Rachel, no insurer can amend the agreed terms and conditions without notifying you and issuing a relevant endorsement or a policy addendum (sp) However, I am quite certain that if an insurer has taken over a book of business they have to continue cover - the price is another issue altogether but this can only increase at renewal
I would imagine that the main issue here is pre-existing conditions and continuation of treatment - it is unlikely that they would be able to amend this in the policy, they can increase excesses but doubt that they can change this aspect - I will stand to be corrected though. TBH I havent come across this scenario in block pet insurance but have in household insurance. In household they have to take on the polices as per the previous contract so if you have been burgled umpteen times and had a £200k subsidence claim whereby no other insurer would touch you, the existing or rather continuing insurer would be obliged to remain on cover - in these circumstances however, it is always better to be with a Broker.
All insurers are different as I am sure you will appreciate - a fresh insurer or rather an actuary working for an insurer will look at various statistics from the claims experience and see if there is any
trend in certain types of dogs and certain types of claims so say for example and in lay terms and very losely
if there has been an increase of 10% in vets fees for cockers as opposed to only a 5% growth of business for cockers then the premium for that type of dog will obviously increase
I have said on previous threads on M&S that the bubble will burst and it appears to have done so. There original prices were extremely low for the comprehensive cover that they provided with the addition of the nil excess.