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The Importance Of Weighing - Ideal Weight / Overweight / Underweight

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Senior Guinea Pig
Nov 4, 2008
Cambs, UK
The importance of regular weighing

Why do I need to weigh?
Keeping track of the weight is an important way to monitor their health. When diagnosing an illness, it can significantly help a vet to know the size and timescale of the weight loss.

How often should I weigh?
Lifelong weekly weight checks are recommended.
Ideally you combine them with an overall check of the body and mouth to make sure that all is well!

It is fine to weigh healthy adults once every two weeks, but no less often; fluctuations would not be monitored as effectively and a sudden drop in weight perhaps not spotted soon enough.

Guinea pigs who are ill and not eating fully should be weighed daily at the same time.

What kind of scales can I use?
Normal kitchen scales work just fine but both mechanical or digital scales will do, as long as they give an accurate reading. Many people find the scales with bowls that sit on top to be ideal, but as long as the pig can fit on the scales, almost any type should be fine! With jumpy pigs you can use a hidey or tunnel.
How To Pick Up And Weigh Your Guinea Pig

What is a healthy weight?
Very young guinea pigs grow quickly for the first 4-6 months at about an average weekly weight gain of 20-30g.
The growth rate is slowing down once they come close to their genetically determined optimal size/weight. Be aware that weight gain and growth happen in bursts.
Don't panic if your new baby is on the small side! As long as it is gaining weight on a weekly basis, most will eventually realise their genetically determined optimal weight and size!

Most guinea pigs reach their adult weight at 9-12 months. Their weight should stabilise, although it is normal for another notable gain to occur a few months later. As with every other species, some are naturally very large while others are far more petite. The generally accepted weight range 800-1500g (900-1300g on average) although some piggies may be perfectly healthy outside these margins. As long as your piggies are eating well, healthy and have a good heft, you should not need to fret about their weight.

Older piggies over 4 years old can gradually lose condition and become bonier. Please still have any weight loss checked by a vet to make sure that it is not due to an underlying health condition, including the back teeth.
Any sudden weight gain in older piggies should also be investigated (water retention).

There can be some seasonal weight fluctuations, especially around the lawn season when piggies can gorge on rich fresh grass or during weather extremes.
Guinea pigs coming from a background of neglect can put on as much as 50g/2 oz of weight per week.
Major weight gain in a pregnant sow usually happens only during the last 2-3 weeks of a 9-10 week pregnancy when there should be usually other signs visible. If you are worried, please open a thread in our pregnancy section (you need to be registered for that).

Checking the 'heft' (weight/size ratio)
'Feeling' the condition of your piggies is still important as some guineas slim down without actually losing weight - a common development as they start to head towards their senior years.

Feeling the heft it is a good way of judging whether your guinea pig is a good weight for his individual size; it complements weighing on the scales as the heft tells you whether the individual weight/size ratio is fine or not.

You always check the heft around the ribcage. Ideally you should be able feel the ribs, but they should not stand out (underweight). If you can't feel any ribs at all, your guinea pig is overweight.


Guidelines for weight loss:
- 30g / 1 oz can simply be the difference between a full or empty bladder and/or tummy
- 50g / 2 oz switch to daily weighing and see your vet if the weight loss is ongoing. Consider starting topping up with syringe feed.
- 100g / 3 oz see a vet as an emergency if the weight loss has happened quickly. If it has happened within 24 hours, it means that a guinea has not eaten or drunk at all and needs urgent hand feed and rehydration in addition to any medical treatment in order to prevent the guts from closing down. Also see a vet promptly if the weight loss has been due to a slow downwards trend.

Complete Syringe Feeding Guide

How to recover lost weight?
Guinea pigs can be slow in regaining weight after a major illness or operation with complications; it takes time for the body to heal and be able to take on nutrients. The older they are, the less likely they are to regain any lost weight, no matter what you try.

Please always use a good, nutritionally hay based balanced diet! If your guinea pig has lost a lot of weight, you can supplement with offering porridge oats, and a little carrot and sweet corn in their daily veg mix, but please do not overdo it and feed fatty/sugary veg exclusively. An unhealthy diet will only lead to further problems.
It can take weeks and months after a major operation or severe illness for the weight to come back.

It is always better to top up a guinea pig with syinge feed or up the amount of dry or mushed up pellets.
Feeding a bit more rich readigrass can also help, unless your guinea pig is prone to bladder problems.
These foods are also not likely to upset a delicate digestion and cause bloating issues.

Overweight and obesity
Very few piggies are actually acutely obese because of their fast metabolism. For that, it needs a long term combination of lack of space and exercise with overfeeding/too many fat sugary treats.

However, vets are concerned about a rise in overweight pet guinea pigs, as the yellow fat around their organs puts them at an increased risk of health problems and complications during operations.

It is normal for guineas to have quite a large double-chin (known as a 'dewlap').

Signs that a guinea may be overweight are a lethargic lifestyle (typically only moving to get some food, and then shuffling back to his favourite sleeping spot!) and a lot of excess fat/flab around the abdomen and around the tops of the legs.
If a piggie is unable to move freely because of overweight, then it urgently needs a diet adjustment!

How to reduce overweight?
If you suspect your guinea pig is overweight, do not put him on a radical diet! Implement any changes gradually.
- Provide unlimited hay (you cannot overfeed it; it should make over 80% of the daily food intake).
- Reduce the amount of pellets you are feeding to 1 tablespoon for an adult guinea pig. Stay off products that contain fat and sugar.
- Limit the amount of vegetables to 50g/1 cupful per piggy per day or even a bit less.
- Cut out all shop treats that contain sugar/honey, fat, seed, nuts or dairy/yoghurt!
- Feed rich readigrass and/or dry forage only in pinches as a very occasional treat.
Here are our tips for a balanced diet: Long Term Balanced General And Special Needs Guinea Pig Diets

How to encourage daily exercise?
Adult and older guinea pigs, as well as overweight ones are usually not running around like mad during run/roaming time; they will have a little sniff and then happily curl up in a favourite corner, so you have to actively encourage them to move.

One way to encourage mobility is to spread the daily servings of fresh veggies all around the exercise area, so the piggy has to search for his favourite foods. You can also feed the pellets singly from different points, so your piggy has to move around to pick them up from you; alternatively, you can sprinkle feed pellets, too!

Lots of toys - blankets, tunnels, balls, newspaper tents, soft toys - will also encourage a guinea pig to take an interest in his surroundings. An absolute minimum of 1 hour exercise time should be offered every day to overweight piggies, ideally more.

Avoid the treat trap!
Piggies are very good at making the best of their cuteness and learn quickly how to scrounge treats out of you.

If your piggies pester you for treats in between their main salads and hay/dry food top-ups, it is worth buying in a few different types of hay to use as treats. However taxing, you need to stay firm and ignore any amount of wheeking, cage gnawing and cold shouldering for a few days until your little monsters have twigged that their behaviour is no longer successful and given up.
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