A delicate balance
Small ruminants have some challenging health issues. One problem occurs almost exclusively in males and can be deadly.
In a recent presentation, Dr. Heather Glennon, North Carolina small ruminant Extension specialist, discussed urinary calculi. This is a serious issue in wethers and is also referred to as water belly.
“These calculi are stones, usually made of phosphate salts that become lodged in the urinary tract, especially in male sheep and goats,” Glennon said. “They are painful, and when they build up enough, they can prevent urination. In a severe case that isn’t treated, the bladder can rupture, urine leaks into the peritoneal cavity and gets into the bloodstream. Ultimately the animal will die.”
The anatomy of the male urinary tract is what makes urinary calculi a complicated issue. Males have a long, narrow urethra with an ‘S’ turn in the tract, making them more susceptible than females. Phosphate salts tend to accumulate in two areas: the sigmoid flexor and in the urethral process (or pizzle).
Phosphate salts accumulate primarily due to dietary imbalance. This often occurs from a diet of grain or other concentrates that’s high in phosphorus and low in calcium. Ideally, the small ruminant diet should have a calcium to phosphorus ratio of 2:1. A high concentrate diet usually means proportionately higher phosphorus and insufficient calcium, resulting in salt buildup.
The animals most at risk are young lambs and kids that have been castrated at less than 30 days of age. Younger males experience less stress at castration and rebound more quickly. However, castration stops the testosterone production that would have allowed reproductive structures to reach full size.
Although it’s uncommon, urinary calculi can also affect young, intact males. Females can get stones, but their anatomy allows easier passage. Depending on herd or flock size, management options and markets, it may be more desirable to leave males intact.
“Intact young males grow faster than wethers and will be leaner,” Glennon said. “With show wethers it’s a different story because they need to be castrated and will be fed a high-grain diet that puts them at risk for urinary calculi.”
While wethers are more at risk, if they’re fed properly, it may not matter if they are castrated when young because the calcium-phosphorus ratio is correct and salts are not building up.
Symptoms of urinary calculi include restlessness, hunched appearance, kicking at the belly due to pain, straining to urinate, blood in urine and urine dribbling. If a rupture has already occurred, there will likely be visible edema in the belly area.
“Observe your animals and know what’s normal and not normal,” Glennon said. “If you see this happening, act quickly. You can administer ammonium chloride to help lower the pH and make the urine more acidic, which will help break up salts.”
Glennon advised working with a veterinarian to manage animals that develop urinary calculi. Ammonium chloride has a bitter taste; adding flavor helps. A vet may prescribe a smooth muscle relaxant or anti-inflammatory medicine to manage discomfort. In some cases, the tip of the urethral process is snipped off to help small stones pass. A stone that blocks the urinary tract will likely require surgery. In severe cases, euthanasia is the only answer.
Reducing the risk of urinary calculi involves appropriate feeding. If a wether diet is properly balanced, it may not matter if they’re fed.
The goal is to supply twice as much calcium as phosphorus. Add calcium by providing ground limestone, or add legumes such as clover, alfalfa or lespedeza. However, if a wether receives a 100% alfalfa diet, there’s a risk of calcium stones. Glennon said it’s a good idea to discuss diet with a nutritionist prior to making dietary changes or adding supplements, especially if corn will be added to a high-grain ration.
Providing a diet of legumes or grasses also helps prevent urinary calculi. The more forage (fiber) an animal eats, the more cud chewing occurs.
“The rumen needs to be a specific pH,” Glennon said. “When ruminants chew their cud more frequently, they make more saliva, which helps buffer rumen pH, which keeps them healthy. Saliva also helps bring up phosphorus that’s been coming into the digestive system and passed in the feces rather than the urinary system. If the diet high is high in phosphorus but you feed a lot of forages, some of that phosphorus will exit via the digestive tract rather than the urinary tract.”
Some commercial feeds are formulated with additional ammonium chloride. A rate of 0.5% to 1% ammonium chloride will help acidify the urine to a pH of below 6.5. Urine pH can be easily monitored with a test strip.
Clean, fresh water dilutes salts and helps animals pass more easily. Increased salt intake aids in water consumption. Animals may avoid water in winter if it’s frozen or in summer when there might be algal growth in water. Water is essential for diluting salts and helping them pass in urine.
Considering the many options for salt and mineral supplements, Glennon said whatever type of salt supplement works best for a farm is what they should use. However, free choice minerals may not ensure all animals are getting all the minerals they need unless there’s a specific measure of minerals added to individual rations daily.
If animals are receiving a balanced diet and still have urinary calculi, check the hay and water source to see if they are high in phosphorus.
“Preventing urinary calculi boils down to proper feeding,” Glennon said, “and possibly castrating at an older age.”
by Sally Colby
