LEPTOSPIROSIS UPDATE 18th October, 2019
There has been another case of confirmed Leptospirosis this week in a dog living in Darlinghurst. This dog was not vaccinated against leptospirosis. It had frequented parks in the area before it became unwell and had been rummaging in some leaves – direct contact with rats was not observed.
Unfortunately, the dog died at another inner city specialist clinic. We are in the process of determining which serovar was involved.
This brings the case numbers to 9 with 6 cases since May. All were from Surry Hills, Darlinghurst and Glebe. So far the mortality rate is 100%.
We again want to emphasize the importance of considering the differential diagnosis of leptospirosis in all dogs with nonspecific clinical signs (lethargy, vomiting, diarrhea, haemorrhages, conjunctivitis) that are from the area in question. In these dogs (and especially if owners mention contact with rats or stagnant water) we recommend offering blood tests (CBC, biochemistry) and urinalysis. Consistent clinicopathological abnormalities include marked azotaemia, marked increases in liver enzymes and glucosuria. However these can be absent very early in the course of disease. Therefore, urine and blood collected into EDTA should be sent for leptospirosis PCR (important: take samples BEFORE antibiotics are given) and serum should be collected for MAT to determine the serovar. Serum can be stored until results for PCR return and then sent if PCR is positive or can be sent to the University for research. In suspicious cases please retain some EDTA, serum and urine samples for leptospirosis research if possible. If rat contact is confirmed (and the dog has been in the affected area) we recommend:
- treatment with doxycycline 10mg/kg SID if no hepatopathy is present
- treatment with IV penicillin or their derivatives (ampicillin, amoxicillin, amoxicillin clavulanate) if liver enzymes are elevated pending PCR results, if PCR positive start doxycycline as soon as administration of oral medication is possible
Duration of treatment
Treatment should be continued until PCR and serology results have returned.
In dogs with a positive PCR result the diagnosis is confirmed. Treatment with penicillin derivatives should be continued. As soon as it is possible to give oral medication, a two-week course of doxycycline (10mg/kg SID) is recommended to ensure that the infection is cleared from the kidneys.
A negative PCR result does not exclude the diagnosis in a dog that has been treated with antibiotics before taking blood and urine. Acute and convalescent (after 7-14 days) MAT titres should be tested, where a 4-fold increase in titre for individual serovars is consistent with infection. In these patients, treatment with penicillin and its derivatives should be continued until the convalescent titre has been tested. In case of a 4-fold increase in titre the diagnosis is confirmed. As soon as it is possible to give oral medication, a two-week course of doxycycline (10mg/kg SID) is recommended to ensure that the infection is cleared from the kidneys.
A negative PCR result in a dog that has not been treated with antibiotics before taking blood and urine and with a negative MAT titre excludes Leptospirosis. Antibiotic treatment can be stopped.
Zoonotic risk
Importantly, leptospirosis is a zoonosis. Therefore, suspicious cases should be isolated. Ideally, a urinary catheter should be placed to avoid contamination of the environment as well as to monitor urine volume output. It is imperative to avoid contact with urine and to wear appropriate personal protective equipment (PPE) including gloves, impermeable gowns, a face mask and glasses. Isolation is usually maintained until the dog has been treated with IV penicillin derivatives for at least 72 hours.
In dogs that are not unwell and have no clinicopathological abnormalities consistent with leptospirosis but have had contact with rats, their owners should be advised to avoid contact with their dogs’ urine.
