Anaplasmosis

Written by Dr. Patty Khuly, VMD MBA

Summary

Anaplasmosis is a bacterial disease of dogs that’s spread by ticks. It’s especially important to veterinary medicine because of its rapid spread around the world, and its ability to affect humans as well (though not directly from dogs).

Two species of bacteria are known to cause anaplasmosis in dogs and humans:

  • Anaplasma phagocytophilum is the most common bacteria associated with anaplasmosis. It leads to lameness, and as such, it’s commonly confused with Lyme disease.

  • Infection with the other bacteria, Anaplasma platys, results in a disease state in which the levels of platelets in the bloodstream are reduced. This reduction has serious implications for blood clotting in infected patients.

The disease has a worldwide distribution:

  • In the US, it’s common in the upper Midwest, East, and Northeast, as well as the western coastal regions.

  • In Europe, the UK, Norway, Sweden, Switzerland, and Germany have reported infections in cows, dogs, and humans.

  • Anaplasmosis is less common in South America and Asia.

In the US, the disease is considered a seasonal threat during tick-heavy times of the year. Spring/early summer and the fall are the most likely times for both dogs and humans to become infected. Several species of ticks are known to carry these bacteria. As with Lyme disease, white-tailed deer and small rodents are considered the ticks’ preferred reservoirs.

Anaplasmosis has been identified most often in dogs eight years or older.

Symptoms and Identification

Anaplasmosis usually manifests when dogs are first infected. This is called the acute phase of the disease. They can also experience a less obvious, longer-term version of the disease. Dogs can sometimes suffer from this chronic kind of anaplasmosis for several months at a time.

Infected dogs typically display limping or joint pain. Less commonly, they can also suffer GI symptoms like vomiting and diarrhea, respiratory symptoms such as coughing and sneezing, or even signs of meningitis should the bacteria infect the nervous system as well.

Because these signs are fairly non-specific and may be caused by any number of diseases, laboratory testing through is the most typical approach to diagnosis. But this can be problematic, especially since dogs in the acute phase don’t always have abnormal test results, and those experiencing the chronic version of the disease typically look normal on all routine blood testing.

Eighty percent of acutely infected dogs do, however, tend to have a deficiency of platelets. They can also have abnormal white blood cells in which the bacteria’s presence can be detected. In dogs with painful joints, evaluation of the joint fluid for these organisms may be of some benefit as well.

But the best method of detection of anaplasmosis in those for whom we suspect the disease is a very specific kind of blood testing: either indirect fluorescent antibody (IFA) testing (in an outside lab) or ELISA testing (usually performed in the hospital) can detect the disease in most patients within days of infection.

Affected breeds

There is no confirmed breed predisposition in dogs but Golden Retrievers and Labrador Retrievers are overrepresented in most reports. It's not clear whether this is because of true breed susceptibility or because of the higher frequency of exposure among these outdoorsy, popular breeds.

Treatment

Treatment typically includes the use of the antibiotic doxycycline. Dogs suffering from acute infection with anaplasma tend to feel better within a day or two but, depending on their symptoms and changes in platelet numbers, they may still require hospitalization for expended periods of time.

Veterinary Cost

The cost of diagnosis can be expensive in these cases, more so if owners don’t report tick exposure and non-specific symptoms, which can confuse the process. In these cases, a great many tests might be run before specific anaplasmosis testing is undertaken. Lab expenses ranging between $150 and $500 are typical.

Treatment, if undertaken early, can be very inexpensive, as doxycycline is considered an inexpensive antibiotic. However, dogs who require hospitalization for expended periods of time due to the less common severe effects of anaplasma (meningitis, for example) can experience invoices into the thousands of dollars.

Prevention

Aggressive tick control programs are the ideal approach to prevention. Use of veterinarian-recommended tick prevention products is considered extremely helpful. But removing all ticks within 24-hours of attachment is considered one hundred percent effective.

References

Alleman AR, Wamsley HL, Abbott J, et al. Experimental Anaplasma phagocytophilum infection of dogs by intravenous inoculation of human and canine isolates and treatment with doxycycline (abst). Vet Pathol 2007;44:19.

Beall MJ, Chandrashekar R, Eberts MD, et al. Serological and molecular prevalence of Borrelia burgdorferi, Anaplasma phagocytophilum, and Ehrlichia species in dogs from Minnesota. Vector Borne Zoonotic Dis 2008 Feb 27 [Epub ahead of print].

Breitschwerdt EB, Hegarty BC, Hancock SI. Sequential evaluation of dogs naturally infected with Ehrlichia canis, Ehrlichia chaffeensis, Ehrlichia equi, Ehrlichia ewingii, or Bartonella vinsonii. J Clin Microbiol 1998;36(9):2645-2651.

des Vignes F, Piesman J, Heffernan R, et al. Effect of tick removal on transmission of Borrelia burgdorferi and Ehrlichia phagocytophila by Ixodes scapularis nymphs. J Infect Dis 2001;183(5):773-778.

Egenvall AE, Hedhammar AA, Bjöersdorff AI. Clinical features and serology of 14 dogs affected by granulocytic ehrlichiosis in Sweden. Vet Rec 1997;140(9):222-226.

Greig B, Armstrong PJ. Canine granulocytotropic anaplasmosis (A. phagocytophilum infection). In: Greene CE, ed. Infectious diseases of the dog and cat. 3rd ed. St. Louis, Mo: Saunders, 2006;219-224.

Greig B, Asanovich KM, Armstrong PJ, et al. Geographic, clinical, serologic, and molecular evidence of granulocytic ehrlichiosis, a likely zoonotic disease, in Minnesota and Wisconsin dogs. J Clin Microbiol 1996;34(1):44-48.