Cattle:
- A common manifestation of Leptospira infection in
cattle is abortion. The abortions occur most often in the 3rd
trimester, and the fetuses are generally autolyzed and icteric
when expelled.
- 30% of cows re-abort during the next pregnancy.
- Stillbirths, birth of weak calves and significant drops in
milk production can also accompany Leptospira infections.
- Along with reproductive tract disease, occasional cows will
show evidence of systemic disease with fever, icterus and hemoglobinuria.
- Multivalent (including multiple serovars) vaccines are used.
Swine:
- Leptospirosis in swine also typically presents as reproductive
disease.
- Occasionally, typical signs of systemic leptospirosis will
develop in young pigs.
- Multivalent vaccines are used.
Horses:
- The most common manifestation of Leptospira infection
in horses is recurrent
uveitis ("moon blindness"). This typically
develops 12+ months after infection and is an immune-mediated
disorder. It has been suggested that the basis for this immune
reaction is antigenic cross-reactivity between a 90kD Leptospira
protein and a protein in the equine cornea.
- In one study, 56% of horses with uveitis were sero (+) to
Leptospira pomona, compared with 9% of horses without
uveitis.
- 59% of these horses with uveitis progressed to blindness.
- In another study, 76% of horses with uveitis had a 4-fold
or greater difference in antibody titer against Leptospira
in their vitreous humor versus their serum, and Leptospira
organisms could be isolated from the vitreous humor of 52% of
the horses with recurrent uveitis. These data suggest that horses
with recurrent uveitis also have long-term persistent infections
with the Leptospira bacteria in their eyes.
- Leptospira infection has also been suggested to be
a cause of abortion in horses. Abortions have been reported to
be associated with Leptospira infections in horses in
Ontario and several states in the U.S. For this reason, some
horse breeders are using the cattle vaccine (off-label use) in
horses.
- The horses are seropositive to Leptospira, and the
fetuses have histopathologic lesions and silver-staining organisms
in tissues consistent with Leptospira, but the organism
has not been recovered in culture.
Dogs:
- Many, if not most, Leptospira infections in dogs are
subclinical. However, when clinically apparent, the classical
presentation includes:
- fever and inappetance
- vomiting
- hepatic disease and hemorrhages (petechiae and ecchymoses)
- This acute form of hepatic and hemorrhagic disease is most
often associated with infection with L. icterohaemorrhagiae.
The coagulation abnormalities may be due to reductions in the
production of clotting factors because of hepatic failure, but
the LPS of Leptospira can stimulate platelet activation,
which may also contribute to consumptive coagulopathy.
- The overall prevalence of leptospirosis in dogs in the U.S.
and Canada has increased since 1983, according to a large study
of nearly 2 million canine patients examined at Veterinary Medical
Teaching Hospitals. Dogs at greatest risk according to this study
are male herding and other working dogs and hounds. However,
leptospirosis has also been documented in house pets. German
shepherd dogs may be at increased risk.
- A NOVEL FORM OF LEPTOSPIROSIS, PRESENTING AS ACUTE RENAL
FAILURE (ARF) with fever, anorexia, lethargy, depression, vomiting,
polyuria and polydypsia and sometimes abdominal pain has also
recently identified in dogs in WI, MI, NY, NJ and GA.
- This syndrome has most often been associated with infection
with L. grippotyphosa, bratislava and/or pomona
(not the typical "canine" Leptospira
serovars of L. icterohaemorrhagiae and L. canicola).
- This form of leptospirosis is characterized by unique
ultrasonography and pathology
findings.
- The cases have primarily occurred in the fall of the year
in WI.
- These dogs require aggressive antibiotic therapy as well
as supportive therapy for renal failure.
- IV penicillin first to eliminate the leptospiremia, followed
by 3 weeks of oral doxycycline to eliminate the leptospiuria.
- ARF with oliguria/anuria predicts a poor prognosis.
- Interestingly, acute renal failure has also been linked recently
to L. grippotyphosa infection in a person.
Cats:
- Leptospira infection and disease are very rare in
cats.
Diagnosis of Leptospira infection in animals:
- darkfield microscopy of urine -- but absence of the organism
does not rule-out infection.
- culture (or FA, PCR or Ag-capture ELISA identification) of
the Leptospira organism in blood (early in the course
of disease) or urine (later in the course of disease).
- It is important that culture samples be collected prior to
initiating antibiotic therapy!
- Routine urine culture should also be conducted in cases of
ARF to rule-out non-Leptospira pyelonephritis.
- histopathology (silver staining for the organism in tissues)
- serology (microscopic agglutination test [MAT] most commonly)
- As a guide, vaccine-induced titers in dogs rarely exceed
1:400 and generally decrease to ~1:100 by 2-3 months after vaccination.
An important point regarding vaccination in dogs:
Leptospira vaccines for dogs are now available in 2
forms. The original vaccines contained only the L. canicola
and L. icterohaemorrhagiae serovars; vaccines have more
recently become available against L. grippotyphosa and
L. pomona.
- In either case, however, it is very important to realize
that vaccinated dogs, though possibly protected from clinical
disease, can still persistently shed Leptospira organisms
in their urine and, therefore, serve as a source of infection
for humans. (The same is also true for vaccinated livestock.)
