Ticks On Your Dog: Bloodsucking Parasites That Can Transmit Serious Diseases
By Rachele Baker, DVM – Ticks are parasites that feed on the blood of their hosts. They can transmit serious diseases while feeding. Ticks avoid detection by their hosts by secreting saliva with anesthetic properties into the area in which they are feeding.
Ticks locate hosts by detecting animal body odors, body heat, moisture, or vibrations. Some tick species can recognize shadows.
Ticks cannot fly or jump. They wait for potential hosts while holding onto the tips of grasses and shrubs using their third and fourth pair of legs with their first pair of legs outstretched. When an animal brushes by the grass or shrub where the tick is waiting, the tick climbs on.
When ticks find a feeding spot on their host’s skin, they cut into the skin and insert their feeding tubes. Barbs on the ticks’ feeding tubes and a cement-like substance secreted by the ticks help to keep them firmly attached while they are feeding. Saliva from ticks enters the skin of their hosts during feeding. If a tick is infected with a disease-causing organism (bacteria or protozoa), the organism may be transmitted from the tick to the host while the tick is taking a blood meal.
Ticks can transmit serious diseases to dogs including Lyme disease, Ehrlichiosis, Babesiosis, Rocky Mountain Spotted Fever, and Anaplasmosis. In addition to potentially transmitting diseases, tick bites can cause skin irritation and inflammation. Tick bites may also become infected and require treatment.
The Tick Life Cycle
Ticks have four life stages: egg, larva, nymph, and adult. Female ticks lay eggs in the spring in secluded areas with dense foliage. Depending on the species of tick, ticks may lay as few as 100 eggs or as many as 3,000 to 6,000 eggs at a time. The eggs hatch into larvae and begin to search for a host from which to take a blood meal. Most types of ticks require three hosts at different stages of development. The larvae attach themselves for several days to the first host. After feeding, the larvae fall off the host and develop into nymphs.
Nymphs are inactive during winter. In the spring, nymphs will find a second host. After feeding, the nymphs fall off the host and develop into adult ticks.
In the fall, adult ticks locate and attach to a third host. An adult female tick will take a blood meal from the host animal for eight to twelve days. The female tick will mate while attached to a host. Then both the female and male ticks will fall off the host and the male ticks die.
Female ticks have a partial scutum (a hard, protective covering or shield) on their back that allows them to expand as much as one hundred times their original weight when taking a blood meal. Male ticks have a full scutum that covers their entire back, so they do not undergo a large increase in size while feeding.
Common Ticks In The United States
The most common ticks that parasitize dogs in the United States are the Lone Star Tick, the Blacklegged Tick (Deer Tick), the American Dog Tick, and the Brown Dog Tick. The Centers for Disease Control and Prevention (CDC) has excellent, color-coded maps that show the geographic distribution of each of these tick species in the United States.
Lone Star Tick
Lone Star Ticks are usually found in wooded areas with dense foliage. Adult Lone Star Ticks are about one-seventh of an inch long. Lone Star Ticks feed on animals such as coyotes, deer, cattle, dogs, and humans.
Females feed for about a week to ten days before they are engorged. They will lay 2,500-3,000 eggs. Lone Star Ticks can transmit diseases to dogs such as Granulocytic Ehrlichiosis.
Eastern Blacklegged Tick (Deer Tick)
Blacklegged Ticks (Deer Ticks) are usually found in deciduous forests. Their reproductive hosts are white-tailed deer. Adult Blacklegged Ticks are about one-eighth of an inch long.
Adult ticks are active from October to May as long as daytime temperatures remain above freezing. Females lay about 1500-2000 eggs in mid to late May and then die. Larvae emerge in the summer. Males do not feed.
The diseases that Eastern Blacklegged Ticks can transmit to dogs include Lyme disease, Ehrlichiosis, and Anaplasmosis.
Western Blacklegged Tick (Deer Tick)
Western Blacklegged Ticks (Deer Ticks) are found along the Pacific coast of the United states. These ticks prefer cooler coastal climates. Adult Western Blacklegged Ticks become active in October and remain active throughout the winter, spring, and early summer. Many people think that ticks are only active in the summer, but the habits of Blacklegged Ticks (Deer Ticks) highlight the importance of year round tick protection for dogs.
Western Blacklegged Ticks can transmit diseases to dogs such as Lyme disease and Anaplasmosis.
