Table 5. Association between E2, tumor grade, ER, and non-mammary tumors (NMT).

Variable	n (%)	E2 category n high(H) vs low (L)
Grade		H	L
1	67(56.3)	39	28
2	37(31.1)	15	22
3	15(12.6)	5	10
P-value		p = 0.091
ER		H	L
Positive	51(56)	31	20
Negative	40(44)	18	22
P-value		P = 0.145
Tumor events		H	L
New NMT Controla	26(26)	8	18
P-value	74(74)	45	29
		P = 0.012

Association between estrogen (E2, high versus low) and tumor grade, ER expression, development of non-mammary tumors (NMTs) in spayed dogs (Chi square).

^a Control group are dogs with no tumor related events, including mammary tumor metastasis or non-mammary tumors)