Back in May 2013, during the first two weeks of surveys at Las Guacamayas, we were fortunate enough to find a Yucatán cat-eyed snake (Leptodeira frenata).

I had seen a photo of Leptodeira frenata taken at Las Guacamayas, so I knew it was found here, but I had never seen one before. They are a medium sized snake with maximum recorded length of around 70cm.

The genus Leptodeira are widely accepted to be docile creatures and, although they have rear-fangs at the back of the mouth and are mildly venomous, they are not considered dangerous to humans.

Published literature suggests that only mild local swelling results from their bite.

It was also in May 2013 that I was unfortunate enough to be bitten by the above snake on my middle finger, while handling the snake in the field.

At first I was merely surprised as the snake was quite calm in hands and not showing any signs of feeling threatened. I thought it would let go fairly quickly as is normal for a defence response. It soon became clear that this was not going to be the case.

The snake had a very strong hold on my finger. It was about this time that I started to feel a burning sensation in my finger. At this point the snake was carefully removed so not to damage it and placed in a cloth bag. It had been no more the 60 seconds.

What followed over the next 24 hours demonstrates how little we actually know about snake venoms – in particular the toxins of rear-fanged colubrids.

Within 10 minutes my finger had started to swell and was intensely painful. The burning pain and swelling increased during that first night – it was the most intensely painful night of my life. In the light of the next morning we were all shocked to see the swelling had developed into blood blisters covering most of my middle finger and the swelling had almost reached my elbow! It looked more like a viper bite than the mild swelling described in the literature.

Thankfully, over the next few weeks the swelling reduced and my finger (eventually) returned to normal, with no lasting damage done!

Knowing that this reaction had not been recorded for this species, or genus before, we diligently recorded the symptoms and our first aid procedures all the way through. As I said before, we know very little about rear-fanged snake venoms and their effects so this information is important to document.

Excitingly, this case study has been written up into a medical paper, in collaboration with Scott Weinstein who is a specialist in the effects and treatment of snake bites.

This has now been published in Weinstein et al (2014) – click to download .pdf.

Although academically this is all very interesting, and goes to show how little we know about snake venom, it is not an experience I wish to have ever again – once in a lifetime is enough!

– Rowland Griffin

Leptodeira frenata

Unexpected effect of snake bite from Leptodeira.

Leptodeira frenata, Indigo Expeditions

Leptodeira in its natural habitat.



Last updated: 23 March 2018