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Caring for your Guinea Pig by William Love, DVM
Guinea Pigs

Guinea Pigs, also known as “cavies”, are rodents native to South America that are believed to have been domesticated between 1000 and 1500 years ago.  They are active, friendly, and have excellent personalities.  They tend to live 6-8 years with proper husbandry and have very good attitudes when properly socialized and frequently handled.   

Housing and Husbandry 


There are many different cages marketed for guinea pigs.  In general, a single pig requires an enclosure that is at least 2 ft deep and 4 ft long.  More space is absolutely preferred and helps improve you pig’s behavior.  Better cages are at least 30 inches deep and as long as available space will allow. This allows your guinea pig do tear around his house at a full run when he gets excited.  The bottom of the cage should be solid and the sides made of mesh with squares no greater than 1 ½” wide.  Hide boxes at least 6 inches on a side should be provided for each guinea pig in the cage.  Multiple levels are encouraged, but not required.  Guinea pigs do not tend to climb, and therefore open topped cages are acceptable.  The top of open cages should be at least 10 inches above the highest level in the cage.


Aspen chips, wood pulp products (such as CareFresh) or recycled paper products (such as Yesterday’s News) are recommended.  These products are absorptive and easy to clean.  Aspen chips tend to be a bit more expensive than the paper and fiber products, but some owners prefer the wood chip appearance to the other products.  Soft wood chips are not recommended since they often contain cedar and pine wood.  Cedar and pine oils in these woods are irritating and lead to lung irritation and damage.  Corn cob products are also not recommended since they can be ingested and then swell in the stomach, or cause an obstruction.  Leaving the bottom of the cage bare, especially with wire bottom cages is not an acceptable husbandry practice.  These bare bottom cages or bedding not changed frequently enough can lead to infections on the bottom of the guinea pigs feet. 

If a glass sided aquarium/terrarium is used to house your guinea pig, it is important to frequently change the bedding.  Glass sided enclosures have poor ventilation and trap the odors and ammonia from the pig’s droppings in the bottom of the cage.  These chemicals are irritants that can do significant harm to your guinea pig’s respiratory tract.  Dirty bedding or bare wire at the bottom of the cage will likely lead to damage and infection of your pig’s feet.


Timothy hay is the recommended staple diet for guinea pigs.  Timothy, or grass hay, should be available to the guinea pigs at all times.  This hay has the appropriate amount of calcium, fiber, protein and other nutrients.  Alfalfa hay is not recommended as the primary hay source for guinea pigs, since it is too rich in calcium and other nutrients and can lead to obesity and bladder stones. 

Pellets are higher in calories than hay, and are often fed to guinea pigs in addition to timothy hay.  Timothy based pellets are recommended instead of alfalfa based pellets for the same reasons listed above.  Many guinea pigs are simply not active enough to require pellets and do well on hay only.  Guinea pig pellets are recommended over rabbit pellets.  Guinea pig pellets often have vitamin C added when the pellets are milled.  However, check to see what the milling date is (it is often printed on the label) for the pellets.  The vitamin C will not last in the pellets more than 90 days from the milling date. 

Fresh vegetables and greens can be offered to your guinea pig as well.  All produce offered should be washed as if being prepared for people. Fresh greens can be offered, but should be removed after several hours so to prevent them from going bad.  Fruits should be offered in small amounts, since they too are high in sugars and calories.   


Clean water should be available at all times.  Water should be changed frequently.  Daily changes are best, especially if vitamin C is added to the water (see below).  Plastic bottles are recommended instead of metal bottles. 

Cage Mates 

Guinea pigs are often housed together and do well in small groups (four or less).  If your family has multiple guinea pigs in the same cage, you need to make sure they have enough space to move around freely.  Keep the following guidelines for space in mind when housing multiple guinea pigs in the same house:

Number of Pigs

MINIMUM Requirement

Recommended space

Example Dimensions (for recommended space)


7 ½ sq feet

10 ½ sq ft

30” x 50”


10 ½ sq ft

13 sq ft

30” x 62”


13 sq ft

More is better

30” x 76”

Adapted from  

Vitamin C 

Like humans, guinea pigs are unable to produce their own Vitamin C and need daily dietary supplementation to maintain proper health.  Typically, vitamin C is supplied by offering food items naturally high in the vitamin C, vitamin C supplemented pellets, or supplementing water with vitamin C.  Guinea pigs which are deficient in vitamin C may develop signs of pain, poor appetite; limping and other signs (see vitamin C deficiency below). 

It is recommended to supplement vitamin C in food items naturally high in Vitamin C.  Fresh produce from the list below should be offered.  Not all guinea pigs will have a taste for everything on the list, so it’s important to find what your guinea pig likes and feed those items routinely.  Be sure to prepare all produce by thoroughly washing the vegetables as if you were serving them to people.

