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.
Nutrition: Successful breeding programs result from optimal and not minimal nutrition. Only two types of food are needed. These include one for maintenance in early and mid pregnancy and one for late pregnancy and lactation. The nutritional requirements of reproducing bitches are as much as 2-4 times greater than that of the inactive adult dog. Nutritional deprivation during pregnancy can compromise immunological competence of the offspring and may adversely affect the production of colostrum. If the bitch becomes overweight or underweight, there may be problems in successfully gestating all pups to term or the bitch may suffer dystocia.
Bitches tend to put on weight more readily during pregnancy due largely to hormonal changes and reduced physical activity. In the first trimester (weeks 1-3), no added food intake is necessary and the bitch fed a balanced diet with no additives necessary. During the second trimester (weeks 3-6) there must be an increase in calcium intake (e.g. needed in milk production) to ensure normal blood calcium levels in the bitch and normal puppy bone development. Two teaspoons of di-calcium phosphate plus 400 units vitamin D is adequate. Early or overzealous supplementation of the diet with calcium may have an adverse impact on the bitch's ability to mobilise calcium reserves in parturition or lactation. The growth of the pups is most rapid during the final trimester (weeks 6-9). It is during this time that the bitch is given more to eat; she should get about one and a half times her normal intake. Bitches at this time can be changed to a complete puppy diet with its increase protein and calcium content. Protein sources of high biological value including eggs, chicken, cheese, red meat and offal can be added to diet to increase the quality. In the later stages of pregnancy however, the bitch has less room for a large amount of food at any one time due to an abdomen full of pups. The bitch must be given a number of small meals rather than one large meal. As whelping nears, the bitch may lose appetite entirely. In some bitches, food refusal during the ninth week of gestation is an indication that whelping will occur during the next 24-48 hours. Usually within 24 hours after whelping, appetite will return and food consumption will increase dramatically.
A manual physical examination involving gentle palpation of the abdomen from 3-4 weeks. Most bitches go off their food for 3-7 days around days 20-28 of pregnancy. Ultrasound examination can detect pregnancy from 21 days. A radiography after 7 weeks (there needs to be sufficient calcification of the foetal puppy bones) A blood test for the hormone relaxin after 35 days.
PSEUDOPREGNANCY (FALSE PREGNANCY)
This is a normal hormonal condition and a psychological state in a bitch that has either been mated and has not conceived or has never been exposed to a male. All signs of pregnancy occur including mammary development, weight gain, and abdominal enlargement and even nest making. Various hormonal therapies exist to treat this condition provided radiology confirms the absence of any pups.
VACCINATION AND PARASITE CONTROL
The bitch should be de-wormed at breeding time and during the second trimester to reduce environmental contamination. Products include Drontal plus (praziquantel, febantel and pyrantel) and Panacur (fenbendazole). Before the mating the bitch should receive a booster vaccination against parvovirus, distemper, adenovirus, coronavirus, and leptospirosis to ensure that an adequate immunity is developed and concentrated in the colostrum to be passed to the pups for protection during the first few months of life. There is widespread use of these live attenuated virus vaccines during pregnancy without any adverse effects, however it should be noted that this procedure is contrary to manufacturers recommendations.
Moderate exercise throughout pregnancy is important to prevent the bitch becoming fat and any strenuous exercise such as jumping or rough playing should be avoided but regular walking can be encouraged right up to whelping.
THE LAST WEEK OF PREGNANCY
During the last week of pregnancy, the bitch should be placed in her whelping box to acclimatise her to her new environment. The area should be clean, quiet, have good lighting and ventilation and provision for heating. It is advisable to whelp the bitch on sheets of newspaper as this is easy to dispose of and replace once soiled during the birth process. Within 2-5 days of giving birth, the bitch becomes more sunken in the loin area with a pendulous abdomen. Some bitches may become very large close to the end of term and may develop oedema in the back legs as a result of reduced drainage from the legs. This is not a cause for undue concern. The vulva will become enlarged with possibly a clear to straw coloured mucus discharge visible and the ligaments around the tail base slacken. Within 24 hours of whelping, nesting may be exhibited. The temperature will drop from normal (101-102°F) to below 100°F. Progesterone levels also drop below 2ng/ml (immunoassay) during the last 24 hours. If the vulva discharge is a dark green/black/blood colour, something is wrong and veterinary assistance should be sought immediately.
DRUGS AFFECTING PREGNANCY
Certain drugs may cause congenital malformation or embryonic toxicity and should be avoided during pregnancy. These include: enrofloxacin, doxycycline, metronidazole, corticosteroids, griseofulvin, pentobarbital, DES, testosterone and most analgesics and anaesthetics. It is advisable to always question the safety of drugs administered during pregnancy in regard to the foetus and the bitch. Certain treatments or surgical procedures should be postponed until after parturition if possible.