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by: Pam Barbe
1. What is Tick Disease?
In this context, we are using Tick Disease as a catch-all phrase for the following group of diseases that can infect animals and man. These include, but are not limited to, the following:
*Although most strains of Ehrlichia are transmitted by ticks, please note:
For Neorickettsia (Ehrlichia) risticii (also the causative agent of Potomac Valley Fever in horses), no known tick vector has been established. In numerous attempts, the tick was shown NOT to spread N. (Ehrlichia) risticii. In horses (studies have not been done in canines), N. (Ehrlichia) risticii infection has been confirmed to be transmitted transplacentally 24 and via infected horse manure23. Studies have shown experimental transmission and isolation of N. (Ehrlichia) risticii in freshwater stream snails (trematodes) as well a actual isolation in snail secretions and from aquatic insects in endemic areas.(ref. 18-20). And in a very recent study, "Upon ingestion of adult aquatic insects, horses developed clinical signs of Potomac horse fever, and Neorickettsia risticii was isolated from the blood 22.
2. What are the signs and symptoms of tick diseases?
Sometimes the symptoms are few and subtle to see in the later stages of tick disease (sub-clinical or chronic). It is unlikely a dog would have all of the symptoms, as the list is quite long. Here are some of the symptoms of Ehrlichiosis. Babesiosis, RMSF and Lyme disease have many of these symptoms too.
3. What is meant by the terms acute, sub-acute (sub-clinical) and chronic
when referring to tick disease?
Generally, in the acute phase of illness, 1-4 weeks post infection, the dog may present with a flu-like illness. Fever, lethargy, depression of appetite, diarrhea and/or lameness may be present. The dog may act like it is very painful to be touched and will yelp when picked up or when played with. The laboratory profile will be variable, showing decreased red blood cells and increased white blood cells (WBC) and/or platelets. Alkaline phosphatase (liver enzyme) may be elevated. Immunologically competent dogs may be able to eliminate the infection without treatment, however, antibiotic therapy is very effective during this stage of illness and is recommended to completely eliminate the organism.
Untreated, the disease may move into the sub-clinical phase. The dog's body weight normalizes and laboratory abnormalities may be quite subtle. Thrombocytopenia (low platelets) may or may not be present. This phase of disease can last for months or years as long as the dog is not subjected to something that causes undue stress. The parasite is essentially living with the host in stasis; not overpowering the dogs immune system.
However, if this balance is disturbed by environmental conditions, concomitant infections (combination of diseases), immuno-deficiency, splenectomy, surgery, stress, excessive work, pregnancy, immunosuppressive therapy (including corticosteroids like Prednisone), the organism can gain the upper hand and the dog enters the chronic stage of illness. Because the organism is possibly sequestered in an organ or organs (bone marrow, spleen, liver, etc.), it is harder to treat effectively. Immune capabilities are impaired (like ability to make antibodies). Sometimes, when a dog has entered the chronic stage of tick disease, there is no form of effectual treatment and death can occur.
4. Can tick disease mimic other medical conditions?
Ehrlichiosis may be confused with:
Babesiosis may imitate:
The above can be documented in the scientific literature. Unpublished data on approximately 30 Samoyeds who have been followed for the last couple of years, who titered positive to one or more tick diseases, and who had clinical symptoms consistent with tick disease, had previously been diagnosed with IBD (Inflammatory Bowel Disease), pancreatitis, chronic giardiasis, liver failure (including liver cancer), obsessive/compulsive fur chewing on extremities, hypothyroidism and reproductive problems including abnormal seasons, recurrent vaginitis and pyometra in bitches and enlarged prostates and penile discharge in dogs.
5. What routine lab tests can be indicators of possible tick disease?
Laboratory findings vary depending upon the stage of illness. The CBC (Complete Blood Count ) may be within normal limits, or can show:
6. How many strains of Ehrlichia are there?
Lots of work is currently being done in the field of Ehrlichiosis research due to the fact that this is an emerging pathogen for humans. While it was once thought that each strain was species specific, as more research is being done, they are finding that there is much crossing over between strains and their target vertebrate hosts.
