Reported factors leading to candidiasis in people and animals include immune suppression, neoplasia, chemotherapy, prolonged
antibiotic or glucocorticoid use, diabetes mellitus, burns, infectious disease, and prolonged intravenous or urinary catheter
placement.13,14 Multiple factors may have contributed to disseminated candidiasis in this cat, including the oral ulceration and gastric
perforation that represented a break in mucosal defenses. Additionally, the cat had received broad-spectrum antibiotics in
the recent past that may have inhibited resident microflora, allowing C. albicans to proliferate in the gastrointestinal system. Candidiasis in cats has been associated with gastroenteritis, pyothorax, diabetes
mellitus, urocystitis, and uveitis.2,15-18 Ocular and systemic candidiasis was documented in two cats that had negative test results for FIV and FeLV, as was the case
in this cat.2,18 Although FIV and FeLV cannot be completely ruled out based on serology, the ELISA is considered a sensitive test, so it was
unlikely that either of these was a contributing factor in this cat.19 Candida albicans is the most frequently isolated fungal pathogen in immunocompromised people14; however, the cat in this report had evidence of an active immune system supported by a leukocytosis. The white blood cell
count was elevated at each examination, suggesting that the cat was not immunosuppressed. In fact, a leukocytosis was a common
finding in cats reported to have candidiasis.2,16-18 Multiple clinicopathologic abnormalities in this case could be attributed to chronic inflammatory disease, including the
neutrophilia, lymphopenia, and hyperglobulinemia. A mild left shift can be associated with an infection but can also be part
of a chronic inflammatory condition or granulomatous disease.
Other clinicopathologic abnormalities included an elevated blood urea nitrogen concentration, which may have been due to azotemia
(prerenal or renal) but was more likely due to blood in the gastrointestinal tract, as was seen during necropsy evaluation.
Gastrointestinal hemorrhage may lead to increased absorption of protein and subsequent elevation in blood urea nitrogen. The
normal creatinine concentration might have been inappropriately low because of the cat's emaciated condition and associated
loss of lean muscle mass.20 The icterus and hyperbilirubinemia were most likely due to hepatic or posthepatic causes, since no hemolysis was observed
and severe lymphocytic infiltrative hepatitis with fibrosis and biliary hyperplasia were noted on histologic examination of
the liver. It is not clear why the liver enzyme activities were normal in the face of obvious histologic abnormalities. Because
the liver enzymes evaluated (alkaline phosphatase and alanine aminotransferase) are inducible or leakage enzymes, not tests
of liver function, measuring bile acids or blood ammonia concentrations may have been beneficial in this case.
We never definitively diagnosed toxoplasmosis in this cat. Because toxoplasmosis can be difficult to diagnose, a combination
of serologic test results and clinical signs is often required. Serologic tests for T. gondii, a protozoal organism, measure detectable antibody to IgM and IgG. Current or recent infection is generally suspected when
there is an elevated IgM titer or at least a fourfold increase in IgG titers with paired serum samples.21 Cats can have persistently elevated IgG titers years after exposure; consequently, the single elevated IgG titer for T. gondii in this cat may not have been evidence of current infection.21 Convalescent serum was not available for evaluation. Ocular lesions such as chorioretinitis and anterior uveitis are common
manifestations of toxoplasmosis.22 Most lesions consist of a lymphocytic-plasmacytic infiltrate without identifiable organisms, as was the case in this cat.
We thought that the elevated IgG titer combined with the clinical signs consistent with T. gondii infection, including pulmonary disease and chorioretinitis, warranted appropriate antibiotic therapy even if the organisms
were not identified.
The positive result on the Western blot for Bartonella species antigen in our patient was suggestive of Bartonella species exposure. Cats that test +3 or +4 are considered to be currently infected, and appropriate antibiotic therapy is
recommended.23 Multiple studies have suggested that bartonellosis can lead to chronic disease, and simultaneous infection with T. gondii and Bartonella species may be required to observe more pronounced disease manifestations.24 Although bartonellosis was not confirmed with a positive blood culture result or by polymerase chain reaction testing, it
is a disease with vague historical and clinical signs such as those observed initially in this cat, so we initiated appropriate