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Sheep Health

Caring for your sheep involves being familiar with common diseases that can affect them. Today, our Douglasville veterinarians share some common illnesses and conditions that can affect sheep, as well as their symptoms and treatments. 

Sheep are classified as small ruminants, which are herbivores that have special four-chambered stomachs to help them with the digestion of grass and other fibrous vegetation. While there are a number of diseases that can affect these animals, some common ones can cause issues with reproduction, cause serious infections, respiratory disease and more. 

Common Diseases In Sheep

Bacterial Pneumonia

The bacteria Pasteurella multocida or Mannheimia haemolytica (previously Pasteurella haemolytica) are often found in the upper respiratory tract of healthy sheep. These bacteria are also the most frequent reason for respiratory infection and death in farm sheep. 

Signs include:

  • fever (104º F/40º C to 106º F/41º C)
  • moist, painful cough and difficulty breathing
  • mucopurulent (mucus and pus) discharge from the nose and eyes
  • crackling sounds when the animal's chest is listened to with a stethoscope 
  • loss of appetite
  • lethargy or tiredness

Your veterinarian will make a diagnosis based on your animal's clinical signs and the history of your herd. If the animal dies from the disease, an autopsy may reveal the cause of pneumonia. Antibiotics are prescribed by a veterinarian, and infected animals are to be kept in a dry, well-ventilated area away from the healthy herd members. Preventive vaccination and herd management are two methods of prevention.


Abortions in sheep can be caused by a variety of factors, including infectious diseases, toxic substances, and fetal development abnormalities. Chlamydiosis, listeriosis, toxoplasmosis, neosporosis, and other diseases caused by microorganisms are common. These can cause abortion in sheep and are zoonotic, which means they can infect humans after passing from animals to humans. It is critical to wear protective clothing, latex gloves, or plastic arm sleeves when attending a lambing or kidding or handling aborted lamb or sheep fetuses.

The diagnosis of abortion in sheep is based on clinical signs and herd history. Diagnostics may be run on samples to identify the infectious agent.

Treatment will vary widely, based on the identified cause of the abortion. For prevention of the spread of disease and conditions that cause abortions in your dairy herd/flock, try some of the following tips:

  • Immediately contact your vet for help carrying out an investigation
  • Use protective clothing and latex gloves or plastic sleeves to stop infection. Incinerate the sleeves or gloves afterward to prevent contamination.
  • Isolate the animal from the healthy members of the herd, quarantining it until further veterinary investigation.
  • Keep the placenta and fetus on ice or refrigerated (do not freeze), as your vet may need samples to examine and send to a diagnostic lab. 

Pregnancy Toxemia (Ketosis)

This metabolic disorder is most commonly seen in older, overweight does/ewes with multiple fetuses, 1-3 weeks before kidding/lambing. Ketosis is linked to prepartum mortality.

If there is a lack of nutritional energy in the later stages of the animal's pregnancy, the doe/body ewe's will use fatty tissue as a source of energy and milk production. The body's use of fatty tissue is generally not harmful, but excessive use releases an excess of ketones (toxic byproducts) into the bloodstream, potentially damaging the liver and kidneys.

Symptoms of pregnancy toxemia include:

  • Little or no appetite
  • Low energy or lethargy
  • Clumsiness or imbalance (many animals lay down and can't rise again)
  • Teeth grinding
  • Blindness
  • Coma

Herd history and symptoms will be used for diagnosis, and ketone levels can be tracked to determine a more accurate prognosis for the animal. 

Your veterinarian may treat the condition with propylene glycol, or another energy supplement if the disease is caught early on. 

To lessen the likelihood of ketosis in your pregnant animals, it's important to ensure they are eating well, especially at the later stages of pregnancy. It's also important to help them avoid stress or sudden changes in diet.

Caseous Lymphadenitis (CL)

Corynebacterium pseudotuberculosis bacteria can be found throughout the world. Sheep can develop Caseous Lymphadenitis (CL) after coming into contact with pus from an ill animal, or by ingesting contaminated food or water.

CL is characterized by the formation of internal and external abscesses containing thick, yellow-green pus with a foul odour. There is currently no cure, and the disease is diagnosed through a physical examination of the animal's body or blood tests.

Prevention is the best method to stop the spread of CL. Steps include:

  • Having the abscesses carefully drained to avoid ruptures and infection of healthy animals
  • Culling infected animals
  • Check CL history of farms and avoid purchasing animals with visible abscesses or abscess scars
  • Male animals should be carefully examined, as an infected male can spread CL to the females
  • Use clean needles for each animal, and thoroughly disinfect equipment (e.g. ear taggers, wool shears)
  • Consider a closed herd


Coccidiosis is caused by a parasite that is specific to the host (different animals are infected by different species of Coccidia). Sheep can consume oocytes while grazing or by drinking contaminated water (developing eggs). When the oocytes enter the animal's body, they infiltrate the intestinal lining cells and cause inflammation. Stressed children/lambs are predisposed to the condition, and outbreaks can occur during stressful events (e.g. farm relocation).

Signs of coccidiosis infection can include:

  • Watery diarrhea (may contain mucus or blood)
  • Constipation
  • No appetite (along with fever)
  • Dehydration
  • Weakness
  • Weight loss, emaciation
  • Hemorrhaging or ulcerations of the intestinal wall
  • Sudden death 

Your vet can diagnose the condition based on the health history of your herd, symptoms, and fecal examinations. Options for treatment include administering a vet-prescribed coccidiostat, whether via drenching or adding to the drinking water. If the animal is severely dehydrated, intravenous (IV) fluid therapy may be necessary until the animal is rehydrated.

Prevention and control can include:

  • Improving hygiene in facilities, pens, feeding areas and water sources, and pastures
  • Minimize kids'/lambs' stress during weaning
  • Avoid keeping animals in damp environments without direct sunlight
  • Be prepared for potential outbreaks post-weaning or during severe weather 

Contagious Ecthyma (Orf/Sore Mouth)

Orf is a zoonotic (transmissible from animal to human) disease that affects sheep through direct contact with the parapoxvirus. Infected animals typically show symptoms of the disease 2-5 days after exposure, lasting 1-2 weeks. Sore mouth is common in sheep after stressful events such as weaning, relocation, or transport.

The main symptom of orf is blisters that become wet scabs on the face (lips, nose, ears, eyelids) and is transmissible from nursing kids/lambs to the doe/ewe. The nursing female can develop extremely painful lesions on the teats and udder, which can even prevent them from eating. 

Diagnosis is based on physical symptoms, including where the lesions are located on the body, but a more conclusive diagnosis can be reached from virus isolation and an immunologic test.

Luckily, sore mouth usually resolves without intervention but in more severe cases your vet might prescribe antibiotics to fight secondary bacterial infections.

Prevention and management can include:

  • Avoid stress during transportation
  • Quarantine new animals for 6 weeks before integrating them into the herd
  • Separate sick animals for observation and treatment
  • Wear gloves when handling sick animals
  • Do not consume milk from does/ewes with lesions on the teats/udder
  • If recommended by your vet, have your animal vaccinated 

 Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets. For an accurate diagnosis of your pet's condition, please make an appointment with your vet.

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