The stomach of ruminant animals like sheep produces gas, a by-product of digestive fermentation. As a result, animals belch every minute to get rid of the gas. Bloat in sheep happens if the fermentation is too rapid or anything interferes with the belching cycle.
Bloating is the trapping of excess gas in the rumen. It is a life-threatening condition, meaning you have little time to save affected animals.
Feeding on wet pastures is the leading cause of bloat. Sometimes, the condition might result from overeating human food, such as dry bread. Another cause is obstruction of the esophagus when the sheep eat plastic.
If treated quickly and correctly, most animals can recover from bloat. However, providing nutrient feeds and managing your flock’s behavior is best for preventing the condition.
Types of Bloats
Three bloat types affect sheep. These include frothy bloat, free-gas bloat, and abomasal bloat. The latter only involves bottle-fed lambs.
Frothy Bloat (Primary Ruminal Tympany)
Frothy bloat, also known as pasture blat, mainly occurs in spring and autumn. It usually occurs due to overfeeding on lush, leguminous pastures in the early budding and vegetative stages.
Protein-rich legumes like alfalfa, clovers, and ladino have high nutritional value. However, when ingested, the stomach digests them quickly and produces gas as a by-product.
The rapid production of gas produces a thick foam and causes an instant change in stomach pH, increasing the viscosity of the rumen fluid.
The increased density prevents the tiny gas bubbles in the foam from merging into bigger ones. As a result, the animal can’t release the gas through belching.
As the amount of trapped gas increases, the rumen expands, especially on the left side. The expansion displaces internal organs, restricts blood flow, and interferes with normal breathing. Without immediate attention, a bloated animal dies from circulatory or respiratory failure.
Free-gas Bloat (Secondary Ruminal Tympany)
Free-gas bloat, also known as grain bloat, occurs when sheep cannot belch because of functional problems, obstruction, or poor bodily posture.
Obstructions mainly occur when sheep ingest foreign bodies, such as plastic bags. Other causes include abscesses and tumors, restricting airways that expel gas from the rumen. When the gas can’t get out, the animal bloats.
Pregnant sheep are susceptible to obstruction-induced bloating in the latter stages of their gestation period. As the fetus grows, the uterus expands, displacing the digestive tract and thus interfering with gas expulsion.
This is especially common in ewes bearing twins and triplets. However, it’s not life-threatening. You can resolve it by feeding the ewe small amounts of bulky roughage and encouraging moderate physical activity.
Functional problems resulting from overeating grains, internal damage, or some diseases can also prevent belching. Grain bloat occurs when sheep eat large amounts of a new grain type before the rumen adapts to the high digestibility.
As the stomach breaks down the grain, it ferments normally. However, its high digestibility causes a change in pH, causing reduced ruminal contractions. Without contractions, the gas accumulates, resulting in rumen distension.
Ruminants cannot belch while on their backs. If your sheep falls on its back, bloating will occur rapidly until it assumes an upright position.
Clinical Symptoms of Primary and Secondary Ruminal Tympany
The clinical signs of frothy and free-gas bloat are similar. Unless you monitor your flock closely, it usually takes instant, unexpected death to learn of these conditions.
The most common symptoms of bloat include:
- Distended abdomen – a bloated animal looks swollen on the left side, behind the ribs. The swelling is a sign of trapped gas in the rumen. It might later progress into an enlargement of the abdomen that produces drum sounds when tapped.
- Discomfort – your sheep will display signs of distress such as restlessness, neck extension, teeth grinding, grunting, frequent defecation and urination. If the pain persists, the animal will try to kick its belly or maintain a rigid standing posture with hind limbs wide apart.
- Poor appetite – bloated animals stop eating because of stomach fullness and general discomfort.
- Breathing difficulties – when bloating advances, the animal experiences severe breathing difficulties. You might notice excessive panting and staggered movement.
- Organ failure and death – in severe bloat, the distended rumen exerts too much pressure on the diaphragm, restricting proper breathing and circulation. The animal falls and dies due to suffocation and heart failure.
Preventing Frothy and Free-gas Bloat
As mentioned earlier, prevention is the best way of dealing with bloat. Here are some useful bloat prevention tips.
Eating lush, leguminous pastures is the primary cause of frothy bloat. However, it’s only a few legumes that cause this condition.
Others, including birdsfoot trefoil, crown vetch, milk vetch, and Sainfoin, don’t induce bloating because the stomach digests them slowly.
Besides growing non-bloating legumes, adding grasses to your pasture helps prevent bloating. Ensure your field comprises 50% grass and 50% legume.
If you graze your sheep on open fields, provide fiber-rich feeds to counter the effect of wet pastures that increase bloat risk. You can achieve this by giving grass hay in the morning before releasing the sheep for grazing. The hay should be at least 1/3 of their recommended daily intake.
Secondly, it helps to limit access to bloat risks, especially legumes in the early budding and vegetative stages. Ideally, restricting free foraging to a few hours daily is best. Also, avoid turning your animals into moist pastures.
The third step involves monitoring your flock once you introduce them to potential bloat-inducing grazing fields. Remove any sheep that show signs of tympany.
Lastly, it’s advisable to administer an antifoaming agent to your sheep during the risk period. Most of them are administered orally and don’t require a vet’s prescription. Alternatively, you can purchase a surfactant for spraying over the pasture.
Treatment for Frothy and Free-gas Bloat
Bloat treatment consists of measures to stop the formation of additional gas and the expulsion of the present gas. The techniques used depend on the extent of the bloat.
