Blackstaff Rats

From talking to Ann Storey, Microbiologist and NFRS Standards Officer about this -- and she has actually seen some of the longevity experiments in situ -- you would have great difficulty replicating the results of these experiments at home without the intervention of animal welfare organisations. The rats that lived longest (just under 5 years) were fed as little as 40% of what is usually considered to be the required amount of food and lived more or less in a state of partial suspended animation: the lack of nutrition slowed down their metabolism to the point that their life was extended in quantitative terms only. These rats had extremely sparse coats and moved very little. Most time was spent semi-comatose, conserving energy. In appearance they were likened to toast-racks and concentration camp victims (not my images - this from a first hand observer). Thus while life expectancy was increased quantitatively it was vastly decreased in qualitative terms. Put simply, the animals were miserable, and to my mind a short happy existence is preferable to a drawn out miserable one.

Postmortems have shown that most rats from this line have died from strokes -- or more accurately a succession of small strokes. I think that it is likely that with better breeding and welfare practices pet rats can live considerably longer than they currently do, but highly unlikely that they will ever reach anything like 5 years of age as an average. Based on the lab findings on longevity, I don't think that an excessively extended lifespan has any benefit to the animal at all, and is neither a realistic nor humane goal. A rat is a rat -- it does not celebrate its birthdays, nor keep track of how old it is. A rat is, however, acutely aware of discomfort and pain. I do not believe that rats are even aware of the difference between living 18 or 36 healthy months; I am certain however, that they are very conscious of many symptoms that can occur with age -- loss of mobility, pain, and general discomfort.

There has (on several internet forums and newsgroups) been some discussion about breeding cancer-free rats. While it is true that the incidence of cancer in domestic rats is many times higher than that observed in wild rat populations, it should be remembered that cancer is a disease that comes with old age. The incidence of cancer equalises between the wild and domestic rat population once wild rats lives are extended in captivity (the longer they live, the higher the incidence of cancer). It could be argued that by extending the lives of our pet rats, we have exposed them to a greater risk of cancer. While there are some lines of rats that appear to be more cancer-resistant than others -- and I think that breeding from these lines can only be a good thing -- cancer is always going to affect our geriatric rats. The older the rat, the greater the risk. It is this correlation between age and incidence of disease, infirmity etc. that worries me when people discuss attempting to extend the lifespan of domestic rats.