As Sammi has not eaten the last two morning and is only on day 21 I thought I'd have a look online for more information. My memory is diabolical but I thought that previously my bitches went off their food at around day 28 after their season, whether they had been mated or not. Anyway I found this on a "Vets Corner" page. Though I'm only interested in the current time (21+ days) I found it all interesting and reassuring! I may have bred a few litters over the years (well to date 9 litters in 25 years) but there is always so much to learn, we can only gain from knowledge.
Pregnancy is divided into three stages, the first trimester (mating to day 21), second trimester (day 21-42) and third trimester (day 42 to full term). Gestation lasts an average 63 days (60-67) so it is important to note the service date so that due whelping date can be calculated.
In the first trimester, the bitch may show mood changes and variable picky appetite. There is no real change in the bitch's body condition during this period. Bitches, like humans, may suffer from morning sickness. At about 3 weeks of gestation many bitches undergo a short period of transient anorexia that lasts for 3-10 days. A slight transient weight loss may occur in some bitches. This refusal of a complete and balanced diet may be a natural behavioural change in a healthy bitch during pregnancy. In the first week of the second trimester (weeks 3-4) the foetal puppies may be felt for the first time. They are gently palpated about the size of golf balls. Towards the end of the second trimester, the abdominal wall begins to sag and enlarge and the mammary glands start to develop. The third trimester is the period of maximum puppy growth and places the greatest demands on the bitch. The abdomen enlarges to its maximum size to become pendulous. The mammary glands enlarge and fill with milk and may begin to excrete milk up to 24 hours before parturition.