Nephrolithiasis and Ureterolithiasis in Rabbits
The kidneys serve several important functions for the body. Chief among them is the regulation of the body's blood pressure, regulation of electrolytes, and as a natural filter for the body's blood supply, removing waste materials and disposing of them through the urinary system. The ureters are a system of tubes that are connected to the kidneys and urinary bladder, carrying waste materials from the kidneys to the bladder, a hollow organ that serves as a storage receptacle for the waste fluid until it is released from the body via the urethra.
Nephrolithiasis and ureterolithiasis refer to conditions affecting the kidney and ureters in rabbits. Typically this happens when these organs become obstructed or inflamed, or when calcium salts form in the body, blocking the passages and resulting in urinary retention, which can in turn lead to inflammation of the bladder wall and urinary tract. Left untreated, over time these conditions can lead to systemic infection and other complications.
Any breed of rabbit can be affected by these conditions. Rabbits that are middle-aged or up to five years of age are most likely to be affected by nephrolithiasis and ureterolithiasis.
Symptoms and Types
The renal and urologic systems are usually the most affected. Many rabbits will not present with symptoms, even when they present with large crystal deposits of calcium in the bladder, or with nephroliths (kidney stones) or ureteroliths (ureter stones).
Rabbits that do have symptoms of will frequently suffer from anorexia, weight loss, and problems with obstruction of the urethra or ureters. Some may also have dark urine, and others will have symptoms of early or developed kidney disease.
Experts are not entirely certain what causes a rabbit to develop nephrolithiasis and ureterolithiasis. However, some believe conditions including inactivity and obesity can be contributing factors. Nutrition, including a diet high in alfalfa-based commercial pellets, a food that has been found to have overly high amounts of calcium, can also contribute to the formation of crystals in the urine, which are a leading cause of obstruction of the ureters. These crystals can slowly build up over time, eventually preventing free flow of urine from the bladder, preventing it from fully emptying, or obstructing flow almost entirely.
You will need to give your veterinarian a thorough history of your rabbit's health and onset of symptoms. A blood profile will be conducted, including a complete blood count and a urinalysis. If there is an infection present in the bladder, kidney or urinary tract, these tests should confirm higher than normal white blood cell counts, in both the blood and urine. A urine culture will need to be done as well to determine the chemical makeup of the urine fluid, such as whether crystals are present in the urine, or whether there is bacteria present. It is not uncommon for a rabbit to present with laboratory findings that include crystals in the bladder; however, not all rabbits will show this on testing.
Your veterinarian will also for risk factors for nephrolithiasis and ureterolithiasis, which usually includes obesity, unhealthy environmental conditions, inactivity, and kidney disease. Remember that pellet-fed animals are more at risk than animals that eat fresh greens on a regular basis. These foods include lettuce, carrot tops and a fresh, good quality grass hay.