Page 1546 - Small Animal Internal Medicine, 6th Edition

1518 PART XIV Infectious Diseases

choice for treatment of H. canis and may also be effective transmission is necessary (Solano-Gallego et al., 2012). The
for H. americanum. A recent study showed administration intracellular organism induces extreme immune responses;
VetBooks.ir of ponazuril as a single therapeutic agent did not clear the polyclonal gammopathies (and occasionally monoclonal);
proliferation of macrophages, histiocytes, plasma cells,
infection (Allen et al., 2010). Administration of nonsteroidal
antiinflammatory agents may lessen discomfort for some
complex formation resulting in glomerulonephritis and
dogs. Administration of doxycycline or oxytetracycline has and lymphocytes in lymphoreticular organs; and immune
been used in some cats in Europe suspected as having hepa- polyarthritis are common. Co-infections like Ehrlichia canis
tozoonosis (Lloret et al., 2015). may potentiate the development of clinical manifestations of
disease (Attipa et al., 2018).
Zoonotic Aspects and Prevention Cats have generally been believed to be more resistant
No evidence exists for zoonotic transfer of H. americanum that dogs to leishmaniosis. However, when illness occurs,
or H. canis from infected dogs to people. Tick control is the the syndrome usually includes cutaneous lesions (Pennisi
best form of prevention. Glucocorticoid administration et al., 2015).
should be avoided because it may exacerbate clinical disease.
However, prednisone was used in the management of one Clinical Features
case with meningoencephalomyelitis without obvious exac- Dogs generally develop visceral leishmaniosis. A subclini-
erbation of infection (Marchetti et al., 2009). cal phase of infection may persist for months or years.
Weight loss in the face of a normal to increased appetite,
polyuria, polydipsia, muscle wasting, depression, vomiting,
LEISHMANIOSIS diarrhea, cough, petechiae, ecchymosis, epistaxis, sneez-
ing, and melena are common presenting complaints. Sple-
Etiology and Epidemiology nomegaly, lymphadenopathy, facial alopecia, fever, rhinitis,
Leishmania spp. are flagellates that cause cutaneous, muco- dermatitis, increased lung sounds, icterus, swollen painful
cutaneous, and visceral diseases in dogs, human beings, and joints, uveitis, and conjunctivitis are commonly identified
other mammals. Rodents and dogs are primary reservoirs of on physical examination. Cutaneous lesions are character-
Leishmania spp., people and cats are probably incidental ized by hyperkeratosis, scaling, thickening, mucocutaneous
hosts, and sandflies are the vector in most endemic regions ulcers, and intradermal nodules on the muzzle, pinnae, ears,
other than the United States. Cats are also commonly exposed and foot pads (Fig. 98.2). Bone lesions are detected in some
in areas with endemic canine infection. In one study, sand- dogs. Infertility and prostatitis were detected in a chroni-
flies could be infected by feeding on a naturally infected cat, cally infected dog (Mir et al., 2012). Most dogs die or are
suggesting this species should be further evaluated as a euthanized as a consequence of chronic kidney disease. Cats
potential reservoir (Maroli et al., 2007). are usually subclinically infected; when infection occurs, the
Leishmaniosis was considered unimportant in the United major clinical manifestations are cutaneous. The skin lesions
States until recently, with cases only reported occasionally. are usually nodular and ulcerative on the pinnae and less
In 1999, Leishmania infantum infection was confirmed in commonly on the muzzle and periorbital skin (Navarro
multiple dogs in a Foxhound kennel in New York State et al., 2010; Trainor et al., 2010). Histopathology reveals
(Gaskin et al., 2002). Further investigation of more than
12,000 Foxhounds and other canids documented L. infan-
tum infection in 18 states and two Canadian provinces
(Duprey et al., 2006). Infection of canids other than Fox-
hounds appears to be uncommon in North America. In the
United States, Leishmania spp. appear to be transmitted ver-
tically (Freeman et al., 2010).
In other countries, flagellated promastigotes develop in
the sandfly and are injected into the vertebrate host when the
sandfly feeds. Promastigotes are engulfed by macrophages
and disseminate through the body. After an incubation
period of 1 month to 7 years, amastigotes (nonflagellate)
form and cutaneous lesions develop; sandflies are infected
during feeding. In Foxhounds in the United States trans-
mission appears to be primarily from dog to dog (Duprey
et al., 2006). Transmission by fighting, shared needles, blood
transfusions, breeding, and vertical transmission can occur
(Boggiatto et al., 2011; Duprey et al., 2006; de Freitas et al., FIG 98.2
2006). Leishmania infantum DNA has been amplified Characteristic Leishmania spp.–associated skin lesion on the
from Rhipicephalus sanguineous ticks collected off natu- foot of a dog in Spain. (Courtesy Dr. Arturo Font,
rally infected dogs; further study of this potential route of Barcelona, Spain.)