Ehrlichia is a type of bacteria. It infects dogs, cats and other species worldwide, causing a disease called Ehrlichiosis. Other names include “tropical canine pancytopenia” (and several other names).
Ehrlichia is commonly transmitted by ticks.
What causes Ehrlichia?
Ehrlichia bacteria infects white blood cells. There are many species of Ehrlichia, which infect a wide variety of animals, but there are only a few species that affect dogs.
A closely related infection affecting platelets is caused by a bacteria called Anaplasma platys and is sometimes referred to as Ehrlichiosis as well (Anaplasma platys used to be called Ehrlichia platys until recently). Most Ehrlichia infections are acquired through tick bites. Infection is also possible via blood transfusions.
Ehrlichiosis occurs worldwide in areas where the ticks that carry the disease are common – even here in South Africa.
While any dog can be infected, some breeds, most notably German Shepherd Dogs, are prone to more serious chronic infections. Retired racing greyhounds or rescues from areas where Ehrlichiosis is common may suffer from chronic, undetected infections and should be checked for Ehrlichiosis and other tick-borne diseases when adopted.
Signs and Symptoms of Ehrlichiosis
Symptoms of Canine Ehrlichiosis [ur-lik-ee-oh-sis] may not be obvious. If left untreated, these diseases could progress to a chronic (persistent) infection, which can last days, months or years without showing any symptoms.
The symptoms and severity of illness seen with Ehrlichiosis depend on the species of Ehrlichia involved and the immune response of the dog. This is important, as healthy dogs with strong immune may only show signs of “he’s just not right” while suffering from Ehrlichiosis.
Generally, Ehrlichia canis can also appear to produce the most severe illness and infections tend to progress through various stages.
The acute phase occurs within the first few weeks of being infected and is rarely fatal. Recovery can occur, or the dog can enter a “subclinical phase” (with no obviously noticeable symptoms other than “he’s just not right”), which can last for years and sometimes there are no symptoms at all.
Some dogs eventually progress to the chronic phase, where very severe illness can develop. However, in practice, it is difficult to distinguish these phases.
Signs and symptoms of Ehrlichiosis in dogs may include:
Common symptoms can include any of the following:
- Depression and/or lack of energy
- Loss of appetite and weight loss
- Runny eyes and nose/discharge
- Abnormal bleeding (e.g., nosebleeds, bleeding under the skin — looks like little spots or patches of bruising)
- Bruising on gums and belly
- Lameness/stiffness and joint pain (similar to arthritis and inflammation in the joints)
Other symptoms also include:
- Enlarged lymph nodes.
- Enlarged spleen.
- Discharge from the eyes and/or nose.
- Vomiting and diarrhoea.
- Inflammation of the eye.
- Neurological symptoms (e.g., incoordination, depression, paralysis, etc.).
Signs of other organ involvement can appear in the chronic form, especially kidney disease.
Note: Anaplasma platys causes recurrent low platelet counts but tends to produce only mild symptoms, if any.
Diagnosis of Ehrlichiosis
It can be difficult to confirm a diagnosis of Ehrlichiosis. Blood tests typically show a decreased number of platelets (“thrombocytopenia”) and sometimes decreased numbers of red blood cells (anaemia) and/or white blood cells.
Changes in the protein levels in the blood may also occur. Blood smears can be examined for the presence of the Ehrlichia organisms. If they are present, the diagnosis can be confirmed, but they may not always show up on a smear.
Blood can also be tested for antibodies to Ehrlichia — though this can sometimes produce incorrect results.
Specialized testing can check for genetic material from Ehrlichia and while this is the most sensitive test, it is not widely available and has some limitations as well. Generally, a combination of lab tests along with clinical signs and history are used to make a diagnosis.
The diagnosis is further complicated by the fact that dogs infected with Ehrlichia may also, but not always, be infected with other diseases carried by ticks, such as Babesia, Lyme disease, or Rocky Mountain Spotted Fever. Infection with a bacteria called Bartonella has also been found in conjunction with Ehrlichiosis and other tick-borne diseases. The presence of these other diseases can make symptoms more severe and the diagnosis can be more complicated.
Treatment of Ehrlichiosis
Ehrlichiosis responds well to treatment with the antibiotic Doxycycline and/or Tetracycline. Treatment should be maintained for at least 4 weeks. Improvement in symptoms is usually very quick, but several weeks of treatment is usually needed to ensure a full recovery. In severe cases where blood cell counts are very low, blood transfusions may be needed. Reinfection is possible, as immunity to Ehrlichia bacteria is not long lasting.
Prevention of Ehrlichiosis
Preventing exposure to the ticks that carry Ehrlichia is the best means of preventing ehrlichiosis. Check your dog daily for ticks and remove them correctly as soon as possible (it is believed that ticks must feed for at least 24-48 hours to spread Ehrlichia – avoid at all costs, any compression to the abdomen of the tick when removing it). This is especially important in peak tick season, or if your dog spends time in the woods or tall grass (consider avoiding these areas in tick season).
Ensure that you use a correct and safe method to remove tick such as when using the Tick Twister. Keep grass and brush trimmed in your yard, and in areas where ticks are a serious problem, you may also consider treating the yard and kennel area for ticks.
No preventive or vaccine is 100% effective, which makes annual check-ups which include vector-borne disease screening even more important to your dog’s health.
Please note: this article is intended to inform you on Ehrlichia and is for informational purposes only. If your pet is showing any signs of illness, please consult a veterinarian as quickly as possible.
~ Source: IDEXX Laboratories
Lianne McLeod, DVM