In the previous article, we talked about the Babesia infection which is one of the most common tick fever diseases. Today let’s focus on another one: Ehrlichiosis.
What is Ehrlichiosis?
Ehrlichiosis is another common tick-borne disease which is caused by the Ehrlichia Canis (E. Canis) bacterium. Tick is the main carrier, and transmission could occur through infected ticks. Blood transfusions, or other means by which infected WBCs can be transferred, may also transmit the organism.
E. Canis organism infects a certain type of white blood cell (called monocytes) in dogs and leads to periodic losses of platelets, which causes problems with blood clotting.
In addition, this disease may be difficult to diagnose infected dogs during the very early stages of infection, it may be lack clinical signs as the immune system usually takes two to three weeks to respond to the presence of the organism and develop antibodies.
What are the signs of E. Canis infection?
Signs of ehrlichiosis can be divided into three stages: acute (early disease), sub-clinical (no outward signs of disease), and clinical or chronic (long-standing infection).
In acute phase, infected dogs may have fever, swollen lymph nodes, respiratory distress, weight loss, bleeding disorders (spontaneous hemorrhage or bleeding), and occasionally, neurological disturbances (they may seem unsteady or develop meningitis). This stage may last two to four weeks and some dogs may eliminate the infection or head in to the sub-clinical phase.
The sub-clinical phase represents the stage of infection in which the organism is present, but not causing any outward signs of disease. Sometimes a dog will pass through the acute phase without its owner being aware of the infection. These dogs may become sub-clinical and develop changes observed at the laboratory level, yet have no apparent signs of illness. The sub-clinical phase is often considered the worst phase because there are no clinical signs and therefore the disease goes undetected. The only hint that a dog may be infected during this phase may be after a blood sample is drawn, when the dog shows prolonged bleeding from the puncture site. Dogs that are infected sub-clinically may eliminate the organisms or may progress to the next stage, clinical ehrlichiosis.
Clinical or chronic ehrlichiosis occurs because the immune system is not able to eliminate the organism. Dogs are likely to develop a host of problems: anemia, bleeding episodes, lameness, eye problems (including hemorrhage into the eyes or blindness), neurological problems, and swollen limbs. If the bone marrow (site of blood cell production) fails, the dog becomes unable to manufacture any of the blood cells necessary to sustain life (red blood cells, white blood cells, and platelets). Dogs in the chronic stage are more difficult to treat as they are sicker and more debilitated, mortality rate is also much higher.
How is Ehrlichiosis diagnosed?
There are two main tests for Ehrlichia: PCR testing for Ehrlichia DNA or blood testing for Ehrlichia antibodies. Antibody testing has been the main diagnostic for many years but the recent availability of PCR testing has changed the approach.
- Antibody Testing
Traditionally, when Ehrlichiosis is suspected, a blood test for antibodies against Ehrlichia organisms can be ordered or performed in minutes using an in-house test kit. There are some limitations to antibody testing. A positive test indicates that the dog has been exposed to Ehrlichia but does not necessarily imply an active current infection. A negative titer does not fully rule out Ehrlichia, either, as a very sick patient may be too ill to produce antibodies and an early case may not yet have started to produce them.
- PCR Testing
This is a laboratory test for the presence of Ehrlichia DNA. PCR testing remains positive for several weeks after the infection has cleared as it does not distinguish between live and dead organisms. It takes time to clear dead organisms from the body.
These two forms of testing are complementary, which means an antibody test can be used to screen dogs to identify those that have been infected. Treatment can be prescribed and after the treatment has completed and a couple of weeks have passed, the PCR test can check for any residual Ehrlichia DNA to indicate the infection has cleared.
Certain antibiotics, such as doxycycline, are probably the most effective against Ehrlichia. A long course of treatment, generally a month or even longer, is needed. This is the treatment of choice as it is easily accessible and generally well tolerated.
When dogs experiencing severe anemia or bleeding problems, they may require blood transfusion, especially for chronic cases, supportive care may also be needed.
Ehrlichia infection can be fatal if untreated, although the dogs are surviving from the disease, they can also become re-infected as Ehrlichia immunity is not life-long.
Your veterinarian will discuss treatment options with you as some supportive medications or treatments may be needed depending on the clinical state of the patient and blood parameters.
As always prevention is better than cure, inspect your dog daily for ticks, and regularly, reliable tick prevention is important in protecting your pet. Applying tick preventive is the most effective means of prevention, there are topical and oral chewable options. Your veterinarian will help you determine which preventive is right for your dog.
If your dog is showing any signs of the disease, contact your veterinarian as soon as possible, because early treatment provides the best chance for them to recover.
“For emergency, surgical, and medical needs, Wellness veterinary Hospital is providing packed red blood cell (pRBC) for dogs now, you can call us at 2572 2088 for more details and information, our medical team is in the clinic 24/7 to assist you.”