Vitamin C Deficiency and Scurvy in Guinea Pigs

Quick answer

Almost every mammal makes its own vitamin C in the liver. Guinea pigs cannot. They are missing the last enzyme in the pathway, so the vitamin has to arrive in the food, every day, for the whole of the animal's life.

A guinea pig that moves freely, sits square on its feet and comes to the front of the cage is telling you a great deal about its vitamin C status.

When it does not arrive, the body cannot build proper collagen, and collagen holds everything together: blood vessel walls, gums, joints, skin, bone. The result is scurvy, and it looks like pain rather than like a nutritional deficiency, which is why it is so often missed.

• Guinea pigs cannot make vitamin C and store very little, so signs can appear within a couple of weeks on a deficient diet.
• The classic picture is a guinea pig that has become reluctant to move, sits hunched, squeaks when handled, and has a rough coat.
• Partial deficiency is far more common than dramatic scurvy, and it shows up as slow healing, recurring infections and a guinea pig that is never quite thriving.
• Vitamin C in the drinking water is the least reliable method there is. It degrades within hours, it changes the taste so animals drink less, and you cannot know what dose went in.
• Rabbit food is not guinea pig food. It contains no added vitamin C, and feeding it is a common route into deficiency.

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Do not treat a painful, reluctant, hunched guinea pig at home with a vitamin supplement and wait to see what happens.

Scurvy looks like several other conditions that need different treatment: sore feet, dental disease, bladder stones, arthritis, spinal injury and infection all produce a guinea pig that will not move and objects to being handled. All of them hurt, and pain relief is part of the treatment in every case. A guinea pig that is off its food and passing fewer droppings is also heading into gut stasis, which kills quickly in this species. That is a same-day veterinary appointment, not a shopping trip.
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Decide in 60 seconds

Why guinea pigs are different

A missing enzyme, not a fussy metabolism.

Most mammals convert glucose to vitamin C through a short chain of reactions in the liver. Guinea pigs lack the enzyme that performs the last step, so the chain stops one reaction short. Humans and other primates have the same gap, which is why guinea pigs became the classic laboratory model for scurvy in the first place.

There is no way around this. No amount of hay, water or sunshine produces vitamin C in a guinea pig.

Collagen is the thing that fails.

Vitamin C is required for the enzymes that modify the amino acids proline and lysine inside a newly built collagen molecule. That modification is what allows three collagen strands to wind into a stable triple helix.

Without it, the body assembles collagen that falls apart. Since collagen is the scaffolding of blood vessel walls, gum tissue, tendon, cartilage, bone matrix and skin, everything made of it becomes weak at once.

That is why scurvy is such a scattered-looking disease. Bleeding, sore joints, loose teeth, poor healing and rough coat are not five separate problems. They are one problem showing up in five tissues.

Stores run out fast.

Guinea pigs hold only a small reserve. A diet that suddenly loses its vitamin C, for example when a bag of pellets has been open in a warm kitchen for months, can produce clinical signs within a few weeks rather than a few years.

Illness raises the requirement and lowers the intake.

A guinea pig with a respiratory infection or a dental problem needs more vitamin C and is eating less of everything. This is why vets so often supplement vitamin C alongside whatever else they are treating.

What to feed

Fresh food offered in the same place at the same time each day makes it obvious when a guinea pig has stopped eating it.

Unlimited grass hay, always.

Timothy, meadow, orchard or another grass hay should make up the bulk of the diet. It contains no meaningful vitamin C, but it is what keeps the continuously growing teeth worn down and the gut moving, and dental disease is itself a route into deficiency because a sore mouth stops an animal eating vegetables.

Guinea pig pellets with added vitamin C.

A plain, uniform pellet formulated for guinea pigs, fed as a measured daily portion rather than free choice. It must say guinea pig on it. Rabbit pellets contain no added vitamin C, and muesli-style mixes let the animal pick out the sugary bits and leave the fortified pellet behind.

Pellets containing a stabilised form of vitamin C hold their potency better than plain ascorbic acid, but nothing holds it indefinitely.

Fresh vegetables every day.

This is the part that actually carries the load in a well fed guinea pig. Sweet peppers are an excellent source and most guinea pigs like them. Leafy greens, broccoli, and fresh herbs such as parsley and coriander are also rich in vitamin C.

Rotate them rather than feeding one thing constantly. Some of the richest sources are also high in calcium or oxalate, which matters in a species prone to bladder stones, so variety protects on both fronts. Keep fruit to very small occasional amounts, because the sugar causes more trouble than the vitamin C is worth.

Offer vegetables fresh and remove anything uneaten. Vitamin C content falls once the food is cut, warmed or left standing.

Storage is part of the diet.

Buy pellets in small bags you will get through quickly. Check for a milling or best-before date rather than assuming. Store them sealed, cool and dark, never in a warm cupboard above a cooker or in a clear tub on a sunny shelf. Discard old stock rather than finishing it.

