BACKGROUND: Spirocerca lupi is a nematode of Canidae that matures within
the esophageal wall to form fibroblastic nodules with potential for malignant
transformation. Diagnosis is based on histopathologic examination,
but false-negative results may be obtained from samples collected by
endoscopy. Serum alkaline phosphatase (ALP) activity, frequently increased
in hepatobiliary disease, is also increased in a variety of neoplastic
conditions in dogs, including appendicular osteosarcoma, and has also been
reported to be increased in dogs with spirocercosis.
OBJECTIVE: The aim of this study was to evaluate serum ALP activity
as a marker for malignant transformation of esophageal nodules in
S. lupi-infected dogs.
METHODS: In this retrospective study, medical records of dogs diagnosed
with spirocercosis from 1991 to 2008 were reviewed, and serum ALP
activity determined at presentation was compared between dogs with nonneoplastic
and neoplastic nodules. Owing to use of multiple analyzers,
ratios of ALP activity to the upper reference interval for ALP were calculated
RESULTS: Median ALP activity ratios were 0.65 (0.07–4.00) and 0.86
(0.10–3.40) for dogs with nonneoplastic (n = 88) and neoplastic (n=32) nodules,
respectively,with no significant difference (P =.18) and substantial overlap
between groups. Tumors included osteosarcoma (15 dogs), fibrosarcoma
(15 dogs), and anaplastic sarcoma (2 dogs); there was no difference in ALP
activity between the dogs with osteosarcoma and fibrosarcoma.
CONCLUSION: ALP is a poor marker of malignant transformation in canine