God some of the comments on here are bloody depressing.
One PP suggesting their vet offering a blood test as being "sneaky"? Really?
As a vet who worked in a very low income area for several years the amount of verbal abuse I got for offering medical investigations and suggesting the gold standard of treatment was ridiculous.
Damned if you do, damned if you don't.
Agree with PPs that the crux of the issue is that the NHS is free and people are completely ignorant about the cost of medical care.
OP, if you walked away without paying for the blood test, who exactly would be funding the cost of the needle, syringe, blood vials and the time it took the vet or nurses to take the bloods? Even without the blood test ever being run the clinic would be at a loss. Obviously not the biggest issue here, but something to consider. A vet clinic is a business trying to stay afloat just like any other.
I agree costs need to be discussed before procedures are carried out but surely when the vet starts suggesting a blood test, if they don't mention cost, you ask?
As an aside, I'm no longer working in clinics. Life is too short to put up with the level of stress you experience on a daily basis (thanks to the clients of course, not the animals).