How can you tell if a hedgehog is a healthy weight? Thin underweight hedgehogs are likely to be sick and will need specialist treatment.
Hedgehogs being kept in captivity (because they have been sick or were too small to survive hibernation) can also get too fat. For optimum health and survival chances, it is important that hedgehogs are neither too thin or too fat.
Hedgehogs need to be over 650g to have a good chance of surviving hibernation but, like in people, the right weight depends on their size and will vary between individual hedgehogs.
Firstly, whatever its weight, any hedgehog found out in the day is likely to be poorly. This is unusual behaviour for a nocturnal animal and is usually a warning that something is wrong. Always seek advice from a hedgehog rescue.
You can tell if a hedgehog is too thin by holding it on its back (wearing thick gloves) and looking at its rear end. A hedgehog that is underweight for its size will have a tapered ‘v-shaped’ rear end like in the picture above. It may also appear ‘baggy’. A healthy hedgehog should have a nice firm rounded end like in the picture below.
You can read more about the importance of the size/weight ratio here.
Being too fat can also cause problems. If a hedgehog gets so fat that it cannot curl up fully into a ball, it will be vulnerable to predation and other problems. Sadly, it is not unknown for hedgehogs that have been kept in captivity for Winter to end up being too fat. Fed on a high fat diet (especially meaty dog or cat food), if the carer does not carefully monitor the hedgehog’s weight, it can end up so obese that it cannot fully curl up into a ball. You can read about an obese wild hedgehog here.
It is much easier to prevent this happening than to put the hedgehog on a diet. It can take many weeks for the hedgehog to lose the weight and they will get stressed being kept in captivity for so long. This in itself can cause more problems. Ringworm, for example, is often triggered by stress, along with the bacterial infection Coccidiosis.
If a hedgehog in captivity is getting so fat that it can no longer fully curl, its food needs to be restricted until it starts losing weight.
This is also where the size/weight ratio is important. For some hedgehogs, 900g may be too fat. For others, they could be well over 1kg and still the right size for their weight. Being able to curl fully into a ball is critical.
The picture below is of a wild hedgehog from my garden. This weight would be too heavy for some hedgehogs but you can see that he can still fully curl into a tight ball.
The importance of making sure the hedgehog is a healthy weight means you should always seek guidance from an expert wildlife rescue if you are considering looking after a hedgehog. A thin, underweight hedgehog is likely to be very sick and in need of urgent specialist treatment.
I run a hedgehog rescue in York, England. My work is entirely self-funded. You can find out more about my work here and also how to support it. I also make silver jewellery to raise funds for my hedgehog hospital and you can visit my shop here.