Which mouse pups count in a breeding protocol?

Does your IACUC ask that every pup born on a mouse breeding protocol be counted and reported in protocol updates, or only weanlings? Our chairman and I attended an IACUC Advanced workshop at Cornell in September 2006, and at a session discussing breeding protocols, every institution present (except for us) counted only weanlings. Pups euthanized prior to weaning were not counted at all.
We have been trying to establish that practice for our breeding protocols since we returned from that meeting, but our Vet keeps blocking the suggestion because he says it is "misleading." Our PIs are eager to establish this practice because it is often difficult for them to report accurately the numbers of pups euthanized or found dead. To my understanding of regulations, animals need not be counted until they are living independent of the mother.
The most relevant number is the number of pups with desirable characteristics that are weaned to experimental protocols. Investigators with a poor success rate in producing pups that are suitable for their experimental protocols take the initiative to discuss the problems with the IACUC and to try to improve success.
Which pups do YOU count? Thanks!

Hi Donna,

Someone else just asked the same question - so this is a copy and paste response. To preface, OLAW suggests animals should be counted at birth (or perhaps at the first cage change), but we identified a fundamental problem with OLAW’s logic on doing it for example at the first cage change. At the end of the day, a point in time for counting is being established (by the institution or OLAW in this example). They choose ~2weeks (cage change), but we choose ~21 days (weaning). We asked - why would the first cage change be a better time point to start counting then at weaning? What if you lose half a litter before the first cage change – they don’t get counted. So this logic implies an institution has to decide when a new born mouse graduates from embryo to animal (i.e. when do you start counting). Some will say once it’s born it’s no longer an embryo, but others will say it’s still “developing” from birth to weaning (mother dependency), so it’s an embryo.

If we say at birth for mice do we use the same logic for zebra fish - OLAW implies we need to count zebra fish “larvae” at 3 days post-fertilization (Applicability, FAQ5); not an easy task.

We went through this situation and just established a policy that say’s mice will be counted at weaning unless they’re used for research, teaching or testing prior to weaning in which case they will be counted when they’re used.

Hi, Donna-

We don't count pups born, but we do require that they count weanlings. As these numbers get "charged" to the protocol, it doesn't seem fair to count animals that may die for any number of reasons before weaning (e.g., mom eats them). We don't breed fish or other cold-blooded vertebrates, so I can't attest to what people do with those species.

Hope this helps.

We recently changed our in house policy to count any live animal at first observation. So if a litter is born and they are not observed until 24 hrs old the number of live pups at that time is the number to report during the annual review. We changed this so IACUC community members and other members not familiar with breeding protocols could have a better understanding of how many animals are produced versus used. For example if a PI produces 1000 pups a year but only 50% make it to weaning age because the other 50% do not have the correct genotype and are euthanized that is 500 pups that were produced but were euthanized. In addition, we were having issues of PI's allowing their animals to breed even though they did not have protocols to use the pups on at that time. This was causing euthanasia of 100's of pups and that did not feel like the spirit of the IACUC.