The following is an extract from a paper presented at an Urban
Animal Management Conference (the full paper is available online at: http://www.farmwide.com.au/nff/vetasscn/confer/uam/proc95/webb.htm).
The desex/replacement technique for controlling
unowned cat populations
This technique has been suggested and used, particularly in Great Britain (Anon 1982), to address the problem of unowned
cat colonies particularly in suburban areas. The technique involves a program of trapping these cats (as they cannot otherwise
be handled), desexing them, and then returning them to the colony (they are not
re-housed due to temperament). The aim is the
control of reproduction within the colony, the presence of the desexed returned cats preventing the entry of new undesexed
cats to the colony. Males have sometimes been vasectomized so that mating effectively takes entire females off season. Desexing also reduces some of the problems caused by
e.g., fighting, spraying.
Although this seems a very sensible and humane approach to the problem there are unfortunately many drawbacks - the most important of these, from our
point of view, being the welfare of these cats. Many years ago, the CPS conducted such
programs throughout the Melbourne area. We no longer do this because of the following welfare problems encountered:
- These colonies are wholly reliant on the ?cat-feeder' for food. Whilst these people
are totally committed to the welfare of their colony, practically we found difficulty
with the continuation of food supply particularly as this needs to be 7 days a week. In
particular, illness or in some cases, the death of the feeder led to the colony starving
for long periods of time. This raises serious welfare considerations for the cats
- After the cats had been trapped once (for desexing) they became ?tray-shy' and
would not re-enter a trap. Thus, if the cats became ill, required routine health care
procedures (e.g., vaccination, worming) or were injured, they could not be caught to
be treated and medicated. Because routine vaccination was realistically impossible,
disease was a significant problem in these colonies. We encountered several cases
where the cat had been involved in a car accident and as a result had a broken leg.
These cats could not be caught until they had become so weak they could be netted.
This also raises serious welfare considerations.
- In the cases where the cat-feeder had for one reason or another been unable to continue maintenance of the colony, it was
very difficult to re-trap these cats for either relocation or euthanasia. Thus, effectively, a colony was without a food source,
and there was no means to address the situation.
It is important to comment that the welfare and quality of life that the cat leads is of paramount importance.
For these colonies of cats, although they were fed and had stopped breeding, they were under constant threat from disease,
car accidents and human persecution and for many their life span was very short. They became totally reliant on their feeder
and if for any reason feeding ceased the threat of starvation quickly became a reality.
In judging the effectiveness of these programs as a technique for controlling unowned
cat populations, we found that overall there was little effect. There were several reasons for this:
- the cats were still present in the area and therefore still caused problems:
- community nuisance;
- threat to owned cats - fighting, disease spread (FIV); and
- threat to wildlife (perhaps more important in Australia than Europe.
- We found that although the initial colony was desexed, new cats did enter the area
and so the process had to be an ongoing one. In particular new entire males, because
of their aggressiveness posed considerable threat to the desexed members of the
- It was necessary to desex the whole colony - if one entire female remained she was
sufficient to regenerate the problem.
- The technique is a costly and labor-intensive process - as a welfare society our
financial resources are limited and as there were serious welfare concerns, it was
decided to apply these resources to more beneficial programs for the overall welfare