My 2 year old bitch started to cock her leg and scent mark after she was spayed. She also has got quite aggressive with some other dogs when she's on the lead. Shes fine with all the dogs she knew before her op but aggressie with a lot of the new ones we come across(but not all). Can dogs have hormone problems like humans? We are off to the vets next week but was interested if any one else has had problems. Maybe the timing is just a coincidence and its nothing to do with being spayed?

The female hormones tend to have a softening effect, so some already dominant individuals can become more so after spaying. 

All my spayed girls have been more dominant (not aggressive as they are not that way inclined or allowed to be), but that may be coincidence as they have been older fully mature individuals.

So you mean your bitch is being bossier?

She lunges and barks at some other dogs when we are out. Her hackles are up but her tail is wagging? Other dogs she is friendly to.
If I can get her attention I can sit her down and feed her treats until they are past,but some days she is fixated on the other dog.         Its the dogs that the owners allow to come over to her that are the main problem, Im trying to keep her calm and their dogs are right in her space.Can I be rude and say 'please take your dog away from mine'

Of course you can and that is what she is saying to, and you are frustrating her efforts.  sounds like she is a self confident bitch who expects to be treated with due courtesy by dogs she meats.  chances are if she were off lead there would be a bit of stiff legged posturing, until the other dog had acknowledged her superiority.

Chances are also that these dogs are young and likely male?  I have found my girls most often want to put adolescents straight.  They so not hurt them of course, but make it quite clear mate.

As you are not allowing her to sort out the situation really then you have to, and ask the other owner to recall their dog or shoo it away.

For preference if her recall is good and she is not the one to go up to and menace another dog then I would let her sort it out off lead.  If a dog runs up to her and doesn't greet nice and is overbearing or rude she should be allowed to tell it off.

We sometimes cause problems by over controlling canine meetings.

my neutered dog behaves the same way when a strange dog invades his space if he is on lead, i have now come to realise that he doesnt want to meet dogs in this unnatural manner as he is good offlead and although its awkward i have to stop people in their tracks if they appear to be marching over to us.

Onlead dogs can feel trapped and vunrable to attack and will, as others have already said appear to be aggressive.

"Can I be rude and say 'please take your dog away from mine' "

Of course you can, they are being extremely rude letting their dogs come over, it is something that absolutely infuriates me. How do they know your dog isn't kept on a lead  because it bites anyway?! There is a choccy lab un neutered male who always shows excessive interest in my bitch where we walk. The owner always lets him come over without asking me first. He is too keen, and my girl hates him, although she is good with all dogs. I have now asked him to call his dog back several times, but it usually ends with him having to put the dog on the lead as otherwise it won't leave my girl alone. Last time it happened I lost my patience and asked if the dog was like this to all bitches, apparently only 'the ones he likes', so I asked him if he showed the dog or used it at stud, his answer was no. So I suggested he had it neutered or kept it on the lead. He didn't like it, but if his dog got bitten one day, you can guarantee it would be the other persons fault.

Just call over 'can you call your dog back please', although usually they can't. :rolleyes:

I sometimes find it easier to swap my lead to the other dog. If my dog is bothered they'll leave well enough alone anyway and I can bring the other dog back to its owner with a minimum of fuss and stress. Of course you have to be somewhere safe to be off-lead before going that route. :)

> Onlead dogs can feel trapped and vunrable to attack and will, as others have already said appear to be aggressive.

Exactly what I find with my GSP, after multiple attacks over the years - he can't run when on lead, and can't express himself properly, so he has hissy fits to keep other dogs away. Where I don't want to let him off lead (but also obviously not near roads) and he will meet other off lead dogs I have been using a flexi, which means he has some freedom to move round and display body language as he wants, and he's much better with that.  I've given up on getting people to call their dogs back - either they look at me as though I've landed from Mars, or they just can't....

Was your girl spayed recently? Occasionally they can get false pregnancies after spaying, but you'd need to check that with your vet.

She was spayed about a year ago.She started cocking her leg straight after op,dont know if there is a link or just a coincidence