Very long answer to your first question. Here in Portugal, our situation is different because the law is that all cats must be microchipped, including street cats. Even if the colony caregiver asks for no chip, we have to put one in.
I can say it is really helpful! We can easily identify cats who are picked up again for treatment of injuries (sometimes quite a distance from where they were trapped and released) or cats who are found dead. The municipal kennel and I know which of us did the cats too.
If the colony caregiver wants the chip under their name, we are happy to allow this and we don't pass on the cost, many people here cannot afford this. It costs 20-22 € and as a registered animal organisation we receive a government rebate of 7€. We do not have access to the chip system, only vets and municipal kennels do. That's why we pay retail if done at a vet clinic. We also need the chips in order to apply for the government refunds for sterilisation.
There is an observations field on the Portuguese registration system where we ask the clinic to put the name of the street. We can also add there that our charity handled the TNR if chip isn't in our name.
For cat name, I use their colony ID, but if the carer has a name that is also added, eg BAL-01-27 Caramelo (BAL is the village, 01 is the colony, cat no 28, Caramelo is the cat name). The municipal TNR programme doesn't put a cat name, just 'programa CED' and puts the street in the observations field.
Occasionally we'll need to transfer a chip to someone who has decided to adopt a street cat and take it home with them (the last two I did went to the US and Canada). And it's nice to have those happy endings! Some vets charge 3-5€ for the transfer, some do it free - but it has to be done by an authorised vet and they have to put their legal seal sticker on the transfer form.
For TNRs, at surgery the cats are sterilised, ear tipped and chipped. We don't vaccinate because rabies isn't an issue here. They are photographed before release (also very helpful).
For your second question: We would not ear tip if the animal comes in and goes back to the street immediately but it would not be put back without a chip. If we scan it in street and there's no chip, we leave it there. But if we have space, we hold the cat for the legal 15-day period, then chip with first triple vaccine, then offer for adoption. If we don't have space, we'd ask if the municipal kennel has room (they don't have a cattery but can hold small numbers of cats) to avoid leaving the cat in the street. Whether we hold them or not, we advertise them as found on our social channels and a Portuguese lost & found animal site, plus inform vets and municipal kennel.
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Bettina Vine
Animal Health Director
The Kitten Connection
Peniche, Portugal
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