A kitten's growth can be gauged by measuring its weight gain, an easy parameter to record. All kittens in the litter must be weighed every day at the same time. By recording this measurement, we can see the change in weight for each kitten and also compare kittens to each other.
A kitten should gain weight every day. There are a few guidelines for determining whether a kitten is developing properly. If the kitten does not gain weight for two consecutive days or if it loses weight, we must determine the cause: insufficient feeding by the mother, illness, etc.
Normal growth in kittens from birth to adulthood occurs in three phases:
- The neonatal period, or approximately the first four days after birth, during which the rate of growth is highly variable, particularly with relation to birthing conditions. Kittens that had a difficult birth may stay at the same weight, but weight loss is rare.
During the strict nursing period of the first four weeks, growth is regular and linear, and it is even possible to predict weight as a function of age. Thus, the weight at seven to ten days is equal to twice the birth weight, and the weight at four weeks is equal to four times the birth weight.
Growth during the strict nursing period is directly dependent on the quality of lactation and the mother's care of her kittens.
- The pre-weaning period is a time of dietary transition occurring when kittens are four to seven weeks old. At approximately four to five weeks old, the kittens' growth rate declines; this corresponds to a decrease in lactation associated with temporary undereating. Around the seventh week, another growth spurt occurs, indicating the end of weaning: The kitten is now consuming enough solid food for its growth to continue. Even during this transition period, the kitten continues to gain weight. The weight at eight weeks is generally equal to twice the weight at four weeks, or eight times the birth weight.
- The post-weaning period starting after eight weeks signals the beginning of the kitten's autonomy and corresponds to the expression of genetic potentialities. Individual variation is fully expressed at this time. The kitten eats by itself when it wants and grows to its full adult size. Once the cat reaches full size around ten to twelve months, it should maintain a constant weight.