Discussion
Figure 4: Hyphae and narrow-based budding yeast (inset) morphologically consistent with Candida species are present in the
bronchial exudate and debris (Gomori's methenamine silver stain; 400X [inset 1,000X] original magnification).
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Pneumoperitoneum is an accumulation of free air or gas within the peritoneal cavity. Frequent causes of pneumoperitoneum in
dogs and cats include trauma from perforating wounds and motor vehicle accidents, gastrointestinal perforation from neoplasia,
gastric ulceration and perforation from the use of nonsteroidal anti-inflammatory drugs and glucocorticoids, and iatrogenic
air introduction during surgery.4,5 Reports of cats with pneumoperitoneum have documented gastric perforation from penetrating ulcers and gastrointestinal lymphoma.6-9 The cat in this report had been chronically ill, and a gastric perforation from a focal ulcer was the most likely cause.
None of the documented causes of gastrointestinal ulceration, including neoplasia or the use of nonsteroidal anti-inflammatory
drugs and glucocorticoids, were present in this cat. However, in a previous report, 35% of patients had pneumoperitoneum due
to gastrointestinal perforation without an underlying cause.4 In a recent retrospective report of dogs and cats with gastrointestinal perforation, cats were found to conceal their illness
four times longer than dogs.10 All reported cases had concurrent disease, and most had prolonged illness before diagnosis and treatment.10 Pneumoperitoneum is treated by performing a surgical exploratory to identify and correct the underlying cause.
A second problem in this cat was disseminated candidiasis. The mucosal barrier is the first line of defense against fungal
organisms, and cell-mediated immunity is important in the suppression and control of fungal infections once they become systemic.
Both the oral ulcers and gastric perforation in this cat allowed for a breakdown in the mucosal barrier and were the most
likely points of origin for C. albicans. Candida albicans is an opportunistic pathogen. It is a dimorphic organism normally found on the mucosal surfaces of the proximal gastrointestinal
and distal urinary tracts and is rarely isolated from the soil. The histologic identification of the yeast and hyphal forms
of C. albicans within the respiratory tract of this cat is definitive evidence of dissemination. Numerous hyphae were isolated from the
bronchi and alveolar spaces, and pulmonary candidiasis in people is associated with a 70% mortality rate.11 The yeast to hyphal transition of C. albicans has been associated with the production of fungal exotoxins and can lead to septic shock, which may have been one of the
reasons for this cat's sudden decompensation and subsequent death.12 Additionally, the large amount of yeast present within the adrenal medulla may have led to adrenal hypofunction and postoperative
decompensation. Further support of adrenal hypofunction included the cat's vague signs of anorexia, vomiting, and lethargy
together with a leukocytosis, nonregenerative anemia, and mild azotemia. The high normal potassium and low sodium concentrations
in an anorectic, dehydrated patient were further evidence of this possibility. Treatment for candidiasis includes administering
antifungal medications (amphotericin B or imidazoles such as ketoconazole, itraconazole, or fluconazole), but once the candidiasis
is disseminated, the prognosis is guarded.13
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