Prevention is Easier than Correction
Like everything else in life, it is easier to prevent problems between your new guinea pig and your household Pets than it is to convince them to get along after a bad experience.
The best time to introduce your guinea pig to your household Pets is when they are hungry.
The younger Pets are when they meet each other for the first time, the easier it usually goes. Cats and dogs accept other species more easily when they are in their critical socialization developmental period - for cats before ten weeks of age and for dogs before 16 weeks of age.
In difficult severe cases, the guinea pig-household Pets peace process might takes weeks or longer. Trying to push it too quickly will cause the problem to worsen, instead of improve.
Brokering An Agreement
Ask your self this question, "What can I do to help my household Pets to perceive my guinea pig as the one who makes my life better?"
Think about all the ways you can help your household Pets relax around and accept your guinea pig as an upgrade to the household. And, remember that bribery works!
1. Calm introductions -
Allow your Pet to see you set up your guinea pig's pen and safe room. Be jolly and happy talking to your Pets about the guinea pig's upcoming arrival. Give your Pet treats for calm behavior in the new room and when you are introducing your Pets to the new scents without the guinea pig.
2. Safe room - Allow your guinea pig to adjust to the new pen and "safe room" without the potential stress of other Pets outside of the door for day one.
3. Keep your guinea pig separated
from your household Pets for about a week. Separated means no physical contact or eye contact.
4. Scent introduction. Feed your household Pets on the outside of the guinea pig's room door. If your dog or cat becomes too aroused, in a jolly, relaxed tone, remove the Pet from the guinea pig's door. Do not scold (negative association with guinea pig), simply "change the subject". If your dog likes a ball, bounce the ball. Have a treat ready and ask your dog to sit. For cats, have a treat and toy that your cat likes to chase and use the toy (or treat) to move your cat away.
5. Positive associations.
In addition to sharing meals outside of a door, introduce your guinea pig as a new wonderful addition to your home by preparing some REALLY special treats for your household Pets. Use treats to reward relaxed or friendly postures or simply ignoring the scent of your guinea pig from under the door. Ideally, ask your Pet to "earn" the treats by following an instruction such as "sit".
6. Scent transfer. During this isolation time, you want to introduce your guinea pig and your household Pets to each other by scent only. First, stroke your guinea pig with a wash cloth and place it by your Pet's food bowl. When your Pet is calm with the scented washcloth, you are ready for the next step. Use the wash cloth to stroke your guinea pig, then use the same washcloth to stroke your dog. Use another wash cloth to stroke your dog, then stroke your guinea pig. Be very calm, happy and relaxed during the cloth stroking.
7. Small safe doses of eye contact. When Pets are relaxed around each other's scent, begin small doses of safe eye contact from a distance. Open the door to the guinea pig room with the dog on a tether or on a long-down-stay or in a kennel and cats inside of a kennel (or the guinea pig inside of the kennel). Praise and give treats to guinea pig and Pets for calm, relaxed behaviors. Stop the eye contact session after one to two minutes or before at the first signs of arousal. Your goal is to keep guinea pig and other Pets learning to be calm around each other by rewarding that!
8. Two person stroking. When guinea pig and other Pet is relaxed and calm around each other at a distance, then at a closer distance have two people each with a Pet (guinea pig and other household Pet) on their laps. With control (not allow Pet to escape), stroke the Pets in sight of each other.
9. Getting closer. Each day, move a foot closer together for the stroking sessions. Give the Pets treats during the stroking and praise for calm, relaxed behaviors.
10. Cross petting. When the guinea pig and household Pet can be calm during stroking while the people stroking them (and controlling them) or on the same couch, begin by having one person lean over and stroke the other Pet. Take turns doing this "cross petting" to help the guinea pig and household Pet become more comfortable around each other.
11. Dog close tethering. Once the guinea pig can be in the kennel right next to the dog or cat who loses interest in sniffing and the Pet is unconcerned about the guinea pig during cross petting then you can begin to hold the guinea pig on your lap and have the dog close tethered near you. If you feel confident that you can contain the guinea pig (not allow an escape from your lap), you can allow your cat to free roam.
12. Guinea pig roaming. The next step is to have the dog close-tethered while you let the guinea pig run around. Be RIGHT there with your dog praising all calm responses and able to help your dog accept a friendly approach and greeting by the guinea pig. If the dog gets excited and tries to pull on the tether, you are going too fast. Back up to previous steps.
13. Keep supervising and teaching. Be there to interrupt but not physically punish any dog barking or cat stalking of the guinea pig. Praise the dog and give treats for ignoring the guinea pig or acting relaxed. When you cannot closely supervise, put the guinea pig away in the safe room.
When your guinea pig meets your other Pets, be sure the guinea pig or the other Pets are secured and safe from any potential bad experience. You will keep your dog on leash around the guinea pig until you are 100% confident in the dog's calm, friendly response to the guinea pig.
Dog controls. Teach your dog to be calm and settled on a mat (leashed indoors until reliable). Give your dog something engaging to chew if needed to help teach calm, settled mat behavior. Work with your dog on a reliable "sit-wait" and "down-stay" to help gain verbal control. Avoid any scolding or physical punishment during training. Instead, give your dog something to do to earn praise. Work with your dog just outside the door of your guinea pig's room.
Use rewards. Increase the behaviors you want with food treats, favorite toys and praise.
Positive associations. During these desensitization sessions, give special attention to each household Pet while the guinea pig watches. The goal is for each household Pet to think, "all good things seem to happen when the new guinea pig is nearby."
Be more clear. To help your Pets really focus on your attention and to think of the new guinea pig as a new positive, do not give them any (or very little) attention when around the new guinea pig.
Interrupt any unwanted behaviors or whenever any Pet becomes too aroused.
A tired dog is easier to train. Give enough exercise to tire the dog and release pent up energy and stress so that good behavior is easier during guinea pig introductions.
Dog head collars. If you think your dog will be difficult to calm around the guinea pig, get your dog comfortable wearing a head collar like a "Gentle Leader" in addition to being on leash. If using a head collar for control, you must be sure to use treats to keep your dog's positive association with your new guinea pig.
Cat controls. Before your cat meets your guinea pig, be sure you can engage your cat in play sessions by dragging a string or other toy designed to get the cat to chase. You want a means of distracting your cat away from your guinea pig that is also a positive experience for the cat. Toss in treats during play sessions when your cat pounces on (catches) the prey-like toy. Play with your cat up to 30 minutes daily using prey-like toys get your cat tired and happy. Exercise relieves a lot of tension and helps the cat exercise normal behaviors. Consider harness and leash training your cat for added control.
Using kennels. Use a molded plastic portable kennel as a safe place to confine your guinea pig or your household dog or cat during introductions. First, help the Pet to become comfortable in the kennel. Feed the Pet inside of it for a week or more. Feed meals not "free choice". Throughout the day, place treats and new toys inside of the kennel to help your Pet to think about the kennel as the provider of good things.
Keep your guinea pig in a safe (covered) pen or kennel as you watch how your cat responds to the movement of your guinea pig. Remove your cat for any focused, aroused responses.