Prevention and treatment of clostridial disease in sheep

06/02/2023

Blackleg, pulpy kidney (enterotoxaemia), black disease, tetanus, malignant oedema and botulism are clostridial diseases that cause death in sheep and cattle throughout Australia. Other animals, particularly goats, are also susceptible.

The Clostridial Family of Bacteria
Clostridial organisms of various types are found in the soil, where they can survive for a very long time. In fact, when conditions are favourable, some organisms can even multiply in the soil. Most clostridial organisms can also occur quite naturally in the gut of healthy animals. They live there causing no trouble, pass in the manure of animals, and consequently, contaminate the soil. When conditions are favourable for the uncontrolled growth of clostridial organisms they produce powerful toxins (poisons). The effects of these toxins are usually fatal.

Diagnosis
The most important thing to do when sudden deaths of stock occur is to get an accurate diagnosis. This is important to rule out other conditions, such as metabolic diseases, poisonings and anthrax. Animals suspected of dying from anthrax should not be moved or cut up in any way. Many of the clostridial diseases can look like anthrax and so should be approached with caution. If anthrax is suspected, contact your veterinarian immediately. Clostridial diseases are usually fatal. Death occurs rapidly with pulpy kidney, black disease, blackleg and botulism, but takes several days to weeks with tetanus. In severe outbreaks, many animals die suddenly. Occasional deaths may be due to these diseases also. These are often undiagnosed.

Treatment
Treatment with antitoxins and large doses of antibiotics is expensive and not usually successful. Vaccination is vital to prevent these diseases.

Prevention and Control
The major factor in controlling clostridial diseases is to develop satisfactory immunity within the animal at risk through vaccination. The vaccination program undertaken in a herd or flock must take into account the principles of immunity, the diseases likely to occur and economic factors.

The Principles of Immunity
Passive immunity is transferred from the mother to the offspring in the first milk (colostrum). If the mother is boostered with 5-in-1 vaccine about one month before the offspring is due to be born the level of protection and period of time for which the young animal is protected is increased. Active immunity requires a primary course of two doses of vaccine 4 to 6 weeks apart to give a reasonable period of protection. The first dose only primes the animal’s immune system – hence the need for a second dose. The first dose is usually given at marking time, when the protection from the mother’s milk is starting to decline. Annual boosters are required to maintain the protection, as well as providing antibodies in the colostrum to protect the young until they are old enough to be vaccinated. Boosters should be given strategically before high-risk periods.

Diseases Likely to Occur
The diseases likely to occur will vary from district to district and season to season. Each disease has particular conditions that can usually be mitigated through planning and good hygiene practices. Owners should check with their veterinarian for advice regarding their own situation.

Pulpy Kidney (Enterotoxaemia)
Enterotoxaemia or pulpy kidney is a common and fatal disease of sheep and cattle. It is caused by the toxin of the bacterium Clostridium perfringens (type D) when it is absorbed from the intestinal tract. The bacteria that cause enterotoxaemia normally exist in small numbers in the gut of healthy animals. The disease develops when the environment in the intestine favours bacterial growth and bacterial numbers increase dramatically with a large increase in toxin production. This can be caused by increased feed intake, new or better pasture, dramatic change in diet, or the introduction of grain based diets. It is difficult to diagnose pulpy kidney as death is often the only clinical sign and it is often confused with bloat. Prevention can be achieved through careful management of the animal’s diet, together with a comprehensive vaccination program. Immunity to pulpy kidney after vaccination lasts around 3-4 months, so boosters may be required when a sudden change in diet is anticipated.

Blackleg
Blackleg is a generally fatal bacterial disease of young cattle and sheep of any age. It is caused in most cases by the bacterium, Clostridium chauvoei. The disease usually causes lameness due to localised inflammation of muscle with heat, swelling and gas formation (gas gangrene). This is followed by a generalised toxaemia (blood poisoning) of the animal causing rapid death. The bacterial spores can survive in soil for many years. Spores are ingested from pasture by the animal, they then enter the bloodstream and lodge in the muscle where they can remain dormant without causing ill-effect. Blackleg in sheep is frequently associated with wounding as a result of shearing, tail docking, castration, injury to ewes at lambing or infection of the navel soon after birth. In cattle, unknown ‘triggering’ factors cause the organism to germinate, multiply and cause the onset of blackleg although outbreaks following handling and associated bruising are common. The disease is more commonly seen in young, rapidly growing cattle or cattle on a high plane of nutrition. The organism has been documented to also damage heart muscle and diaphragm resulting in clinical signs not usually associated with this disease.

