Sudden death and up to 30% mortality rate of clostridial diseases in sheep is waiting for the unvaccinated sheep against these serious diseases.
Let's address all about clostridial diseases in sheep through the next article, which will include:
- What are clostridial diseases in sheep?
- Predisposing factors of clostridial infection.
- Clinical signs and diagnosis of each clostridial disease in sheep.
- Vaccines against clostridial diseases in sheep.
What are Clostridial Diseases in sheep?
They are diseases caused by Clostridial organisms of various types that are present in the soil, or normal inhabitants in the gut of healthy animals, and become pathogenic, causing sheep diseases under specific conditions.
The clostridial diseases that can affect sheep include:
Enterotoxemia type C (hemorrhagic enteritis, bloody scours)
It's caused by Clostridium perfringins type C and strongly affects lambs of a few week's age, causing a bloody infection of their small intestine.
It is predisposed by a sudden change in feed such as the sudden increase in milk intake or beginning creep feeding causing indigestion.
Treatment by subcutaneous injection of antitoxin is usually unrewarding.
So, it's recommended to vaccinate pregnant ewes 1 month before lambing as prevention.
Pulpy kidney disease (Enterotoxemia type D)
It's a common Clostridial sheep disease caused by Clostridium perfringins type D.
It mainly affects the fastest growing, the largest lambs, and over 1 month of age in the flock.
It's mainly predisposed by a sudden change in the feed that allows the normal inhabitant organisms in the lamb's gut to proliferate, causing the disease.
Predisposing Factors of Enterotoxemia Outbreaks
Enterotoxemia can be overgrown in the sheep intestine under specific conditions such as:
Excessive intake of milk or high grain concentrated ration.
The weak immune response of the sheep is due to illness or stress.
A heavy parasitic infestation of the gastrointestinal tract of the sheep.
Consumption of low roughage and high carbohydrates ration.
Reduction of the gastrointestinal tract motility of the sheep.
Clinical Signs of pulpy kidney disease
The typical clinical signs of this clostridial disease include:
Abdominal discomfort.
Loss of appetite.
Watery or bloody diarrhea.
Some young lambs may show neurological disease signs such as convulsions and excitement.
These signs may appear for a very short time, between a few minutes and approximately 12 hours, followed by sudden death.
Diagnosis of pulpy kidney disease
This clostridial disease is diagnosed through:
History of sudden death.
Clinical Signs of the alive sheep.
The presence of glucosuria and hyperglycemia either in live or dead animals can be a strong suggestion for enterotoxemia.
Postmortem examination
By postmortem examination of the internal organs, this clostridial disease shows:
- Grossly, soft pulpy consistency of the kidney and microscopically there is acute diffuse necrosis of the proximal renal tubules.
- Hemorrhages on the kidney and heart, and under the skin.
- The sac around the heart may be blood-tinged or straw-colored fluid, either with or without soft, jelly-like clots.
- The contents of the small intestines are creamy or watery, mixed with blood and fibrin clots.
- The decomposition of the carcass occurs within a few hours of death.
- Presence of small ulcers in the intestinal mucosa.
- Brain encephalomalacia may be found, especially in sheep who showed neurological signs.
Laboratory tests
There are many tests usually used to confirm this serous clostridial disease, including:
PCR for detection of DNA of Clostridium perfringens type D.
ELISA test for the detection of different clostridial toxins, such as the epsilon toxin.
Bacterial culture to detect the Clostridium perfringens organism from intestinal contents.
How to treat pulpy kidney disease?
The treatment of this clostridial disease can include:
Use of antibiotics intramuscularly, especially penicillin.
Oral administration of antacids and anti-bloating drugs.
Intramuscular injection of vitamin B1 to treat the encephalomalacia and also prevent it.
Supportive therapy by using intravenous fluids and corticosteroids.
Providing the animal with probiotics after antibiotic therapy is a very important step to help the microflora repopulation in the gastrointestinal tract.