American Dog Tick
American Dog Ticks are usually found in open areas such as fields and along walkways and trails. Female American Dog Ticks are about one-fifth of an inch long. American Dog Ticks feed on raccoons, skunks, opossums, and coyotes as well as dogs, cats, and humans. Females feed for a week or more. Males feed for a short time. Female American Dog Ticks lay about 4,000 eggs before dying.
American Dogs Ticks can transmit diseases to dogs such as Ehrlichiosis and Rocky Mountain Spotted Fever.
Brown Dog Tick
Brown Dog Ticks are found throughout the world. In the United States, Brown Dog Ticks are seen more frequently in southern states.
The diseases that Brown Dog Ticks can transmit to dogs include Anaplasmosis, Babesiosis, Monocytic Ehrlichiosis, and Rocky Mountain Spotted Fever.
Some species of ticks can transmit neurotoxins to a dog while feeding which can cause paralysis of the legs. This condition is called Tick Paralysis. In severe cases, muscles required for breathing may also become paralyzed. Clinical signs improve rapidly once the ticks have been removed.
Diseases that ticks can transmit to dogs include Lyme disease, Ehrlichiosis, Babesiosis, Rocky Mountain Spotted Fever, and Anaplasmosis.
Lyme disease: Lyme disease is caused by bacteria called Borrelia burgdorferi. The primary ticks that transmit Borrelia burgdorferi are Blacklegged Ticks (Deer Ticks). Larvae and nymphs in the northeastern United States feed on rodents and small mammals. In the southern United States, larvae and nymphs feed on reptiles. Adult ticks feed on deer and other large mammals. The larvae and nymphs acquire Borrelia burgdorferi when taking blood meals from rodents.
The bacteria are transmitted in tick saliva when ticks are feeding. Borrelia burgdorferi bacteria then migrate into the skin, joints, connective tissue, and central nervous system of the new host. The bacteria may also localize in kidneys and other organs.
According to the Companion Animal Parasite Council, Blacklegged Ticks (Deer Ticks) must be attached and feeding for approximately twenty-four to forty-eight hours before Borrelia burgdorferi bacteria are transmitted to the new host.
Ninety to ninety-five percent of dogs exposed to Borrelia burgdorferi will not develop any clinical signs of Lyme disease. Dogs that do develop signs of Lyme disease will usually start to show signs within two to five months after infection. Skin lesions are rare in dogs. Clinical signs may include fever, decreased appetite, enlarged lymph nodes, lethargy, joint swelling, and shifting leg lameness. The first leg to become lame is usually the leg that was closest to where the tick was attached. The lameness in one leg usually lasts for a few days and then shifts to a different leg. Some dogs with Lyme disease may develop acute onset kidney failure.
Ehrlichiosis: There are two forms of Ehrlichiosis seen in dogs: Granulocytic Ehrlichiosis and Monocytic Ehrlichiosis.
Granulocytic Ehrlichiosis: Granulocytic Ehrlichiosis is caused by bacteria called Ehrlichia ewingii. In the United States, the tick that transmits Ehrlichia ewingii is the Lone Star Tick. Some dogs infected with Ehrlichia ewingii may not have any clinical signs. The most common clinical signs are fever, lameness or stiff gait, and lethargy.
Monocytic Ehrlichiosis: Monocytic Ehrlichiosis is caused by bacteria called Ehrlichia canis. The primary ticks that transmit Ehrlichia canis are Brown Dog Ticks. Ehrlichia canis infections have been reported in the Americas, Europe, Asia, and Africa. The period from the bite of an infected tick until clinical signs appear is approximately one to three weeks.
After transmission, Ehrlichia canis bacteria spreads throughout the body. This can result in vasculitis (inflammation of blood vessels) and enlarged organs such as the liver and spleen. Clinical signs may include fever, decreased appetite, weight loss, lethargy, enlarged lymph nodes, and bleeding abnormalities such as anemia and bruising. Eye problems such as uveitis (inflammation of the eyes) and central nervous system abnormalities such as seizures may also occur.
Babesiosis: Babesiosis is a disease caused by protozoa (single celled organisms) called Babesia. Babesia is transmitted to dogs in tick saliva. Babesia invade red blood cells in the dog’s body. As the protozoa multiply in red blood cells, they cause the red blood cells to rupture. This results in anemia.
Ticks must be attached and feeding for approximately twenty-four to forty-eight hours before Babesia protozoa are transmitted to the new host. The primary ticks that transmit Babesia are Brown Dog Ticks.
Clinical signs may include fever, lack of appetite, depression, enlarged liver and spleen, and moderate to severe anemia.