Black Disease
Black disease is an acute, highly fatal disease of sheep, goats and cattle and is usually associated with a liver fluke infestation. It is caused by the bacterium Clostridium novyi. The organism produces toxins in the liver usually following damage to the liver by migrating liver fluke, causing death. Spores can survive in soil and pastures for many years. Spores are ingested from pasture by the animal and pass into the liver where they may remain for some time with no apparent effect. However, should the liver tissue near the spores become damaged, usually by liver fluke, the spores will be activated, they will multiply and begin producing a toxin which causes the disease. Although sheep are the animals mainly affected, losses can occur in cattle and goats. The onset of the disease may be rapid, with stock simply found dead in the paddock.

Malignant Oedema
Malignant oedema is a clostridial disease that more commonly affects sheep but also goats and cattle. It results from infection of wounds with certain clostridial organisms (Cl.chauvoei, Cl.novyi or Cl.septicum), which cause local swelling and discolouration. General toxaemia and death of the animal occurs within days. Susceptible wounds may occur during routine operations like shearing, mulesing, and marking. Infection is not uncommon if these operations are carried out under dirty, unhygienic conditions. The ge***al tract may become infected following prolonged or assisted lambing, kidding or calving. Swelled head is a similar condition seen in rams. This occurs in young animals due to fighting, with the bacteria entering wounds on the head, resulting in the typical ‘swelled head’ appearance.

Botulism
Botulism is caused by the toxin produced by Clostridium botulinum (type C and D). It is a major problem of cattle in Northern Australia that are more likely to graze on phosphorus-deficient pasture, which may lead to bone chewing (pica). It can also affect horses, sheep, goats, pigs and poultry. Favourable conditions for C.botulinum and its resulting toxin include decaying dead animals, rotting vegetation, mouldy grain or wet hay. Animals become infected if they ingest material containing the toxin or if they ingest bacterial spores, which then multiply in the animal’s gut and produce the toxin. Affected animals typically display hindlimb weakness progressing to paralysis, collapse and death. Paralysis of the tongue may be observed, displaying as refusal to eat or drink or excessive drooling. The animal may also display aggression. In some cases the animal may simply be found dead.

Tetanus
Tetanus is a bacterial disease caused by the toxin produced by Clostridium tetani. Tetanus occurs when C.tetani are present in damaged body tissue with lowered oxygenation. Puncture wounds such as nail pricks in horses’ feet, penetrating splinters of wood, shearing cuts and lamb marking wounds provide very good conditions for tetanus to develop. However, tetanus can also follow mulesing, dehorning or ring application and even wounds too small to be noticed. Signs of tetanus occur from about four days to three weeks or longer after infection is established in a wound. The animal may have a stiff gait, ‘lockjaw’ can develop and the third eyelid may protrude across the eye. The animal will usually go down with all four legs held out straight and stiff and the head drawn back. Convulsions may occur and the animal usually dies due to muscle paralysis and asphyxiation.

Economic Factors
Economic factors include the value of the stock, the cost of vaccination and degree of risk the owner is willing to accept. The cost of vaccination is cheap insurance against the death of valuable stock. An effective 5-in-1 vaccine is available in combination with cheesy gland vaccine (for sheep), leptospirosis vaccine (for cattle), botulinum vaccine (for cattle and sheep), anthelmintics, vitamins, protein supplements and trace elements such as selenium and phosphorus.

Ensuring Vaccine Effectiveness
It is important to follow the manufacturer’s directions for storage, handling and administration to ensure the vaccine’s maximum effectiveness. Keep the following in mind when purchasing and using the vaccine:

Only buy vaccine which has been stored according to directions.
Purchase quantities of vaccine sufficient for use on the day, as the vaccine deteriorates overnight.
Keep the vaccine cool according to directions.
Always carry the vaccine in a cool, insulated container, removing it only for use.

