Description

While it would be easy to assume that bladder stones in horses could be a common problem due to the large amount of minerals in normal horse urine, that is not the case. Although bladder stones are a concretion of minerals primarily made up of calcium, heredity, diet and bacterial infection are often related to development of the stones.

The formation of bladder stones in horses is dependent on a number of factors that are not fully understood. Two types of stones occur and both are believed to be formed as a result of desquamated cells (cells that are peeling off the tissue) and mucus in the bladder.

Although infection is not believed to be a cause of stones, it may be significant in creating circumstances where crystals begin to form and may cause them to increase in size.

Symptoms

• Difficulty in urinating
• Urinary incontinence
• Blood in the urine
• Recurrent colic
• Increased white blood cell count
• Penile prolapse

Causes

The cause of bladder stones in horses is not fully understood. When stones occur in horses, they are formed by various forms of calcium carbonate. Excessive concentration of urine following water deprivation or excessive water loss is thought to lead to the formation of stones.

In many animals, stones are related to diet, and this may be a factor in the development of bladder stones in horses. If the mineral content of the diet is not right for the individual horse, it may be the cause of crystals forming in the urine. The crystals irritate the bladder wall and cause some bleeding. The crystals combined with blood and mucus may form the core around which a bladder stone forms.

Bacterial infection may also play a role, as may acidity of the urine. Bacterial growth is favored if the urine is alkaline rather than neutral or acidic. These bacteria may attach to the crystals and may lead to the development of stones.

Prevention

Dietary supplements with ammonium chloride to alter urine pH can be helpful. Decreasing intake of concentrates and calcium in the diet are important along with making sure the horse is drinking plenty of water, especially after exercise or excessive sweating.

Addition of salt to the diet to increase water consumption may decrease future stone formation. A horse with a history of bladder stones should not be fed beet pulp, alfalfa, or clover due to high calcium. Wheat bran should be avoided because of the high phosphorus content. Reducing the protein in the diet may also be helpful.

Treatment

Treatment depends largely on the size of the bladder stones. A rectal examination can facilitate the identification and size of bladder stones. Endoscopic examination of the uretha and bladder will identify urethal injuries, the state of the bladder and any abnormalities. In some cases, treatment requires the insertion of a catheter into the uretha to flush the bladder.

Surgery may be required to remove large stones or to correct an obstruction caused by stones. In horses, bladders can be difficult to reach through traditional surgical techniques.

Laprascopic removal of bladder stones has been successful in many cases and new and better techniques are being developed. Videoendoscopy and an anthroscopic lavage pump help expedite the procedure. If the bladder stones are large, one of the portal incisions may need to be enlarged to get the larger stones out of the abdomen.