Page 1490 - Small Animal Internal Medicine, 6th Edition

1462 PART XIV Infectious Diseases

clinical signs. Chloramphenicol administered orally or intra- serovars vary by country and regions within countries
venously at 15 mg/kg q12h can be used in cats with central (White et al., 2017). In the United States, antibodies against
VetBooks.ir nervous system signs. Antibiotics should be administered L. autumnalis, L. bratislava, L. canicola, L. grippotyphosa, L.
hardjo, L. icterohaemorrhagiae, and L. pomona have been
orally for 21 days after the cat has survived the bactere-
mic phase; doxycycline at 5 mg/kg q12h is an appropriate
of Leptospira spp. DNA in urine from dogs in the United
choice. Care should be taken to avoid doxycycline-associated detected most commonly. One study based on PCR analyses
esophageal strictures in feline cases by giving water after States showed L. grippotyphosa in 78 of the 98 positive
drug administration or liquefying the product. In one study, samples (Harkin and Hays, 2016). Recently, the L. santaro-
90.9% of cats treated with antibiotics survived, whereas only sai serogroup Sejroe was amplified from healthy dogs in Sao
23.8% of untreated cats survived (Eidson et al., 1991). In a Paulo (Miotto et al., 2018). The Leptospira spp. that infect
dog case series, 73% of the 62 suspect cases were treated cats are less clear, and cats appear to be more resistant to
with antibiotics and 97% of the dogs survived (Nichols et al., clinical disease than dogs.
2014). The prognosis is believed to be worse for the pneu- Prevalence and risk factors for cases of canine leptospi-
monic form of Y. pestis infection. A recent case seen at the rosis have been evaluated in several studies. In the United
author’s institution developed a consolidated lung lobe and States the number of seropositive dogs increased between
died after lobectomy. 2002 and 2004 (Moore et al., 2006). Leptospira spp. exposure
can be common in the United States; 8.1% of 33,119 canine
Zoonotic Aspects and Prevention serum samples had titers greater than 1 : 1600 in one study
Pets should be housed indoors when possible and not (Gautam et al., 2010). Infection by Leptospira spp. occurs in
allowed to hunt. Flea control should be used, and the rodent both rural and suburban environments in semitropical areas
population should be controlled if possible. Sleeping in the of the world with alkaline soil conditions. In one study in
same bed with the family dog was associated with plague Kansas, an association between leptospirosis in dogs and
in one study, which suggests dogs can bring infected fleas urban environments was made, so leptospirosis should be
into the human environment, and that flea control should considered in all appropriate clinical situations (Raghavan
be maintained on all pets in the home (Gould et al., 2008). et al., 2011). Exposure to water outdoors, wetlands, and
Doxycycline at the doses listed for therapy should be admin- public open spaces were identified as risk factors in one
istered for 7 days to animals with potential exposure. Human case-control study (Ghneim et al., 2007). Clinical cases are
infection occurs after contact with infected fleas; contact most commonly diagnosed in the summer and early fall, and
with the tissues or exudates from infected animals, including numbers of cases often increase in years with heavy rain-
cats and dog; and from bites and scratches from infected cats. fall. Infection by host-adapted species results in subclinical
Even though fomite transmission is unlikely, because the infection; the host acts as a reservoir, shedding the organism
organism is sensitive to drying it can survive for weeks to intermittently.
months in infected carcasses and for up to 1 year in infected Infection by non-host-adapted species results in clinical
fleas. Cats and dogs from endemic areas with clinical signs illness. Leptospira spp. are passed in urine and enter the
of bacteremia, respiratory tract disease, or cervical draining body through abraded skin or intact mucous membranes.
areas or masses in the spring, summer, and early fall months Transmission also occurs through bite wounds; by vene-
should immediately be treated for fleas and handled with the real contact; transplacentally; and by ingestion of contami-
clinician wearing gloves, a mask, and a gown until the diag- nated tissues, soil, water, bedding, food, and other fomites.
nosis is made or discarded. While hospitalized, as few people In an experimental study, L. pomona but not L. bratislava
as possible should handle infected cats and dogs while in was successfully transmitted by conjunctival inoculation
isolation. Exposed personnel should see their physicians and resulted in fever and lethargy starting within 7 days
to discuss prophylactic antibiotic therapy; antimicrobial- (Greenlee et al., 2005). Hosts with preexisting antibody
resistant strains of Y. pestis are uncommon (Welch et al., titers usually eliminate the organism quickly and remain
2007). It is believed that cats and dogs are not infectious subclinically infected. Leptospira spp. replicate in multiple
to human beings after 3 days of antibiotic therapy. Areas tissues of nonimmune hosts or hosts infected by a non–host-
where infected cats or dogs are handled should be thor- adapted species; in the dog, the liver and kidneys develop
oughly cleaned with routine disinfectants. the highest levels of infection. Inflammation induced by
organism replication and production of toxins leads to
renal, hepatic, or pulmonary disease. Dogs that are treated
LEPTOSPIROSIS or develop appropriate immune responses usually survive.
Some animals clear the infection 2 to 3 weeks after expo-
Etiology and Epidemiology sure without treatment but develop chronic active hepatitis
Leptospires are motile, filamentous spirochetes that infect or chronic kidney disease. Cats are generally subclinically
animals and human beings. Leptospirosis can be caused by affected but may shed the organism into the environment
many different serovars of Leptospira interrogans and Lepto- for variable periods after exposure and occasionally develop
spira kirschneri (Sykes et al., 2011). Seropositive dogs have polyuria, polydipsia, and renal insufficiency (Arbour et al.,
been detected in many countries, and the most prevalent 2012).