Anti-Tick Warfare Part 3 – Ehrlichiosis
By: Peter Demmon
Another reason to engage in all-out tick-warfare is ehrlichiosis. Ehrlichiosis is also known as tracker dog disease, canine rickettsiosis, canine hemorrhagic fever, tropical canine pancytopenia, and canine typhus. First described in 1935 as am illness with Algerian dogs, this sneaky, horrifying disease can ruin or claim the life of your pet if not caught in time. Ehrlichiosis is similar to both Rocky Mountain Spotted Fever and Lyme Disease with several of its signs. This is a disease that occurs worldwide. It is transplacental, meaning a mother dog can pass it to her offspring through the placenta. Dirty needles or a compromised blood transfusion can also bring about infection. The damage that ehrlichiosis can wreak upon a dog's system is brutal, possibly even comparable to a slow-moving ebola virus. With the following information on tick carriers, processes for tick removal, symptoms, treatments, and preventative measures a dog owner should be better prepared for ehrlichiosis and general anti-tick warfare.
Ticks are the undisputed carrier of ehrlichiosis. There is research taking place to determine other vectors of the disease such as mosquitoes, flies and chiggers. Another interesting aspect of ehrlichiosis is that the disease adheres to the principles of zoonosis. This means that is can be transmitted via vector from animals to humans and vice-versa. At this time, what is known is that ehrlichiosis is transmitted by the Brown Dog Tick and the Lone Star Tick (which can also carry Lyme Disease). The hard tick species known as Dermacentor variabilis (the American Dog tick) has been implicated as an ehrlichiosis carrier as well. While the Lone Star Tick is rather easy to identify because of its “star-splotch” on its back, the particulars of these other ticks are rather finicky. The fact is that if you find a fully engorged tick on your dog, your best bet is to (obviously) remove it, and then schedule a blood test.
The disease cycle works like this: an immature tick feeds on an animal that is a host of ehrlichiosis, then the ehlrlichiosis stays alive within that tick for up to 5 months. If the tick gets to another animal, it is able to transfer the ehrlichiosis. Ehrlichiosis is another rickettsia, like Rocky Mountain Spotted Fever (see my article Anti-Tick Warfare part 2). This means that ehrlichia are classified somewhere between a virus and a bacteria. There are two species reported in dogs, E. canis and E. risticii. It is possible for a dog to be infected with both species simultaneously, however, the standard prescribed antibiotic treatment will knock them both out. It is fortunate that both respond to the same method of treatment.
If your dog does indeed get bitten by a tick, there are many different methods for removal. One older method is to light a match behind the swollen tick and have the tick back out of the wound. I have personally done this method and watched the tick burst to the heat. I don't recommend it. Also, the heat may cause the tick to release even more of its contaminated saliva into the wound before exiting. Ticks burrow into the flesh head first so the best method by far is to get a pair of tweezers and gently extract the tick by grabbing it by its head, as close to the skin as possible. Pull slowly, and don't yank or twist it out like a splinter or thorn. Also try not to molest or bend the tick's body too hard in the process or the body will break off leaving the tick's head attached. If your dog has been bitten and you aren't sure about the time frame of the bite, it might be wise to schedule a visit to the vet.
Ehrlichia, named for Dr. Ehrlich who first described them, are a special type of infection that live within the white blood cells of their hosts. Once infected, white blood cells start dying faster than they can be generated. The dead white cells are then moved to the spleen. This is because the spleen's primary purpose is to remove old red blood cells and hold a reserve of blood in case of an emergency. Most blood creation (haematopoiesis) happens within bone marrow. However, it also happens in the spleen. The ehrlichia proceed to slow down the new blood cell making process that takes place in bone marrow.
In my information takedown of ehrlichiosis, I found it referred to as "the AIDS of the canine world." Ehrlichiosis earns this monicker because it mimics other diseases well. Sometimes ehrlichiosis is misdiagnosed as leukemia or lymphosarcoma (cancer of the lymph nodes). It can also be misdiagnosed as any number of other diseases including brucellosis, thrombocytopenia, Valley Fever, blastomycosis and more.