09/09/2022

Tetanus is an acute, often fatal, infectious neuromuscular disease in all farmed mammals caused by Clostridium tetani. The disease is sporadic but outbreaks of tetanus have been described, as a result of wound contaminated with spores of C. tetani, which sporulates to the vegetative form and produce toxins. The present study reports an outbreak of tetanus in a sheep flock, shortly after ear tagging. Three sheep from a large flock (with a population of 1000 sheep) were presented with signs of: convulsion, limb stiffness, incoordination and trismus ("lock jaw"). There were wounds and scabs in most livestock where ear tags had been attached 1 week prior. Clinical examination revealed tachycardia, dyspnoea with dilated nostrils, mild fever, erected ear pinnae, teeth grinding, mild bloat, muscles rigidity, prolapse of third eyelid and anxiety. According to the history stated by the owner, the case fatality rate of the disease from the beginning was 50% during the outbreak. Necropsy did not reveal any significant finding. Gram-positive bacilli with terminal spores representing C. tetani were isolated in anaerobic cultures which were taken from ear wounds. Procaine penicillin G was administrated at 20 000 IU/kg BW for 5 days, but antiglobulin was not available to treat affected animals. Mortality significantly declined one day after onset of treatment. In this report, the organism was probably introduced by contaminated instruments which were used for ear tagging of sheep. Wound exudation and adhesion following rubbing, created a favourable anaerobic condition for the spores to germinate with production of neurotoxin. Vaccination can protect animals against tetanus, but it does not preclude the need to apply standard hygienic principles when performing management procedures causing wounds. In pasture holding system, many pathogens are present in environment, so tetanus should be considered important in farm animals, because of its high fatality rate and the long course of convalescence.

09/09/2022

Tetanus is caused by the neurotoxin produced by Clostridium tetani , which is found in soil and intestinal tracts and usually introduced into tissues through deep puncture wounds. The toxin causes a generalized muscular spastic paralysis. Clinical signs and history are usually sufficient for diagnosis. Treatment is supportive, including thorough flushing of the wound, along with injection of tetanus antitoxin. Tetanus toxoid is given for active immunization.

09/09/2022

Tetanus (lock jaw)
Tetanus is caused by Clostridium tetani, a soil inhabitant that is a prolific spore producer. This disease is usually related to docking and castrating by elastrator bands, though any wound can harbor the tetanus organism.
Signs of tetanus occur from about four days to three weeks or longer after infection is established in a wound. The animal may have a stiff gait, "lockjaw" can develop and the third eyelid may protrude across the eye. The animal will usually go down with all four legs held out straight and stiff and the head drawn back. Convulsions may occur and the animal.
Treatment consists of the tetanus anti-serum and antibiotics. It is usually unrewarding. Tetanus can be prevented by vaccinating pregnant ewes 30 days before lambing. If pregnant ewes were not vaccinated for tetanus, the tetanus anti-toxin can be administered to lambs at the time of docking and/or castrating. The tetanus anti-toxin provides immediate short-term immunity and can be used at the time of docking and castrating to prevent disease outbreaks.