Foods high in Vitamin C:

  • Leafy greens (kale, parsley, beet greens, chicory, spinach)
  • Red and green peppers
  • Broccoli
  • Tomatoes
  • Kiwi fruit
  • Oranges
  • Other citrus fruits  

If the guinea pigs do not like any of the above products, some guinea pig pellets have vitamin C in them.  However, this vitamin C tends to break down quickly.  Guinea pig pellets that were milled more than 90 days ago will not have enough vitamin C in them to keep your guinea pig healthy.  The milling date is frequently several weeks before the date the pellets are purchased, so check to see when the pellets were milled.  You can also supplement vitamin C in the drinking water.  Vitamin C in the drinking water will only last about 1 day, so the water needs to be changed every day.  Metal and hard water cause the vitamin to break down even faster, so plastic water bottles and soft water are preferred for drinking water. 

Recommended/ Routine Health Care 

New pet exam 

Soon after acquiring a new pet, whether it’s a new dog, cat, guinea pig, rat, bird, lizard, or tortoise, a visit to the veterinarian is always recommended.  Ideally, the visit is within 1-2 weeks of adding a new member to your family.  This visit helps familiarize you with appropriate care of your new pet in addition to making sure that there are no health problems evident with your guinea pigs.  Common points of examination are dental health, activity, listening to the heart and lungs, and evaluation of body condition (is the guinea pig overweight or underweight, etc) 

Annual physical exam 

Similar to the new pet exam, annual visits allow your veterinarian to follow your guinea pigs health through life, answer questions you may have, and possibly detect early signs of disease and therefore treat problems more effectively.

Spay or Neuter 

Spayed and neutered animals live longer, healthier, happier lives.  Females who have been spayed are no longer at risk for uterine infections, difficult births, and uterine or ovarian cancer, and less likely to develop some undesired behaviors, not to mention avoiding unwanted additions to the family in the form of baby guinea pigs.  Neutered males are less likely to develop aggressive or territorial behaviors and are less likely to develop some forms of cancer.  

Common Health Problems 


Guinea pigs, and other rodents, have sensitive respiratory tracts and are prone to developing upper respiratory infections and pneumonia.  Typically, stressed guinea pigs, and young and old guinea pigs are considered to be at risk for respiratory infections.  There are many common bacteria that can cause pneumonia in guinea pigs.  Improper bedding (such as pine or cedar chips) and poor ventilation (especially from solid sided enclosures, such as aquariums) can also lead to severe respiratory problems.  To prevent these problems in your guinea pig, it is important to practice good hygiene: Keep your guinea pig’s cage well ventilated, keep the bedding clean, and be sure to wash your hands before and after handling your pig. 


Guinea pigs occasionally become infected with lice or mites.   Affected pigs are typically itchy and show hair loss along their backs over their chest and abdomen.  Some of these parasites can spread to humans.  These mites and lice are typically treated successfully with anti-parasite drugs prescribed by your veterinarian.  All the guinea pigs in the cage need to be treated at the same time and frequent cleaning of the cage may be necessary to be sure that the parasites are eradicated.


Guinea pigs are also susceptible to ringworm.  Ringworm is a fungus that causes hair loss in discrete areas starting on the head, face, and ears, and then typically spreading to the back of the animal.  These lesions are typically itchy, but not always.  Treatment consists of topical medications, and occasionally oral meds and occasional “dips” to control the fungus.  Guinea pigs can also occasionally carry ringworm with no itching or hair loss.  Ringworm can also be transmitted to humans from guinea pigs and vice versa.  Even guinea pigs without any signs may have ringworm.  If any member of the family is diagnosed with ringworm by your doctor, your guinea pig should make a trip to the veterinarian for an examination and possible treatment. 

Dental Disease 

Guinea pigs and other rodents have teeth that constantly grow throughout their lives.  Normally, the teeth are worn down by chewing on hay, wood, and other hard, fibrous materials.  However, when there is insufficient fiber in the diet, or if trauma or infection damages the jaw, the teeth may wear and align improperly, causing the teeth to over grow.  Animals with overgrown teeth are often painful and reluctant to eat.  These animals with dental problems require their teeth to be trimmed to maintain proper dental health.  Frequently, this will need to be performed at frequent intervals to maintain proper dental health. 

Bladder stones 

Bladder stones are common in guinea pigs, and may be associated with excess calcium in the diet or bladder infection.  These stones are best prevented by feeding timothy or grass hay only and limiting alfalfa in the diet and by maintaining proper hygiene.  

Vitamin C deficiency/Rickets 

Guinea pigs and humans are among the only mammals that cannot produce their own vitamin C and must consume a small amount daily.  Vitamin C is important for immune function, skeletal development, joint health, wound healing, and many other bodily functions.  Insufficient vitamin C in the guinea pig’s diet causes scurvy, just as it does in humans.  Scurvy causes limping, painful joints, poor wound healing, rough hair coat, and poor appetite.  A daily source of vitamin C should be supplied as directed above.

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