i also believe that when the top dog becomes sick,and very vunerable,the next in line will try and take over the top dog postion,when our tigger was real ill the next in line zoeybau,kept trying to attack,tigger,since tigger has got better zoey never bothers her,

im really sorry for you,having a decision to make like this,polo himself will let you know when hes had enough,you look in to them eyes and you can see the world,you can see what hes thinking,the love for you and the will for life,when you no longer see this youl know its time ,he will be waiting for you on the bridge dont worry,his will to go on is strong,so is the will to go,deccy you yourself will know when that time is right,and im sending you big heart felt hugs,and arms of strenght to help you when the time nears.xx

Thanks to everyone who replied and for your support. The problem is, although everything was back to normal within minutes, there is no knowing when the next incident will be or how severe. Luckily, they are supervised pretty well constantly being in doggy daycare while I am at work, the kennel owner is very experienced and we each have an emergency dose of rectal valium just in case.
I can't afford to have Polo scanned to see what is happening as it is €1,500 and a trip to Dublin, and money is tight.
For the time being, he will be watched very closely. I spent most of last night wrapped around him while he mumbled appreciatively.

Aww Deccy, all you can do then, is what you are doing, and I know Polo is in the best hands...you will know yourself if/when you need to do anything more.
More *hugs*

Oh Gill you poor thing. All I can offer is my support to you. As Meganrose has said you will know yourself when the time is coming for Polo and you can't do much more than you already are. Big hugs coming out to you all xx

I am so sorry deccy what a terrible thing to be going threw. I have only had experience with brain tumours in people, and it is a known fact that the patient can suddenly get very bad tempered for no reason and then minutes later be totally normal. I would have thought by other peoples experience this is what is happening, but i am no expert.

My thoughts are with you.

Deccy I really am so sorry to hear about Polo particularly as you lost your lovely girl so recently.

In your situation I would try to keep things as calm and normal as you can for Polo but avoid leaving him alone with the others when you are not there to observe his behaviour.

I have heard of many quiet dogs who develop violent mood swings when they have a brain tumour, one moment calm the next snapping at other dogs or humans, it is quite understandable though for a dog in that situation. xx