09/09/2022

Feeding Strategies
Smart feeding strategies will also enable you to limit the potential for this disease to affect your herd or flock. Since the causative bacteria proliferate in the intestine in response to ingestion of abnormally high levels of starch, sugar, or protein, you need to be careful how you feed certain feedstuffs that contain high levels of these nutrients, such as grains, silage or haylage, lush pasture, milk or milk replacer, and protein supplements. Complete feeds – such as pellets designed to be fed to induce gain in lambs or kids – can also trigger this disease if fed in excess.
When feeding these high-risk feedstuffs, divide the daily allotment for each animal into as many small feedings as is feasible (say, three to four feedings), rather than providing such feeds in a single, large meal. It is also advisable to feed roughages such as hay before feeding these higher-risk feeds, simply to allow the animals to become full on hay beforehand. This helps to limit the potential for overeating on high-risk feedstuffs, such as grain. Consult your veterinarian to determine what feeding strategy is optimal for your situation.
Always make feed changes slowly. If you plan to increase the amount of grain fed to a flock or herd, always do so in gradual increments over several days. This helps the bacteria in the stomach to accommodate to the diet, making it less likely that the troublesome bacteria will get access to the nutrients. Make sure that you watch your animals for signs of dominance by one or more individuals – they can boss the others away from the grain and overeat; alternatively, the shy animals can hold back from feeding and become so hungry that they overeat. Divide your herd or flock as necessary, and make sure to provide an adequate number of feeding sites or feeder space to enable all animals an equal chance to eat.
For animals being turned out onto pasture after being fed hay or other stored feeds, a conservative thumb rule is to begin by allowing only about 10 minutes of grazing time on the first day. Double this with each subsequent day – it will take about a week for them to work up to a full 24 hours on pasture.
Heavily milking dams may need to be fed more roughage and less concentrate to limit the excessive milk production that might endanger their offspring. Keep the feed schedule consistent to lactating does and ewes to limit fluctuations in milk volume for their nursing offspring.

09/09/2022

Prevention
Prevention of enterotoxemia is far more likely to be successful than trying to treat the disease.
Vaccination
Vaccination is the cornerstone to prevention of this disease. For sheep and goats, there are multiple vaccines available that induce immunity to the toxins generated by Clostridium perfringens types C and D. Because tetanus is also an important disease to prevent in sheep and goats, many veterinarians recommend that sheep and goats be vaccinated with a vaccine that also induces protection against tetanus. These vaccines are often termed “three-way” vaccines because they induce protection against the three bacteria involved: Clostridium
sheep
perfringens type C (enterotoxemia), type D (enterotoxemia) and Clostridium tetani (the bacterium that causes tetanus). Adult sheep and goats: When initiating vaccination for a given sheep or goat, all enterotoxemia/tetanus vaccines require two doses to induce effective immunity. These doses are usually administered 10 to14 days apart. Once each adult sheep or goat has received these two doses, repeat vaccination should occur at least once per year. Many veterinarians recommend that ewes and does be vaccinated roughly one to two months ahead of the anticipated birthing date, in order to maximize the amount of antibody present in the colostrum (first milk) – this helps to protect the neonate against enterotoxemia. If immunization of pregnant animals during that time frame is not feasible for you, then vaccinating the ewes and does at other times of the year appears to be effective.
For juvenile and adult sheep or goats fed diets rich in grain or allowed to graze lush pasture, more frequent vaccination for enterotoxemia may be warranted; some producers immunize these higher-risk animals two to four times per year to achieve adequate protection.
Keeping the mothers well-vaccinated is the best way to protect newborn animals against this disease, as the antibodies to the bacterial toxins are transferred to the newborns in the colostrum (first milk). Obviously, you need to ensure that newborns receive colostrum for this to work! Growing babies are typically vaccinated for the first time at six to 10 weeks of age, and one to two repeat (booster) vaccinations are typically given afterwards. Consult your veterinarian to determine what vaccination strategy best suits your operation and feeding program.
Feeding Strategies

09/09/2022

Treatment
Treatment of enterotoxemia may not be successful in severe cases. Many veterinarians treat mild cases with analgesics, probiotics (gels or pastes with “good bacteria), oral electrolyte solutions, and antisera, which is a solution of concentrated antibodies that neutralize the toxins that these bacteria produce. More severe cases may require intravenous fluids, antibiotic therapy, and other types of supportive care, such as supplemental oxygen.

