I volunteer for a Chihuahua rescue as their go-to dog trainer. One of the most common issues I hear is trouble with potty training. Unfortunately, Chihuahuas are notorious for being difficult to potty train. This is due to several factors: small size, lenient owners, and lack of crating. Unless you can watch your dog 24/7, crating is something you need to consider when getting ready to potty train.
Here are some steps to follow for successful potty training:1) Contain the dog in a crate (sized small enough for the dog) when the dog cannot be watched. Have the dog sleep in the crate at night instead of on the bed until he gets a good schedule going. Then you can wean him off the crate with a watchful eye.
(Introducing the crate: http://www.humanesociety.org/animals/dogs/tips/crate_training.html)
2) Take him outside 15-25 minutes after he drinks water or eats meals. Make sure you have a regular feeding schedule so that it is easier for you to predict his needs.
3) Celebrate when he goes potty outside. Bring treats with you (depending on the dog, he may prefer lots of affection or playing with a toy instead- it is up to you to figure out his preferences). As soon as he starts going say “good boy” in a calm, happy voice. Once he finishes, through a party! Be excited and show him how happy you are with him. Shower him with his favorite things and lots of praise. Use lots of excitement for the first week of training, then slowly lower your excitement. Always continue to praise him for it through out his life to reinforce this behavior.
4) Set him up to succeed. Don’t wait for him to fail. Take him our frequently and wait outside until he goes potty. Repeat step #3 when he goes potty outside.
Make sure to give him a regular potty schedule so he can learn when to expect to go outside. At the beginning, for the first few weeks, be consistent. Crating is not forever, it is until he learns the rules for being indoors. He has to earn his privileges (like sleeping on the bed)! Be consistent, after a few weeks of consistency, his pottying needs should be on a regular schedule. Keep a good eye on him when you do feel comfortable letting him sleep on the bed. If he has an accident again, go back to crating him for a few more days, repeat as necessary.