic hepatitis.
Clinical signs tend to be vague -- poor appetite, weakness, yellow tinge to the whites of the eyes -- and may not become apparent until the condition is far advanced. Vomiting, diarrhea, weight loss and excessive thirst and urination can also be signs of chronic liver disease. Canine chronic hepatitis usually affects middle-aged dogs, male or female, but adults of any age can be affected.
It may also impact certain breeds more commonly, including cocker spaniels, Doberman pinschers, Dalmatians, Labrador retrievers, Skye terriers, standard poodles and West Highland white terriers. In Bedlington terriers, chronic hepatitis is caused by a buildup of copper that eventually damages the liver.
Depending on the apparent cause and stage of the disease, treatment may involve antibiotics, medications to help support the liver, anti-inflammatory drugs or drugs that treat or prevent the buildup of copper in the liver. Your veterinarian may also recommend certain dietary changes or vitamin supplements to help reduce the level of copper in the body or help the body excrete copper more effectively. It's a good idea to test dogs at high risk for chronic hepatitis early in life. -- Dr. Marty Becker
Do you have a pet question? Send it to email@example.com or visit Facebook.com/DrMartyBecker.
Dog's nose for cancer
may improve treatment
-- A scent-trained German shepherd mix named Frankie had an 88 percent success rate in detecting thyroid cancer in human urine samples. A study presented earlier this month at the Endocrine Society meeting in San Diego found that the accuracy of the canine "diag-nose-tician" is only slightly less than that of the more invasive fine-needle aspiration biopsy, not to mention less expensive.
"Frankie is the first dog trained to differentiate benign thyroid disease from thyroid cancer by smelling a person's urine," says study co-author Arny Ferrando, Ph.D., of the University of Arkansas for Medical Sciences in Little Rock, where the study was conducted.
-- Have you ever wondered which cat breeds are largest and smallest? Compared to dogs, cats don't vary a great deal in size: There might be a feline equivalent to the Chihuahua, but not to the Great Dane (lucky for us!). Among the heaviest breeds are Norwegian forest cats and Maine coons, weighing 7 to 22 pounds; Siberians, 10 to 20 pounds; Turkish vans, 7 to 19 pounds; and Savannahs, 20 pounds or more. Falling into the featherweight category are the singapura, 4 to 7 pounds; and the Cornish rex, Devon rex and Japanese bobtail, all weighing 6 to 9 pounds.
-- Genetic testing isn't enough to improve the health of purebred dogs, say scientists at the University of Edinburgh's Roslin Institute. To improve genetic diversity, they recommend a combined approach using DNA analysis, health screening, limiting the use of individual stud dogs, and cross-breeding -- an approach that has been successful in breeding Dalmatians lacking a genetic defect that causes kidney stones, a common problem in the breed. Screening dogs for health problems before breeding them has helped to reduce the prevalence of some diseases, and DNA tests may help to eliminate disease-causing genes, but relying solely on tests and screening can reduce the gene pool. -- Kim Campbell Thornton
ABOUT PET CONNECTION
Pet Connection is produced by a team of pet-care experts headed by "The Dr. Oz Show" veterinarian Dr. Marty Becker and award-winning journalist Kim Campbell Thornton. They are affiliated with Vetstreet.com and are the authors of many best-selling pet-care books. Joining them is dog trainer and behavior consultant Mikkel Becker. Dr. Becker can be found at Facebook.com/DrMartyBecker or on Twitter at DrMartyBecker. Kim Campbell Thornton is at Facebook.com/KimCampbellThornton and on Twitter at kkcthornton. Mikkel Becker is at Facebook.com/MikkelBecker and on Twitter at MikkelBecker.
CAPTIONS AND CREDITS
Caption 01: Help protect yourself from tick-borne diseases by wearing gloves when removing the nasty bloodsuckers from your cat or dog. Position: Main Story
Caption 02: Dogs trained to detect cancer could lead to cost savings in diagnosis and prevention of unnecessary surgeries. Position: Pet Buzz/Item 1