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Canine hepatozoonosis

Hepatozoonosis is a parasitic blood disease linked to Hepatozoon canis, a protozoan transmitted by the brown dog tick. Its particularity is that it is not caught by the bite: the dog becomes infected by swallowing the tick, by biting itself...

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Definition Signs Causes Transmission Diagnosis Treatment Prevention Complications When to see a vet Prognosis FAQ Sources Affected species

What is it?

Hepatozoonosis is a parasitic blood disease linked to Hepatozoon canis, a protozoan transmitted by the brown dog tick.

Its particularity is that it is not caught by the bite: the dog becomes infected by swallowing the tick, by biting itself or by chewing it during grooming.

It is present in the Mediterranean region, including North Africa, where the brown tick is abundant.

Commonly observed signs

These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.

Related signs — each one links to its page:

Fever Reduction Fatigue Weight loss Pale mucous membranes Swollen lymph nodes Loss of appetite Pain Dull coat

Often no signs: the parasite is discovered by chance on a blood test.

In the expressed forms: intermittent fever, depression, fatigue during exercise.

Progressive weight loss, dull coat, decreased appetite.

Pale mucous membranes indicating anemia.

Lymph nodes and spleen enlarged.

Discharge from the eyes and nose in some dogs.

Muscle pain, stiff gait and reluctance to get up in severe forms.

Marked signs often suggest an associated disease, transmitted by the same ticks.

When to consult without delay

This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.

Causes and risk factors

A single-celled parasite, Hepatozoon canis, which multiplies in white blood cells, bone marrow, spleen and lymph nodes.

The brown dog tick, Rhipicephalus sanguineus, harbors the infective form.

The expression of the disease depends greatly on the dog's immune status and the presence of other infections.

Lives in a Mediterranean or warm region where the brown tick is established.

Heavy tick infestation, untreated kennels and niches.

Stray dogs, shelter dogs or dogs living permanently outdoors.

Young dogs or dogs in poor general condition.

Coexistence of other diseases transmitted by ticks, such as ehrlichiosis or piroplasmosis.

Lack of regular external antiparasitic treatment.

Transmission

By ingestion of an infested tick, swallowed during grooming or by biting: this is an unusual route among diseases transmitted by ticks.

A simple tick bite is not enough to transmit this parasite.

Transmission from mother to puppies before birth is described.

There is no direct contagion between dogs or to humans.

Diagnosis and care

Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.

Diagnosis is by microscopic examination of a blood smear, where the parasite can be seen inside the white blood cells.

A molecular test looking for parasite DNA is more sensitive, especially when the parasite load is low.

Blood counts may show anemia and an increase in certain white blood cells.

The veterinarian systematically looks for other diseases transmitted by ticks: their association is common and changes the treatment.

A general assessment assesses the impact on the organs.

Treatment

The treatment is prescribed by the veterinarian and combines specific antiparasitic molecules, often over a prolonged period.

Treatments reduce the parasite load and make the signs disappear, but complete elimination of the parasite is difficult: residual carriage is common.

Supportive care accompanies severe forms: rehydration, adapted diet, pain management, transfusion in cases of profound anemia.

Associated tick-borne diseases are treated at the same time.

The fight against ticks is part of the treatment: without it, reinfestation is certain.

Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.

Prevention

Regular external antiparasitic treatment against ticks, without interruption during periods of risk, according to the veterinarian's prescription.

Daily inspection of the dog and removal of ticks with a suitable hook, preventing the dog from swallowing them.

Environmental treatment in the event of a brown tick infestation: niches, kennels, wall cracks, textiles.

Avoid letting the dog chew its coat unsupervised during periods of infestation.

Control of newly adopted dogs from areas with high tick density.

Possible complications

Marked anemia and weight loss in chronic forms.

Renal damage linked to prolonged immune reaction.

Persistent muscle and bone pain in severe forms.

Marked worsening when another tick-borne disease is present.

Relapses due to a drop in immunity or an intercurrent illness.

When to see a veterinarian

Your dog has a fever that comes and goes, with no obvious cause.

He loses weight, gets tired quickly or stays in bed more than usual.

His gums are pale.

He walks stiff, seems painful, or has trouble getting up.

You regularly remove ticks from him.

He comes from a region where ticks are numerous and his general condition is deteriorating.

Prognosis

Good in dogs with little parasitism and no associated disease: the signs disappear under treatment and many lead a normal life.

More reserved in forms with a high parasitic load, in weakened dogs or in cases of multiple infections transmitted by ticks.

Residual carriage is common: veterinary monitoring and rigorous antiparasitic prevention limit relapses.

Frequently asked questions

Can my dog catch this disease from a simple tick bite?

No, and this is its particularity: it must swallow the tick, which happens easily when it bites itself or grooms itself. Removing ticks quickly and preventing the dog from biting them therefore reduces the risk.

Is it contagious to other dogs or to me?

No. There is no direct transmission between dogs, nor from dog to human. The parasite needs the tick to complete its cycle.

My dog is positive but has no symptoms, is this worrying?

Carrying without signs is common in the affected regions. The veterinarian decides whether to treat taking into account the parasite load, the dog's condition and associated diseases.

Does the treatment permanently eliminate the parasite?

Not always. It makes the signs disappear and greatly reduces the parasitic load, but carriage may persist. This is why prevention against ticks remains essential after recovery.