It curls in agony big as itself and the star goes out in its eye

I had to take one of my hamsters to the vet to be put down today.

I could leave it at that, but I feel I would reap sympathy that I do not deserve, because I am in fact deeply ashamed of myself.

When I first got my hamsters, I spent quite a lot of time petting them and socialising them, letting them climb on me and occasionally losing them in the innards of the sofa. It soon became obvious to me that, though I had optimistically thought I would be, I'm not really a hamster person; the pets that, for me, are worth having are the ones that can be companions and don't need to live in a cage - cats, dogs, certain parrots, and so on. But, I wanted to enjoy them for what they were, and they were super-cute and fluffy. One, Hermione, was sweet-tempered and friendly, but Lucita tended to bite, and it was harder to motivate myself to handle her.

Then, a few months ago, I was really busy for a while, and I went away, and somehow got out of the habit of handling them every day. As they got less used to being handled, both of them got more likely to bite, and I got less keen to handle them, to the point where I developed an absurd and irrational terror of being bitten by them (irrational because, really, it does hurt, but it's no big deal).

I don't think of myself as being sentimental about animals, but I do feel strongly that if you make yourself responsible for another creature's life you should do your best to treat it well. So I have never neglected my beasts' material needs... but I haven't exactly loved them either.

On Sunday night, I came home to find Hermione looking extremely sick - eyes half-closed, chin wet, sort of trembling and rocking. I looked on the internet to see if I could figure out what was wrong with her, but nothing seemed to fit, and she was so ill that I was sure she would be dead by the morning.

She wasn't. I didn't really think about taking her to the vet, because I have the impression that vets here have very little experience with small animals as most Mexicans simply wouldn't bother treating them, and because I remained convinced that she was at death's door.

This morning, she still wasn't dead. Her eyes were closed, her breathing was laboured, and she was in a kind of pathetic heap in a way a healthy hamster simply wouldn't rest. I realised I had to at least try to help her, even if there didn't seem to be much I could do. I thought I'd try to figure out if she had impacted food stuck in her cheek pouches - the only thing, other than a stroke or something like that, that even vaguely matched her symptoms. And then when I picked her up I saw a huge tumour growing under her belly.

Up until Sunday, I don't believe it was affecting her behaviour - she was feeding and moving quite normally. And I think it would have grown fairly quickly. I also don't think it would have made any practical difference if I had known it was there - she had a smaller tumour on her paw and the vet recommended leaving it unless it began to affect her, and I know that internal tumours in tiny rodents are even more difficult to operate on, even if you know what you're doing. Nonetheless, I feel enormously guilty and ashamed that I didn't even notice it.

Clearly, she was going to die. I cried and watched her try to breath and tried to work out if there was a humane way to kill her. I almost broke her neck, I had my hands in place, only I couldn't work out how to do it and be certain of getting it right - it sounded easier written down. And then I cried some more that I couldn't even do that for her.

Over in my office, I had a bit more clarity - clearly, I should take her to a vet as soon as possible to put an end to her suffering. They might not be very experienced in saving small animals, but there can't be that much room for failure in killing them. So I went back to the guy who had trimmed her claws and looked at the tumour on her paw, and he was incredibly kind. He waited for me and did it in his lunch hour. After the first injection had knocked her out, he lifted her gently and brushed away the sawdust from her fur. He stroked her while she was dying. I just wish there were people I could recommend him to, because he is simply lovely.

He suggested I step outside but I watched him giving her the lethal injection, not feeling like I deserved to be spared. Only a minute or so afterwards, she already felt cold. When I got her home, I trimmed her too-long-again claws, because I am in truth pathetically mawkish and sentimental, and I stroked her beautiful soft fur, and I made myself look at the tumour. This evening, I buried her.

I am fully aware that she was only a hamster and I am not, by any means, devastated. Yet, I've lost relatives - and not relatives I hated or anything - and not shed a tear, but today the tears keep coming back. She was only a hamster, but I took her life into my hands - she did not choose to be mine - and I failed her.

Tomorrow, I am going to buy some thick gloves and start handling Lucita. She doesn't deserve to be abandoned.

And when I find myself neglecting the responsibilities I choose for myself, I'll think of Hermione.