Ron Hines DVM PhD
|Your cat might be susceptible as well|
To What Diseases Do Ticks Expose My Dog?
The three I want to tell you about here are babesia (babesiosis) , ehrlichia (ehrlichiosis) and anaplasma (anaplasmosis).
There are others. Lyme disease is one of them. You can read about Lyme disease here.
Another one is rocky mountain spotted fever (RMSF). RMSF and closely related rickettsia bacteria affects dogs as well as humans. (ref) In one study, thirteen percent of a group of stray dogs in Louisiana had contracted a similar form of spotted fever. (ref) RMSF is also present in dogs in Canada (ref) It is present in Europe, although different ticks spread the disease to dogs there (ref)
Ticks also transmit tularemia (rabbit fever). Dogs as well as people can catch this disease. Although ticks can transmit tularemia, dogs are more likely to contract the disease from eating or coming in contact with rodents or rabbits. (ref)
Tick paralysis is the only tick-borne disease of dogs that is not caused by an infectious organism. Tick paralysis is caused by a neurotoxin produced by the ticks themselves. (ref)
I am disconcerted when I find fleas on your dog. But I am mortified when I discover ticks.
How Likely Is It That My Dog Will Be Exposed To One Of These Three Tick-Borne Diseases?
When blood samples collected between 2008 and 2012 from 6,582 randomly selected dogs were checked for exposure to three of these tick-transmitted diseases (borrelia, ehrlichia and anaplasma), 18.2% were positive for exposure to at least one of them. The authors looked for antibody the dogs had produced against the organisms. These were dogs from the USA, Canada and the Caribbean islands. This sort of study is not the most accurate way to decide the true number of dogs that encounter these diseases – it may be higher. That is because some infected dogs produce too little antibody to be detected while others overcome the disease and no longer produce detectable antibody. But it is the best study we currently have. Read that article here. Other sources give much lower positive numbers: 2.22% (of 2,366,999 dogs tested) positive for ehrlichia, 4.21% positive for anaplasma and 6.85% positive for borrelia (Lyme). (ref)
None of the current test methods are perfect. Manufacturers squabble as to whose test might be best. Generally whichever company paid for the research finds their test to be the best. (ref1, ref2) There is no doubt in my mind that all three of these organisms are widely distributed in dogs in North America and that they occasionally cause your pet health problems. However, the frequency with which they cause negative health issues in pets is probably overstated in many of the reference articles I link to – particularly when authors beholding to Idexx Laboratories or other commercial interests are involved.
Babesia are microscopic blood parasites (a protozoa) that cause disease in many animal species. Over 100 different babesia species are known – each “preferring” (but not confined to) a particular animal species. The one of deer mice and their ticks (Babesia microti) occasionally infects humans as well as dogs. (ref) Whichever the species of babesia, once infected, these parasites live within your dog’s red blood cells. Ticks are their preferred method of moving from dog to dog. In the United States, babesia are primarily spread by the common brown dog tick (Rhipicephalus sanguineous). On very rare occasions, it is possible to spread the disease through an infected blood transfusions. Once inside the red blood cells, these parasites reproduce, destroying the cells and liberating immature parasite forms (merozoites) that infect and destroy more red blood cells (RBCs). The result is often anemia. Much of that anemia is due to mechanical destruction of the dog’s RBCs as the babesia reproduce, but some is probably due to your dog’s immune system attacking its own RBCs that it now regards as abnormal. In addition to anemia, many of these dogs have abnormally low blood thrombocyte counts. Thrombocytes are an essential part of your dog’s blood clotting process. Babesia disease tends to be more severe in younger dogs and puppies. There are several species and sub-strains of babesia that infect dogs. They appear to vary in the severity of the disease they are capable of producing. Even the severity of the disease caused by a single babesia strain is highly dependent on your individual dog’s genetics and the current state of its immune system. Also coming into play is the fact that a tick can infect a dog with several different babesia strains at one time or even several different tick-borne diseases at one time. So chronically infected dogs that are doing a good job in keeping babesia numbers under control can break or relapse with babesiosis when facing multiple health issues or stress. Occasionally, liver and kidney damage occur secondary to severe babesia infections. (ref1, ref2)
How Will My Veterinarian Tell If My Dog Has Babesiosis?
