How to tell if a hedgehog is too thin or too fat – the importance of a rounded bottom

Round hedgehog

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.

benny thin

You can see that this hedgehog is underweight for his size. His rear end is tapered and a ‘v-shape’.

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.


Healthy hedgehog with a nice round rear end.

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.


Wild hedgehog that I named ‘Whopper’. Despite being heavy at over 1.3kg, 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.

Why you shouldn’t feed hedgehogs mealworms

Hedgehogs feeding in garden

Like many people, I used to feed dried mealworms to my visiting garden hedgehogs. I used to feed them in moderation but I had no idea quite how bad they were for the health of my spiky friends.

I knew that mealworms were to hedgehogs what sweets are to children. If given the choice, they would live on nothing but this junk food. They are highly addictive and hedgehogs will soon choose to consume nothing else.

What I didn’t know though was that mealworms, and probably also foods like peanut kibble and sunflower hearts, actively strip bones of calcium. This is the likely cause of increasing numbers of hedgehogs coming into hedgehog rescues with metabolic bone disease, including Benjamin who was cared for here last year.

Hedgehogs feeding in garden

I used to feed visiting hedgehogs a mix of kitten biscuits and a few mealworms. Now I’ve cut out the mealworms completely.

Please read the article to find out the full reasons why you shouldn’t feed these foods. A good quality kitten or cat biscuit, water and some meaty cat or dog food (non gravy) is all you need to keep your prickly visitors healthy.

You can also help by making your garden insect friendly to ensure there are plenty of beetles and caterpillars – their favourite natural foods. There is plenty of calcium in the exoskeletons of beetles.

I run a hedgehog rescue in York, England. Like all wildlife rescues my work is entirely self funded. You can find out more about how to support my work here.

Hedgehog with metabolic bone disease


Meet Benjamin. He is very poorly.

Benjamin was admitted to my rescue at only 330g. He has been surviving by eating bird seed over the Winter.

Benjamin has metabolic bone disease. Basically, his bones are very thin due to calcium deficiency. This is why he has problems walking. He will be in a lot of pain – it is like a human who has rickets or osteoporosis.

He was fed on a mix of sunflower hearts, mealworms and hedgehog biscuits but he has been seen picking out his favourite bits and leaving the hedgehog biscuits. This means that he will not have got enough calcium in his diet. Mealworms actively strip bones of calcium and sunflower hearts also have a calcium/phosphorus ratio that is too high.

There is little natural food around at this time of year and so his diet will not have been enriched by natural foods, such as the exoskeletons of beetles, that hedgehogs eat in the summer.


The wild hedgehog diet. They will get calcium from the exoskeletons of beetles

Benjamin is receiving calcium injections and a high calcium diet. He has to be handled very carefully because his bones are so brittle, they can break easily. The thinnest bone is on his front right leg and this is the one that he struggles most to walk on.

It will be a long road to recovery for Benjamin – for the nutrients to build up in his bones. He will also require extensive hydrotherapy to build the strength in his bones and muscles.

As well as metabolic bone disease, he also has a high burden of internal parasites – fluke and roundworm which he also needs to fight but his immunity will be low due to his poor nutrition.

To avoid problems like this, please feed wild hedgehogs only cat/kitten biscuits, meaty cat or dog food (not gravy or fish flavours) or specialist hedgehog food. This diet will contain all the nutrients they need to supplement wild food.

Benjamin’s problems were diagnosed by a vet following an x-ray. It is vital not to self-diagnose or give hedgehogs supplements without a professional diagnosis. Giving too much vitamin D or calcium can cause many problems in wild hedgehogs that do not have metabolic bone disease.

I will keep you posted on his progress.

You can support my hedgehog rescue work at

You can also make a donation here.



What to feed garden hedgehogs

Hedgehogs feeding in the garden

Hedgehog numbers are declining at an alarming rate, with there thought to be less than a million now left in the wild. Supplementary feeding is crucial to help them survive.

What do hedgehogs eat?

It is a myth that hedgehogs solely or mainly eat slugs. Whilst they do occasionally like to get their teeth into a juicy fat slug, they mainly eat insects, including beetles and caterpillars. Hedgehogs are also opportunistic and will eat a wide range of other foods including birds’ eggs and small dead animals like mice.

wild hedgehog diet

wild hedgehog diet

Too many slugs, snails and earthworms are bad for them as they carry lungworm and roundworm which, in large numbers, can cause hedgehogs to become very poorly and die.

One of the best things you can do to help hedgehogs find their favourite food sources is to grow a wide variety of shrubs and plants to attract insects. Also provide plenty of piles of old logs and other hidey holes for beetles.

Providing extra food and water helps to keep hedgehogs fit and healthy and to put on weight for hibernation. It also stops them resorting to worms and slugs. Supplementary feeding is particularly important in the Spring as hedgehogs are emerging hungry from hibernation and in the Autumn to help them get up to weight for Winter. Leave out a shallow bowl of water year round.

NEVER feed hedgehogs bread and milk. They are lactose intolerant and it can make them very ill.

Also avoid dried mealworms, peanut kibble and sunflower hearts. You can find out why here.

Suitable hedgehog foods include:

  • Meaty cat or dog food (they don’t tend to like fish flavours but there is nothing wrong with feeding fish flavour. You can always mix it in with other flavours). I go for loaf varieties.
  • Cat or kitten biscuits
  • Specialist hedgehog food e.g. Spike’s or Ark Wildlife


Watching hedgehogs feeding is a popular pass time for all members of our family, including our cat Alfie!

My hedgehog hospital is entirely self funded. You can support my work by purchasing my handmade silver jewellery or by making a donation.