Many new owners do not realize how sensitive guinea pigs are until health problems appear. As their size may suggest, guinea pigs are ‘delicate’ animals that can develop an illness even from the most minor mistake.
Their health can change quickly without any notice. A problem that is only worse as guinea pigs intentionally hide anything that may be wrong to them as a result of their prey nature.
That is why, in addition to knowing the ‘warning signs,’ it is also good to understand the most common illness a guinea pig can have, no matter how brief that understanding is.
This guide will go over the most common guinea pig illnesses that may develop over a period of time. It will contain explanations of each illness, symptoms, as well as its causes.
It is, however, not a replacement for a veterinarian’s advice. Remember to always consult with a veterinarian regarding the health of your pet.
To learn about the warning signs, refer to this guide here: [Sick Guinea Pig: Warning Signs & When to See a Vet].
Common Guinea Pig Illnesses
While the same illness may look different from one guinea pig to another, changes in behavior are a consistent red flag. Understanding your pet and paying attention to any unusual changes is the best way to identify an illness before it progresses further.
These are all the general prognosis of each illness.
Dental Problems
Dental issues are exceedingly common in guinea pigs because their teeth are always growing. A guinea pig must have a high fiber diet consisting of hay to trim and maintain their teeth.
Hay should be the majority of a guinea pig’s daily diet, specifically around 80% and roughly around the size of their body. It is crucial to your guinea pig’s developing healthy teeth that they are worn down naturally. In addition to hay, providing chew toys works to file down teeth.
The majority of dental issues are caused by a poor diet.
Malocclusion (Misaligned Teeth)
This occurs when the upper and lower teeth do not meet properly during chewing; the teeth become misaligned, and their abnormal position can cut into the tongue or cheeks, causing pain while eating and excessive drooling.
As the condition worsens, the guinea pig may begin avoiding harder foods or refuse food entirely.
This disease is also genetic.
Overgrown Teeth
The overgrowth of teeth that have not been worn down properly. The teeth grow too long, creating sharp points known as “spurs” that cut into the cheeks and tongue.
Stomach & Digestion Problems
Guinea pigs are known for having extremely sensitive guts that rely heavily on a delicate diet.
Even small disruptions can quickly lead to serious problems, and digestive issues in guinea pigs are often more immediately life-threatening than other common health concerns. Their guts are so fragile, anything that alters normal digestion, whether it is changes in diet or stress, can have serious consequences
Diarrhea
Loose, watery, and smelly droppings. It will be misshapen and sticky. Droppings may stick to the fur around the rear, sometimes accompanied by a strong odor.
Diarrhea is often caused by a dietary imbalance. An excess amount of water-based foods such as lettuce or celery are often the cause.
Other factors like stress or bacterial/parasitic infections can also disrupt a guinea pig’s digestive system.
Diarrhea can quickly grow into a serious issue if it persists. The loss of water intake can result in severe dehydration and lethargy.
Fecal Impaction
When feces remain stuck within the anus. The guinea pig will be unable to release it, causing the feces to continue building up.
Any food they eat will accumulate within the stomach and cause painful bloating that could lead to a rupture.
The guinea pig will stop pooping; although there may be diarrhea as the liquid passes through the solid obstruction.
This can be the result of weakened anal muscles from age or an improper diet, creating hard and dry stool that is difficult to pass.
GI Stasis
When a guinea pig stops eating, their digestive system stops at a standstill. Their digestive systems need new food to push older food through the digestive tract. When there is no more new food, the older food remains within the gut.
GI Stasis is a very life-threatening condition that can rapidly result in death.
Respiratory Infections
The lungs of a guinea pig are easily irritated by their environment. With a sensitive respiratory system, guinea pigs rely almost entirely on nasal breathing.
Once their nose is irritated or blocked, they can deteriorate quickly. A guinea pig can not breathe through their mouth easily, and with small airways, even a small blockage can be life-threatening.
A blockage can result from an assortment of factors. Everyday irritants like dust, strong smells, and poor ventilation can inflame the passages. Bacterial and viral infections invade the nasal passages.
Poor environments are one of the biggest cause of respiratory infections. However, infections can still occur in clean environments should a guinea pig be exposed to sick animals or certain pathogens.