Many dogs that harbor babesia in their blood stream show no symptoms at all. Others just don’t seem to have their former energy. But veterinarians become suspicious of this disease when dogs arrive with signs of anemia without another obvious cause (such as autoimmune disease [ref], traumatic blood loss, fleas or intestinal parasites). Besides their gums being pale, the gums and the whites of the dog’s eyes are often jaundiced (yellowish) as well. Their respiration might be rapid due their blood’s reduced ability to transport sufficient oxygen. Importantly, they often run a fever. With this disease, it is not uncommon for your veterinarian to notice that the superficial lymph nodes distributed around your dogs body as well as its spleen to be larger than normal (lymphadenopathy). Suspicions increase when ticks are found on your dog’s bodies or there is a history of tick exposure. The blood work results that are most likely to bring babesia, ehrlichia or anaplasmosis to your veterinarian’s mind are anemia accompanied by thrombocytopenia.
A stained blood smear, examined under the microscope, might reveal to your veterinarian the babesia organisms themselves. But the number of babesia organism in the RBCs of infected dogs cycle up and down in number. So when organisms cannot be found, or just for confirmation, many veterinarians will send a blood sample from your pet off to a commercial laboratory for a babesia PCR test when no parasites are seen microscopically. (ref) PCR tests, which magnify and recognize the distinctive protein signature of babesia themselves, are the most accurate tests available in 2018.
How Will My Veterinarian Treat My Babesia-infected Dog?
If your pet is severely anemic (PCV ~15% or less), it will require hospitalization, a blood transfusion, intravenous fluids and 24hr supportive care. Experienced veterinarians have learned to size up a dog’s degree of illness and the need for hospitalization quite well, based on their visual observations and test results. So your vet might suggest hospitalization as the safest course of action even if anemia is not that severe.
In the United States, imidocarb dipropionate (Imizol® ) is the most commonly used drug to treat babesiosis in dogs. It is a powerful drug that must be given by deep intramuscular injection or subcutaneously and the dog closely observed thereafter. The most common side effects are pain during injection, drooling, vomiting and diarrhea (in that order of frequency). Some vets try to counter these effects with a pre-injection dose of atropine. Occasionally, the drug will negatively affect the liver and be reflected in rise in liver enzymes. That generally subsides. A second injection dose is given two weeks after the first. Azithromycin and clindamycin are thought by some to also be helpful in resolving clinical cases of babesiosis. Others claim success using doxycycline and metronidazole. Read an article on these and other medications used with varying success to treat babesiosis around the world here.
It is unclear to veterinarians if these treatments are always effective in completely ridding a dog’s body of babesia. The dog’s general health generally returns rapidly (within a week or two) to normal. But high stress environments, nutritional deprivation, kennel stays and a variety of future health challenges sometimes cause the disease to “relapse”. Since a case of babesiosis does not leave your dog with lasting immunity to future infections, it is really impossible to tell the difference between relapse and a new infection from another tick.
Veterinarians are often cautious about using substantial doses of corticosteroids or immune suppressive drugs in dogs that have recovered from babesiosis for fear of perhaps causing a babesiosis relapse. Surgery that involves removal of the dog’s spleen has also led to relapses. Some veterinarians run a follow-up PCR test on your dog two or three months after treatment, but most rely on clinical improvement, resolution of anemia and thrombocyte number rebound as sufficient evidence that the treatment has been effective.
How Can I help Prevent My Dog From Catching Babesiosis?
The secret of keeping your dog free of babesia and all other tick-transmitted diseases is effective tick control and tick exposure prevention. It can be done. Ticks do not come hat-in-hand a calling. Once they drop off a babesia-infected animal, they rarely if ever journey more than a 8-foot radius from where they first fell. What they do do is climb surrounding vegetation and patiently wait for another host animal to pass by (“questing”). The brown dog tick is a common carrier of babesiosis and other tick-borne diseases. Generally, your dog will be exposed to them through visiting an area that many poorly-maintained dogs, wildlife or feral animals frequent: parks, dog parks, wooded trails, poorly maintained boarding kennels. If you must bring your pets to those sort of areas, apply a Permethrin/ Pyriproxyfen containing product similar to K9Advantix® II or an amitraz-containing tick collar such as Preventic® These products repel other woodland ticks that are also a threat to your dog and to you. American dog ticks and Lone Star ticks are the most aggressive in seeking out a new host through the C02, vibrations and heat that pets emit; but these products are effective in repelling them as well.
