Page 1057 - Clinical Small Animal Internal Medicine

109 Fungal Infections 995

from inhalation of the mycelial form, which can develop
VetBooks.ir in tissues if they are stored for long periods after death of
an infected animal. Physicians should be notified imme­
diately in the case of inoculation or possible inhalation of
a mycelial form. Necropsies should be performed with
appropriate precautions and take place soon after death
to prevent mycelial form growth. Bodies of infected
animals should not be buried but should be cremated
as soon as possible. Laboratories should be warned if
coccidioidomycosis is suspected.

Aspergillosis

Etiology/Pathophysiology
Aspergillus are hyaline molds, the conidia of which are
found commonly in soil, water, air, and decaying vegeta­
Figure 109.5 Cytology of a tracheal wash specimen showing a
Coccidioides spherule surrounded by pyogranulomatous tion. Aspergillus spores are inhaled, and in the absence of
inflammation. adequate immune defenses, enlarge and germinate to
form hyphae, subsequently leading to a variety of nonin­
and, in hyperendemic areas, other diagnostic tests (such vasive to invasive disorders that include keratomycosis,
as cytology, histopathology or culture) should also be fungal otitis externa, sinonasal aspergillosis (SNA),
used to confirm the diagnosis. sinoorbital aspergillosis, bronchopulmonary and dissem­
inated aspergillosis. Keratomycosis, otitis externa, feline
sinoorbital aspergillosis, and bronchopulmonary asper­
Therapy gillosis in dogs are relatively rare conditions, and beyond
Dogs with pulmonary coccidioidomycosis often respond the scope of this chapter. A variety of other molds less
well to azole monotherapy with fluconazole or itracona­ commonly cause infections in dogs and cats, including
zole. Treatment with amphotericin B is recommended nonpigmented molds such as Penicillium, Paecilomyces,
either alone or in combination with an azole antifungal Pseudallescheria, and Geotrichum (hyalohyphomycoses);
for dogs with refractory disease or those with severe pigmented molds such as Alternaria, Exophiala, and
clinical signs. Successful treatment of Coccidioides peri­ Cladophialophera (phaeohyphomycoses); and zygomy­
carditis has been reported after subtotal pericardiectomy cetes such as Basidiobolus, Conidiobolus, and Mucor. The
and epicardial excision in conjunction with antifungal reader is referred elsewhere for detailed discussions of
drug therapy. Referral to a specialist surgeon with expe­ these pathogens.
rience in the technique is strongly recommended. Sinonasal aspergillosis is a subacute to chronic disease
of the nasal cavity and sinuses that is most often caused
by organisms that belong to the A. fumigatus complex.
Prognosis In most cases, affected dogs have no evidence of immune

The prognosis for resolution for coccidioidomycosis compromise, but sometimes SNA occurs as a result of
depends on the severity of infection and the extent of implantation of a foreign body or other preexisting nasal
dissemination. The duration of treatment ranges from disease, such as nasal neoplasia. SNA is a noninvasive
six months (localized pulmonary coccidioidomycosis) to disease, and the fungus does not extend beyond the
many years, and in some cases, life‐long treatment is mucosal epithelium. Production of toxins by the fungus
needed. IgG antibody titers decrease with successful and a profound host inflammatory response are thought
treatment, which in general should be continued until to lead to extensive turbinate and bony destruction.
lesions resolve and the titer is 1:2 or lower. Disseminated (invasive) aspergillosis in dogs is most
often caused by A. terreus or A. deflectus, although other
Aspergillus species have also been isolated.
Public Health Implications
Coccidioidomycosis is an important and serious Epidemiology and Signalment
infection in people that is generally acquired from envi­
ronmental exposure. Disease and death may occur from Sinonasal aspergillosis in dogs is most common in large,
direct inoculation from needle‐stick injuries and also nonbrachycephalic breeds. SNA uncommonly occurs in