Of all the things we can train our cats, this has to be the number one that will eliminate headaches down the road. Carrier training can begin at any age. You will NOT regret it!!
The best carrier is hard sided, has a front door and attachment clips on the side. The clips allow the carrier lid to be taken off quickly and easily when needed. A good carrier should be large enough for kitty to stand and turn around, yet surround the cat in a den like manner. In other words, it should fit your cat, not be too large or too small.
Having a carrier that breaks down easily makes cleaning a breeze. An easy-remove lid is preferable at vet visits. If your kitty is shy and doesn't easily walk out of the carrier, there is no need for kitty to be dragged out or "dumped" out as some vet offices will unfortunately do. Instead, unclip the sides, remove the lid and cover kitty with a towel to allow hiding. The veterinary staff can easily work around the towel during the exam. This makes for a somewhat low stress visit to the veterinary office. If the covering towel is sprayed with Feliway or a "calming travel" spray prior to the visit (follow directions regarding application times), place it in the carrier with kitty for comfort during travel and while waiting.
Introduction to the carrier
Like many training plans, it is important to introduce kitty to the subject of training (the same would hold for a harness, leash, clippers for nail trims, etc.). When first introducing kitty to the carrier, have the door open and let kitty's curiosity take over. Have treats nearby and feed them to kitty as well as sprinkling them on, in and around the carrier.
Leave the carrier out at all times with the door open. Create an inviting atmosphere by having bedding inside. During the training period, put catnip or treats inside daily to entice kitty to explore and go inside. Do this occasionally even once kitty likes the carrier.
Training kitty to go in the carrier
Kittens are easy to train. Just toss some treats or toys into the carrier and they will happily follow. Start using the cue "get into your carrier" and over time you will have trained your kitten! Be sure to have that positive reinforcement until the behavior is down solid. However, if you want to still give kitty a treat, that is ABSOLUTELY fine!
Many cats will also follow treats into the carrier, especially if you have introduced them to it as described above. The carrier is no threat, so following treats in is nothing to fear. If your cat won't follow the treats in initially, 1) be sure kitty is hungry (cut back on meal portions) and eager for treats, or 2) begin to feed kitty near the carrier. This will further place positive associations with the carrier. Every other day or so, move the food bowl closer to the carrier, eventually moving it just inside and then deeper until kitty is fully in the carrier. During this process, begin to use the cue, "go into your carrier" so kitty will understand that is the behavior you are working toward.
There's more to carrier training than getting inside!
Congratulations, kitty is getting into the carrier! However, closing the door, getting in the car and going for a ride is a different matter.
Closing the Door
The next step is to close the door as kitty is eating treats. When shutting the door, it is important to do so quietly and gently. Close the door fully, then open it right back up. Kitty may have realized what you have done. That's fine, open the door casually, say "release" and if kitty tries to dart, toss treats for kitty to follow. Done this way a few times, kitty will understand that's part of the behavior. If kitty leaves the carrier normally, offer treats once kitty is outside. Give lavish praise with either exit!!!
The Next Steps
The next steps are just as important as getting kitty into the carrier. From closing the door without stress, move on to closing the door and lifting the carrier, put it right back down and open the door (giving treats). Then, practice taking a few steps; then walk to the car and place kitty in the car, but do not crank it up. Then try cranking the car, but don't go anywhere. From there drive down the drive way and back to your parking spot. Now, drive around the block. Progress to driving to the vet office, going inside and placing the carrier on the sign in counter. Work up to having social visits. Continue to do practice runs so kitty doesn't forget the training. Before proceeding through each phase, be sure kitty is comfortable and eager to continue. If kitty is nervous or hesitant at any stage, slow down. It may be necessary to back up a step or so in the training process. Through each stage in the process, always use positive reinforcement (praise and treats).
The culmination of these exercises will desensitize kitty to the carrier and traveling. From here on, kitty will be well trained and comfortable for future car rides. There will be no more fighting with kitty and possibly getting hurt due to kitty's fear.