Urinary Calculi in Sheep and Goats

Urinary calculi are a significant problem affecting male sheep and goats. Every year, especially around county fair time, we get many emails and phone calls asking about urinary calculi. Why does this occur in males, and why does this happen more often in castrated males?

What Are Urinary Calculi?

Urinary calculi is a metabolic disorder in sheep and goats caused by an imbalance of calcium and phosphorus. The stones are comprised primarily of phosphate salts. When phosphorus is taken in nature, most excess exits through the feces. In cases where phosphorus intake is too high, the excess forms calculi/stones, which eventually get stuck in the urethra. Once the urinary calculi block the urethra, the affected animal may not survive. Long-term urinary retention can result in high levels of potassium buildup in the system, followed by severe neurological abnormalities and cardiac arrhythmias.

Urinary Calculi Symptoms

Urinary calculi in sheep and goats have many names, often referring to the symptoms. Often, urinary calculi are referred to as “water belly” due to the increased fluid retention and the enlarged belly of the affected animal. Signs and symptoms in addition to the water belly include lethargy, teeth grinding, bleating, and “hunching up” of the back while attempting to urinate. Depending on the stage of the urinary calculi, the affected animal may pass small amounts of urine with straining, pass blood-tinged urine, or strain with no urine at all.

Urinary Calculi is almost always the result of improper feeding by the producer. Proper calcium to phosphorus ratio in feed, hay and minerals is critical; this ratio should be 2 1/2 to 1.

Michigan State University Extension

Urinary Calculi Prevention

Monitoring the calcium to phosphorus intake is the number one way to prevent urinary calculi. The calcium to phosphorus ratio is frequently discussed, and most veterinarians advise a ratio of 2 to 2-1/2-parts calcium to every 1-part phosphorus. Some literature states a 1-1/2 to 1 ratio, but many agree more is needed.
Click this link for more information regarding the calcium and phosphorus ratio from university studies.
Specialized feed and minerals are available with little or no added phosphorus to help keep this ratio in check. Foundation Feed offers a unique no-phosphorus mineral designed for males, which can be found here.

Ammonium Chloride

Ammonium chloride is a white crystal-like salt that dissolves well in water. This is an inorganic compound with the formula NH4Cl. The appearance of ammonium is like table salt.
Ammonium chloride can be purchased over the counter through multiple online vendors and most veterinary offices and clinics. Ammonium chloride is available for purchase through Foundation Feed by clicking here.
When consumed in appropriate amounts, ammonium chloride acidifies the urine and can help to dissolve urinary calculi. Ammonium chloride can be found in many feeds and minerals and is a critical feed additive to help prevent urinary calculi from forming. Ammonium chloride is used as a treatment for urinary calculi. Still, it is usually administered as an oral drench for this purpose. It should be noted that treatment for urinary calculi once the animal is symptomatic is typically unsuccessful.
Generally, ammonium chloride is added to processed feed at a rate of 1 pound of ammonium chloride per 100-pound feed. Many producers use a “1 tsp per head per day” when adding to untreated feed.
Don’t hesitate to contact your veterinarian for specific administration rates for existing illnesses. Rates of administration vary widely depending on multiple factors. Usually, they consist of an oral drench administered numerous times per day.

Adding Limestone to Feed

Crushed limestone is approximately 97% calcium carbonate, which can help offset a less desirable calcium-to-phosphorus ratio. Crushed limestone is readily available in most farm stores and is sold in 50-pound bags as “barn lime.” It is important to note that the label should always be checked to ensure the product is, in fact, crushed limestone. Quick lime and other forms of lime are unsuitable substitutes and should not be added to animal feed. Limestone is usually added to calcium-deficient feed at a rate of 1-1.5%.

Surgical Intervention for Urinary Calculi

Surgical intervention is an option as a last resort for a male with a blockage due to urinary calculi.
Since the calculi are often lodged near the end of the penis, a veterinarian can sometimes remove the head of the penis and thus remove the blockage. Long-term negative consequences of this intervention are the inability to breed, recurrent urinary tract infections, and lameness. Usually, this option is forgone, and the animal is euthanized since most producers have no practical use for a male unable to breed.

What About Females?

While females can and do develop urinary calculi, it rarely negatively affects them. This is because females have a very short, straight urethra which allows urinary calculi to pass quickly. On the other hand, males have a urethra that folds upon itself to allow expansion and contraction of the penis during mating. A good visualization of the urethra is like a tube sock folded upon itself. These folds and added urethral length are the main issues causing blockages in males.

Are Castrated Males at Increased Risk for Urinary Calculi?

Castrated males are more prone to urinary calculi. There is anecdotal evidence to support higher incidents of calculi in castrated goats as compared to castrated sheep. The consensus regarding why castrated males are more prone to calculi is based on testosterone and urethral development. When the lamb or goat kid is castrated, urethral growth is slowed. The smaller urethra places the animal at increased risk for blockage. Many producers have elected to castrate only when necessary and as late as reasonably possible. Late castration is not without risks and should be discussed with your veterinarian when developing a plan.

Conclusion

Urinary calculi are a severe concern and can quickly become a lethal problem. When in doubt, always consult your veterinarian. Establishing a relationship with a small ruminant veterinarian can pay substantial future dividends. Establish a relationship with a veterinarian before you have a problem!