What are Bladder Stones?
The concretions that comprise urinary stones in horses are named based upon the location of the stone. When located in the bladder, they are referred to as cystoliths, when found in the kidney, they’re referred to as nephroliths, in the ureter they’re called ureteroliths and when found in the urethra they’re urethroliths. The presence of these stones can cause urinary problems for the animal which can lead to urinary tract infections as well as urinary flow obstructions, which can ultimately lead to kidney failure and death if not treated.
Bladder stones in horses are defined as a concretion of minerals. These concretions are mainly made of calcium in horses while they may also be made of magnesium ammonium phosphate and called struvite in other species.
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Symptoms of Bladder Stones in Horses
The symptoms for bladder stones that you will likely notice in your horse can be similar to those you may notice when you experience bladder or kidney stones. The symptoms are:
- Difficulty with urination
- Urinary incontinence (involuntary leaking of urine)
- Blood in the urine
- Recurrent colic (flank pain sometimes accompanied by vomiting and sweating)
- Penile prolapse (penis may protrude for long periods of time while dripping urine intermittently)
- Altered gait sometimes can accompany recurrent colic
- Scalding around the urethra (the area that lies between the vulva and anus in females and inside the hind legs of males) - this is caused by of the uric acid burning the skin with contact over time
- Horses may stretch out to enable them to urinate and they may remain in this pose for some time before and after urination
- If the urethra becomes blocked from trapped stones, you will likely note restlessness, sweating, colic and more frequent attempts to urinate
Urinary stones are usually called by the minerals of which they are made along with the location of the stone (bladder, kidney, ureter, urethra). They are also referred to as uroliths and calculi and they are formed by minerals which are naturally contained in the urine by clumping together, forming crystals and growing in size as more minerals attach.
- Uroliths can be formed in young horses but more often seen in adult horses
- No one particular breed is seen as more prone to develop them, though these stones are not common in horses
- When found in horses, they are more common in males than in females
- Types of uroliths or calculi are mainly based on the various mineral compositions that are possible
- Stones can be 0.2 to 8 inches (0.5 to 20 centimeters) in size and can weigh as much as 14 pounds (6.5 kilograms)
- Most often found in bladder
Causes of Bladder Stones in Horses
There doesn’t appear to be a distinct cause of bladder stones in horses, but many veterinary professionals feel that feeding and watering horses with water and foods high in mineral content may be a factor. Additional causes are:
- Bacterial infection in urinary tract (UTI)
- Damage to kidneys from medications like phenylbutazone and flunixin (Benamin)
- Imbalance between calcium and mucous in the urinary tract
- Since the horse is an herbivore, the urine is high PH (alkaline) which is a condition that can begin the formation of stones naturally
Diagnosis of Bladder Stones in Horses
Your veterinarian will start the diagnostic process for bladder stones by using a transrectal assessment of the bladder (examination of bladder through the rectum). Ultrasound and endoscopy can also be used to assess the size, number and location of the stones. Your veterinarian may also utilize cystoscopy to locate any stones that are suspected to be in the urethra. This method will also be useful in determining if the urine is moving freely from both kidneys to the bladder or if there is a blockage or other obstruction. It can also help to ascertain if there is any underlying kidney disease or even stones in the kidney itself. An analysis of the urine may also be done to obtain additional information.
Treatment of Bladder Stones in Horses
The treatment most frequently utilized by veterinarians for bladder stones in horses is surgical removal. While there are several types of surgical options available, your veterinary caregiver will make his recommendation based upon the size of the stones, number of stones, and the location of the stones. Also, the gender of the animal will have an influence on the type of surgical recommendation made by your veterinarian, especially in males.
- Perineal urethrostomy is a procedure that involves making a small incision in the urethra, just below the anus while the horse is sedated and with an injection of lidocaine locally
- Larger stones will likely require a midline incision made in the abdomen while the animal is under general anesthesia to gain access to the bladder for the stone removal in a procedure that is similar to one done for colic surgery
- Lithotripsy is also an option so that surgical removal won’t be necessary; this procedure breaks up the stones into small pieces so that they can be passed more easily
These options are considered by your veterinary professional and he will give you his educated opinion as to the best one for your animal. The goal is to remove the offending stones in order to reduce the inflammation being caused and to prevent the possibility of a total blockage of the urine flow, a situation which can be life-threatening to any species.
Recovery of Bladder Stones in Horses
As the owner, you will likely receive several recommendations from your veterinary professional, one of which will be to dilute the urine by encouraging your horse to drink lots of water. Here are some suggestions for accomplishing that goal:
- Try adding flavoring to the water
- Feeding various types of mash
- Salt supplementation
Another suggestion for prevention is to use less drugs such as NSAIDs as these drug types can damage kidney function in your horse.The veterinary team may recommend dietary changes that may include the removal of legume hays, like alfalfa, from the diet. These types of legume hays are higher in calcium, and calcium is one of the minerals commonly found in the makeup of bladder stones in horses. You also might try to feed your horse vitamin C and ammonium chloride as these have been found to be used successfully as a preventative for bladder stones. Additionally, it has been found that the use of a dairy cattle feed supplement has also been effective.