Sheep Stones: Urinary Calculi in Sheep
Causes, Symptoms, and Treatment of Urinary Stones in Sheep.
Reading Time: 5 minutes
Learn about the causes of urinary stones and how to treat urinary calculi in sheep.
by Sherri Talbot
In the late summer of 2022, our young Soay ram, Flannan, developed a limp. We initially thought nothing of it. He was a young ram, and the older ram had been determined to drive Flannan away from the ladies. Mild injuries aren’t uncommon in these cases. We divided the flock into two smaller groups, thinking this would solve the problem.
A week later, when we fed the sheep, Flannan was lying down behind a tree and didn’t come for food. When I approached, he stood up before I reached him, limping severely on one of his back legs and went to eat with “his” girls. We became seriously concerned. He was getting worse, not better, and he wasn’t going to be able to mount ewes in his condition.
Fearing neurological damage from fighting or parasites, we called the vet, brought him to the isolation stall in the barn, gave him supports to help him stand, and waited for his appointment day to arrive.
He didn’t make it.
Heartbroken over the loss of our beautiful ram and panicking because the Soay sheep breeding season is short, we began to look for another male. Luckily, we found one from Flannan’s line with similar appearance and only a little younger than he was. Fraggle was from out of state and cost us a pretty penny. A friend was kind enough to transport him and he was at our homestead by the beginning of December, with a few weeks of the breeding season left to go.
Almost exactly two weeks after his arrival, he began to limp.
This time, we took action immediately. The moment I noticed the limp, I tried to bring him to the car, but he already couldn’t walk. He actually allowed me to load him into a wheelbarrow and ride him to the car without issue, a sign of how severe his condition was. We got him to the vet, he was diagnosed with a urinary blockage, treated and released with daily medications and dietary changes to prevent further problems.
Five months later, he died anyway.
I called the previous owner, only to discover that Fraggle’s brother had already passed away from the same issue. In fact, I was unable to find any surviving male from that line over the age of 18 months. The issue in all three rams was a development of crystals in the bladder which eventually formed stones and blocked off the urethra, resulting in death. This was an unusual case, since one study suggested that older rams are also far more likely to develop blockages than young males.
Symptoms Of Urinary Calculi in Sheep
Another study showed that 3.7% of the examined rams having urinary stones. However, like other prey animals, rams will hide their symptoms as long as possible, making early recognition and diagnosis difficult. When they do show symptoms, they may seem unrelated to urinary issues. Because of this, any ram showing signs of illness should be checked for a blockage during their exam.
Some possible symptoms of a blockage include straining during urination, refusing food, dribbling urine, and weakness. Some sheep show no symptoms at all, and diagnosis is only made during necropsy.
How to Treat Urinary Calculi in Sheep
Treatment of urinary stones is difficult. Crystals can be made up of several different minerals, and testing to determine the correct treatment is needed — if treatment is even possible. If stones can be felt in the prepuce, surgery to remove the obstruction may be an option. Most mineral buildups in the studies here were made up of calcium. In these cases, studies have shown that treatment with ammonium chloride can be effective. Finally, some veterinarians suggest heavily sedating the ram and filling the bladder with a mix of acetic acid and acetate, known as Walpole’s solution.
If other medical treatments fail, amputation of the penis may be the only option. The ram is unable to reproduce after this, so the procedure is mainly done on animals already marked for slaughter. In many cases, treatment is entirely unsuccessful, leaving euthanasia as the only option. Without intervention, the most common outcome for the adult ram is the rupturing of the bladder.
Causes of Urinary Stones in Sheep
The formation of stones is often believed to be purely a dietary issue resulting from too much grain. However, there are a number of factors that can play a role in the formation of blockages. Wethers, especially those castrated before their urethras fully develop, are more likely to develop issues. Blockages are also more common as the weather gets colder, since rams are apt to drink less and this can lead to a failure to flush out the urethra. The intake of certain types of forage can result in crystal formations as well. Even the breed of sheep or heritable anatomical issues can affect the animals’ likelihood of building up crystals or their ability to pass them.
Prevention of Urinary Calculi in Sheep
Unfortunately, this means that prevention of urinary stones is more difficult than simply avoiding grain for rams. Even in cases where the ram is successfully treated, the stones will need to be analyzed and attempts made to avoid resurgence. Many sheep feeds can be found with ammonium chloride already added, helping to increase the acidity of sheep urine and dissolve calcium buildups. In other cases, feeding a mix that correctly balances the sheep’s calcium and phosphorus needs can prevent build up. Vets may prescribe extra ammonium chloride in certain high-risk cases. Salt blocks can encourage more water intake and help flush out mineral build ups. However, as our case shows, taking all of these steps isn’t foolproof. The role of breed type and genetics plays a role that isn’t yet well-known and, in those cases, only care with the breeding lines can prevent a long-term issue in the flock.
References
- Constable PD, Hinchcliff KW, Done SH, Grunberg W. 2007. Veterinary Medicine: A Textbook of the Diseases of Cattle, Horses, Sheep, Pigs and Goats. 11th ed. St. Louis (MO): Saunders Ltd. p. 1095-1151. ISBN 97807052460.
- Fthenakis GC. 2011. Veterinary Clinics of North America Food Animal Practice: Therapeutics of Sheep and Goat Diseases. 27(1) Menzies Paula I., editor. Philadelphia (PA): WB Saunders Company. p. 38-39. ISSN 0749-0720.
- Jones M, Miesner M, Edmondson MA. 2020. Sheep, Goat, and Cervid Medicine. 3rd ed. New York (NY): Elsevier-Health Science Division. p. 15; Chapter 12, Diseases of the urinary system; p. 281-310. ISBN 9780323624633.
- Navarro FC, Bentin LAT, Bovino F, Baptista RS, Feitosa FL, Peiró JR, Mendes LCN. 2021. Use of ammonium chloride to prevent urolithiasis in sheep. Arquivo Brasileiro De Medicina Veterinária E Zootecnia, 73(4):834–842.
- Navarro FC, Bentin LT, Bovino F, Peiró JR, Feitosa FLF, Mendes LCN. 2022. Crystallurical profile in sheep after ammonium chloride supplementation. Arquivo Brasileiro De Medicina Veterinária E Zootecnia, 74(5):927–935.
- Nozohour Y, Najarnezhad V. 2023. Study on the frequency and chemical composition of urinary stones of Moghani sheep in Northwest of Iran. Journal of the Hellenic Veterinary Medical Society, 73(4):4841–4846. https://doi.org/10.12681/jhvms.27984.
Sherri Talbot is the co-owner and operator of Saffron and Honey Homestead in Windsor, Maine. She raises endangered, heritage-breed livestock and hopes someday to make education and writing on conservation breeding her full-time job.
Originally published in the September/October 2024 issue of Countryside and Small Stock Journal and regularly vetted for accuracy.