What healthy looks like

Compare posture week to week. A guinea pig that has started sitting hunched with its weight shifted off a limb has changed for a reason.

Moves freely and easily, runs when startled, popcorns when pleased, and gets up without hesitation.

Sits square on all four feet rather than hunched with the weight shifted backwards.

Coat smooth, flat and glossy, with the animal grooming itself normally.

Eats hay for much of the day and eats vegetables with enthusiasm.

Gums pink and firm, teeth well seated, no blood in the saliva or on the food.

Droppings plentiful, firm, evenly shaped and produced constantly.

Weight stable or rising gently in a growing animal, checked on the same scale each week.

Skin free of bruises and pinpoint red marks, and any small graze heals within a normal timeframe.

Changes that mean act today

Reluctance to move.

The single most characteristic sign. The guinea pig stays in the hide, does not come out for food, and shuffles rather than running.

Crying or squeaking when picked up or handled.

Ribs, joints and long bones are painful in scurvy. Vocalising on being lifted is a pain signal, not temperament.

Swollen or painful joints, or a stiff, straddling gait.

Most obvious in the hind limbs.

Bleeding gums, loose teeth, or reluctance to chew.

Bruising or pinpoint red marks.

Check the inside of the ears, the gums and the thin skin inside the hind legs.

A wound, graze or surgical site that is not closing.

Repeated infections.

A guinea pig that keeps getting respiratory infections or gut upsets is often a guinea pig whose diet is not delivering enough vitamin C.

Any reduction in hay intake or droppings.

This outranks everything else on the list for urgency. Guinea pigs that stop eating develop gut stasis quickly, and that is what kills them, whatever started it.

Poor growth in a young animal, or a sudden decline in a pregnant or nursing sow.

Both have sharply raised requirements.

What the vet does

A vet who sees guinea pigs will examine for pain, check the teeth properly rather than with a glance, feel the joints and long bones, and look for bleeding and bruising. Radiographs, urine testing and blood work separate scurvy from bladder stones, dental disease, arthritis, pododermatitis and injury, which all look similar from the outside.

Treatment for confirmed or strongly suspected deficiency is vitamin C given at a therapeutic dose, by injection or by mouth, calculated by body weight. Improvement is often noticeable within days, which is one reason a vet may start it while other results are pending.

Pain relief matters as much as the vitamin. A guinea pig in pain does not eat, and a guinea pig that does not eat develops gut stasis, so analgesia and assisted feeding are usually part of the plan.

The diet review comes next, and it is the part that prevents a recurrence.

Doses are not given in this article deliberately. The therapeutic amount is far above the maintenance amount, it is calculated on the individual animal's weight, and over-supplementing long term is not harmless. Ask the vet who examined your guinea pig.

The routine that prevents it

What never to do

Do not rely on vitamin drops in the drinking water.

Do not feed rabbit pellets, rabbit muesli, or a food that does not say guinea pig on the packaging.

Do not use a muesli-style mix with visible seeds, flakes and coloured pieces. Selective feeding leaves the fortified pellet in the bowl.

Do not keep a bag of pellets going for months. Vitamin C decays in storage even in a sealed bag.

Do not treat a suspected case at home with a human vitamin C tablet chosen by guesswork. Doses differ enormously, and some human supplements contain other vitamins that are harmful to guinea pigs in the amounts included.

Do not assume a guinea pig that is eating is getting enough, if what it is eating is hay and a stale pellet.

Do not skip vegetables because the pellet is fortified. The pellet is the backup, not the main supply.

Do not feed large amounts of fruit as a vitamin C source. The sugar disrupts the gut and encourages selective feeding.

Do not delay a vet visit for a guinea pig that is hunched, reluctant to move or off its food, on the basis that you have started supplementing.

Do not supplement heavily and indefinitely without advice. More is not better, and a vet can tell you what your animal actually needs.

When to get help

Recovery looks like a guinea pig that rests loosely, gets up without hesitation, and goes back to eating hay for most of the day.

Contact an exotics or small mammal veterinarian the same day for a guinea pig that is reluctant to move, hunched, crying when handled, showing swollen or painful joints, bleeding from the gums, bruising, or eating less hay and passing fewer droppings.

Contact a vet urgently for any guinea pig that has stopped eating altogether, since gut stasis in this species progresses within hours rather than days.

Book an appointment within the week for a rough coat, slow healing, poor growth in a young animal, repeated infections, or a downward weight trend, and say clearly that you want the diet assessed.

Bring your weight log, the exact pellet brand and how long the bag has been open, the list of fresh foods you offer and which ones actually get eaten, any supplement you are using and how you give it, the hay type, the number of guinea pigs sharing the food, and a note of when you first saw the animal moving differently. In this condition the shopping list is most of the history.