Missed heat cycle
Enlarged nipples
Darkened nipples
Slight vaginal discharge
Increased appetite
Decreased appetite early on
Weight gain
Enlarged abdomen
Tiredness
Nesting behavior
More affectionate behavior
Restlessness
Vomiting
Enlarged mammary glands
Clearer signs after 3 to 4 weeks
Veterinary exam
Ultrasound
X-ray later in pregnancy
Blood test for pregnancy-related hormones