Tasmania is an island state of Australia and sheep farming is a major component of Australia’s agricultural industry. The protozoan parasite toxoplasmosis is well known. The domestic and stray cat is the primary host. They shed Toxoplasma gondii oocysts for about eight days in faeces but the oocysts are durable and survive in the environment for a long time. Sheep can be infected with the protozoan but there is a vaccine against toxoplasmosis, which is effective.
Tasmanian sheep farmers are concerned about toxoplasmosis in their sheep because it can cause heavy economic losses due to losses during pregnancy. Pregnancy in sheep can be aborted due to a toxoplasmosis infection. Because of this, some farmers kill the feral cats on their land and controversially they string up their dead bodies on fences and leave them to rot as a statement to the Tasmanian government that they haven’t done enough about feral cat control.
For example, Cindy Brook who lives in Longford has said that she often saw dead cats on fences at her uncle’s farm at Blackwood Creek near Cressy. She says that the cats are killed because some farmers believe that “their [excrement] makes the ewes lose their lambs” (ABC Radio Hobart).
This unpleasant and controversial habit is said to be unhelpful in discussions about how to control feral cats and the impact that they have on sheep farming in Tasmania. It is said that it tends to polarise opinion. This means that animal advocates i.e. those who support animal welfare, regard farmers who do this as cruel and insensitive, at the least, which would tend to provoke a response from the farmers leading to polarised opinions.
Rod Knight, the chief executive of Landcare Tasmania, said that he was both concerned about the problem of feral cats and the habit of killing them and stringing up their bodies on fences. He believes that the incidences of this treatment of feral cats is fairly isolated but it implies cruelty and the debate on feral cats will come down to animal cruelty rather than how to mitigate economic losses by sheep farmers due to their presence (ABC News).
There’s no doubt, based on my research, that toxoplasmosis does present a genuine economic problem to sheep farmers so what can they do about it? They shouldn’t be doing what these Tasmanian farmers are doing which is patently cruel and immoral. It is not illegal apparently because it is happening with impunity. Clearly the law in Tasmania allows it but in the UK these farmers would be prosecuted under the Animal Welfare Act 2006 for animal cruelty. This shows the huge divergence in attitude towards animal welfare across the planet.
The point is that the farmers don’t need to shoot or kill feral cats in anyway possible. Alternatives are available. The most cost-effective strategy would be to vaccinate sheep. There is an effective vaccine available. It induces very good immunity after only one injection according to two studies as reported on the Farm Health Online website. The vaccine lasts several years and doesn’t need a booster every year. Farmers probably don’t take this option for reasons of cost. It is cheaper and more fun to shoot feral cats. Is that correct?
It is believed that the ewes are normally infected with toxoplasmosis when they eat stored food contaminated with cats’ faeces containing oocysts (Farm Health Online). Farmers should intervene by preventing cats depositing faeces containing oocysts onto food that the sheep will eat. I presume this means simply ensuring that the feed is protected from feral and stray cats.
Also, they could ensure that TNR is carried out on their farms. This may be a nuisance to them but it would neuter and spay the cats thereby preventing the population size increasing and ultimately reduce numbers.
Another aspect of management to deal with toxoplasmosis in sheep is that chronically infected ewes are resistant to the effects of toxoplasmosis during pregnancy and therefore young, non-pregnant replacement stock might be exposed to the disease to ensure that when they are pregnant there are no difficulties.
Of course there are difficulties in managing this situation but there are less cruel ways of dealing with it and Tasmanian farmers should understand that humans created feral cats through careless cat ownership and therefore they have a moral obligation to avoid cruelty towards them.