Cats are territorial creatures. They're particular about marking out their own turf and not always quick to welcome home a new arrival. They also need to know who's boss, and live to a strict social pecking order. Any newcomer that breaks the rules is likely to be put in their place swiftly. So if you're bringing a new cat into a home that already has a resident or two, here are some tips to help make introductions easier.

• When choosing a new cat, it's worth noting that your chances of domestic harmony are greatly increased if one of the cats is a kitten or juvenile, and if both cats are neutered. The older the cats, the more intolerant they're likely to have become.
  
  
• Introduce your new cat gradually. Don't try to bring residents face-to-face with a new arrival immediately. When you bring the new cat home, make sure that your resident pet is safely shut away in a room he or she is comfortable with. Bring the new cat into a separate room that will be their home for a settling in period, with his or her own food and water bowls and a litter tray.
  
  
• Once your new cat is settled, you can allow the resident out, letting him or her smell your hands and clothing while talking softly and offering a reward. While your new pet is acclimatising, remember not to neglect your other cat. Stick to its normal routine, otherwise he or she will become upset. Meanwhile keep the new cat in its safe room. How long this separation lasts will depend on the reaction of both cats.
  
  
• Get your resident cat used to the smell of their new companion. During the first few days mix your newcomer's smell with that of the household. Swap feeding bowls and bedding, slowly, over the first week. If either cat reacts badly to the scent, quickly associate it with a positive experience, like a tasty treat.
  
  
• Once both cats appear comfortable with the other's scent you can allow them to explore each other's territory - at different times, still not letting them come face-to-face. Finally, when both cats seem relaxed in the other's area, it's time to start formal introductions.
  
  
• The best time for a first meeting is at mealtime. Put their bowls in the same room - but quite separate. The desire for food will probably override suspicion. Don't force them to approach each other, and allow plenty room for them to keep apart if they wish. Expect a certain amount of staring, hissing and 'making myself big' body language as they work out hierarchy. This is normal. But have a blanket ready just in case you need to stop a fight. Should there be any violent reaction, separate them immediately and go back a step.
  
  
• Separate your cats immediately after feeding. At subsequent feeds you can leave them together for progressively longer periods until they become relaxed in each other's presence. Slowly your resident cat will associate the company of the new pet with their favourite food. Share your time equally with the cats so that your scent is also integrated with theirs, and there's no perceived favouritism.

If your cats are consistently aggressive, you could speak to your vet about medication. This may help calm the cats while you begin introductions again. But keep in mind that some feline personalities just don't mix, in which case you should ultimately consider rehoming the cat you were hoping to introduce.