Scent Applications

• A number of concentrated, scented oils are natural deterrents to cats. Citrus scents, including lemon, lime and orange, as well as eucalyptus and citronella, are offensive to a cat's nose. Spraying these oils along the top of a fence can help deter cats from walking on it. However, the oils may need to be reapplied after a rain or periodically throughout the season to ensure their potency.
  
  

Tape

• Double-sided sticky tape is an easy method for deterring a cat from walking on a fence. Cats do not like anything that sticks to their paws or fur and therefore will avoid the area at all costs. This method works best on plastic or metal fences and may not adhere well to wood fences. The sticky tape may also require occasional replacement due to buildup of dust, dirt and pests over time, making it less sticky.
  
  

Motion Activated Sprinklers

• A motion activated sprinkler can be placed at a fence's base to deter cats from walking on it. They can also be positioned in the yard to point at the fence and go off whenever it senses a cat walking across the top. Cats have an extreme aversion to water, so getting sprinkled on will easily deter them from using the fence as a personal walking path.
  
  

Foil

• Foil works in two ways. First, it manipulates the light around the area, making the cat unsure of whether or not the fence is a safe place to walk. Secondly, according to Cats of Australia, they do not like to walk on aluminum foil. This may be due to the noise it makes or the texture of the foil if it is crinkled. It can be nailed along the top of the fence to aid in deterring cats.
  
  

Wire or String

• Either a taut wire or string can be strung between small posts on top of the fence. Cats cannot balance around the string and therefore will no longer attempt to walk along the top. Ideally, the wire or string should be 3 to 6 inches high. This height is high enough to prevent the cat from being able to maneuver the area, but not too high so as to allow the cat space beneath the wire to walk.
  
  

Specialized Products

• Small, plastic spike strips also prevent cats from walking on a fence. These plastic strips utilize small plastic spikes or bumps, which cats do not like to walk on. They can easily be nailed to the top of a fence and are also not easily visible, making them ideal for someone who does not wish to detract from their landscaping while in the process of warding away unwanted felines.