Many people feel faint at the sight of blood, so you can be forgiven if seeing blood in your guinea pig’s hutch makes you anxious. Apart from obvious injuries, blood in the urine is one of the most common reasons for this. Today’s article will explain how a vet may go about investigating blood in your guinea pig’s urine, the common causes of bloody urine and their treatments.

Where is the Blood Coming From?

You’re feeding your guinea pig their breakfast when you notice something red in their bedding material. Is this blood? Should you be worried? 

First of all, consider if this red stuff is indeed blood. Was something red spilt nearby? Is any of their food red? Have they not been cleaned out for a while (old litter can turn funny colours if not cleaned regularly)? If you are sure that it is guinea pig blood, ring the vets to let them know; if your guinea pig appears very unwell, it will be an emergency and you should rush them down to the vets. Otherwise, check your guinea pig over and look for any obvious wounds blood may have oozed from. This is especially true if your guinea pig has a housemate and they don’t get on – they may have been fighting. 

Red staining on their bottom will generally indicate that the blood originates from there. If there are no obvious wounds, you should suspect blood in the urine, also called haematuria. Alternatively, if you have a female guinea pig that has not been spayed (neutered), the blood could be originating from her reproductive tract. Guinea pigs do not bleed from their reproductive tracts normally, like some other animals, so this is abnormal. In either case, let your vet know immediately. 

Check your pet's symptoms
Symptom Checker

Investigation at the Vets

Your vet will first ask questions about your guinea pig’s husbandry, such as diet, habitat, exercise, companions, water intake and other important factors. After that, they will examine your guinea pig, look for signs of pain like a hunched over appearance, weigh them and assess how hydrated they are, feel their abdomen for pain, check their rear-end, take their temperature and more.

Further testing includes taking blood and urine samples to look for abnormalities (particularly those related to the kidneys), an ultrasound or radiograph/x-ray to try and visualise any abnormalities, or exploratory surgery. 

Diseases Causing ‘Bloody Urine’


Uroliths, or calculi (the technical term for bladder or kidney stones) are the most common cause of haematuria in guinea pigs. The term “urolith” just means stones, composed of minerals like calcium, that cause irritation and blockages throughout the urinary tract; the kidneys, in either ureter (the tubes that connect the kidneys to the bladder), the bladder itself, the urethra, and the penis in males.

Urolith formation is often dependent on your guinea pig’s diet and urine pH – a diet high in certain minerals means that more minerals are excreted into the kidneys, and different pHs cause some minerals to precipitate (form solids and clump together). Most guinea pigs have alkaline urine, so mainly form calcium stones. Diets that are low in hay and a good variety of veg, as well as high in pellets, are linked to uroliths in guinea pigs. Excessive supplementation of minerals can also increase the risk. Other risk factors include low water intake, poor hygiene, obesity, a lack of exercise, and renal disease or infection. Males and females are equally likely to get uroliths, though they can be more severe in males, as they are more likely to form blockages. 


A guinea pig with uroliths may have blood in the urine, reduced or painful urination (listen for excessive squeaking as they urinate), a hunched over appearance, teeth grinding, weight loss, lethargy, licking or biting around their back end, have a bad smell, dehydration, kidney disease or even death if severe. These signs can progress over days and weeks, or can suddenly appear if there was a sudden blockage.

Treating uroliths usually involves pain relief and fluid therapy, especially if your guinea pig is in a particularly bad way. If the stones are stuck in your guinea pig’s urethra, they can be flushed back into the bladder by a vet. Bladder stones are usually removed via a general anaesthesia and surgery. Stones further up in the ureters or kidneys are more difficult to remove and almost always require surgery. Some severe cases or those with complications can be untreatable.

Preventing uroliths will mostly involve changes in diet and husbandry, depending on the exact cause.


Cystitis is the term for bladder inflammation, though often involves inflammation of the whole urinary tract. It can be sterile inflammation, or caused by a bacterial infection (a UTI). Inflammation or infection can occur due to dirty surroundings, a blood-borne infection, kidney disease, uroliths (stones – see above) and more. Cystitis is more common in females due to their shorter urethra.

The clinical signs of cystitis are very similar to uroliths – differentiating the two usually requires culturing urine, an ultrasound or an x-ray. To make matters more complicated, uroliths can cause cystitis and vice-versa, and both are often present at the same time. 

Treatment usually involves pain relief and antibiotics, as well as fluid therapy to keep the kidneys functioning. If there is an underlying cause, such as uroliths, this must be treated as well. Prevention is much the same as uroliths; improving hygiene and increasing water intake.


There are sadly some cancers that may cause haematuria in guinea pigs. Depending on their location, they may cause difficulties urinating or defaecating, frequent cystitis, other organ disease, and general weight loss, anorexia and pain. Often the signs will progress slowly over weeks and months. Cancer is more common in older guinea pigs, but can occur at any age. 

Depending on the type of cancer, the vet may be able to remove it surgically or offer drugs. However, the prognosis is usually poorer than in larger species like dogs and cats, as cancer in guinea pigs is less well studied. 


Pyometra is a disease seen in entire (non-spayed) female guinea pigs – the guinea pig’s uterus fills with pus because of a bacterial infection. Red discharge is often produced, which mixes with urine when the guinea pig urinates, appearing like haematuria. However, other signs include a swollen abdomen, discharge from the vagina, behavioural changes, issues with reproduction and shock if severe.

Treatment usually involves stabilising the guinea pig on fluids and antibiotics, and then spaying to remove the infected uterus. As a spayed guinea pig cannot get a pyometra, we recommend spaying all guinea pigs who are old enough, particularly if they live with an entire male. 

Cystic Ovary Disease

Cystic ovary disease is another female guinea pig reproductive disease that can sometimes give the appearance of haematuria. During her normal reproductive cycle, a female guinea pig’s ovaries produce follicles that rupture to release eggs ready for fertilisation. Sometimes, they do not burst but grow large and fluid-filled, becoming cysts that cause disease.

The older the guinea pig is, the more likely cysts will form. As well as haematuria, cystic ovary disease can lead to abdominal enlargement, pain, hair loss, reduced fertility, as well as increasing the risk of pyometra. As with pyometras, the best treatment is to spay her. 

Final Thoughts

Haematuria, or blood in the urine, is a shocking sight and always worth contacting the vet for. Many of the most common diseases that cause haematuria are thankfully treatable with veterinary input. Some are even preventable with good diet and husbandry. Talk to your vet if you are concerned your guinea pig may have blood in its urine.

You may also be interested in;

Further Reading: