they emit high frequency sound that animals can hear. The neighbors dog will hear it too, and if close by will probably bark like mad. We decided not to buy one because the effect on the neighbors dog would be a bigger problem than the cat problems.

Oh that was what I was afraid of.

I have had this device for several years to stop the neighbours cat calling and it works brilliantly. At first it wandered though trying to ignore it but now it never comes in at all. They also have a dog that is seemingly unaffected.

The trick is to move them round the garden every couple of weeks, else the cats get used to where they are. Eventually, they assume the whole garden is wired to make a noise and give up and go elsewhere. Not sure how loud the sound is but it never seemd to affect my neighbour's dogs

I've had one in my front garden for years, got fed up of all the local cats using my lawn as a toilet (don't cats bury their mess any more?) It works brilliantly but I agree with Andrewr's comment that they work best if you move them around occasionally. A neighbour's elderly dog was (unfortunately) completely unaffected by the scarer, turned out unaccompanied late at night to 'do her business', I've spotted her on more than one occasion in my garden literally inches from it leaving a nice present for me to clear up the next day. I think older animals (and this includes cats) can suffer hearing loss just like us and then the scarer has less impact. Incidentally, when the cat problem moved to my back garden I tried the scarer there too, but as my daughter kept guinea pigs in a run outside I was very careful to make sure they were not affected. I directed the scarer away from them as far as possible but they didn't seem in the slightest bit bothered by it (mind you they were old and maybe deaf by then too!)

I too have a cat scarer which seems to do the trick - I keep it covering the veg patch - It works - since its been up over a year now I havent had any cats come near - they go elsewhere in the garden which isnt covered by the scarer. Only problem I found was going through the batteries so I invested in an electric one which works great - the kids can hear it also (they dont tend to hang around the corner anymore - not such a bad thing!! and if my kids invite their friends in they just switch if off)

Using the ScareCrow® is easy. Simply attach a standard garden hose to its base, set the ScareCrow® in the ground in the area you want to protect, and then turn on the water. Once you switch the unit on, it is ready to go.

The ScareCrow® uses a combination of sudden noise, unexpected movement, and a startling blast of water to create a memorable and unpleasant experience for the trespasser.

The animal immediately associates this unpleasant experience with the location, and to avoid similar surprises, learns to avoid the area. If an animal chooses to return, the ScareCrow will be waiting.

While a human may flee several steps after activating a ScareCrow®, animals are typically affected to a much greater degree. In most cases they run much farther, and stay away longer. Because the unit only triggers when the animal moves, the ScareCrow®'s behavior is difficult for animals to anticipate, making it a very effective deterrent.

Thanksyou for this information.