Page 1059 - Clinical Small Animal Internal Medicine

109 Fungal Infections 997

Therapy Many dogs with disseminated aspergillosis have
VetBooks.ir Treatment of SNA requires thorough mechanical advanced disease at diagnosis, sometimes with respira­
tory distress, pathologic fractures, vertebral subluxa­
debridement of plaques with endoscopic biopsy forceps
under anesthesia, followed by topical antifungal drug tions, and cord compression. The prognosis for these
dogs is poor.
therapy. Frontal sinus trephination and curettage or
open surgical debridement of the frontal sinus may be
required. Provided the cribriform plate is intact, debride­ Public Health Implications
ment is followed by lavage with 0.9% saline and suction, Aspergillosis occurs in people who have significant
followed by topical therapy with clotrimazole or enilcon­ immunosuppressive disorders, such as transplant recipi­
azole. Several protocols for topical antifungal drug ents, and is usually due to Aspergillus fumigatus complex
administration have been described. The reader is organisms. Infections are acquired from the environ­
referred elsewhere for description of these protocols. ment, and transmission from dogs and cats has not been
Debridement and a second treatment are then per­ described.
formed one month later; sometimes, a third treatment
may be necessary. Additional systemic treatment with
antifungal drugs could also be considered, but it is not Candidiasis
clear whether this improves outcome. Systemic azole
antifungal drug therapy could be considered as an alter­ Etiology/Pathophysiology
native to topical therapy in dogs with cribriform plate
destruction, when topical treatment has the potential to Candida species are yeasts that belong to the normal
lead to death or life‐threatening neurologic signs. gastrointestinal, urogenital, and cutaneous flora but can
Canine disseminated aspergillosis is treated with itra­ invade tissues and cause disease as a result of disruption
conazole, voriconazole, posaconazole, and/or ampho­ of normal host defenses. Candida species can also be
tericin B. Terbinafine has been used in addition to azole isolated from soil, inanimate objects, and hospital
therapy with limited success. At best, treatment leads to environments. The yeasts are small (3–6 μm), ovoid and
remission for months to more than a year, but usually reproduce by budding. Budding results in the formation
antigen titers remain high and eventually relapse occurs, of new yeast cells, pseudohyphae (chains of elongated
leading to euthanasia or death. Although expensive, vori­ yeast cells), and true septate hyphae.
conazole is a treatment of choice in humans with inva­ Disease syndromes caused by Candida spp. that
sive aspergillosis, and has led to remissions of many occur in dogs and cats include keratitis, cutaneous or
months’ duration in some dogs. A. terreus is resistant in mucocutaneous candidiasis, otitis, urinary tract infec­
vitro to amphotericin B, but clinical improvement still tions (UTIs), gastrointestinal candidiasis, peritonitis,
occurs after treatment of some dogs with lipid com­ and disseminated infections. The most commonly iso­
plexed amphotericin B. Caspofungin is also used to treat lated species is Candida albicans, and only C. albicans
invasive aspergillosis in humans, but expense and the appears to cause disseminated disease in dogs and cats.
need for daily intravenous administration have limited
its use in dogs. Epidemiology and Signalment
Predisposing factors in dogs or cats with local or dissem­
Prognosis inated candidiasis have included diabetes mellitus, treat­
ment with immunosuppressive drugs or broad‐spectrum
Success rates for treatment of SNA have varied from less antibacterial drugs, a history of gastrointestinal surgery,
than 30% to 100%. Low success rates reflect extensive parvoviral infections, and/or underlying malignancy.
disease that is often present at diagnosis, together with Disseminated candidiasis has also been described in
irreversible turbinate loss. Dogs with turbinate loss are apparently immunocompetent animals, which may
predisposed to recurrent bacterial infections of the reflect an underlying genetic immunodeficiency.
nasal cavity, which lead to persistent nasal discharge Urethrostomy or cystostomy tube placement may be in
and sneezing. Therefore, attempts should be made to the history of some animals with Candida UTIs.
reach a diagnosis as early as possible when SNA is on
the differential diagnosis list. Treatment with antibacte­
rial drugs without pursuing a diagnosis only leads to History and Clinical Signs
disease progression, and is inappropriate because pri­ Lower urinary tract candidiasis may be subclinical or asso­
mary bacterial infections of the nasal cavity are rare in ciated with signs of lower urinary tract disease. Cutaneous
adult dogs. candidiasis may manifest as erythema, alopecia, erosions,