Subcutaneous injection of Clostridium perfringens C & D antitoxins but it may be unrewarding, so prevention and vaccination courses are the keys.
Tetanus (lockjaw)
This clostridial disease is usually related to the presence of wounds such as docking and castration by elastrator bands.
Clinical signs of tetanus
The first clinical sign of tetanus appears within 4 days to 3 weeks or longer after wound infection.
Stiff gait, "lockjaw" of the affected animal.
Protrusion of the third eyelid may protrude across the eye.
The affected animal will go down with stiff, straight-four legs and a drawn-back head.
Convulsions may be observed.
Treatment of tetanus
Usually, treatment of this clostridial disease with tetanus antiserum and antibiotics is unrewarding.
So, prevention of Tetanus by vaccinating the pregnant ewes 30 days before lambing.
Lambs from unvaccinated ewes should take the tetanus anti-toxin at the time of docking and/or castrating.
This tetanus anti-toxin gives an immediate, short-term immunity, so it's recommended to be used at the time of docking and castrating to prevent disease outbreaks.
Enterotoxemia type B (lamb dysentery)
It's a clostridial disease caused by Clostridium perfringins type B.
It causes lamb dysentery, especially in strong lambs under 2 weeks of age.
Symptoms of lamb dysentery
This clostridial disease is characterized by some clinical symptoms before sudden death, including abdominal pain, recumbency, and listlessness, and fetid diarrhea which may be bloody.
The postmortem examination shows inflammation, severe ulcers, and necrosis of the intestine.
The disease mortality rate may reach 100%. Especially in Europe, South Africa, England, and the Near East where it's more common than in the USA.
Black Disease
It's a clostridial disease that is mainly associated with the presence of liver flukes.
It is caused by Clostridium novyi which can become active in the damaged liver tissue due to liver flukes.
Malignant Edema
The main cause of this clostridial disease is Clostridium septicum by a wound infection.
It's rapidly fatal within 24 hours after infection, which is associated with shearing, and/or castration wounds.
What are the sheep vaccines against clostridial diseases?
- Pulpy kidney.
- Blackleg.
- Black diseases.
- Malignant edema.
- Tetanus.
5 in 1 vaccine
It's a common vaccine that is used to protect sheep from the most 5 common types of clostridial diseases.
6 in 1 vaccine
It is more recommended as it also protects sheep from the cheesy gland (which causes abscesses in the lymph gland) in addition to its protection against clostridial diseases.
8 in 1 vaccine
Helps prevent 8 clostridial diseases (contain 5 in 1 mentioned above) + helps protect against lambs' dysentery and post-parturient gangrene in ewes.
It doesn't prevent cheesy gland.
Does of 8 in 1 vaccine:
The vaccine is given to sheep over 8 weeks through 2 courses.
The first course includes 5ml subcutaneously as a first dose.
The second dose is 2 ml, given after 6 weeks.
All subsequent doses are 2ml every 6 months as a booster vaccination.
Both ewes of unknown vaccination history or Lambs 2-8 weeks of age from unvaccinated ewes need 2ml initial dose followed by a second dose after 4-6 weeks.
Selenium boosted vaccine.
It's a vaccine against the clostridial disease, but it contains selenium to protect from white muscle disease, which is common among lambs as a result of selenium deficiency.
Principles considered administration of sheep vaccines against clostridial diseases.
Some principles must be considered with this type of sheep vaccine, including:
Vaccines must be given subcutaneously in the upper part of the neck.
The vaccine is given in 2 doses,
The first dose is given at lamb marking, and the second one is given 4-6 weeks later or at weaning time.
An annual booster every 12 months must be given to pregnant ewes 4-6 weeks before lambing to ensure the passing of immunity onto lambs via colostrum.
6 in 1 vaccine must be given within 6 months of shearing to provide excellent protection against cheesy glands' disease.
Non previously vaccinated sheep must be vaccinated.