Granulocytic ehrlichiosis

What is it?

It is a disease resulting from a white blood cell (neutrophils) infecion caused by microorganisms known as Anaplasma phagocytophilum or Erlichia ewingii

Although dogs can catch from ticks from other dogs, the microorganisms are not directly transmittable from one dog to another. 

The disease is most often observed in the southeastern or central part of the United States, though the Amblyomma americanum tick, which is responsible for the transmission of Ehrlichia ewingii, has been detected in the Eastern Townships.

Life cycle of the organism

The organism is transmitted by the Ixodes scapularis tick's saliva in the case of Anaplasma and by the Amblyoma amercanum tick in the case of Ehrlichia when they ingest blood from their canine host 24 to 48 hours after they've attached themselves. 

Thereafter, the organism infiltrates its neutrophils and tissues (spleen, liver, and lymph nodes) where it rapidely multiplies. 

The incubation period, meaning the period between acquiring the infection and the appearance of clinical signs, is from 1 to 2 weeks. 

The symptoms

  • Pain and inflammation around the joints, causing lameness
  • Depression
  • Nasal and ocular discharge 
  • Loss of appetite
  • Fever 
  • Abdominal pain 
  • Increased size of ganglia 
  • Abnormal behaviour 

The diagnosis

There many tests that exist to diagnose the infection. Some are specific and used to highlight evidence of the organism, whereas others are routine and allow to identify the presence of "collateral damage" caused by the microorganism.

Specific tests include: 

  • Blood smear examination under a microscope. It is sometimes possible to observe the organisms inside the neutrophils, although false negatives are frequent;
  • serological tests to quantify the number of antibodies against the organism. The test should be repeated two to four weeks later to confirm infection; the number of antibodies should increase;
  • DNA testing.

The routine tests include bood tests and other complementary tests. 

Blood tests often reveal the following changes: 

  • A moderate to severe decrease in platelets, though not often present, and in neutrophils; 
  • Anemia; 
  • An increase in the number of lymphocytes, monocytes, and eosinophils; all of the white blood cells; 
  • An increase in the number of antibodies;
  • A possible loss in proteins in the kidneys if there is inflammation. 

Among the additional tests, we have: 

  • Examination of the fundus of the eye. We can sometimes observe a hemorrhage and/or detachment of the retina; 
  • Abdominal xrays. The spleen can be visibly larger; 
  • Puncture of the lymph nodes when they are enlarged; 
  • X-rays of the limbs and sampling of the joint fluid if inflammation is present' 
  • Bone marrow puncture if a decrease in the number of platelets is noted on the blood test; 
  • Sampling of cerebrospinal fluid when there are neurological symptoms present.  

The treatment

Antibiotics will be used for two to three weeks in order to eliminate the organism. Supportive treatment will be added to this depending on the present anomalies: blood transfusion in case of severe anemia, painkillers in case of pain, etc. 

Prevention

The best way of preventing the infection is by having access to proper tick control, particularly if a pet travels to our neighbors to the south.

Different types of medications, sold under prescription, exist which are safe and effective in preventing tick infestations.

Do not hesitate to ask one of our staff members for advice on which product best suits your pet. 

The prognosis

The pet has good chances of recuperating as long as the symptoms quickly disappear. 

This is an infection that usually is resolved on its own. However, the death of the animal is still possible, albeit rare, because of secondary infections.

Is the organism contagious to humans?

Humans can catch ticks from dogs, but cannot contract the infection by the organism directly from dogs.