Urinary Tract Infections, Urine Sludge, and Bladder Stones of Rabbits
Rabbits often pass crystals in their urine. This is normal in small amounts. As more crystals are formed and get larger you may notice that there are white to tan crystals forming where your rabbit urinates. If your rabbit is producing a large amount of crystals it may even have these clinging to the fur on its perineum. This condition is often called “urine sludge” and indicates a rabbit has started to have an infection of its bladder, also known as a urinary tract infection (UTI) or cystitis. An experienced rabbit veterinarian needs to evaluate your bunny as soon as possible to determine what treatment is appropropriate.
What causes urine sludge in rabbits?
As I wrote, a bacterial infection seems to cause the crystals to change from too small to see to ones that are big enough to notice. Bacteria produce certain chemical that attract the calcium and phosphorus in rabbit urine. Once a crystal forms, it makes it easier to capture more calcium and phosphorus to make the crystal larger. With enough time the crystals get as big as a grain of sand or even a stone. The sand-sized crystals may cause pain when a rabbit urinates. The larger stones may be life-threatening as they can block the urethra and prevent a rabbit from urinating.
There’s likely a second reason that bacterial infections cause sludge to develop. Almost everyone was watched a Slushee or Icee machine operate. The chamber is constantly being stirred to keep the ice crystals small and easy to pass through a straw. If the motor is damager and it no longer turns at the right speed, the ice starts to clump into bigger and bigger chunks. The bladder has its own motors that keep urine moving around so that the crystals never get too big to handle. These motors are tiny little hair-like structures called “cilia” and they line the inside of the bladder. Bacterial infections damage the cilia so they no longer move properly. Just like a broken Slushee or Icee machine can’t stop the tiny ice crystals from forming into large chunks of ice, the cilia of an infected bladder (known as cystitis) aren’t able to prevent larger crystals from forming.
It’s difficult to identify the bacteria that causes these bladder infections, urine sludge, and bladder stones (uroliths). The underlying infectious agent may never be known except that the rabbit’s condition improves with antibiotics.
How does the infection start?
I believe that the bacteria contaminate the urethral opening of the penis or the vagina, particularly in rabbits that like to sit in their litter boxes. The bacteria then go up the urethra and colonize the bladder. Certain conditions also seem linked to bladder infections. Overweight rabbits are more likely to develop cystitis, urine sludge, and bladder stones than normal weight rabbits. Rabbits that are offered mineral blocks and too much alfalfa hay seem more at risk. Older spayed female rabbits may not fully empty their bladder with each visit to the litter box and this leaves urine in the bladder that may foster bacterial growth. There are likely many factors that play a role but little study has gone into this condition of rabbits.
What would you do with a rabbit with one of these conditions?
A lot depends on what I find on a physical examination. I often recommend a urine test, x-ray films and ultrasound, and bloodwork if your rabbit is showing signs of cystitis, urine sludge, or bladder stones. It may need to be anesthetized so that a urinary catheter may be passed into the bladder and the bladder flushed to remove the sludge. A surgery known as a cystotomy may be needed to remove bladder stones.
As a general rule I start a rabbit with any of these conditions on antibiotics and continue the treatment for 6 to 12 weeks. I usually start them on a pain reliever and anti-inflammatory known as meloxicam too.
I’ll teach you how to administer subcutaneous fluids (i.e., fluids beneath the skin) to try and flush out any bacteria and crystals in the bladder. You must closely watch your rabbit to be sure it is urinating. If it goes more than 12 hrs without urinating it will need to be seen by a veterinarian.
Female spayed rabbits may be started on estrogen supplements to try and improve bladder muscle tone and function.
If your rabbit shows urine scalding you need to clean the area multiple times a day with warm water and then gently dry it as much as possible. Apply corn starch to the fur and let it dry, then gently brush it out. If there are areas of hair loss you may apply HealX Soother Plus ointment to reduce irritation.
Glucosamine seems to help the bladder heal. You may give 50 to 200 mg of glucosamine daily depending on the size of your rabbit. Myristol for horses sometimes helps or you may get a glucosamine supplement from the health food store.
Coenzyme Q at a dose of 10 iu every one to three days seems to help as dose 40 iu of vitamin E every three to seven days.
Provide multiple litter boxes with grates to keep your rabbit off the soiled litter. A litter box should have a tall lip so a rabbit has to hop in and out. This helps bring the sludge into solution (like shaking a snow globe) so it is urinated out of the body.
Provide fresh water daily rather than “topping off” the water bowl or bottle. Add one or two more drinking bowls or bottles to your rabbit’s home.
Green bell peppers seems to be helpful in guinea pigs. It may be worthwhile to provide your rabbit a 2 inch x 4 inch slice of fresh green bell peppers daily.
Even with ideal care many rabbits battle urinary tract infections, urine sludge, and bladder stones for the rest of their lives.
Copyright 2012 Dr. Kevin Wright, DABVP (Reptile & Amphibian Specialist)
Member of the Association of Exotic Mammal Veterinarians
Wright Bird & Exotic Pet House Calls
Distinctive Veterinary Care for Unusual Pets
4908 S. Val Vista Drive, Gilbert, AZ 85298
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