There are three stages of ehrlichiosis. The stages are as follows: acute, subclinical, and chronic. Initially, there is an incubation period of 8-20 days after the bite. In the first to third week after the bite the dog will experience the acute phase of the disease. Depending on the formidability of the dog's immune system, the acute stage is where the signs of ehrlichiosisehrlichia are entering the white blood cells and reproducing inside of them. White blood cells are being hijacked throughout the dog's body, particularly within the lymph nodes, spleen, liver, and bone marrow. The acute stage, if addressed and handled properly with antibotics, leaves the dog just as good as before the infection. Lots of dogs are able to shake the acute stage off. However, some don't, and if the infection goes untreated, it gives away to the subclinical stage.
In the subclinical stage, the dog seems to be relatively fine. The subclinical stage has no outward signs and can potentially last for years. The ehrlichiosis has now limited itself to the spleen. However, there can be fevers and a loss of appetite during this stage. A dog can potentially be in the subclinical stage for an extended period of time, not really giving much of a hint that there is something wrong. Although, there is attrition, there aren't any grand signs of the infection. Also, the subclinical stage can be discarded and the chronic stage can start if the pet feels stress. Environmental stress (such as a move), a different illness, hard work, etc are all potential catalysts that could kick the dog's immune system over into the compromised “chronic” stage of ehrlichiosis.
If the dogs system remains unable to overcome the infection, then it will the chronic stage which is the final stage of this disease. The chronic phase is where the damage is really wreaked upon the dog's system. At this point, it is now official that the dog has a low white blood cell count (thrombocytopenia). In the chronic stage, the virus has taken up residency in the bone marrow. The chronic stage is also where the dog will probably suffer from some irreversible damage. It is not unusual for dogs in this stage to suffer massive internal bleeding, have a sudden stroke, have a heart attack, have kidney (renal) failure, splenic rupture or liver failure, most of which result in death. There are also a host of minor signs during this stage as well, such as neurological problems (repetitive obsessive actions), spontaneous bleeding, increased thirst and urination, skin sensitivity, disorientation, vomiting (primarily bile), diarrhea, inflammation of the eye, seizures, muscle wasting, skin infections, bleeding from the nose or eyes, arthritis, pneumonia, cough, neck or back pain, bleeding under the skin or a rash (purpura), swelling of the legs or joints, and more. With so many potential symptoms, the nickname of "the AIDS of the canine world," really makes a lot of sense.
The best prevention of canine ehrlichiosis is tick control. The drug of choice for treatment for all forms of ehrlichiosis is doxycycline for at least one month. Reinfection is possible after the dog clears the disease. Some dog owners who have gone through this disease with their dogs even state that a slight change in your pet's behavior is enough to look into ehrlichiosis. This is extremely important if there has been a recent tick bite.
There are several different options available at pet stores for tick management. Flea and tick collars are a common standard as are products like Spot On by Zodiac. Spot On is basically a treatment for the skin (applied between the shoulder blades) that spreads out over the dog's body and prevent ticks from hitching a ride. These types of preventative maintenance are usually good for several weeks to a month before they need to be re-applied. There are also anti-tick sprays that can be used outside and near where your dog is likely to play. Vigilance is the operative word here. Pay close attention to your dog's comings and goings during tick season.
If you live in an area that is heavily wooded or has a lot of untended grass and vegetation, the chances of ticks are relatively high. A dog owner whose dog frequents such areas should remain vigilant with all forms of anti-tick warfare. It is good to know that not all ticks carry ehrlichiosis, however, there are some serious steps that can be taken to minimize the chances of your dog being bitten. Comprehension of erhrlichiosis carriers, the processes of tick removal, the stages and symptoms of the disease, and general tick preventative measures are all pieces of information that can help a dog owner with both ehrlichiosis and full-on anti-tick warfare.
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