By: Delores Gockowski, DVM
Fever, fatigue and lameness are often signs a dog is sick with a tick-borne disease, but some dogs will not show any signs of illness. Of regional importance are Lyme disease caused by Borrelia burgdorferi and Anaplasmosis is caused by Anaplasma phagocytophila formerly called Ehrlichia equi.
Identify the Players:
Deer ticks, officially known as Ixocles scapularis, are also called the black-legged tick or bear tick and they carry this region’s tick-borne diseases. Deer ticks are smaller in size and lack the white markings on their backs found on the wood or dog tick. The adult female is reddish-brown and the adult male is brown. Both are 1/8” or less in length, which increases their ability to not be detected.
Deer ticks are very dependent on their hosts and environment to survive. Of the four stages deer ticks go through, the most important stages that transmit disease to dogs and humans are the nymph and adults, stages that begin in the second year of the two-year life cycle. A blood meal is needed to progress to the next stage.
Adult deer ticks prefer white-tailed deer, living nestled under their hair where they feed on blood and mate. The female then falls off the deer, lays thousands of eggs and dies. In the spring and summer, the eggs hatch into larvae that feed on migratory birds or small rodents, like the white-footed mouse, chipmunks, or squirrels where they may become infected. The next stage, nymphs are dormant in the fall and winter and become active in the early spring and summer. They feed on rodents, dogs, and humans. During the summer and fall, they mature into adults and feed on deer, dogs, or humans. Otherwise, they patiently wait until winter or the next spring to feed.
Research has shown that ticks can be active all year round, even with a snow cover. The main source of infection for deer ticks is small rodents, but deer may play a role in Anaplasmosis transmission.
There is no evidence that dogs can transmit either disease directly to humans; an infected tick must bite a human.
Where Do Ticks Live?:
Deer ticks are found in tall grass and wooded areas. They prefer living at ground level to a few feet about clinging with their 8-legs to tall grass or brush. By using the dog’s carbon dioxide, scent, body heat and other stimuli, ticks are able to ‘find’ a dog and attach. Unless found by the observant human, the can remain on a dog for two to six day, long enough to take a blood meal. The tick must be attached for 24-48 hours for a dog to get Lyme disease and likely a shorter time for Anaplasmosis. The longer a tick stays attached to your dog, the better the chance of infection. It only takes one infected tick bite to cause disease. A co-infection with Lyme disease and Anaplasmosis can occur.
Ticks are more active when humidity is high. Activity peaks in the spring and fall and decreases with increased summer temperatures.
Signs of Infection:
Tick-borne infections can be difficult to diagnose on symptoms alone as they often act like other diseases or there are no signs. It may take as long as 2-5 months after exposure before a dog shows signs of Lyme disease infection. Younger dogs or those with immune system compromise may show symptoms earlier or have more severe symptoms than older or healthier dogs.
Dogs usually have a fever as high as 105F (normal temperature 102.5F), refuse to eat, and act depressed. Sudden lameness, reluctance to move or moving stiffly due to joint and muscle pain, and finding the dog unable to rise is also seen. Lyme disease tends to affect one joint or leg and it appears the leg that becomes lame is likely the leg closest to the tick bite. Some dogs have swollen lymph nodes. Anaplasmosis infected dogs may also experience vomiting and diarrhea, and have small pinpoint hemorrhages in their mouths.
Some dogs may experience recurring arthritis and complications including hear and central nervous system disease, and a small group of Lyme-infected dogs may develop a fatal kidney disease.
Testing Your Dog:
Diagnosing tick-borne disease on symptoms alone is not easy, but with a simple blood test, your veterinarian can quickly determine if your dog has been infected with one or both of these diseases. Testing can be done annually at the time of heartworm testing to screen for either disease.
To Treat or Not To Treat?:
For both tick-borne diseases, prescribed antibiotics have a rapid response noticeable within 1-2 days of starting treatment for acute infections. Doxycycline is usually the antibiotic of choice as it has the benefit of anti-inflammatory properties, but some dogs may require other antibiotics due to pregnancy, intolerance, or lack of response. Duration of treatment is 28 days.
For Lyme disease, to treat or not to treat is based on whether the dog is showing clinical signs, usually lameness and if the titer, a rise in proteins, is elevated. The titer requires and additional test that your veterinarian may suggest. If the titer is more than 30 and the dog is showing signs of disease, treatment is recommended. If less than 30 and without illness, treatment may not be necessary. Following ‘successful’ treatment, the titer number should be one-half its original value in 6 months.
The use of antibiotics to treat tick-borne diseases needs to be weighed because humans can also contact the same diseases and the same antibiotics are prescribed. To prevent antibiotic resistance (the antibiotics will no longer work), owners need to follow the strict schedule of giving their dogs the antibiotic as prescribed and for as long as prescribed.
For hunting dogs, sitting on the sideline is not an option to avoid tick exposure. The best prevention is frequent checks of your dog when in high risk areas and early removal of ticks. Remove the tick by grasping it close to the skin, and then clean the area with an antiseptic.
Use topical products to repel or kill ticks. A recent study showed K-9 Advantix (permethrin) repels ticks better than Frontline Plus (fipronil). Frontline requires a tick to take a blood meal to die, allowing time for Anaplasmosis to be transmitted. Spot-on topicals should be applied every 30 days to the skin, not the hair and applied two days after or before the dog gets wet (bathing, swimming) to be most effective. Depending on your area, some products may be superior to others, but nothing works better than removing the animal from tick exposure.
Amitraz tick collars (Preventic) are considered the gold standard tick control for dogs. They should be removed before your dog swims or is bathed. To ensure proper placement, allow enough room between the collar and the dog’s neck so 2 fingers can be inserted and extra length removed. Remove after 3 months of use and dispose of properly. They should not be used on pregnant or lactating bitches. Do not allow dogs to chew on the collar. In high tick exposure areas, they are often used in addition to topical products.
Locate kennels in open areas away from the edges of woods and tall grass. Keep leaf litter, brush and wood piles a distance from your dogs and keep the lawn mowed. After checking with local regulations, apply environmental insecticide sprays (permethrin or carbaryl) to reduce ticks in the environment. Manage the tick’s host: Guinea hens eat ticks, cats hunt mice, and deer hunting season is a legal harvest.
A vaccine is available for dogs for Lyme disease, although some controversy exists regarding its use. Owners should consult with the local veterinarian to determine if it would be beneficial. In general, the vaccine should be administered to puppies according to the vaccine manufacturer’s recommendation with boosters prior to periods of highest exposure.
Lyme disease and Anaplasmosis are two regional tick-borne diseases that have had a serious impact on dog health. In addition to preventing tick exposure, early recognition of changes in your dog’s behavior and annual testing can result in early treatment.
An excellent site for more information on Lyme disease in humans is the CDC (Center for Disease Control) webpage http://www.cdc.gov/ncidod/dvbid/lyme