Decay of MDA

For the reasons just given, some puppies and kittens will have high levels of MDA whilst in others the level of MDA may be low. Variation of MDA levels even within a litter is common. MDA is also known as "passive" immunity because it is not actively produced by the puppy or kitten; thus it decays over a period of some weeks.

Trying to predict the rime when the MDA level has decayed to a point where the young animal is no longer protected is possible by means of blood tests, but this is not practicable on a routine basis.

However, thanks to the co-operation of many guardians and their veterinary surgeons, Intervet's research staff in the UK, with additional assistance from independent laboratories, have examined blood samples from over 3,000 dogs (fewer numbers of cats) to help establish the timings of MDA decay for the various diseases.

This is important because:- it provides a guide to the "average" age at which a puppy or kitten is no longer protected by the mother's immunity and is therefore at risk.it gives an indication of the best time to start the vaccination course.