Abstract

Background:
Hemangiosarcoma (HSA) is a highly aggressive malignant neoplasm of vascular endothelial origin in dogs, exhibiting pathophysiological and molecular features analogous to human angiosarcoma. β-adrenergic receptors (β-ARs) are significantly upregulated in human angiosarcoma, and β-AR antagonists are under investigation as potential therapeutics.

Aim:
This study aimed to quantify β₁- and β₂-AR expression in canine splenic HSA tissue relative to non-neoplastic splenic tissue.

Methods:
Splenic tissue samples were obtained from ten client-owned dogs—four with splenic HSA and six with non-neoplastic nodular lesions (NNL), including nodular hyperplasia (NH) and nodular lymphoid hyperplasia (NLH)—and subjected to immunohistochemical (IHC) analysis using primary antibodies targeting β₁- and β₂-AR. Quantification of IHC expression was conducted using the histochemical score (H-score) and immunoreactive score (IRS).

Results:
Compared with NNL tissues, HSA specimens showed higher β₁-AR immunoreactivity (H-score: 30.74 vs. 1.78, respectively, p < 0.01; IRS: 2.45 vs. 0.52, respectively, p < 0.05) and β₂-AR immunoreactivity (H-score: 100.50 vs. 1.69, respectively, p < 0.01; IRS: 7.36 vs. 0.50, respectively, p < 0.01). Within HSA tissues, β₂-AR expression was higher than β₁-AR (H-score: 100.50 vs. 30.74, respectively, p < 0.05; IRS: 7.36 vs. 2.45, respectively, p < 0.05).

Conclusion:
These findings demonstrate marked β-AR overexpression, especially β₂-AR, in canine splenic HSA and provide foundational tissue-level evidence for further investigation into the pathophysiological role and therapeutic relevance of β-adrenergic signaling in HSA.

Key words: Angiosarcoma; Beta-adrenergic receptor; Dogs; Hemangiosarcoma; Spleen.