The Ehrlichial strains that infect the monocytes are:
The Ehrlichial strains that infect granulocytes (segmented white blood cells) are:
Note: E. equi, HGE and E. phagocytophila have been combined into a single genus specie - Anasplasma phagocytophila.21
One strain of Ehrlichia infects platelets (cells associated with blood clotting):
7. Which ticks in the US transmit disease?
The two ticks now known to transmit Lyme in the US are Ixodes scapularis (NE and S US-- formerly called I. dammini) whose common name is the deer tick; and I. pacificus (common name- western black-legged tick) in the W US including all of the W coast states, plus Arizona, CO and Nevada. However, what is important for transmission in any locale is 1) the availability of animal reservoirs--deer and small mammals--the contact with domestic animals and humans is incidental to that. And 2), how many of the ticks actually carry the infection. Literature reports show that in Connecticut where Lyme is endemic, the population of I. scapularis ticks that carry Lyme ranges from 10 to 30 % depending on which reports you read. But, in studies done in W coast I. pacificus habitats, infection rates were only in the 1 to 3% range. So the odds of transmission drop accordingly.
Rocky Mountain Spotted Fever (RMSF) is transmitted by both Dermacenter variabilis (american dog tick-occurs W of the Cascades and Sierra Nevadas, from Nebraska to the Atlantic and in E Canada and Mexico ) and Dermacentor andersoni (wood tick-range is Nebraska westward to the western mountains-Cascades and Sierra Nevadas, in northern NM and Arizona and in W Canada). The name RMSF is somewhat misleading because the disease has been reported in all states except Hawaii and Vermont.
Human monocytic ehrlichiosis (HME), caused by the organism Ehrlichia chaffeensis, is transmitted normally by the Lone Star tick, Amblyomma americanum (distribution is southern USA from TX to MO to the Atlantic coast and ranges northward into New Jersey) and Dermacenter variabilis (american dog tick). This disease has been reported in thirty states in humans. Reservoirs include white-tailed deer, dog and small rodents. The monocytic form of this disease in canines is called E. canis and it is transmitted by the brown dog tick or kennel tick, Rhipicephalus sanguineus, with worldwide distribution. E. platys (now called Anaplasma platys) is also transmitted by the brown dog tick.
E. ewingii, which causes canine and human granulocytic ehrlichiosis, is transmitted by the Lone Star tick, Amblyomma americanum (distribution is southern USA from TX to MO to the Atlantic coast and ranges northward into New Jersey).
HGE (now called Anasplasma phagocytophila), human granulocytic ehrlichiosis, is transmitted by the tick I. scapularis, which also transmits Lyme and Babesiosis. Other vectors include I. pacificus and I. ricinus (Europe). The primary reservoir for HGE is thought to be the white-footed mouse.
8. Which diseases should my dog be tested for?
There may be some variability depending on the locale where the dog resides, was bred or has traveled. The following would constitute a good screen:
9. Where can the testing be done?
MSU College of Veterinary Medicine
The Diagnostic Center for Population and Animal Health
Clinical Pathology Laboratory
A215 Veterinary Medical Center
Michigan State University
East Lansing, MI 48824-1314
Tick Borne Disease Antibody Screen at MSU- This panel consists of antibody titers for the following organisms: Borrelia burgdorferi (Lyme), Babesia canis and gibsoni, Ehrlichia canis, Anaplasma phagocytophilum, and Rickettsia rickettsii (Rocky Mountain Spotted Fever). Titers for Neorickettsia risticii must be ordered separately. Results are reported as an antibody titer. Various pcrs are also available and must be ordered separately from the antibody screen.
Testing for tick disease is not inexpensive. Having the titers done at competent laboratories will save money in the long run.
10. What will the result of the titer tell me?
The titer result will need to be interpreted by the veterinarian who has examined the dog in conjunction with the referral laboratory's guidelines for positive and negative titer results. Generally, the following is true:
Negative titer result:
Technically, a negative titer means the dog does not have detectable antibody to the strains tested. There are several reasons this could occur:
Positive titer results:
A positive result indicates that the dog has, at some point in its life, been exposed to the strain of tick disease for which it was tested. (Note: Exposure to more than one strain is possible.) With clinical symptoms consistent with tick disease, one option is to treat until titer and symptoms disappear. This may require several courses of treatment.
A positive result without symptoms consistent with tick disease, probably bears watching and repeat titers should be done at a later date or if symptoms later occur.
11. How do you remove an attached tick?
Do not use alcohol, nail polish, hot matches, petroleum jelly, or other methods to remove ticks. These methods may actually traumatize ticks causing them to regurgitate their gut contents. Essentially, you don't want to do anything to make the tick expel its gut contents into the individual or animal--this greatly increases the chance for infective organisms to be transmitted. You also don't want to crush the tick after removal and get the contents of a potentially infected tick on your hands.
