Lyme disease is the most common tick-borne disease in dogs. Dog owners need to be aware that ticks can transmit other serious diseases.
DOG LYME DISEASE
Lyme is the most common tick-borne disease. Lyme is easy to treat and causes only classic symptoms. It rarely causes any serious illness. This is the exception. Lyme nephritis is a condition that is always fatal.
Borrellia burgdorferi, a spirochete-shaped bacteria that causes Lyme disease in dogs, is transmitted by Ixodes species ticks such as the black-legged and deer tick. Incubation (the time from tick bite to clinical illness) can take up to two to five years. The organism moves from the bite site to the joint capsules.
Antibody tests are the blood tests that veterinarian hospitals use to detect Lyme disease. (See “Tests for Tick-Borne Diseases”) These tests are often combined with heartworm antibodies tests. A positive antibody test will give you an index of suspicion. To diagnose Lyme disease, you must have a history of tick exposure and classic clinical signs.
While some dogs may show signs of mild fever, inappetance and lethargy occasionally, the most common presentation is lameness with a painful or swollen joint.
Doxycycline is the preferred treatment. It’s an oral antibiotic that lasts for four weeks. The treatment is quick and results in a resolution of symptoms within 24 to 48 hours. As long as the infection does not get into the kidneys, the prognosis for this condition is good.
Due to the possibility of kidney involvement and the seriousness of this scenario, Lyme-positive dogs should have their urine tested for protein loss.
Lyme nephritis in nature is immune-mediated. Immune complexes are formed when pathogenic organisms and antibodies against them combine to form compounds called immune complexes. These immune complexes can cause kidney damage, including proteinuria (excess protein in the urine) or kidney failure. Although aggressive treatment with antibiotics or immunosuppressive therapy can sometimes be successful in these cases, the overall mortality rate for Lyme nephritis patients is very high. Lyme nephritis incidence is relatively low in comparison to Lyme-infected dogs.
NAPLASMOSIS IN DOGS
Anaplasmosis refers to two distinct clinical syndromes that are caused by bacteria.
Anaplasma phagocytophilum, a bacteria that can infect white blood cells, causes Canine Granulocytic Anaplasmosis. Anaplasma platys causes Canine Infectious Cyclic Thrombocytopenia. Both Anaplasma bacteria types are transmitted by the same ticks that also carry the spirochete bacteria which causes Lyme disease. This means that it is possible to coinfect with Lyme and anaplasmosis.
The incubation time (from the tick bite to the dog’s disease) for each type of anaplasmosis is between one and two weeks. Both syndromes can cause fever, inappetence and lethargy. CGA can cause lameness in dogs. Dogs with CGA often present with signs of bleeding disorders, such as bruising, bloody stool, urine or urine, and nosebleeds.
The same screening antibody test used to diagnose Lyme disease is used for diagnosis. This does not mean that you have been exposed. A polymerase chain reaction (PCR), which is the best test for active anaplasmosis, is the best. However, false negatives may occur due to the cyclic nature CICT.
Doxycycline is used for treatment. It should be taken for at least 14 days. Anaplasmosis can be treated immediately. This means that the organism doesn’t stay around after treatment. The prognosis for anaplasmosis is generally good and treatment is successful.
EHRLICHIOSIS IN DOGS
Ehrlichia canis (brown dog tick) and Ehrlichia ewingii (bacterial cause) are the bacterial causes. These organisms are transmitted by the Rhipicephalus sanguineous, a brown dog tick, and Amblyomma, a Lone Star tick. They infect white blood cells. Incubation takes between one and three weeks.
The symptoms of ehrlichiosis in dogs can be similar to anaplasmosis: fever, lethargy and inappetence, splenic enlargement and lymph node enlargement. Some dogs may develop lameness and ocular or nasal discharge over time. Sometimes Ehrlichia can cause neurological derangements such as seizures and incoordination.
