Lethargic Frogs – We suspect Ranavirus Outbreak

Over the last couple of weeks, team members at Everything Dinosaur have observed some strange behaviour in the frog population around our offices.  As many as seven individuals were counted at any one time in the office pond at the height of the spawning season and we logged a record amount of frogspawn laid this year.  However, we have noticed some strange behaviour from the adult frogs.  Three frogs (Common Frog – Rana temporaria) were extremely lethargic, almost in a stupor.  The frogs seemed perfectly healthy but the were very slow to react to any disturbance and almost seemed to be in a trance. 

The first frog, a little thin was moved away from the pond by a team member of Everything Dinosaur and placed in a safe and secure part of the yard, out of harm’s way in case one of the neighbourhood cats discovered it.  The second frog, left the pond but took almost six hours to cross the small courtyard and seek shelter behind some fence panels.  It was raining for much of this time, so the frog remained moist but we were all surprised to see the animal move so slowly and to expose itself to any predation in such a reckless manner.  Some team members commented that this particular frog had a “deathwish”.

At first we put the strange behaviour we had observed down to the fact that the frogs were in poor condition after mating, but the third frog we have been observing is making us question whether or not there is something more serious going on.

This frog, has been observed for the best part of a week now, it barely moves from a small rocky area by the office pond, it is thin and lethargic, not frightened by our approach at all.  It simply does not react.  We think that this lethargy may be the result of viral infection.  We are trying to observe this frog to see if we can spot any red blotches on the skin (erythema) or any bleeding (haemorrhaging), this and the drowsiness and lack of condition could indicate an outbreak of the dreaded Ranavirus.

If this is the case we will report our findings to froglife, the organisation that monitors the UK wild frog population.

Ranavirus was first found in the UK in the early 1980s.  It is most common in south-east England but known from elsewhere in the UK.  This virus could decimate the local population, there is no cure and for all we know if the adult frogs have caught the disease then this may have dangerous implications for the tadpoles in the pond.

We will keep monitoring the situation and if required, we will report this disease outbreak.

Fingers crossed that we have got this wrong.

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