Check your dog and yourself daily for ticks and remove them. Be sure to look in their ears and between their toes. Expand the diagram of the tick above to see the proper way to grasp a tick. Be particularly thorough in brushing and combing if your dog has been in high weeds or brush. Consider shearing long-coated breeds.
When removing a tick try not to crush or squeeze its body. That might force the contents of the tick into your pet. The best way I have found to remove them is to grasp the tick’s mouth parts as close to the skin as possible with a pair of small tweezers and pull the tick away – removing all of the tick’s head and a small tag of skin as you do. Ticks secrete a liquefying enzyme into the skin surrounding their mouth parts. So that portion of skin usually tears off with the tick when you pull. In the long run, removing that small tag of skin with the tick allows for quicker healing of the small residual wound. Then dab the former point of attachment with antiseptic if you wish.
Treat your yard with insecticides approved for controlling ticks or hire a professional to do it. Esfenvalarate-containing products like Advantage® Yard/Premise spray and AsanaXL® are of low toxicity to pets when used as directed. They are for your yard, never put these products on your pets.
Keep your yard closely mowed. Clear brushy areas that harbor ticks and trim your trees so that sunshine reaches the ground. If you have a large estate and no close neighbors, consider some guinea hens . They have keen vision and a taste for ticks.
Over the years attempts have been made to develop canine babesia vaccines. They do not appear to be highly effective. One I was acquainted with that has since been withdrawn from the market claimed to only lower the severity of infections. (ref) I do not know the effectiveness of the one that I believe still remains, Pirodog®. None, to my knowledge, were ever marketed in North America.
Another blood disease that ticks bring to dogs is Ehrlichiosis. The most common ehrlichia bacteria involved is Ehrlichia canis . Several common species of ticks carry this organism. The disease goes by many names: canine monocytic ehrlichiosis (CME), canine rickettsiosis, canine typhus, tropical canine pancytopenia, idiopathic hemorrhagic syndrome, canine hemorrhagic fever and tracker dog disease. It is most common in hot, humid or semi-tropical climates. Subsequent to tick bites, humans are also susceptible to ehrlichia. The most common one affecting people is E. chaffeensis. However, a second tick-carried ehrlichia, Ehrlichia ewingii, infects both dogs and humans. (ref) Whereas babesia live in your dog’s red blood cells, ehrlichia live in its white blood cells – the ones responsible for immunity. The white blood cell type most affected are its monocytes. (ref)
If My Dog Becomes Infected With Ehrlichia What Signs Might I See?
Many dogs that harbor ehrlichia subsequent to a tick bite show no signs of illness at all. Veterinarians do not know the factors that lead to one dog becoming ill while another lives in relative harmony with the parasite. Many suspect that it is co-infection with other tick-borne diseases like anaplasmosis, babesiosis or Lyme disease that causes ehrlichia to cause disease. Other attribute the onset of symptoms to be due to lifestyle stresses, or concurrent health issues. Still others point to genetic susceptibility to ehrlichia disease, as appears to be the case in German shepherd dogs. (ref)
When ehrlichia does produce disease, signs are quite variable. Many dog owners just notice a sudden loss of appetite and energy. With time, that can progress to painful joints, lameness, pale gums, rapid respiration and fever. Like babesia, ehrlichia often causes the dog’s thrombocytes (blood platelet) numbers to drop, decreasing its blood’s ability to clot. So nosebleeds occasionally occur as well. (ref)
How Will My Veterinarian Diagnose Ehrlichiosis In My Dog?
The physical signs of ehrlichiosis are not sufficiently different from babesiosis to tell one from the other. Fever, enlarged lymph nodes (lymphadenopathy), enlarged spleen and joint pain are commonly associated with this disease. As with babesiosis, there is often a deficiency in thrombocytes (=blood platelets) – cells involved in the blood clotting process. Veterinarians are unsure why this is a common symptom in several tick-borne diseases of dogs. As with all tick-borne diseases, it is not that unusual for a dog to be infected with several different species of these bacterial parasites at the same time. Standard canine “tick panels” , offered by a number of commercial laboratories and universities, will detect most dogs that are suffering from ehrlichiosis. Those tests look for antibody the dog produces against the organism. They occasionally give false negative results. In those cases, a PCR test that looks for the ehrlichia organisms themselves is more accurate. (ref) When these tests detect antibody, it only denotes exposure – not active disease. So a confirmatory PCR test is a wise choice in that situation as well.
