Very old and very young animals are less likely than healthy adults to survive poor nutrition, adverse weather and exposure, and they are generally more susceptible to disease. Therefore, age and apparent health of animals prior to death should be considered in evaluating losses.
Young animals, particularly newborn pigs, lambs and kids are extremely vulnerable to exposure during cold, wet weather. If they do not receive adequate maternal care and do not nurse within the first few hours they are not likely to survive. Birth weight also is important to survival; newborn young that are small and weak are less likely to survive than healthy, vigorous young of average or larger size.
Diseases of pregnancy and difficult births may cause the death of either or both the mother and fetus. Necropsy (examination and dissection of a body after death) of females in parturition should include attention to pregnancy diseases and to injuries sustained in giving birth, in addition to unusually large fetuses and those in abnormal positions. Post-mortem examination of newborn and very young animals should include attention to the major characteristics of healthy young, such as: 1) Young born alive will have a distinct blood clot at the closed end of the navel (umbilical artery); stillborn young will not have this clot. 2) If young animals breathe after birth, the lungs inflate, become light pink and will float in water (complete lung inflation may require several hours); stillborn young have uninflated, dark, red-purple lungs which do not float. 3) Firm, white fat deposits around the heart and kidneys indicate health; the lack of this fat indicates poor nutrition or starvation. As young healthy animals grow, they also develop fat deposits in tissues around the stomach and intestines (mesenteric fat). 4) Milk is normally present in the stomach and intestines of healthy young. The absence of milk during the first few weeks indicates poor nutrition; however, milk content of the stomach decreases as the diet changes to solid foods and weaning takes place. 5) Digestion of milk produces chyle, a white emulsion of milk fat and lymph. This is found in the lymphatic vessels which drain the intestinal tract and is present immediately after young animals suckle. 6) The soft membrane on the hooves of newborn animals begins to wear as soon as the young stand and begin walking. Hard, dry soil surfaces cause more rapid wear than soft, wet surfaces.