"Hepatozoonosis in Dogs

"Hepatozoonosis in Dogs

Health & Safety

Hepatozoonosis in dogs is caused by what is referred to as a one-cell organism namely a protozoan called Hepatozoon americanum. Dogs develop the disease when they digest a tick rather than when they are bitten by one. It is more commonly seen in dogs that have travelled abroad with their owners and more especially to certain Mediterranean countries. However, this particular tick can be found in other areas of the world too which includes the Middle East, Africa, Asia, India and the United States although the tick responsible for the disease in America is called H. americanum.

The Causes

The disease as previously mentioned is tick born, but a dog would need to eat a tick to become infected. The tick responsible is known as Hepatazoon canis although the one that's found in the States is called H. americanum.

Symptoms Associated with the Disease

When dogs become infected, they display obvious signs of there being something wrong with them and would need to be examined by a vet sooner rather than later. The symptoms most commonly associated with the disease includes the following:

  • Lethargy
  • Fever
  • Loss of appetite
  • Weight loss
  • Diarrhoea that often contains blood

Symptoms tend to be a lot more severe in dogs with compromised immune systems and typically include the following:

  • Pain
  • Lameness
  • Muscle wastage which is referred to as muscle atrophy
  • Discharge from eyes
  • Pale gums and other mucous membranes
  • Anaemia
  • Kidney failure
  • Hyperesthesia

It is also worth noting that hepatozoonosis can also affect a dog's internal organs, namely their liver, spleen, small blood vessels found in the heart muscle, but it can also negatively impact a dog's bones, muscles and their intestinal tract.

Diagnosing the Disease

A vet would ideally need to have a dog's full medical history and be told which countries they may have visited where they might have come into contact with ticks. The more information a vet has, the easier it is for them to establish a preliminary diagnosis. The vet would thoroughly examine a dog suspected of suffering from hepatozoonosis and would typically recommend carrying out the following tests to confirm a diagnosis:

  • A complete blood count
  • A full biochemistry profile
  • A urinalysis
  • X-rays to establish if a dog's bones have been affected by H. americanum
  • Blood smears

Treatment Options

A vet would treat a dog's symptoms on an ongoing basis every two weeks with specific injections with the end goal being to kill off the infection cause by the parasites. However, even when successfully treated, when tested at a later date the results may still come back as positive because it is hard to completely eliminate an infection, more especially if it’s an H. americanum one.


Providing a dog is treated early and the treatment is successful, the prognosis for dogs suffering from this type of infection tends to be good, more especially if the problem is caused by the H. canis parasite. If, however, it's an H. americanum infection a dog is suffering from, then it is not always possible to completely eliminate the infection and treatments tend to be a lot more complicated.


The only way of preventing a dog from catching ticks is to ensure they are always well protected with good quality products. Any ticks found on a dog should be carefully removed as soon as possible to prevent a dog from swallowing them when they groom themselves which could then lead to them developing hepatozoonosis.

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