I took out a policy with helpucover in 2009. Although it was more expensive than other insurance companies, I wanted an insurance company that gave me long term security and they advertise that 'If your pet develops a long term chronic illness such as diabetes or an ongoing skin condition, provided it didn't pre-date the policy, this will be covered for the rest of your pet's life.'
In 2011 my dog developed a long term illness and since then the premiums have gone up tremendously. Last year it was £84. and this year £141. and I already now have to pay 25% of the costs.
It works out that I am paying the monthly costs of the treatment to them in policy payments, so actually I am the one covering the cost of the lifetime treatment, not them!