9 August 2021
What is the likely impact on wild dog or dingo populations from the tick borne disease decimating some remote indigenous communities in the Northern Territory?
Northern Territory government Ehrlichiosis management coordinator Dr Megan Pickering said the effects of the disease had been dramatic and severe, particularly among the free-ranging dog populations in the territory’s indigenous communities.
From a total of 1194 blood samples analysed by the Berrimah Veterinary Laboratory, 387 were positive for the disease.
Ehrlichiosis is caused by a tick-borne bacteria called Ehrlichia canis. The brown dog tick, which is present across northern Australia, is the main carrier of this disease, and transmission only occurs through infected ticks.
Infected dogs do not directly transmit the disease to other dogs.
Dr Pickering said veterinarians, animal management workers and dog owners were reporting widespread outbreaks of the disease in epidemic form in the Northern Territory.
She said the number of confirmed laboratory tests did not reflect the situation on the ground.
“Anecdotally, thousands of dogs have acquired the infection, with significant numbers of deaths,” she said.
“The impact of this disease on wild dog populations is currently unknown but dingoes that move into areas of human habitation to feed and/or breed are likely to be as highly susceptible to infection as domestic dogs.
“Initially the disease occurred in its acute form, where dogs present with fever and lethargy, are often off food, and may be lame, lose weight, have unusual bleeding and eye disease.
“More recently, reports suggest an increasing number of presentations of the disease in its chronic form.
“This form of the disease occurs months to years following an infectious tick bite, and the clinical signs are extremely severe and often fatal.
“The chronic form of the disease is associated with immune system failure, a slow wasting death, and is of significant concern with respect to animal welfare.”
Dr Pickering said dogs with clinical signs of ehrlichiosis need treatment with antibiotics prescribed by a registered veterinarian.
She said humane euthanasia was recommended for dogs with chronic, progressive ehrlichiosis if the animal did not respond to antibiotic treatment.
The Northern Territory has instigated a management plan with the disease now considered endemic and strategies to manage brown dog ticks to limit the spread of disease being the mainstay.
Dr Pickering said an additional layer of protection was required on individual dogs in the form of an externally applied tick repellent product such as an insecticide-impregnated collar or “spot on” product that disperses through the coat.
Professional pest controller and Northern Territory Cattleman’s Association representative on the National Wild Dog Action Plan Coordination Committee Adam Bowen said the full impact of Ehrlichiosis in the dingo population in the NT was as yet unknown.
Mr Bowen said domestic dog populations in NT indigenous communities had been the hardest hit with losses up of up 60 per cent.
He said healthy, middle aged wild dogs trapped over the past few years had a zero or relatively low tick burden.
“Older and young wild dogs in poor condition and with compromised immune systems could fall victim to the ticks,” Mr Bowen said.
“The ticks can be found on their ears, neck, front legs and underneath their flanks where they can’t groom themselves.”
The first detection of Ehrlichiosis in Australia occurred in May 2020 in the north of Western Australia including Halls Creek, Kununurra, the Kimberley regions of Broome and Derby, and in the Pilbara regions of South Hedland and Port Hedland.
In June 2020, the disease was confirmed in dogs in the Northern Territory town of Katherine, and a remote community west of Alice Springs.
In March 2021, results from a national surveillance program confirmed the disease was established in the far north of South Australia in the Anangu Pitjantjatjara Yankunytjatjara Lands and has since been confirmed in Victoria in June.
Four dogs brought into NSW from the Northern Territory have tested positive for the disease and one in Queensland in July.
Murdoch University research associate Dr Narelle Dybing said sampling had resulted in no trace of the tick borne disease in Western Australian wild dog populations.
“Since 2017-2021, 30 wild dogs have been collected from 18 locations throughout the Gascoyne, Murchison and Nullabor regions and analysed for ecto- and endoparasites,” Dr Dybing said.
“From these 30 dogs, no ticks (including the brown dog tick responsible for transmitting canine Ehrlichiosis) were found.”
Travellers need to be vigilant about tick-infested environments, including places like fuel stations and caravan parks.
Contact your nearest vet if your dog is showing any signs of the disease which include fever, lethargy, enlarged lymph nodes, loss of appetite, discharge from the eyes and nose, weight loss, anaemia and bleeding disorders.
Ehrlichiosis is a nationally notifiable disease click here for more information.
For more information on farm biosecurity around domestic dogs click here.