Dogs who have passed the acute stage without any treatment will then enter the subclinical stage. This stage can last from months to years and the organism hides in the spleen. This stage is usually when the dog has no symptoms and then either goes into a chronic stage, where he gets sick again.
Chronic stage has the worst prognosis and can lead to complete bone marrow loss and secondary immune-mediated conditions that may cause bleeding disorders, eye problems, or kidney failure.
The point-of care antibody test is used to diagnose ehrlichiosis. This is followed by a PCR test. Doxycycline is given for 28 days, just like Lyme and anaplasmosis. Acute cases usually respond within one to two days and have a positive prognosis. Chronic cases can be more difficult to treat and have a guarded prognosis. Some people never respond and it can take several months to get the treatment. Monitoring includes serial PCR tests, complete body counts (CBCs), as well as serum chemistry testing.
Vaccination against Lyme disease
Is it a good idea to vaccinate dogs against Lyme disease Although the canine Lyme vaccine was first introduced in 1992, there has been no consensus over its use. Both sides have their reasons for and against Lyme vaccine.
Opponents of Lyme vaccine express concern about the vaccine’s inconsistency, cost, and duration of immunity. They also point out that tick prevention is still necessary even if vaccination is effective. Because Lyme disease in dogs is mild and easy to treat, most vaccination opponents don’t believe we should be exposing dogs to the risks of vaccines. They continue to be concerned that vaccination could make Lyme nephritis worse in dogs if they were to contract it. However, this is not supported by scientific evidence.
Lyme vaccination is believed to provide protection against Lyme disease, Lyme nephritis and tick-borne diseases. Lyme vaccines are safe and effective for dogs, they say. Dogs don’t develop natural immunity to infection and are therefore always susceptible to reinfection.
Every patient should have a personal risk assessment done by me, as a physician. It is based on the individual’s lifestyle and environmental factors. Lyme vaccination is not recommended if the dog has no tick-related risk. I recommend that the dog be vaccinated if they are at risk of being exposed to ticks. This has proven to be a safe and effective way to prevent Lyme disease in dogs.
BABESIOSIS IN DOGS
Two main bacteria are responsible for this disease, just like Anaplasma or Ehrlichia. The same tick that spreads Ehrlichia is responsible for Babesia Canis. Therefore, coinfections can occur. This bacteria is most common in the south of the United States. Babesia canis is found in large numbers of Greyhounds from Florida.
Babesia gibsoni can also be found in the United States. This is a unique one in that it can be transmitted from dog to dog via bite wounds rather than tick bites.
Babesia organisms can infect the dog’s circulating blood cells. Incubation takes between one and three weeks. The symptoms are similar to other tick-borne diseases (fever, lethargy and lymph node swelling, splenic swelling), but Babesia is the most common symptom. It causes anemia, which results from pale or yellow (yellowish) mucous membranes, as well as weakness.
Babesia can’t be detected using the point-of care test that screens for tick-borne diseases. Babesia infection can be detected by PCR testing.
Babesia is a mild infectious disease with low virulence. Many infected dogs won’t even get sick. The most sick are often young puppies or dogs with compromised spleens.
Babesia can spread from infected dogs that are not symptomatic. Sometimes, the carrier status can progress to a chronic condition, such as Ehrlichia. In this case, the dog can become clinically ill or develop secondary immune-mediated diseases. Sometimes, these dogs require blood transfusions and can take a while to recover. The prognosis for these dogs is uncertain.
The treatment can be complicated, which makes matters worse. This is not the case with doxycycline. The treatment involves injectable imidocarb diproprionate and/or a long-term course of multiple antibiotics and hard-to-find protozoals. In addition to intensive supportive care and treatment for secondary immune-mediated disorders, the treatment usually includes an injection medication called imidocarb. The upside is that Ehrlichia can cause many dogs to become ill.
