Recent change in behaviour - seasonal?

Question
Dear Delores

What a wonderful lady you are with all of this troubleshooting! I wonder if perhaps you can help me? I have an English Cocker Spaniel bitch - Lola 22 months old. She is a calm puppy mid energy not over excitable not aggressive - until now?

We have noticed since she was last in season just over 5 weeks agi she has become less tolerant of other dogs,particularly those younger than her. For example she had a fellow cocker 8 months old whom she used to run around the field with and play with their play was so lovely you would think that they were from the same litter.
Then and there was an incident when she seemed to randomly attack her, when we visited their house (second visit -the first was fine and they spent the whole time running around joyfully playing) On this occasion the other dog retaliated and it turned into a scrap. Lolas energy was then up and I sensed her being irrational and behaving really strange.
We continued with our planned day Lola was all the while making funny noises when near or around the other dog, then by the afternoon they were walking alongside each other on a long walk. We returned to the house kept both of the dogs calm and they actually started playing again happily in the garden, no sooner had we said well would you look at them now I have no idea what that was about this morning than suddenly they turned aggressive on each other, they were literally playing one second and scrapping the next?

We have since met out on the regualar walk and the other cocker now cowers down when she sees her and the playfulness they had has gone, its worth noting that the day she attacked the other dog, she was also physically sick and had been touchy with what she does/doesn't eat. Don't get me wrong the two dogs can play each with a ball and thrower while we walk and not bother each other, but all the time I feel it could turn into a voilent situation. Lola has never outwardly charged towards another dog to attack it, far from it if anything she jumos up at me as if to say pick me up pick me up in a more fearful stance, this attack it seems was a reaction to a provoked situation, my confusion is how it came to be?

Just when I thought we were getting somewhere and the dogs have met several times since, although Lola isn't thrilled about seeing the other dog this morning another quite high energy puppy an orange cocker pushed her one step too far and I feel responsible for not taking Lola out of the situation but she bit the puppy and caused a small wound on it's face. Having read a lot online i am lead to believe its bad manners from these younger dogs but I question why this behavior has occurred since it seems Lola was last in season.

We must meet between 2 and 20 dogs on every dog walk and she has only ever had aggression with these 2 but the source of the behaviour concerns me as I don't understand it and cannot predict it? She isn't interested in the dogs we meet, again once she would have started playful behaviour but doesn't anymore.

I took her back to my Mum (her breeder) and put her back into the pack of 6 dogs to see how she behaved and as I expected she was put in her place by her peers, I thought perhaps this might help correct her behavior but it seems not to have helped.

We have moved house 3 times in the last 18 months and understand this can be unsettling but we are mostly at home working and she gets a great amount of exercise, up to 2 hours some days, she doesn't usually bother with other dogs at all just keeps going forward but seems to have lost her playful side.... yet the other day really surprised me when she met a guide dog puppy around 18 months in training and on its time out and they counded around playing like she always did before, (that has been her only playful/interaction with another dog in the last 5 weeks)

Do you think that this sounds more like a behavioral issue than a potential hormonal problem/illness?

I know its difficult for you to assess as there are potentially lots of intervening factors, she is a good well behaved dog, obedient and well mannered and this change in her behavior really un nerves me?

I would be ever so grateful of your wise comments
Kindest regards
Melanie

Answer
Any time there's a sudden & unexplainable change in behavior/demeanor it's time for a vet visit to rule out any physical causes.

I'd ask if you're breeding her and if not, why isn't she spayed?  Be sure and tell your vet that you connect this to her last heat.