09/09/2022

Enterotoxemia is a frequently severe disease of sheep and goats of all ages. It is caused by two strains of bacteria called Clostridium perfringens – the strains are termed types C and D. These bacteria are normally found in low numbers in the gastrointestinal tract of all sheep and goats. If that is so, when and why do they cause disease?
These organisms are normally “laying low” in the small and large intestine – that is, they are present in relatively low numbers and appear to be in a relatively quiescent state in the normal, healthy animal. What appears to trigger them to cause disease is a change in the diet of the animal. Most commonly, the change that triggers disease is an increase in the amount of grain, protein supplement, milk or milk replacer (for lambs and kids), and/or grass that the sheep or goat is ingesting. Collectively, these feeds are rich in starch, sugar, and/or protein. When
Ewe
unusually high levels of these nutrients reach the intestine, Clostridium perfringens undergoes explosive growth, increasing its numbers rapidly within the intestine. As the organism grows in number, it releases very potent toxins (bacterial poisons) that harm the animal. These toxins can cause damage to the intestine as well as numerous other organs. This can result in fatalities, particularly in the non-vaccinated animal or in the newborn lamb or kid whose dam has not been vaccinated.
The signs of enterotoxemia in sheep and goats include:
• The animals may abruptly go off of feed and become lethargic.
• Affected animals may show signs of stomach pain, such as kicking at their belly, repeatedly laying down and getting up, laying on their sides, panting, and crying out.
• Diarrhea may develop; in some cases, there is blood visible in the loose stool.
• Animals may lose the ability to stand, lay on their sides, and extend their legs, with their head and neck extended back over their withers.
This posture is caused by the effects of the toxins on the brain. Death
commonly occurs within minutes to hours after this sign is seen.
• Because enterotoxemia can progress so quickly, animals may be found dead with no previous signs of disease.

09/09/2022

Entertoxemia is a frequently severe disease of sheep and goats of all ages.
Causative bacteria are present in relatively low numbers and appear to be in a relatively quiescent state in the normal, healthy animal.
Treatment may not be successful in severe cases.
Prevention of enterotoxemia is far more likely to be successful than trying to treat the disease.

09/09/2022

Less Common Clostridial Diseases
Enterotoxemia type B (lamb dysentery)
Clostridium perfringens type B causes lamb dysentery. It usually affects strong lambs under the age of 2 weeks. Symptoms include sudden death, listlessness, recumbency, abdominal pain, and a fetid diarrhea that may be blood-tinged. On post-mortem, intestines show severe inflammation, ulcers, and necrosis. The mortality rate approaches 100 percent. Cl. perfringens type B is not common in the U.S., but is frequently found in England, Europe, South Africa, and the Near East.

09/09/2022

Clostridial organisms of various types are found in the soil, where they can survive for a very long time. Most clostridial organisms can also occur quite naturally in the gut of healthy animals. Sheep can be infected with various clostridial diseases – black leg, botulism, malignant edema, red water disease, enterotoxemias (several types), and tetanus – but the most common are enterotoxemia types C & D and tetanus.

10/08/2022

10/08/2022

11/06/2021

Zoonoses and Food Safety
Top of page
There are no zoonosis or food safety issues with disease caused by Clostridium novyi.

11/06/2021

Clostridium novyi is an important pathogen of ruminant animals worldwide. Bighead affects extensively reared young rams and black disease is most common among sheep maintained under similar conditions. Bacillary haemoglobinuria occurs in cattle grazed on high mountain pastures with appropriate conditions of moisture and the presence of flukes which are the carriers of the spores of C. novyi type D (C. haemolyticum) and which predispose the animals to disease by causing liver damage

11/06/2021

Clostridial diseases
The clostridial family of bacteria are varied and cause a variety of diseases as a result. One common feature is the rapid progression to death, which follows with all the diseases, with the exception of tetanus and botulism, which can affect animals for a couple of weeks before they finally succomb. Below are some notes of the clostridial diseases which affect the farm animal species, along with descriptions and comments.

Blackleg (in cattle and sheep)

Outbreak follows damage to muscles already infected with bacteria, which prompts replication of the Clostridium chauvoei and production of toxin. The muscle damage may be caused by fighting or handling, even if done carefully. The bacteria produce gas, and air pocketing under the skin, causing crackling when touched, is a common finding at post mortem.

See the Blackleg Disease Information Sheet

Malignant oedema or gas gangrene (in sheep, cattle and goats) or Big Head Disease (in rams)

Infection with Clostridium septicum occurs through a deep wound, usually a wildlife attack, although can be something as simple as an injection site. The site swells and there is a discharge. Death follows in 1-2 days. Cleaning the wound and giving antibiotics can be successful. In Big Head Disease the damage is usually through fighting.

