Last Updated: 01/12/2025
Ehrlichiosis in Australian Dogs: Symptoms, Treatment & Prevention
First detected in Australia in 2020, Ehrlichiosis is a deadly disease carried by the brown dog tick. Our vets explain the signs of E. canis, where it is found in Australia, and why using a repelling tick preventative is crucial for your dog's safety.
Author: Dr Carla Paszkowski BVSc (Hons)
Reading Time: 7 minutes - short read
In May 2020, the Australian veterinary landscape changed with the confirmed detection of a microscopic menace called Ehrlichia canis in Western Australia. Previously considered free of this disease, Aussie dogs are now facing a new threat carried by the common brown dog tick. While the emergence of this disease has understandably sparked concern among authorities and pet parents alike, knowledge is the best defence. Understanding how this disease spreads and how to stop ticks in their tracks is the most effective way to keep our furry family members safe. Here is everything you need to know about the current outbreak, symptoms, and prevention of Ehrlichiosis.
How is ehrlichiosis transmitted?
Ehrlichia canis is a small rickettsial organism (a type of bacterium) that lives within the cells of a host animal. Ehrlichiosis is also called 'tracker dog disease' or 'tropical canine pancytopenia' because of its original presentation in military dogs from Vietnam.
Transmission occurs when an infected tick bites your dog. The species of tick that transmits E. canis is the brown dog tick (Rhipicephalus linnaei, previously R. sanguineus), which is widespread in Australia. Although brown dog ticks are generally associated with tropical and subtropical environments, they can complete their life cycle indoors. This allows them to potentially survive in colder climates, like those in southern regions.
A brown dog tick may become infected after feeding from an infected dog, and the tick may remain infectious for up to 5 months. Any species of dog from the family Canidae may maintain the cycle between ticks and dogs - including domestic dogs, foxes, and dingos.
Infected dogs do not directly transmit the disease to other dogs. Nor can they transmit the disease to humans or cats. Humans can theoretically become infected if they are bitten by an infected tick - but this is very rare.
What are the signs of ehrlichiosis?
Ehrlichiosis has three phases, as outlined below:
1. 'Acute' phase - where initial signs of infection are vague and may last 2-4 weeks.
2. 'Subclinical phase' - where there are no obvious signs of disease. The subclinical phase can last for months to years, and dogs may recover, remain infected without symptoms, or move to the chronic stage.
3. 'Chronic phase' or long-term stage, which involves similar signs to the acute phase but in a more severe presentation.
Symptoms occur in the 'acute' and 'chronic' phases, and are more severe during the chronic phase. These symptoms include:
- Fever
- Enlarged Lymph Nodes
- Lethargy
- Discharge from the eyes and nose
- Lack of appetite and weight loss
- Bleeding disorders such as nosebleeds or bleeding under the skin (appears as bruising and spots), and associated anaemia
This disease has a fairly high mortality rate, and is particularly deadly to younger or older dogs that are immunocompromised.
German Shepherds are particularly susceptible to the chronic phase and tend to develop a severe haemorrhagic condition known as tropical canine pancytopenia, which is often fatal.
Can cats catch ehrlichiosis?
In cats, symptomatic disease caused by E. canis is extremely rare, and as yet has not been reported in the current Australian outbreak. Cats are not the primary host for this organism, and disease is therefore uncommon. But infection in cats may be possible if they are bitten by an infected tick, so up-to-date tick prevention is still recommended for cats in high-risk areas.
Where is ehrlichiosis found in Australia?
Technically, Ehrlichiosis can be found wherever there are brown dog ticks. It is now considered endemic throughout the Northern Territory and the northern regions of Western Australia and South Australia. In Queensland, the disease has been detected in the northwest, north, and far north of the state, particularly in areas like Mount Isa and Townsville.
While locally acquired cases are currently limited to these warmer, northern regions where the brown dog tick thrives, positive cases have been detected in dogs in every State and Territory. Crucially, southern cases have almost exclusively been in dogs that have travelled from or through the infected northern regions. However, because the brown dog tick vector exists across much of mainland Australia, there is a risk that the disease could establish in new areas if infected dogs introduce it to local tick populations.
How to protect your pet from ehrlichiosis
It is recommended that all pet parents in affected regions stay vigilant. To prevent your pet from getting Ehrlichiosis, take the following steps:
1. Keep your pet on tick prevention
Since Ehrlichia canis can be transmitted very quickly, the goal is to stop the tick from biting in the first place. This is why repellent products (like tick collars) are preferred over oral chews for this specific disease. While oral treatments are highly effective at killing ticks, they generally require the tick to bite and feed on your dog before they kick in.
If you live in or travel to a high-risk area, we recommend a "double defence" approach:
- Repel: Use a Seresto collar to deter ticks from attaching. This product is registered to reduce transmission of E. canis.
- Back up: Pair it with a systemic treatment like Bravecto, Nexgard/Nexgard Spectra, Simparica/Simparica Trio or Credelio Plus.
Rest assured, it is perfectly safe to combine a Seresto collar with these oral treatments.
2. Complete regular tick searches
No tick preventative is 100% effective, so regular tick searches are crucial. This involves running your fingers through your pet's coat, feeling the skin for small bumps. Pay particular attention to the head, neck, ears, chest, lips, eye folds, and between the toes.
3. If you are travelling to an affected area, be particularly careful around tick infested environments such as bush and long grass.
4. Contact a vet if your dog is showing signs such as lethargy, fever, enlarged lymph nodes, reduced appetite, discharge from the eyes or nose, nosebleeds, or spots on the skin.
Is there a vaccine for Ehrlichiosis?
There is no vaccine for this tick-borne disease, but antibiotic treatment may prove curative if the dog is treated early enough. Chronic, severe, or complicated cases may need a long treatment course and the dog may never fully recover. Tick prevention is the main protective measure against this disease.
Vet recommended tick preventatives
Reporting the disease and further resources
Previously, Ehrlichiosis was a nationally notifiable disease in Australia; however, its status changed in May 2024. It has been removed from the national list of notifiable animal diseases, acknowledging that it is now established in parts of the country.
This means that in endemic states like Queensland, the Northern Territory, and Western Australia, you are generally no longer required to report cases to the government. However, biosecurity laws can vary by state. In non-endemic regions (such as New South Wales, Victoria, and South Australia), the disease is still reportable, to help authorities track and manage the spread of the disease.
To keep track of cases of the disease in your State or Territory, you can use the links below.
FAQs
While the spread of Ehrlichiosis across Australia is a serious concern, staying vigilant and proactive is the best way to ensure our pets stay safe. By maintaining a strict schedule of effective tick prevention - specifically products that repel ticks rather than just killing them - and performing daily tick searches, the risk can be significantly managed. If a pet has travelled to known hotspot areas or displays any sudden signs of illness, seeking immediate veterinary attention is vital. With the right protection, we can help our dogs continue to live their happiest, healthiest lives.
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History
Our experts continually monitor the health and wellness space and we update our articles when new information becomes available.
Mon 1 Dec 2025
Edited by Dr Gillian Hill BVSc (Hons)Dr Carla Paszkowski BVSc (Hons)
Veterinarian
Dr. Carla graduated from the University of Queensland in 2013 with a Bachelor of Veterinary Science and worked for a number of years in small animal clinics across South East Queensland. While Carla enjoys most facets of clinical veterinary work, she holds a special passion for feline medicine, pocket pets, and nutrition.