Most vets in high disease prevalence areas perform the Idexx SNAP®4 in their office when they are suspicious the ehrlichiosis could be your dog’s health problem. These organisms proliferate in the monocytes that circulate in your dog’s blood. They can occasionally be seen there when a stained slide of your dog’s blood is examined microscopically. In addition to abnormally low thrombocyte counts, anemia (low PCV), low lymphocyte numbers (lymphopenia) low blood albumen (hypoalbuminemia) and high blood globulin levels (hyperglobulinemia) are not unusual findings in dogs with an active ehrlichiosis problem. Their blood AP and ALT levels are frequently elevated as well.
What Treatment Are Available When My Dog Has Ehrlichiosis?
Most veterinarians treat this disease with doxycycline – often for about 4 weeks. If your dog appears healthy to you and your veterinarian cannot point out evidence that it is not, there is really no need for it to receive medications. Have the SNAP test results confirmed with a PCR test and concentrate on eliminating ticks from your dog’s life. Ehrlichiosis, when a dog eliminates the organisms with or without medication, imparts no lasting immunity. Use the same prevention strategy I mentioned for Babesia.
The same as babesia. Many veterinarians suggest your dog be tested at their office for tick-borne diseases, including ehrlichia, yearly. That decision needs to be made by you and not your veterinarian. It needs to be based on how likely you feel it will be that your dog is exposed to ticks. If you live where there are tick-borne diseases, you live where there are heartworms. Give a monthly heartworm preventative to your dog all year long.
Anaplasmosis of dogs is the most recent tick-borne disease to receive special attention from veterinarians. For most of the last 100 years, the focus was on a cousin of this organism that affects cattle. (ref) Veterinarians tend to focus on ticks as the primary transmitter of anaplasmosis to dogs. Anaplasma is a rickettsia, as is ehrlichia. So a variety of biting insects such as fleas and mosquitoes are probably capable of spreading it too. That has been confirmed in other rickettsial diseases of animals and humans. Anaplasma and ehrlichia are closely related. In fact, the common anaplasmas affecting dogs, Anaplasma phagocytophilum and Anaplasma platys, were considered to be ehrlichia until 2001. (ref) And like ehrlichia, they have wild animal reservoirs other than dogs. Humans occasionally contract Anaplasma phagocytophilum too (HGE). (ref) But your infected dog is no threat to you. The disease only move from one host to another through insect bites or blood contamination of a wound. Cats are at risk as well. (ref)
Of the three diseases I mention in this article, babesiosis, ehrlichiosis and anaplasmosis, Anaplasmosis tends to be the mildest in dogs. It is often described as “self-limiting”, meaning most dogs overcome the infections without treatment. The few that do not can go on to become normal-appearing (asymptomatic) carriers. Much depends on your pet’s own unique immune system and the strength (virulence) of the particular anaplasma/ehrlichia strain involved. (ref)
What Signs Might I See If My Dog Develops Anaplasmosis?
There have been no large studies, but in one small study in the Netherlands, only two out of 6 infected dogs showed any outward signs of illness. (ref) When dogs do show signs of illness, it is usually confined to a lack of energy and interest (general malaise, lethargy), decreased appetite and perhaps a transient fever that resolves over a week or two. But on occasion, signs of anaplasmosis can be considerably more severe. When they are, the signs mimic the signs of more pathogenic ehrlichia. (ref) Those cases often involve infection with more than one tick-borne disease.
How Will My Veterinarian Diagnose Anaplasmosis In My Dog?
When the history you provide to your veterinarian and the typical symptoms I mentioned for the first two diseases are present in your dog, your veterinarian will run an in-office test that indicates exposure to any of them. As I also mentioned earlier, it is not unusual for a dog to be infected with more than one of these diseases simultaneously. (ref) In severe cases –often those where the tick or vector transmitted more than one disease- the same laboratory test results of low blood thrombocyte counts, low lymphocyte counts and elevated liver enzymes occur. An occasion dog with anaplasmosis will show symptoms of painful joints as well.
What Treatment For Canine Anaplasmosis Are Available?
Antibiotics, such as doxycycline or tetracycline are usually quite effective in reliving anaplasmosis symptoms. As with ehrlichia, it is not always certain that every last anaplasma has been eliminated from your dog’s body. (ref) The most certain way to know your dog’s status with more confidence is to run a post-treatment PCR test. Dogs that do not respond rapidly to drugs like doxycycline need to be carefully evaluated for concurrent health issues that might be responsible. (ref1, ref2)