Black disease (in sheep and cattle)

This is an infectious necrotic hepatitis (inflammation of the liver) usually following from damage to the liver caused by migrating liver fluke.

Pulpy kidney (in sheep, cattle and goats)

This one kills animals quickly. Young animals might only last 2-3 hours and adults are usually dead in 24 hours. The kidneys decompose particularly quickly after death, giving this disease its name, although the infection with Clostridium perfringens type D prior to death is through the whole abdominal cavity. In sheep the disease often affects multiple animals at once, whereas it appears more sporadic in cattle and goats.

Tetanus (thankfully uncommon in cattle, sheep and goats)

Infection with Clostridium tetani follows a penetrating wound - dog bites, shearing wounds, rubber castration rings, calving damage etc.

Botulism

This is the odd one out, from this family of diseases, as the bacteria themselves (Clostridium botulinum) do not normally infect the animal. Instead, the bacteria form toxins which are ingested and cause a flaccid paralysis of the muscles. As such, it is not included in the protection from multivalent Clostridial vaccines. This disease is most common in areas of the world where carcases are accessible to live animals.

Prevention

With the exception of botulism, these diseases and the Clostridial causes are protected against by the use of a multivalent Clostridial vaccine. These offer good protection and are not expensive so represent good value for money. There is a stand-alone blackleg vaccine available, but given the recent case load we have seen, we would recommend the extra expense of the 10-in-1 vaccines.

11/06/2021

Clostridial Diseases.
Certain Clostridium spp. may cause potentially fatal hemolytic anemias in animals; nonhemolytic lesions are presented elsewhere (see Chapters 4, 7, 8, and 19Chapter 4Chapter 7Chapter 8Chapter 19). Clostridium haemolyticum and Clostridium novyi type D cause the disease in cattle known as bacillary hemoglobinuria. (The phrase “red water” has also been used for this disease and for hemolytic anemias in cattle caused by Babesia spp.) Similar naturally occurring disease has been reported in sheep. In cattle the disease is caused by liver fluke (Fasciola hepatica) migration in susceptible animals. Ingested clostridial spores may live in Kupffer cells for a long time without causing disease. However, when migrating flukes cause hepatic necrosis, the resulting anaerobic environment stimulates the clostridial organisms to proliferate and elaborate their hemolytic toxins, causing additional hepatic necrosis. The mechanism of hemolysis involves a bacterial β-toxin (phospholipase C or lecithinase), which enzymatically degrades cell membranes, causing acute intravascular hemolysis. Bacillary hemoglobinuria also occurs with liver biopsies in calves.

Clostridium perfringens type A causes intravascular hemolytic anemia in lambs and calves—a condition known as yellow lamb disease, yellows, or enterotoxemic jaundice because of the characteristic icterus. The organism is a normal inhabitant of the gastrointestinal tract in these animals but may proliferate abnormally in response to some diets. C. perfringens causes intravascular hemolytic anemia in horses with clostridial abscesses, and clostridial mastitis in ewes. C. perfringens type A produces hemolytic α-toxin, which also has phospholipase C activity.

11/06/2021

Necrotizing clostridial infections of the skin and soft tissues have been described in the medical literature for centuries, the principal etiologic agents being Clostridium perfringens, Clostridium septicum, Clostridium sordellii, Clostridium histolyticum, and Clostridium novyi. Clostridial gas gangrene has been historically considered a battlefield trauma–associated infection. More recently, novel histotoxic clostridial infections have been described, such as neutropenic enterocolitis, spontaneous gas gangrene, and pregnancy-associated clostridial toxic shock syndrome. These infections are rapidly progressive and characterized by marked tissue destruction, gas in the tissues, shock, multiple organ failure, and frequently death. While the epidemiology and clinical presentations of these infections are often quite varied, all are mediated by potent extracellular toxins. This chapter reviews the roles of key exotoxins in the manifestations of these life-threatening clostridial diseases.