Did you know urinary stones (otherwise known as uroliths) are a very common condition in guinea pigs, and can become life threatening?! 

Read on to find out all you need to know about urinary stones in guinea pigs. 

HOW ARE URINARY STONES FORMED? 

Most urinary stones are formed from excess calcium in the body. Calcium excretion through the urine is a normal process for guinea pigs, however when there becomes too much calcium (usually from high levels of ingestion through the diet), the excess calcium begins to sediment in the kidneys and bladder, forming what we know as 'sludge'. 

This 'sludge' has a very gritty sand-like texture, and can be dense, heavy, and difficult for the body to excrete. Sometimes this sludge will stick together forming small stones - known as uroliths. These uroliths can continue to get bigger and bigger, and in some cases can get very large! 

WHAT HAPPENS WHEN URINARY STONES FORM? HOW DOES IT BECOME LIFE THREATENING? 

Urinary stones can form anywhere along the urinary tract, including the kidneys, ureters, bladder and urethra. 

These stones can be very painful for the guinea pigs. They cause a lot of pain and localised inflammation as they travel down the narrow passage of the ureters and urethra, and can move around inside the bladder irritating the bladder wall. This can also cause bleeding, which people often notice in the urine. 

Uroliths become life threatening when they either cause so much pain the guinea pig stops eating or behaving normally; resulting in gut stasis, dental disease, pododermatitis and other health conditions, or when the stones cause a urinary obstruction by blocking either the ureters or urethra and not allowing urine to pass through. If this occurs it becomes an emergency and veterinary care is required immediately. 

WHAT ARE THE SIGNS OF URINARY STONES? 

The most common sign people tend to notice is RED URINE. If urinary stones are involved the red tinge is caused by blood in the urine. It is important to note however that guinea pigs can also get pigmenturia, which is a discolouration of urine caused by eating coloured vegetables such as beets, and is not always blood. 

You might also notice VOCALISATION or DISCOMFORT when urinating, or when touching their abdomen, or ABNORMALITIES WITH URINATION such as small frequent amounts, straining to urinate or dripping urine. 

Due to pain your guinea pig may also have a DECREASED APPETITE or appear LETHARGIC. 

WHAT PREDISPOSES MY GUINEA PIG GETTING URINARY STONES? 

• High Calcium diets, such as lucerne and alfalfa hay. These types of hay should be reserved only for young guinea pigs who are growing, or pregnant guinea pigs who utilise the extra calcium through formation of foetal skeletons and producing milk during lactation. There are also some vegetables that are very high in calcium such as spinach, parsley and kale, and should be fed only a few times a week. 
• Not drinking enough water is another common cause. If your guinea pig is not drinking enough or does not have constant access to clean, fresh water, the filtration by the kidneys is reduced, and also results in less 'flushing' of the urinary tract to remove the excess calcium. 
• Urinary tract infections can increase the risk of urinary stone formation. Guinea pigs with UTI's will display similar signs to those with urinary stones and a vet visit is warranted. 
• Obesity, Inactivity and pain from other conditions 
• Kidney disease 

HOW ARE URINARY STONES TREATED? 

If you suspect your guinea pig has urinary stones, or you have noticed any changes with their behaviour or urination, a vet visit is always recommended.

Pain relief is one of the most important modes of treatment, as pain in guinea pigs can lead to many other health conditions such as gut stasis, dental disease and bumblefoot. Your veterinarian will provide your guinea pig with adequate analgesia to make them comfortable. 

Your veterinarian will most likely perform some tests on a urine sample, take blood to assess kidney function and other body organs, and perform imaging such as an xray or ultrasound to help diagnose the condition. 

Image credit: Exotic Vet Clinic 

If your guinea pigs have tiny stones or sludge, your vet may be able to flush the urinary tract with catheterisation under sedation or an anaesthetic. If larger stones are present your guinea pig may require surgery, where they undergo a full general anaesthetic and the stones are removed directly from the bladder through a procedure called a cystotomy. 

Feeding a balanced diet is also an important part of treatment. Limiting the amount of HIGH calcium vegetables to only a few times a week can reduce the likelihood of urinary stone formation. It is NOT recommended to remove these foods completely as calcium along with other nutrients such as Vitamin C are an important part of a guinea pigs diet, and balance and variety is key. You can find many resources online outlining the calcium and vitamin C content of different fruits and vegetables.