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Jane Lefler
Jane Lefler, Animal Behaviorist
Category: Dog Training
Satisfied Customers: 20178
Experience:  Dog breeder/Trainer and Behaviorist 18+ years
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My 5 month old male Chihuahua is aggressive towards his 6 month

Customer Question

My 5 month old male Chihuahua is aggressive towards his 6 month old half brother. He is a bigger Chihuahua and seems to be using his weight. The smaller Chihuahua seems a little fearful now and hides. The aggressive one wants the others food, toys and my attention. Will he grow out of it or do I need to get help. I am worried that he will seriously hurt the smaller dog.
Submitted: 4 years ago.
Category: Dog Training
Expert:  Jane Lefler replied 4 years ago.
Hi JaCustomer,

My name is Jane. I've professionally worked with animals for over 16 years dealing with both health and behavioral issues. I have over 14,000 satisfied customers. It will be my pleasure to work with you today.

I need to ask for some additional information. Once I receive your responses, it will likely take 30-40 minutes to type my response. I hope you can be patient.

Are either of them neutered?
Have you done any obedience training with them yet?
Do you allow them on the furniture?

I do have some commitments tomorrow so if I don't receive your response until then, I will answer as soon as I am back. I hope this is acceptable.
Customer: replied 4 years ago.

They are both booked in to be neutered on 9th August,


I have done a 6 week puppy training class with them. Interesting enough Milo is a cowering baby out in public but aggressive at home. He was too scared to really benefit from the training.


I do allow them on the sofa but only when I am home. Milo can now jump up but Jasper is still tiny so can't. Neither of them are allowed upstairs and have never slept on my bed.

Expert:  Jane Lefler replied 4 years ago.

Thanks for the additional information. It is helpful. Unfortunately, the site does not allow me to make clickable links to supporting websites at this time. So where there is a site listed, you may have to copy that to a separate browser window or tab to access the data there. Dogs are pack animals and there are dominant individuals and submissive ones. The normal order is most dominant intact dog, then most dominant female, then other intact males and females. After that would be your neutered and spayed animals.

Milo, while being younger, is larger and feels that he is more suited to be the boss of the dogs. They are rapidly approaching sexual maturity and a leader will need to be established. Since they are both puppies coming into adulthood, there is no clear leader. Since there is no clear leader, Milo's size is giving him an advantage even though emotionally he is not quite as mature as Jasper. To help establish himself as the "boss" he is trying to impose his wishes on Jasper.

Since Milo can jump up on the couch, that also helps afford him more status since the boss usually sits or lays higher up. I hate to tell you this but it will likely get worse before getting any better unless you take some steps to stop this.

In your home he is comfortable and know that the only other dog around is Jasper and Jasper is smaller and less dominant than Milo is. Outside of the house, Milo knows there are much larger dogs and still being a puppy, those dogs would tend to worry him a bit. However, when he becomes an adult, his size may not stop his dominance. Many chihuahua males don't seem to know they are small. My 7 pound chihuahua dominates my 150 pound male rottie. This probably wouldn't normally happen except that the rottie was a puppy when the chihuahua was an adult, so the chi established his "dominance" at an early age.

There are some things you can do to help the situation. I'm going to want you to start daily training sessions with each dog. This isn't to teach them commands but more to keep them submissive to you. Each time your dog obeys your command, it makes him a little more submissive even if he is doing it for the treats.

The following site is helpful if you need some help with how to train. Be sure and click on the link to the page on obedience at the bottom. and links on subsequent pages leading to detailed instructions.

Training works best if you train at least 30 minutes a day (two 15 minute sessions). I would start making your dog work via the Nothing in life is free program (NILF). It also helps your dogs see you as the boss which is important in this case. It is outlined below.

Since Milo is able to get on the furniture, I recommend you not let him. Dogs that are allowed on furniture (even if put on the furniture) tend to feel that since they are elevated to your level or higher if on your lap, they mentally feel elevated as well in the pack order and thus are the boss. Keeping them on the floor can help lower them mentally back to a submissive position in the pack. So the first thing is to not allow him higher that the humans or even on the same level. In addition, humans shouldn't be on the floor with him either. A small short stool is enough to keep them higher than the dog when petting the dog. Attach a leash and use it to remove him from the furniture. Give a correction in the form of a quick tug and firm "NO" when he attempts to get on and a treat when he starts not trying to get on the furniture. Thus you are providing negative reinforcement for the getting on the furniture and positive reinforcement for the desired behavior (not attempting to get on the furniture).

If Milo was my dog, I would get him back into a class for the socialization if nothing else. Now there is another exercise you will need to do to stop the behavior. All the training helps you be seen as the boss, but you also have to make it clear that you do not approve of the aggression. Both dogs should be leashed and if one dog even looks at the other dog, a correction should be done. Any sign of aggression including a prolonged look, hair raised on the shoulders, a growl or even a stiff legged walk, should be corrected. A correction is a quick tug of the leash and a firm low toned "NO". Once you have done this couple of times, you should notice the dogs ignoring each other. When that happens, you will want to reward them for the desired behavior. Again, use tasty treats like the hot dog slices. This teaches the dogs that you WILL not tolerate fighting in YOUR pack.

Since Milo is likely to remain the "boss" of the dogs, be sure that his food bowl goes down first, he gets a toy before jasper and you show Milo attention first. This strengthens Milo's position and if his position is clear when he is mature, the reprimands by Milo aimed at Jasper should lessen even without other training. If Jasper clearly acknowledges Milo as the boss, then the scuffles should stop when they are adults.

I think you will be pleasantly surprised at how well your dog does with training. Dogs like knowing what is expected of them and they love the little paper thin slices of hotdogs that I use for treats while training. Give this a try and see how it works for you.

In addition, if the situation is not improving using the techniques I've provided, you may have to consult a professional behaviorist. You can usually find a behaviorist by asking your Vet for a recommendation or you may be able to find one using the following site.

I hope this information is helpful to you and you are satisfied with my response. If you would like any additional information or have more questions please don’t hesitate to press the reply to expert or continue conversation button so I can address any issues you still have .

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