Uh oh. Is that blood on your guinea pig bedding? Don't panic yet. Very young piggies often have a brown tint to their pee. Also, urine sometimes can look orange as it dries, due to the oxidation of porphyrins. What has she been eating lately? Certain foods, like beets, can temporarily tint the urine, too.
Still panicking? It was worth a try. The best way to check for the presence of blood (before you can get to a vet), is to put your guinea pig on white towels. You can also feed extra watery veggies like cucumber and put them in an open, sterile container afterward in hopes of collecting a good urine sample. Pour a little hydrogen peroxide on the pee in question. If it bubbles, it suggests there is blood present and you could be dealing with a urinary tract infection (UTI).
Is your guinea pig at risk?
Some guinea pigs are more prone to UTIs than others. Urinary tract infections are more common in females due to their shorter urethras, but the fellas aren't off the hook. Known for being vertically challenged, it's not far fetched some bacteria would find its way up where it doesn't belong due to guinea pigs' bottoms' close proximity to the cage floor.
UTIs are infamous for returning. If your guinea pig gets one, watch them closely for signs of it rearing its head again a few weeks, months, or even years later. Even if no blood is present, a constantly wet bottom/belly and/or squeaking when going to the bathroom is an obvious sign something is up.
Could it be something else?
Blood in the urine - if confirmed it is in fact blood - is never normal. Guinea pigs shouldn't bleed during "that time of the month," either. Blood can, however, be a sign of a serious problem with the reproductive organs, like a uterine infection known as pyometra. Blood and pain when peeing can also be symptoms of dreaded bladder stones.
In most cases, you'll be crossing your fingers at the vet for a UTI diagnosis, as the alternatives often require surgery. Your vet will probably start with a urinalysis to look for blood, bacteria, and white blood cells in the urine. Because the symptoms of bladder stones, interstitial cystitis, and urinary tract infections are so similar, your vet should take an X-ray (two views) to make sure there are no stones present. UTIs and stones can both make a cavy more prone to developing the other, so it's not out of the question she's been hit with a double whammy.
It's definitely a UTI...now what?
Congratulations! First, praise your guinea for her lack of stone formation. Now, let's tackle the problem. Your vet may want to do a urine culture to see what bacteria is causing the infection. Because prey animals hide illness so well and can go downhill quickly, your vet will probably prescribe antibiotics while waiting on results. Bactrim (trimethoprim/sulfamethoxazole) usually works well on bladder infections in guinea pigs and is prescribed as a first means of defense, although there are other safe antibiotic choices.
Symptoms should improve within a few days of starting treatment. If they continue or get worse, ask your vet about switching medications. Even if your guinea pig's symptoms clear up and she's back to her normal self right away, it's important to continue the antibiotics for at least two weeks. Sometimes, it takes more than a month to allow the bladder walls to heal and really knock out the bacteria hiding in there. If the medicine is stopped too soon, the bladder infection is likely to return.
Your vet may also prescribe an anti-inflammatory drug like meloxicam, which will also take care of pain she may be experiencing. Pain control in guinea pigs is super important. Small animals in pain may stop eating, which can cause a host of complications. Eating (especially guinea pig hay) and drinking normally is just as important for a smooth recovery.
She's cured! Are we off the hook?
Most UTIs when treated promptly will clear up without issue, but that doesn't mean they won't return. To lessen the chances of getting future UTIs, keep the cage extra clean and also encourage her to drink as much as possible. Coupled with getting plenty of exercise during floor time, staying hydrated ideally flushes out bacteria before it can hang around too long in the bladder and cause problems.
While it shouldn't be used alone to treat an active bladder infection, you can dilute 100% unsweetened cranberry juice and offer via syringe to prevent UTIs. You can even try offering it in a second water bottle if she likes the taste. A D-mannose supplement may also offer some protection for those pigs prone to chronic urinary tract infections. If your guinea pig is also high-risk due to interstitial cystitis or bladder sludge, a little vegan glucosamine powder offered regularly can soothe irritated bladder walls, discouraging both bacteria and crystals from settling in to multiply. You may also want to talk to your vet about herbs like shilintong.
Learn what's normal - and not - for your guinea pig. Like any problem, urinary tract infections are most easily treated when caught early. And, hay, silver lining...it's not a bladder stone!