The recommended way to remove an attached tick:
**Testing of the tick for disease organisms can be done with a PCR (Polymerase Chain Reaction) test. Check with the laboratory that will be doing the testing before placing the tick in alcohol as this may interfere with the test procedure. Save the tick in a sealed ziploc bag with a little moisture, without alcohol, until this information can be determined. Many state health departments are equipped to handle this type of testing.
12. What preventive measures are available to avoid ticks on my dog?
Avoid tick prone areas--ticks love low shrubs and grasses.
Most Samoyed owners have never seen a tick on their dogs--but how good have they really looked? With all the fur, a tick is very easy to miss. Check for tick attachment as soon as you return from an outing. Line comb or use the hair dryer to examine all areas closely. Depending on the type of tick and the disease it carries, the attachment and feeding for several hours to several days is necessary to transmit disease. So prompt removal is a must.
A couple of products are now available (Please check with your Veterinarian about whether these would be good products to use on your dog; I am not recommending the use of either, that would be your decision to make.).
Frontline® (Rhone-Merieux, Inc. ) spray or Topspot--The active ingredient is
Fipronil which is a neurotoxin specific to invertebrates (including fleas
and ticks); it over stimulates the flea or tick's nervous system causing
convulsions and death within a few hours for fleas and within 48 hours for
ticks. Some tips for a better application
Preventic ® Tick Collar (Virbac, Inc.) for dogs:
13. What is used to treat tick disease?
Ehrlichiosis: Doxycycline*** (a semisynthetic tetracycline) at 10 mg/kg of dog's weight (2.2 pounds = 1 kg), twice per day given 12 hours apart for 6 weeks or longer. Sometimes more than one course of therapy is necessary. Doxycycline should not be given with food (milk or yogurt) or supplements containing calcium iron or magnesium (like antacids) because these agents will interfere slightly with the absorption of the antibiotic. (Allow at least two hours pre or post doxycycline administration.) Do not give Doxycycline on an empty stomach--so administer the medicine with food or 30-60 minutes after the dog has eaten. Wrapping the pills in piece of bread often helps alleviate the upset stomach. Another thing some owners have found helpful--if you can do it with your work schedule--is to keep the dog somewhat active for a while after giving the doxycycline--if the dogs go and just sleep right after administering the doxycycline--the medicine sits in one spot in the stomach and seems to be more irritating to the stomach lining.
***PLEASE NOTE--This dose of doxycycline is at twice the normal published therapeutic amount. Only the veterinarian caring for your dog can make the decision about what dosage to use. Have your vet contact a veterinarian familiar with treating Ehrlichiosis to discuss treatment options.
Babesiosis: The current drug of choice, Imizol® (generic name- Imidocarb Dipropionate), was FDA approved (11/97). It's success rate as stated in research papers is 95 - 98%. While Imizol is the least toxic of all the anti-babesial drugs, potential side effects that can occur within one hour of injection include: pain or irritation at injection site, nausea with vomiting, excessive drooling and salivation, diarrhea, and muscle tremors and twitching. Imizol could potentially cause nephrotoxicity in a dehydrated dog. At least one death of a greyhound has been attributed to Imizol injection. A reduction in side effects has been seen by injecting the Imizol subcutaneously, rather than into the muscle.
14. How do you identify the type of tick?
There are a couple of good websites that have images and video clips of ticks.
Also, most county extension services have a staff entomologist who could identify the tick.
REFERENCES AND VALUABLE LINKS:
The health links and material on this site are provided for educational and informational purposes only and are not intended to be a substitute for consultation with a veterinarian or other pet health care professional. The opinions presented on the links and in the material on this site reflect various sides of issues. No representation is made that any of the information provided on this web site or links from this web site is accurate. Additionally, any mention of commercial products or services within these web pages should not be viewed as an endorsement. Decisions with respect to the specific care and treatment of an animal should always be made with appropriate veterinary advice.
ACKNOWLEDGMENT: I'd like to thank Lynda Adame, list administrator for the Tick-L, for her imput concerning the signs/ symptoms of tick diseases and illnesses that tick diseases may mimic.
Permission is given by the author to reprint this FAQ as long as it is reprinted in its entirety--including author credit, acknowledgement and all disclaimers.
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Last updated Friday, December 31, 2010