Let
G
n
G_n
denote either the group
S
O
(
2
n
+
1
,
F
)
SO(2n+1, F)
,
S
p
(
2
n
,
F
)
Sp(2n, F)
, or
G
S
p
i
n
(
2
n
+
1
,
F
)
G{\mathrm {Spin}}(2n+1, F)
over a non-archimedean local field of characteristic different from two. We determine all composition factors of degenerate principal series of
G
n
G_n
, using methods based on the Aubert involution and known results on irreducible subquotients of the generalized principal series of a particular type.