Page 1492 - Small Animal Internal Medicine, 6th Edition

1464 PART XIV Infectious Diseases

Laboratories). One of the commercial kits is optimized to in combination with penicillins during the acute phase of
detect immunoglobulin M (IgM) antibodies and in one infection, in particular if other gram-negative organisms
VetBooks.ir study was the first to become positive in most dogs during are on the differential list. Ampicillin and enrofloxacin were
used concurrently in one study, and 83% of infected dogs
acute infection (Lizer et al., 2018). If MAT is used, because
of the wide range of leptospires infecting dogs, as many
serovars as possible should be used for screening. Leptospira survived (Adin et al., 2000). Penicillins such as amoxicil-
lin or amoxicillin clavulanate should be administered for 2
bratislava, L. canicola, L. grippotyphosa, L. hardjo, L. ictero- weeks. Doxycycline administered orally at 5 mg/kg q12h for
haemorrhagiae, and L. pomona are commonly used. Positive 2 weeks should be used to eliminate the renal carrier phase
titers can result from active infection, previous infection, (Sykes et al., 2011).
or vaccination. Antibody titers can be negative in animals
with peracute disease; seronegative dogs with classic clini- Zoonotic Aspects and Prevention
cal disease should be retested in 2 to 4 weeks. The serovar All mammalian serovars should be considered potentially
with the highest titer is not always the infecting serovar. The zoonotic to human beings. Some human beings have anti-
highest titer on a convalescent serum sample may be more bodies against canine serovars, suggesting the dog can be a
likely the primary serovar. When the same sera were sent to reservoir for human infection (Brod et al., 2005). However,
different laboratories, the results were not always in agree- results from studies attempting to associate dog contact
ment for the serovar giving the highest titer (Miller et al., with leptospirosis in humans have varied. For example,
2011), and some vaccinated, client-owned dogs have high 0/91 people exposed to dogs with proven leptospirosis were
titer responses (Martin et al., 2014). seropositive suggesting the risk was minimal (Barmettler
Documentation of seroconversion (negative result et al., 2011). As leptospirosis is an occupational risk for vet-
becoming positive over time), a single MAT titer greater erinarians, the organism should be on the list of differential
than 1 : 3200, or a fourfold increase in antibody titers com- diagnoses if appropriate clinical signs of disease develop
bined with appropriate clinicopathologic abnormalities and (Whitney, 2009). Infected urine, contaminated water, and
clinical findings, are suggestive of clinical leptospirosis. A reservoir hosts should be avoided. Infected dogs should be
definitive diagnosis is made by demonstrating the organ- handled with the clinician wearing gloves. Contaminated
ism in urine, blood, or tissues. The organism can be seen surfaces should be cleaned with detergents and disinfected
in urine using darkfield or phase-contrast microscopy, but (see Chapter 93).
because of intermittent shedding of small numbers of organ- To lessen risk of exposure, owners should attempt to
isms these procedures can be falsely negative. The organism restrict dogs from drinking potentially contaminated water.
can be cultured from urine collected by cystocentesis, blood, Healthy dogs can shed Leptospira spp. in urine; 7% of 525
or renal or hepatic tissue. Materials for culture should be col- urine samples from dogs in Dublin were positive in one
lected before administration of antibiotics, placed in trans- study (Rojas et al., 2010). Thus contact with dog urine should
port media immediately after collection, and transported to always be avoided. Vaccines available for some serovars
the laboratory as quickly as possible. Leptospiremia can be reduce the severity of disease and lessen leptospire shedding
of short duration, and urine shedding of the organism can in urine. Several products containing serovars L. canicola,
be intermittent, giving false-negative results. PCR can be L. icterohaemorrhagiae, L. grippotyphosa, and L. pomona are
used to demonstrate the organism in urine, blood, or tissues now available and should be used rather than two serovar
(Harkin et al., 2003a, 2003b). In one study of 500 dogs, 41 vaccines to provide the greatest spectrum of protection (see
(8.2%) were PCR-positive for a Leptospira spp. in urine, and Chapter 93). Numbers of long-term duration of immunity
some of these dogs were clinically normal (Harkin et al., studies are small, but recently, one commercially available
2003a). None of the PCR-positive dogs was culture-positive, product was shown to induce significant protection against
and titers were not always high. Leptospira spp. DNA can L. grippotyphosa for 15 months when compared to unvac-
also be amplified from renal tissues that have no evidence cinated controls (Grosenbaugh and Pardo, 2018). Dogs in
of inflammatory disease (Dash et al., 2018). Recent vaccina- endemic areas should be administered at least two vaccines
tion should not result in positive PCR assay results (Midence 2 to 4 weeks apart, and annual boosters are recommended
et al., 2012). Antibodies induced by Leptospira spp. vaccine (www.aahanet.org). Canine side effects associated with the
did not cross-react with Borrelia burgdorferi peptides in one current four serovar-containing vaccines are generally tran-
study (Caress et al., 2017). sient and mild (Spiri et al., 2017; Yao et al., 2015). In one study,
hypersensitivity reactions to Leptospira spp. vaccines were
Treatment estimated at 6.5/10,000 vaccinated dogs (Yao et al., 2015).
Fluid therapy is required for most dogs; intense diuresis
for renal involvement may be required (see Chapter 41).
Hemodialysis may increase the probability of survival in MYCOPLASMA AND UREAPLASMA
dogs with oliguric or anuric renal failure. Dogs should be
treated during the initial treatment period with ampicillin Etiology and Epidemiology
administered intravenously at 22 mg/kg q8h. Some quino- Mycoplasma spp. and Ureaplasma spp. are small, free-living
lones have an effect against Leptospira spp. and can be used microorganisms that lack a rigid, protective cell wall and