Ticks and Lyme Disease

by Bruce W. Little, DVM

Ticks and Lyme Disease



Each year about this time, our attention turns to external parasites on our pets. These parasites can come in the form of ticks, fleas, mosquitos, mange mites, ear mites and lice. There may be other external parasites native to your area of the country not mentioned above; but we will discuss ticks and the Lyme disease they can and frequently transmit to your pets and people. Not only is it important to know how ticks may impact the health of your pets, it also can be beneficial to the health of your human family members as well.

According to research done by the Companion Animal Parasite Council (CAPC), a group committed to the study and treatment of parasites on the animals with whom we live and love, ticks have been steadily spreading across the United States. Researchers at the Centers for Disease Control and Prevention (CDCP) have documented the number of ticks carrying Lyme disease in the United States has increased to 49% of the counties in 43 states. That represents a 45% increase over the past eighteen years. There are several varieties of ticks, many of these named after the geographical location in which they reside. However, the geographic locations seem to be expanding and spreading in all of the tick populations that are identified. Some attribute this spreading of ticks into areas of the country where they had heretofore been undiagnosed were as a result of the spread of the white-tail deer in search of feeding grounds and the current penchant for family travel into every vacation and business destination in the country. Ticks become attached to our pets and hitch a ride back to the home location where they breed, mutate and/or acclimate to the current environment and survive to set up a new geographical location for their place on this earth. It is a fact, and pet owners must learn to deal with it!

There are eight different varieties of ticks that are common in North America. The American dog tick, the brown dog tick, the Eastern black-legged tick (deer tick), the Western black-legged tick (also called the deer tick), the Rocky Mountain wood tick, the Gulf coast tick, the Lone Star tick and the Spinose ear tick. These ticks can be found all across America; however, their concentration is usually highest in a geographical location to which they have environmentally adapted. The two tick species that are known to serve as vectors for transmitting Lyme disease are the Eastern black-legged tick and the Western black-legged tick, both commonly called deer ticks. Both can be found primarily in wooded areas with the greatest concentration of Lyme disease carrying bacteria in areas of the Upper Midwest and Northeast areas of the United States and Southern Canada. However, these species of ticks are rapidly spreading all throughout North America and preventive measures must be made to keep them from transmitting Lyme disease and other tick carrying diseases to pets and humans.

The life cycle of ticks includes an adult, larval and a nymph stage. The adult female tick lays numerous eggs at a time, some as many as 8,000 to 9,000 at a time, which develops into a larvae that later develops into a nymph stage. All three stages are capable of attaching to animals by biting into their flesh and sinking their mouthparts into or under the skin. You should check your pets daily to see if you can find ticks. They may be in the smaller nymph stage and not be as evident, or they may be in the adult stage but have not yet engorged themselves with a blood meal. You may miss those that are bedded down in the coat of your dog or cat because those ticks that have not engorged with a blood meal are small and may be hard to find. However, the engorged tick is quite noticeable when you run your fingers over the surface of the skin of your pet. If you find a tick, engorged or not, remove it with a pair of tweezers or a pet store purchased plastic instrument shaped like a claw hammer that fits down over the tick and lifts it from its feeding place. These plastic instruments work best on engorged ticks and can be found at most pet stores. Always wear gloves when you remove ticks from your pets to help you from contracting zoonotic infections. Try not to crush the tick as you remove it from your pet, as that may enhance the chances that you might contract whatever disease that tick may be carrying.

Acaricides are parasiticides that are developed for the treatment of tick infestations. These may be administered topically, in long-acting collar formulations or orally. Your veterinarian will guide you as to which acaricide to use and in what dose. It is very important to use parasiticides only on the species prescribed by your veterinarian. NEVER give cats tick control medications prescribed for dogs or medications prescribed for cats to your dogs. Opossums and foxes are natural predators of ticks. Opossums are the main source of tick eradication in many areas, as they eat millions of ticks daily. Foxes prey on mice, shrews and chipmunks that are infested with ticks, thus helping to control the incidence of ticks themselves and of Lyme disease indirectly.