Rocky Mountain Spotted Fever: Rocky Mountain Spotted Fever is caused by bacteria called Rickettsia rickettsii. The primary ticks that transmit Rickettsia rickettsii are American Dog Ticks. Ticks must be attached and feeding for approximately five to twenty hours before Rickettsia rickettsii bacteria are transmitted to the new host.
Clinical signs generally appear two to fourteen days after infection. After transmission, Rickettsia rickettsii bacteria invade the cells that line the walls of small blood vessels (small veins, arterioles, and capillaries) and begin to multiply. This results in damage to the walls of the blood vessels which can compromise normal blood flow to the brain, heart, kidneys, and skin. Damage to blood vessel walls results in blood leakage which may manifest as skin rashes or bruising. Clinical signs may include fever, lack of appetite, depression, lethargy, enlarged lymph nodes, lameness, and generalized pain. Central nervous system abnormalities such as incoordination or seizures may also be noted.
Anaplasmosis: Anaplasmosis is caused by bacteria called Anaplasma phagocytophilum. These bacteria are found worldwide. The primary ticks that transmit Anaplasma phagocytophilum are Blacklegged Ticks (Deer Ticks). Ticks must be attached and feeding for at least twenty-four hours before Anaplasma phagocytophilum bacteria are transmitted to the new host.
After transmission, Anaplasma phagocytophilum bacteria invade white blood cells called neutrophils. Clinical signs are usually seen one to two weeks after transmission and may include fever, lack of appetite, lethargy, lameness, reluctance to move, and enlarged lymph nodes.
How To Remove A Tick From Your Dog
It is a good idea to check your dog for ticks whenever your dog has had possible exposure. Ticks may be found anywhere on your dog’s body but are more commonly found around the head, ears, neck, and feet.
The safest way to remove a tick is with a pair of pointy tweezers specifically designed for tick removal such as TickEase. TickEase tick removal tweezers have a pointy end for removing small, unfed ticks and a slotted end for removing large, engorged ticks (if you are interested in purchasing TickEase tweezers, there is a link at the end of this section to get them from Amazon). First, apply rubbing alcohol to the tick and the tick attachment site. Use the tweezers to grasp the tick as close to the dog’s skin as you can. Then slowly and steadily pull the tick out. Be careful not to squeeze the tick too hard because that may cause the tick to inject bacteria or protozoa into the attachment site.
I strongly recommend wearing gloves while removing ticks to avoid the possibility of exposure to tick-borne bacteria and protozoa. After you have removed a tick, put it in a jar filled with alcohol to kill it.
Do not use hot matches or lighters to try to kill ticks on your dog. This is very dangerous and can result in burning your dog’s skin. I also do not recommend using petroleum jelly, turpentine, or nail polish to try to remove ticks.
After you remove one or more ticks from your dog, there may be redness and inflammation at the tick attachment sites. Cleanse the areas with an antiseptic such as chlorhexidine (Hibiclens) that has been diluted in water. You can also apply a small amount of a triple antibiotic ointment such as Neosporin twice a day for several days. Tick bite wounds can develop secondary bacterial infections. Medicated shampoos or antibiotics may be required. Take your dog to your veterinarian if the inflammation at tick attachment sites is severe or you suspect that the sites may have become infected.
There is a very useful Tick Identification Chart on the University of Rhode Island’s TickEncounter Resource Center website. Click on your region of the United States on the right side of the page to see ticks that are found in your area. You can move the pointer over each tick for a zoomed view. If you left-click a tick, you will get a close-up photo of the tick as well as information about seasonal activity and diseases transmitted. Ticks are arranged from the top of the page to the bottom of the page according to their relative abundance (high to low) in that region.
Protect Your Dog From Ticks
Because ticks are active throughout the year, measures to protect your dog from ticks must be practiced consistently year round. Tick populations around your home can be controlled by trimming brush, keeping grass mowed short, and removing leaf litter in your yard to remove tick habitats. Wildlife that carry ticks can be kept out of the yard by installing fencing and keeping the yard free of debris or food that may attract them.
The Companion Animal Parasite Council recommends that all dogs be maintained on tick control products year round. Flea and tick control products available for dogs include oral and topical treatments as well as flea and tick collars. I have compiled several tables comparing select oral and topical flea and tick control products. Information on select flea and tick collars is included below the tables. You can view these tables on my page entitled Flea and Tick Control Products For Dogs. Not all flea and tick control products are safe or effective. It is important to use good quality, reputable products to treat your dog. Your veterinarian is the best source of these products.