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TICK-TRANSMITTED DISEASES OF DOGS in Australia
Lyme-like
Spirochaetal disease
Canine Babesiosis
Canine Ehrlichiosis
Canine Haemobartonellosis
Other Rickettsia?
Canine Hepatozoonosis
Cytauxzoonosis
Arboviruses?
Lyme-like Spirochaetal disease
Dogs are suspected by some veterinarians to be at risk from an Australian tick-borne spirochaete just as humans are (see tick-transmitted diseases- humans). Anecdotally, some animals with tick paralysis have apparently subsequently developed signs of polyarthritis, CNS disturbances and heart conditions (Collins, 1997). If an illness does occur it may manifest as much as an idiosyncratic immune-mediated disease as a primary infection (see under the US situation below). Dr Henry Collins of the University of Sydney is seeking blood samples from tick exposed/recovered animals to investigate the possibility of spirochaetal infections. Dr Henry Collins can be contacted at the University of Sydney on 02 9351 3102.
In endemic regions of the United States, Borrelia organsisms are ubiquitous in the tick population, exposure of dogs and cats to infected ticks extensive, and many seropositive dogs remain asymptomatic, despite demonstration of spirochaetaemia. In contrast to human Lyme borreliosis, Ig-M titres to Borrelia burgdorferi remain positive for several months in asymptomatic dogs, and antibody titres fail to decrease following appropriate antibiotic treatment in symptomatic dogs. Immunoblot analysis of the Ig-G response to Borrelia burgdorferi indicates that naturally exposed dogs from different geographic regions exposure to similar organisms, and there is no difference in the immunoblot pattern between asymptomtic and symptomatic dogs with high Borrelia burgdorferi antibody titres. Thus serological support for a pathogenic role in cats and dogs is still lacking. Although the varied case reports of canine Lyme borreliosis are convincing, two of Kochs postulates are not satisfied, ie induction of disease in a susceptible dog with the cultured organisms and re-isolation of the organisms from the experimentlly infected animal. Much of the recent literature is derived solely from serological diagnosis of Lyme borreliosis in dogs and cats from endemic regions where seroprevalence approximates 80%. Because seropositivity rather than seroconversion has been used as a criterion for diagnosis, the relevance of these case reports to the clinical spectrum of canine and feline Lyme borreliosis remains highly suspect (Hoskins JD, 1991).
Babesiosis
This disease is seen in at least the Townsville region of Nth
Queensland. Canine babesiosis is an important world-wide, tick-borne
protozoal disease of canids. Although babesiosis primarily
affects erythrocytes, it can result in multi-organ dysfunction.
The disease is classified as either uncomplicated or complicated.
Uncomplicated babesiosis is essentially a hemolytic disease,
whereas complicated babesiosis can result in systemic
inflammatory response syndrome (SIRS) or multiple organ
dysfunction syndrome (MODS). Common complications include acute
renal failure, acute respiratory distress syndrome, hepatopathy,
hemoconcentration, cerebral babesiosis, and immune-mediated
hemolytic anemia. Treatment of uncomplicated babesiosis involves
anti-babesial drugs and, if warranted, blood transfusions;
complicated babesiosis requires more intensive therapy directed
at affected organs.
The causative organism is either Babesia canis or Babesia
gibsoni.There are three subtypes of Babesia canis- Babesia
canis canis (Europe), Babesia canis vogeli (N Africa
and N America) and Babesia canis rossi (S Africa). B.
canis has a pear-shaped trophozoite 4-5 um long, and is usually
found in pairs within the erythrocyte. B. gibsoni is much
smaller at 3 um length and is round to oval. It is found in Asia,
N America and N and E Africa. The ixodid tick Rhipicephalus
sanguineus is known to transmit B. gibsoni.(Lobetti, 1998)
Ehrlichiosis
The blood parasite Ehrlichia canis has been suspected to exist clinically in northern Australia, but its presence has yet to be confirmed. It is transmitted by the common brown dog tick Rhipicephalus sanguineus. Apparently the host and environmental conditions are favourable for its occurrence in northern Australia but at present it is regarded as a potential exotic disease. The disease caused by Ehrlichia canis is known as Tropical Canine Pancytopaenia or Canine Ehrlichiosis.
Canine Hemobartonellosis
A rickettsial organism. Occurrence in Australia?
Other Rickettsia?
Do dogs suffer from Spotted Fever (Rickettsia australis) related disease as do humans?
Canine Hepatozoonosis
A protozoan organism. Occurrence in Australia?
Feline Cytauxzoonosis
no information
Arboviruses?
no information
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