We have a male dog who is neutered. He has always been well socialized and has spent a lot of time with other dogs and gotten along great (both male and female).

We adopted an intact male dog and after a week, things have taken a turn for the worse. My neutered dog starting walking around and posturing with his ears pinned back and his hair standing straight up on his back. Eventually the un neutered male has enough of this and they start fighting. I separate them and then things go back to normal for a period of time. The intact male is always the one to finally strike first but I know it is in reaction to the neutered dogs behavior.

My guess is that the behavior I'm seeing in my neutered dog is his reaction to the fact that the other male is intact.

I have scheduled for the intact male to be neutered this week but my question is, how likely is it that this will improve the situation? Has anyone ever had a neutered dog who is perfectly fine around other neutered dogs but acts up around intact dogs?

I don't want to have to give the new dog back but I fear for my safety as well as both animals safety.

2 Answers 2


According to the ASPCA, some studies have shown a correlation between neutering and decreased aggression, while other studies have shown no effect. They also note that other dogs may detect the high testosterone level of an intact male dog and respond with aggression. If this is what is happening in your case, neutering may help alleviate the problem.

Note that it is not uncommon for dogs to show aggression toward unfamiliar dogs, so perhaps the dogs simply have not had enough time to become used to one another. Issues of territory and dominance could also be contributing to the conflict. The Humane Society has some tips for introducing a new dog to your home, which might be applicable to your situation.

Also, if you adopted from a shelter, consider contacting them for advice on the problem before taking the new dog back.

See also:


I have an unneutered dog who gets reactions from neutered and unneutered males but he does have dominant tendencies and he is very ‘out there’. i.e he likes to be taken notice of though not in an aggressive way, just highly social. I chemically castrated him for a year and did not notice much difference except that he mounted less (this he does normally with other males) and once he submitted to an aggressive dog by rolling onto his back, whereas he does not do this when unneutered. I have had conversations with people who neutered there dogs because of aggressive tendencies who then regretted it because it produced no difference in behaviour and sometimes it became worse, so you may be disappointed in the result if it is purely for this reason.

  • While this is worthwhile information on how neutering affects an intact dog, the question is about how neutering the intact dog will affect the other, already neutered dog.
    – Allison C
    May 28, 2019 at 12:47

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