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Leptospirosis is a zoonotic (transmissible from animals to humans) multiorgan disease seen increasingly frequently in dogs in Hong Kong.

Various animals serve as reservoirs but rats are the most common.

The disease is shed in the urine of infected animals and transmitted by either direct or indirect contact.

Direct transmission occurs through contact with infected urine, during breeding, from mother to offspring through the placenta, via bite wounds, or by eating infected tissue.

Indirect transmission occurs through exposure to contaminated water, soil, food or bedding. Disease outbreaks are more common after periods of heavy rain.

Leptospires enter the blood and other tissues and reproduce and cause damaging inflammation. Common affected organs include kidneys, liver, spleen, brain and eyes.

Clinical Signs

These can be variable depending on the organs most affected.

Very acute (sudden) infections may result in shock and sudden death, but more often fever and reduced appetite are the first signs.

Vomiting, dehydration, jaundice (yellowing of the gums and skin) and anaemia may follow.


Various blood tests are advised in suspected cases

-       Complete blood count (CBC) to evaluate red and white cells and platelets

-       Blood biochemistry to evaluate liver and kidney function

-       Urine tests to evaluate liver and kidney function

-       Polymerase chain testing (PCR) to detect Leptospirosis DNA is diagnostic


Severely affected animals require hospitalization and intensive care

-       Intravenous fluids are required to correct dehydration

-       Antibiotics that kill leptospires are started as soon as possible. Penicillin-type antibiotics are the drug of choice for initial treatment and given for 2 weeks. Then another antibiotic, doxycycline may be given for another 2 to 4 weeks afterwards. This is to eradicate shedding in the urine.

-       During treatment infected animals should be isolated to prevent infection to other animals and humans.

-       Areas of the dog’s environment should be disinfected with bleach

Follow Up and Prognosis

Dogs with leptospirosis have a guarded prognosis, and may develop life-long complications to kidney and liver even with appropriate treatment.

Vaccination against Leptospirosis is included in routine vaccination protocols in Hong Kong, but infected dogs are still seen. At Acorn we stock Fort Dodge Leptospirosis vaccines, considered to be amongst the most effective in prevention.