Tip: Mouth breathing indicates severe respiratory distress
Pneumonia
A lung infection that inflame the airways and impede breathing. Pneumonia causes fluid to buildup within the lungs, reducing the amount of space for air to circulate.
Pneumonia is most frequently caused by a bacterial infection. It is life-threatening.
Upper Respiratory Infections (URIs)
These include infections of the nose, throat, and upper airways. Upper Respiratory Infections are typically caused by bacteria such as Bordetella or Streptococcus. These bacteria are triggered through drafts and poor ventilation.
Symptoms include sneezing, nasal discharge, watery eyes, and reduced activity.
Nutritional & Deficiency-Related Illnesses
The food a guinea pig eats must be nutritionally balanced to support their health.
Scurvy
Guinea pigs rely on their diet for their vitamin C intake. They are unable to produce their own vitamin C. This vitamin is essential in supporting the immune system and forming collagen.
A lack of vitamin C is known as Vitamin C Deficiency or “Scurvy.”
Scurvy is a disease that weakens the body over time. Early symptoms include lethargy, rough coat, reluctance to move, and swollen or painful joints. As the condition progresses, the symptoms worsen. Can become fatal if untreated.
Urinary Tract Issues
Urinary problems are common in guinea pigs, particularly as they age. These issues can range from painful infections to dangerous blockages that require immediate veterinary care.
Bladder Stones
When an excess amount of calcium is consumed, there is a risk of the formation of bladder stones.
Calcium is essential and safe for guinea pigs to consume, but excessive amounts can cause it to crystallize and form stones in the bladder. These stones interfere with normal urination and, in severe cases, can completely block the urinary tract.
The main source of calcium is vegetables. Always check its calcium content.
UTIs
Bacterial infections of the urinary tract. UTIs cause inflammation and pain during urination. Female guinea pigs are more susceptible due to their shorter urethras.
Reproductive Issues
Female guinea pigs are particularly susceptible to reproductive health problems, especially as they age. Many of these conditions require veterinary intervention and, in some cases, surgical treatment.
Dystocia (Difficult Birth)
When a pregnant guinea pig is unable to deliver her babies naturally. This is a life-threatening emergency for both the mother and babies.
Dystocia is most common in guinea pigs bred for the first time after six months of age. The pelvic bones fuse around this age, making it difficult or impossible for babies to pass through the birth canal
Ovarian Cysts
Fluid-filled sacs that develop on the ovaries. Ovarian cysts are extremely common in female guinea pigs, particularly as they age past two years.
Most cysts are benign, but they can grow very large and cause pain, discomfort, and behavioral changes. Affected guinea pigs may show signs of hair loss on the flanks, increased mounting behavior toward cage mates, or discomfort when handled around the abdomen.
In severe cases, large cysts can press on surrounding organs and cause complications. Treatment options include hormonal therapy to shrink the cysts or surgical removal (spaying). Spaying is the only permanent solution and also eliminates the risk of future cysts.
Skin, Feet & Parasitic Conditions
External parasites and foot problems are among the most common yet preventable conditions in guinea pigs. These issues often result from poor cage hygiene or unsuitable bedding.
Bumblefoot
A bacterial infection of the feet that causes swelling, sores, and inflammation. Bumblefoot develops when constant pressure or irritation damages the skin on the bottom of the feet, allowing bacteria to enter.
The condition is most common in guinea pigs kept on wire flooring, rough surfaces, or in dirty cages where urine-soaked bedding irritates the skin. Overweight guinea pigs are also at higher risk due to increased pressure on their feet.
Parasites
Guinea pigs can be affected by several types of external parasites, including mites, lice, and fungal infections like ringworm.
Mites are microscopic parasites that burrow into the skin, causing intense itching. Affected guinea pigs will scratch constantly, sometimes to the point of injuring themselves.
Lice are visible to the naked eye and appear as small, moving specks in the fur. They cause itching and can lead to hair loss and skin irritation, though they are less painful than mites.
Ringworm is a fungal infection that causes circular patches of hair loss, often with crusty or flaky skin. It is contagious to other guinea pigs and humans.
Related Guides:
[Guinea Pig Cage Cleaning Guide (Complete Schedule & Tips)]
[Complete Guinea Pig Diet Guide (2025): Hay, Pellets & Nutrition]