One common misconception is that ticks are active only during warm weather; but because substantial annual seasonal and geographic differences occur in tick prevalence, and because some ticks can infest houses and kennels every month of the year, CAPC supports year-round tick-control products for pets. The black-legged ticks that carry Lyme disease are most active during the fall and winter months. Recently, CAPC has determined that in 2016, there is a high probability the Northeast states, the Upper Midwest and Alaska will have an increased number of ticks. This high number is the result of a moderate winter and a wet and humid spring that provides an environment conducive for tick reproduction and growth. According to a recent study done by CAPC and Bayer Animal Health, ninety percent of pet owners want to be informed about tick infestations, treatment and prevention. If your veterinarian does not communicate with you to your satisfaction about these parasites, ask him specifically about how you should manage your pets and the pet’s environment with regard to ticks.

Lyme disease is caused by a bacterium called Borrelia burgdorferi that is transmitted by ticks to both pets and people. One in sixteen dogs or 6.28% tested positive for Lyme disease in the CAPC study. In 2013 a new or at least unknown strain of bacteria was discovered by scientists at the Mayo Clinic in Minnesota. That strain of bacteria was named Borrelia mayonii after the Mayo Clinic, and can be transmitted to people by ticks. B. mayonii infections appear to have slightly different clinical signs than Lyme disease caused by B. burgdorferi. There have been no cases of Borrelia mayonii diagnosed in dogs and cats of which I am aware.

Symptoms of Lyme disease in dogs vary greatly from those symptoms in people. In people, symptoms of Lyme disease include a very telling “bulls-eye” rash at the site of the tick bite, fever, chills, headache, fatigue, joint and muscle aches and sometimes more complicated signs that spread to the heart and nervous system. The signs of Lyme disease in dogs and cats are much more discreet. The characteristic rash does not develop in dogs or cats. Because the other symptoms of the disease may be delayed or go unrecognized and because the symptoms are similar to those of many other diseases, Lyme disease in animals is often not considered until other diseases have been eliminated. “Affected dogs have been described as if they were ‘walking on eggshells’”, states Dr. Ernie Ward, a noted veterinarian and speaker at veterinary continuing education seminars. Many dogs affected with Lyme disease are taken to a veterinarian because they seem to be experiencing generalized pain and have stopped eating. Often these pets have high fevers and may begin limping. Frequently, the painful lameness may appear suddenly and may shift from one leg to another. If untreated, it may eventually disappear, only to recur weeks or months later. Some pets are infected with the Lyme disease organism for over a year before they show clinical symptoms. By this time, the disease may be widespread throughout the body. If your pet is showing these signs do not wait for things to get worse. Contact your veterinarian for a diagnosis, and if necessary proper treatment.

Dogs with lameness, swollen joints, and fever are suspected of having Lyme disease. However, other diseases may also cause these symptoms, so it is imperative that you seek out the services of a veterinarian to determine the cause of your dog’s condition. There are two blood tests that are used for confirmation of the Lyme disease presence. The first is an antibody test and the second is the polymerase chain reaction (PCR) test. Your veterinarian will advise you on the need for these tests. Many times veterinarians can determine the diagnosis of Lyme disease simply by collecting a history of the pet’s activities and the symptoms shown upon presentation to the animal hospital.

The key to prevention of Lyme disease is keeping your pet and yourself from being exposed to ticks. The causative agent of Lyme disease is not transmitted from pet to pet or people to pets. It can only be transmitted through the bite of the tick. Keeping animals from thick underbrush reduces their exposure to ticks. Stay on the bicycle or walking path. Use tick repellents that contain 20% to 30% DEET before going into areas that may harbor ticks. Check yourself, your children and your pets for ticks after going into these areas. Remove ticks from all persons and pets as quickly as possible after leaving tick-infested areas. Wash the area of the tick bite thoroughly with soap and water. If you encounter ticks, call your veterinarian and get her advice on next steps. A prompt call may save lots of time and money for both the pets and the humans in the family.

Companion Animal Parasite Council (CAPC) http://www.capcvet.org



Bruce W. Little, DVM