Animals experiencing mild bloat have slightly swollen abdomens. However, they can still move freely and display normal eating habits.
Mild bloat mostly occurs due to esophageal obstruction caused by ingesting large chunks of food. If that happens, conduct a neck massage to ease the food down the digestive tract and allow belching. This also relieves distension.
Alternatively, you can induce belching. This is achievable through keeping the sheep in an upright position and a mild agitation of ruminal contents.
You can stir up the stomach by carrying the animal by its belly or sitting it on its butt and rubbing the stomach. Agitation helps in the release of trapped gas.
Another method of treating mild bloat is to tie a smooth stick inside the animal’s mouth. When the animal bites, it produces saliva, which breaks down foam in the stomach.
If left unattended, mild bloat progresses into the intermediate stage. The discomfort levels increase, as does the abdominal distension.
The easiest way of treating intermediate bloat is by inserting a tube into the stomach through the mouth. Stomach tubing is an emergency procedure that’s effective for treating free-gas bloat. The tube provides a clear way for expelling the trapped gas, relieving bloat.
Sometimes, you might have to move the tube to find the gas pocket. After insertion, smell the gases produced to ascertain if the tube has reached the stomach. It should smell like stomach contents. Otherwise, your sheep could suffer from frothy bloat, requiring a different treatment approach.
If the tubing doesn’t work, give the animal a drink. When drenching, be careful to avoid entry into the respiratory tract. You can provide the drench using a stomach tube.
The drench can be a washing detergent, baking soda, or commercial medicine. For frothy bloats, pouring 200ml of vegetable oil breaks up the foam and relieves the bloat. You can use a narrow-necked for administering the drink.
Once the sheep show a little improvement, feed them with dry, coarse to stimulate ruminal contractions.
When the treatments above don’t work, and the abdominal swelling enlarges, it’s wise to puncture the rumen.
A vet stabs a trocar and cannula through the highest part of the distended left flank, between the last rib and the hip.
In such emergencies, you must act fast. Once the animal goes down, it has a few minutes to live – any hesitation results in death.
If you don’t have the puncturing equipment, improvise using a long, high gauge vaccinating needle or a sharp pocket knife. Then, insert a hard plastic tube (at least 5mm diameter) into the hole to expel the gas.
The tube also prevents leakage of rumen contents into the peritoneum, which causes infection. After all the gas is out, remove the tube and disinfect the wound with iodine.
It’s worth noting that puncturing the rumen is a last resort used when other treatment options aren’t viable. Many sheep that undergo this treatment die because of infection.
Also, rabies in sheep has similar symptoms to bloat. If you live in rabies’ prone area, please avoid inserting your hands into a sick animal’s mouth. Rabies is contagious through saliva.
Abomasal bloat is a condition that affects young sheep, from birth to three weeks old. Causative factors include malnutrition, ingestion of foreign objects, bacterial infections in the abomasum, and weak immunity due to inadequate breastfeeding. Poor hygiene and intermittent overconsumption of milk are also risk factors.
When feeding lambs, it’s advisable to do it at regular intervals. However, some farmers compensate for the lack of time by force-feeding the young sheep with an entire day’s ration in a single serving.
This slows down stomach emptying and allows more time for fermentation. As a result, the abomasum produces gas so fast that the sheep can’t expel it, leading to a quick but painful death.
Symptoms of Abomasal Tympany
Here are common signs of abomasal bloat.
- Distended bellies that produce a splashing sound when touched.
- Discomfort due to abdominal pain.
- Restlessness, followed by lethargy and dullness.
The most effective way of preventing abomasal bloat is to ensure lambs get enough colostrum. For this reason, you must provide enough feed and water to the mother so that she produces nutritious milk. Remember, breast milk contains colostrum, which boosts immunity.
Weather changes prompt sheep to seek shelter or remain lying down for extended periods. Sitting engorges the udder. This, coupled with the lamb’s hunger, results in milk overconsumption.
You can discourage this by availing more shelters and feeding spots so that the mothers don’t lie down a lot.
If you choose to bottle-feed the lamb, purchase high-quality milk. More importantly, the milk should contain animal proteins rather than plant-based proteins.
The latter has high digestibility, which risks bloating. The best milk replacement is fermented yogurt, containing prebiotics and probiotics that promote gut health.
Lastly, vaccinate your lambs for Clostridial bacteria types C and D, which are linked to abomasal bloat.
Treatment for Abomasal Bloat in Sheep
Available treatment options for abomasal bloat are largely ineffective, as the condition has a 75% to 99% mortality rate. Prompt first aid is the only way to save bloated lambs.
Here are the available treatment options.
- Stomach tube – This is inserted through the mouth to aid in gas expulsion.
- Oral penicillin – is a prescribed medication that combats bloat-inducing bacteria.
- Baking soda – this neutralizes stomach acidity caused by rapid fermentation in the abomasum.
- Puncturing – in severe cases, a vet can insert an oversized needle into the abomasum to help release gas.
Although gas is a natural by-product of digestive processes in sheep, it’s deadly when available in excess amounts. Regardless of the bloat type affecting your animals, a quick reaction is the best way to preserve life.
However, it is better to take a proactive approach. Bloating mostly comes from poor feeding habits – so ensure you keep an eye on your animals’ feed.
Ideally, it should have lots of fiber and roughages, and fewer legumes. For bottle-fed lambs, insist on high-quality milk with dairy proteins like casein.
Closely monitoring flock behavior can also help in early detection, enabling you to save a life.