The season is upon us now when we see families planning summer trips, which for many include taking their special four-legged companions with them. What people don’t always consider when preparing for these fun family vacations is what might choose to follow you home.
Ticks are known carriers of several diseases that not only afflict humans but also their family companions. In April, a conference was held in Hershey to discuss the recent rise in tick-transmitted diseases in humans. According to the Pennsylvania Lyme Resource Network, Pennsylvania now has the highest number of reported cases of tick diseases in humans. At our practice in the past two years, more than 4 percent of our patients that were tested for tick-transmitted diseases were positive for the organisms that cause Lyme disease, Ehrlichiosis, Anaplasmosis and Rocky Mountain Spotted Fever.
There are several varieties of ticks that exist in the Northeast but two in particular — the black-legged tick, Ixodes scapularis, and the lone-star tick, Ambylomma americanum — carry the most commonly seen diseases of Lyme, Anaplasmosis and Ehrlichiosis. The life cycles of these ticks allow them to spread these diseases by feeding on their primary hosts, either animals or humans. In the spring, the tick’s eggs hatch and the smallest form of tick, the larval form, is created. These larva feed on birds and rodents in the summer months and on humans and animals in the fall and winter. They are smaller than a pinhead and usually are too small to carry the bacterium. The following spring, these larva mature into the nymph stage, still as small as a pinhead, but are large enough to carry the infectious bacterium. This tick is the greatest source of infection since it is too small for human detection. The final stage is the adult form, which the tick reaches in the fall. This type is usually big enough for humans to see so, even though they carry these organisms, they are less likely to cause disease. The adults lay their eggs in late winter to early spring, and the cycle begins again.
The most commonly recognized tick-transmitted disease is Lyme Disease, caused by the spirochete, Borrelia burgdorferi. Flu-like symptoms and/or the characteristic bulls-eye target rash occur in 80 percent of those bit by the Ixodes tick that carries Lyme. Many people never even note the tick nor the rash. In dogs, the disease is very different in that it can take weeks to months after exposure to a tick bite for the animals to show the symptoms of joint pain. Many dogs exposed to Lyme never manifest any symptoms and do not require treatment. But there are some that do succumb to the kidney damage caused by the prolonged response of the dog’s immune system against the spirochete.
Another tick disease on the rise in our canine population is Ehrlichia canis, transmitted by the brown-dog tick, Rhipicephalus sanguineus, or Ehrlichia lewinni, transmitted by the lone-star tick. There are three phases of this disease. The acute phase can cause a dog to become listless, have a lowered appetite and enlargement of the lymph nodes. The organisms cause a reaction in the dog’s immune system that starts to destroy platelets essential in blood-clotting. Some dogs will even have swollen, painful joints. In the subclinical phase, many dogs exposed to Ehrlichia do not show any symptoms until months to years later, as the organism hides in their spleen. Blood tests help determine if the Ehrlichia is causing changes in the platelet count and indicate if the dog is reacting to the organism with an elevated protein globulin level. The last phase is the chronic phase, in which the dog gets sick from abnormal bleeding as its platelet numbers are too low to help form a clot. Some of these dogs have eye changes due to deep inflammation, called uveitis, and/or kidney damage due to the chronic immune stimulation, causing them to lose protein in their urine.
The deer or black-legged tick is also responsible for spreading Anaplasma phagocytophilum, an infection that affects the platelets. Dogs may be sick for one to seven days with lethargy, fever or joint pain leading to lameness. Other less-seen signs may be vomiting, diarrhea, coughing and shortness of breath or seizures. Some dogs may not be sick for close to five-and-a-half months after the tick bite. Blood tests can detect the organism and assess the level of thrombocytes that exist. All of these tick-transmitted diseases, when causing symptoms, are treated similarly with the same antibiotic, Doxycycline, with treatments lasting 28 days.
The tick must feed for more than 24 hours to transmit these infectious organisms. Prevention is essential in protecting your family companion and the members of your family. Many effective flea and tick medications exist that will either kill or repel the tick before it gets to transmit the infection to your companion. These products should be used every month throughout the entire year, since the life cycle of the tick keeps them feeding for more than 75 percent of the year.
Check your companion around its head, ears, neck and legs after any walks through grassy areas, even in the city parks since more than 50 percent of our patients who tested positive for tick-transmitted diseases had not left Philadelphia. Removing a tick is quite easy; place your finger on its body and slowly spin the tick’s body counter-clockwise for about 20 seconds, after which it will release its bite and can then be safely grasped and flushed away.
So as you plan your summer getaway, or even your next walk in Washington Square, make sure your companion has had its monthly dose of prevention or is wearing a tick collar. Talk to your veterinarian about what they recommend as the best protection for your companion and make sure you let them know if you saw a tick on your pet. An annual simple blood test will let you know if your companion has been exposed to Lyme, Ehrlichia or Anaplasmosis and let you know if you have done a great job protecting your family from tick-transmitted diseases.
Dr. Claudia Casavecchia is a general practitioner at Society Hill Veterinary Hospital. For more information, call 215-627-5955 or visit www.societyhillvets.com.