ROCKY MOUNTAIN SPOTTED FEVER IN DOGS
Rickettsia rickettsii is the bacteria that causes RMSF. It is spread by Dermacentor ticks (American dog tick and wood tick), Amblyonna ticks (“Lone Star tick”), Rhipicephalus ticks (“brown dog tick”) It can cause severe, acute disease in humans and dogs.
Endothelial cells, which are the cells that line blood vessels, are infected by Rickettsia. Systemic vasculitis is a condition that causes severe tissue and organ damage. Common symptoms include fever, malaise, and neurological signs. Incubation can take anywhere from two days to two weeks.
Point-of-care tests that screen for Lyme, Anaplasma and Ehrlichia do not include RMSF. PCR tests for RMSF are not reliable because the organism doesn’t circulate in dogs’ blood. It adheres to the blood vessel linings instead. A pair of antibody tests is used to diagnose RMSF. These are called convalescent and acute samples. A positive response to therapy and a rise in antibody titer are all indicators of RMSF.
This disease is extremely severe and should be treated immediately, according to the index of suspicion. This bacterial infection can be treated with Doxycycline.
This terrible disease has a positive side. The prognosis for this disease is good if it’s caught early. The dog that is successfully treated often develops a lifetime immunity. However, cases that aren’t treated quickly often suffer serious, life-threatening complications and a guarded prognosis.
HOW TO PREVENT TICK BORN DISEASES IN DOGS
All of these diseases can be prevented by keeping ticks away from your dogs. Avoid areas that are known to be infested by ticks. Make sure your lawn is mowed and your landscaping is clean. After returning from an outdoor adventure, check for ticks and get rid of them immediately. Use a trusted tick prevention product on your dog. There are many options available, including collars and topical or oral products. Consider vaccination for Lyme disease.
Tick-Borne Disease Tests
There are many “point-of care” or “inhouse” tests that can be used to detect microorganisms in dogs that could cause disease. A tick-borne disease test might be recommended by your veterinarian as part of your dog’s annual routine examination. This test could also be used to confirm a heartworm infection. A laboratory test may be required if your dog shows signs of tick-borne disease.
Antibody tests, also known as serology testing, detect antibodies produced by the immune system in response to disease-causing pathogens. The antibodies are only used to determine if the dog was exposed to pathogenic organisms. This test does not confirm or disprove active infection. There are several combinations of antibody tests available to vets. These include the Antech Accuplex and Idexx 4Dx (pictured at right), and Zoetis Flex4 which can detect antibodies against heartworms, Borrellia burgdorferi (the bacteria causing Lyme disease), Anaplasma and Ehrlichia.
The preferred method to detect tick-borne bacterial infections in the acute phase is polymerase chain reaction (PCR). Although PCR tests are not effective in detecting Lyme disease and Rocky Mountain Spotted Fever, they can detect Anaplasma, Babesia and Ehrlichia.
WHAT TO DO IF A HEALTHY DOG TEST POSITIVELY FOR A TICK BORNE DIISEASE
All dogs should be screened for tick-borne diseases and heartworm disease annually. This is usually done during your dog’s annual wellness check. It includes the above-described point-of care test, which checks for tick-borne diseases, Lyme disease, Anaplasma and Ehrlichia.
Don’t panic if your dog is otherwise healthy and tests positive for Lyme or Anaplasma. These tests do not indicate infection, but only exposure. Any dog that tests positive for tick-borne diseases should have a complete blood test (CBC), serum chemistry and urinalysis. Most veterinary authorities don’t recommend treatment if everything is in order. Pay attention to any clinical signs. You should also increase your tick prevention
Some veterinarians will recommend a second test for Lyme-positive dogs called Quantitative Lyme C6. If they find a high number, they might recommend treatment. This is not a definitive answer. Ehrlichia-positive dogs may be recommended by veterinarians to be treated in order to prevent a chronic condition. There is no definitive answer.
If your dog is positive for Ehrlichia or Anaplasma and you want to be certain that they are not actively infected, have your veterinarian run a PCR test.
Tick-Borne Diseases in Dogs Whole Dog Journal.