Why do tiny litters happen?
There are many reasons why you might get a very small litter ranging from reproductive issues in sire or dam, underlying health issues in the dam, or timing of the breeding. Average Aussie litter size is about 6-7 pups. If an Aussie sometimes has normal size liters and sometimes small ones, and the mates with which it had the smaller ones are not the other parent on the normal size litters, you may want to test both parents for Pelger-Huet Anomaly (PHA.) PHA causes blood cell abnormalities and fetuses that inherit two copies of the gene usually die before birth and are reabsorbed, resulting in smaller litter size.
What is normal infant mortality rate for Aussies?
ASHGI’s 2009-10 health survey indicated slightly over 10%, a troubling number. Some of this may be related to husbandry, but even given that the numbers are reason for concern.