Help with the dosage of doxycycline for cats please

[Stepheow]

My old cat's on Doxycycline and Famciclovir for his eye and respiratory problems.
It lasts for 3 months.I think it's maybe chronic.
We can't do PCR for cats.
Could anyone tell me the right dose for a cat according to his weight?
Thanks

[CML2014]

Hi Steph,
Never take a  persons recommendation for dosage of meds. This is something only your vet can prescribe and that is because he will now what antibiotic is right for your particular condition. The dosage should be given by the vet only. It could be a continuation of his prior illness or it could be something totally different. This needs an expert.
Please see your vet and let us know hoe you make out, K?

CML

[Stepheow]

We've already visited quite a few vets in our city. And my cat's been misdiagnosed for 3 months! They said we can never find out if he has Chlamydophila and Mycoplasma. We can't do PCR in our country.The vet who prescript it to us said: 0.25mg per day. And the vet who gave it to us said: 0.5mg per day. And they didn't even ask the weight of my cat. And if it's chlamydophila for example, it needs 30 days to cure in my opinion. And the vet said: try with this medication for 5 days...and 5 days later, he has no opinion. What a answer! You see the situation in our Country? But I'll never give up to help my cat. And that's why I ask it here. So help me with the dose if you can.