Tick-borne disease: Ecrlichiosis, Lyme borreliosis and anaplasmosis (Proceedings)
In just the past 3 to 5 years, advanced diagnostic capabilities have enhanced our ability to detect infectious pathogens in the dog and have given credence to the term "emerging" infections. However, the ever-expanding list of "emerging infectious diseases", in fact, may not be emerging at all...as it appears; many of these infections have, quite likely, existed in dogs for several years. It's the emerging technology that has enabled our ability to detect these infections.
AND...it's MUCH more than Blue Dots! As we move from the 3Dx test to the 4Dx testing platform, veterinarians now have the ability to test for Anaplasma phagocytophilum antibody, in addition to Borrelia burgdorferi C6 antibody, Ehrlichia canis antibody, and canine heartworm antigen. Specifically, the introduction of the 4Dx SANP Test emphasizes the importance of understanding not only the indications for performing the test, but, most importantly, the implications of a POSITIVE vs. NEGATIVE test result in the sick, versus healthy, patient.
The following highlights some of the key issues behind diagnosis, treatment, and prevention of the most common tick-borne diseases seen in dogs.Canine Ehrlichiosis
1. There are many Ehrlichiae capable of infecting dogs...but we currently only test for one (E. canis)...which infections are most significant for dogs?
What compounds conventional diagnostic strategies is the fact commercial tests are simply not available (yet) for many of these infections. Furthermore, it's becoming more apparent that individual dogs can be (and are) infected with multiple tick-borne pathogens simultaneously...such as Anaplasma spp and Neorickettsia.
2. What is the spectrum of clinical signs associated with ehrlichiosis?
Hyperglobulinemia/hypoalbuminemia may be present (hence the peripheral edema). Granular lymphocytosis (counts between 5,000 and 17,000 lymphocytes/µL). Pancytopenia seems less common today. Less common are a variety of multisystemic signs, including peripheral limb edema, vasculitis (generalized), neurological signs ranging from head tilt (vestibular) to disorientation to meningitis and seizures. Hyperviscosity syndrome, retinal detachment, and a host of immune-complex disorders affecting joints and kidney may develop. Death is possible...despite aggressive treatment.
BUT...the variation in physical signs and laboratory values is significant. For example...the absence of thrombocytopenia does NOT exclude a diagnosis of ehrlichiosis. As such, it is not feasible to rely exclusively on clinical or laboratory findings to establish a diagnosis. Testing is important. The message here is not to limit testing to only those patients that have obvious physical signs that are distinctively associated with ehrlichiosis..."test outside the box"!