This sweater is based on Lion Brands' Turtleneck Dog Sweater. It's been changed to fit different measurements and a different choice in yarn – and also to eliminate seaming. I hope it fits. The dog lives in another time zone.
I chose a 17 st cast on at the end of the BACK section since 17 is about a fourth of 70. I made the leg opening increases and decreases a few sts from the edge but think they'll look better as written below. I made the increases for the BACK 3 sts in from the sides.
1 skein Vanna's Choice Colonial Blue (MC)
½ skein Vanna's Choice Mustard (CC)
size 9 [5.5 mm] knitting needles
16 sts + 32 rows = 4 inches [10cm] in garter st
Garter st pattern: When knitting back and forth, knit every row. When knitting in the round, knit one round then purl the next round. Repeat.
With MC, cast on 29 sts. Work in garter st, increasing 1 st near beginning and end of every RS (knit) row 4 times (to 35 sts), then every other RS row 9 times (to 53 sts). Knit 3 more rows.
Change to CC and knit across 53 sts (on RS). Mark start of round. Cast on 17 sts. Place a second marker. Join to start working in the round. Purl 53 to reach end of round. Work in garter stitch to 6 ridges of CC (10 more rounds).
(The chest is worked in CC, the back and sides in MC.)
Row 1: In CC, ssk, k to 2 sts before marker, k2tog. In MC, ssk, k to 2 sts before marker, k2tog. Turn.
Row 2: In MC, knit to marker. In CC, knit to marker. Turn.
Repeat Rows 1 – 2 three more times.
Row 9: In CC, knit to marker (9 sts). In MC, knit to marker (45 sts). Turn.
Row 10: In MC, knit to marker. In CC, knit to marker. Turn.
Repeat Rows 9 – 10 once more.
Row 13: In CC, k1, make 1, k to 1 st before marker, make 1, k1. In MC, k1, make 1, k to 1 st before marker, make 1, k1. Turn.
Row 14: In MC, knit to marker. In CC, knit to marker. Turn.
Repeat Rows 13 – 14 three more times (to 17 sts in CC and 53 sts in MC).
Break MC to begin knitting with CC only (in the round).
With CC, work in garter st in the round, to 6 ridges of CC (12 rounds), starting with a knit round. Decrease on every knit round by knitting to first marker (17 sts), k3, ssk, k to 5 sts before end-of-round marker, k2tog, k3. End on a purl round.
With MC, knit around.
Set-up round: (k1, p1) 9 times, (k1, p2tog) 4 times, (k1, p1) 13 times, (k1, p2tog) 4 times, k1, p1. (50 sts).
Work in (k1, p1) rib for 4". Bind off in pattern. Fold collar back.
Single crochet around each leg opening in MC. Weave in all ends.