Page 1010 - Clinical Small Animal Internal Medicine

948 Section 9 Infectious Disease

antibiotic therapy in other species, including experimen- whether these vaccines protect against additional sero-
VetBooks.ir tal models of leptospirosis, and large animals such as pigs vars. Contemporary vaccines are purified by subunit
technology or microfiltration processes, and they appear
and cows. Antibiotics used to treat leptospirosis should
terminate leptospiremia and eliminate the carrier state.
to the whole‐cell cultures that were commonly used in
Doxycycline is often used as it is generally believed to to be associated with fewer vaccine reactions compared
achieve both of these goals. Doxycycline is also used pro- the past.
phylactically in humans who have a high risk of exposure Vaccination against canine leptospirosis continues to
to leptospirosis. Penicillins are often used to clear lepto- be an area of controversy, despite a growing body of work
spiremia, which should also reduce the risk of organ regarding vaccine efficacy in dogs. In particular, it has
damage. Penicillin, ampicillin, and amoxicillin all appear been convincingly shown in several studies that vaccina-
to be effective. tion against leptospirosis confers protection against
The choice of antibiotic to be used in the acute phase challenge for at least one year, and also confers signifi-
of the disease is generally dictated by the clinical status of cant protection against urine shedding. It should be
the patient. In general, injectable antibiotics are used in noted that there is little correlation between protection
acutely ill patients that are vomiting or not eating. against clinical disease and antibody titers in vaccinated
Patients that tolerate oral medications may be started on dogs. Postvaccination MAT titers generally fall by four
amoxicillin and then changed to oral doxycycline, or oral months after vaccination, and rarely persist for one year.
doxycycline may be used as the sole therapy if the patient This should be kept in mind when interpreting MAT
tolerates it. Again, there are no published data that titers in vaccinated dogs. It has been shown that vaccina-
address the duration of antibiotic therapy in dogs with tion does not cause false‐positive results in a PCR‐based
leptospirosis. Most clinicians treat with a penicillin for assay for canine leptospirosis.
1–2 weeks, followed by doxycycline for two weeks, or As noted above, leptospirosis is not a disease that is
treat with doxycycline alone for 2–3 weeks. confined to large‐breed, outdoor, rural, or working dogs.
For dogs with AKI due to leptospirosis, supportive This author recommends that the risks and benefits of
care is essential for a successful outcome. Patients with vaccination against leptospirosis be discussed with every
leptospirosis that remain oliguric or anuric are candi- dog owner. It is important to bear in mind that leptospi-
dates for extracorporeal therapies such as hemodialysis. rosis is one of the most commonly diagnosed causes of
canine AKI, and that the disease can be seen in dogs of
any age, breed, sex, or lifestyle. It is also important to
Prognosis bear in mind that currently available vaccines appear to
be both safe and efficacious.
The prognosis for dogs with leptospirosis likely depends
on which body systems are affected, and the extent and Public Health Implications
severity of organ damage. If suspected or diagnosed
promptly, and appropriate specific and supportive ther- Leptospirosis is a zoonotic disease. It is essential that vet-
apy is initiated, the majority of dogs with leptospirosis erinary personnel understand how the organism is spread
will recover from the disease. The prognosis is expected and that infection can occur through damaged skin or
to be guarded for patients with oliguric or anuric AKI, intact mucus membranes. In this author’s opinion, all
unless renal replacement therapy is initiated. Patients dogs with unexplained acute azotemia (including acute‐
with less severe AKI may progress to CKD or return to on‐chronic) should be treated as leptospirosis suspects
normal. In a recent German study of 99 dogs with lepto- until an alternate diagnosis is obtained. It is not neces-
spirosis, dogs that did not survive were more likely to sary to place these dogs in isolation, but it is essential to
have severe dyspnea, oliguria, azotemia, hyperbiliru- avoid human and animal contact with the urine of sus-
binemia, and severe radiographic pulmonary changes, pects. Direct contact with blood should also be avoided.
with the latter being specifically associated with high Leptospirosis suspects should have a urinary catheter
mortality.
placed, or should only urinate in a dedicated area that
can be cleaned and disinfected. Dogs that urinate in their
cages should have a urinary catheter placed with a closed
Vaccination collection system. This is also often a valuable procedure
in the management of AKI patients. If placement of a uri-
Most of the canine leptospirosis vaccines currently used nary catheter is not possible, for example in a small dog,
in the US include the serovars Icterohaemorrhagiae, absorbent pads can be used in the cage to collect urine.
Canicola, Pomona, and Grippotyphosa. It is not known These can also be weighed to monitor urine output.