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A 13 years old, intact female, mixed terrier dog was presented to Tehran University, Small Animal Teaching Hospital of the Faculty of Veterinary Medicine for investigation of sever weight loss and decrease of appetite. In clinical examination a large fleshy mass was palpated at the upper portion of the neck. The dog was
anesthetized, and a biopsy of the mass was obtained, and submitted
for histopatological analysis. The sections composed of nests or
packets of cells generally were uniform in size, with indistinct
cellular borders and moderate to abundant amounts of light,
eosinophilic cytoplasm. Nuclei were round to oval with evenly
dispersed chromatin. Macrophages in capsular connective tissue
and in trabecules had haemosiderrin stain. The final histological
diagnosis was chemodectoma. In view of the poor body condition,
large size of the tumor, the animal was euthanaised and submitted
for postmortem examination. In macroscopic examination the
mass v as encapsulated at the bifurcation of the carotid artery with
some attachment to it. No evidence of distant metatasis was found
in neither macroscopic nor microscopic examinations.
Chemoreceptor tumors (chemodectoma) rarely are diagnosed in
cats and dogs. Aortic body tumors are identified more commonly
in dogs and cats, while carotid body tumors are the most common
in humans.