Lungworm in Sheep: Coughing, Breathing Problems, and Parasite Control

Quick Answer
  • Lungworm in sheep is a parasitic infection of the airways and lungs that can cause coughing, fast breathing, poor thrift, and reduced growth.
  • The main lungworm of sheep is *Dictyocaulus filaria*, though other lungworms can also contribute to chronic respiratory disease.
  • Mild cases may look like a lingering cough, but heavy burdens can lead to labored breathing, weakness, and secondary pneumonia.
  • Your vet may recommend fecal testing such as a Baermann exam, a physical exam, and sometimes response-to-treatment or herd-level parasite review.
  • Treatment often includes a deworming plan plus supportive care, with pasture and stocking management to reduce reinfection and resistance.
Estimated cost: $40–$350

What Is Lungworm in Sheep?

Lungworm is a parasitic infection that affects the breathing passages and lungs of sheep. The best-known sheep lungworm is Dictyocaulus filaria, a roundworm that lives in the respiratory tract. Other lungworms, including Muellerius capillaris and Protostrongylus rufescens, may also be involved in some flocks and can cause more chronic irritation.

Sheep with lungworm may cough, breathe faster than normal, or seem less active on pasture. Lambs and sheep under parasite stress are often affected more noticeably. In some animals, signs stay mild. In others, inflammation in the lungs can set the stage for bacterial pneumonia and more serious breathing trouble.

This condition matters because it can lower weight gain, reduce overall flock performance, and make sheep look like they have a routine respiratory infection when parasites are actually part of the problem. A cough that persists after weather changes, transport, or pasture moves is worth discussing with your vet.

Symptoms of Lungworm in Sheep

  • Dry or moist cough, especially after moving or exercise
  • Faster breathing than normal at rest
  • Increased effort to breathe or abdominal push with breathing
  • Nasal discharge in some cases
  • Reduced appetite or slower growth in lambs
  • Poor body condition or reduced thrift over time
  • Exercise intolerance, lagging behind the flock
  • Open-mouth breathing or severe distress in advanced cases

A mild cough can be the first clue, especially in lambs on pasture. More concerning signs include breathing harder at rest, weakness, fever, or a sheep that separates from the flock. Those findings raise concern for heavy parasite burden, pneumonia, or both.

See your vet immediately if a sheep has open-mouth breathing, blue or gray gums, marked lethargy, collapse, or cannot keep up with the flock. Breathing problems can worsen quickly, and lungworm is only one possible cause.

What Causes Lungworm in Sheep?

Lungworm infection starts when sheep graze infective larvae from contaminated pasture. With Dictyocaulus filaria, larvae are swallowed, develop in the body, and then migrate to the lungs and airways. Adult worms in the respiratory tract produce eggs or larvae that are passed out in feces, continuing the cycle.

Risk tends to rise when sheep are stocked densely, graze the same pasture repeatedly, or are exposed to wet conditions that help larvae survive. Young animals often have less immunity, so lambs may show more obvious signs. Stress, poor nutrition, and concurrent gastrointestinal parasite burdens can also make disease more noticeable.

Not every coughing sheep has lungworm. Bacterial pneumonia, viral respiratory disease, dust, poor ventilation, and other parasites can look similar. That is why flock history, pasture conditions, and diagnostic testing matter before choosing a treatment plan.

How Is Lungworm in Sheep Diagnosed?

Your vet usually starts with the basics: age of the sheep, recent pasture history, deworming history, body condition, temperature, and how the lungs sound on exam. A cough in multiple lambs after turnout or on contaminated pasture can raise suspicion, but symptoms alone are not enough for a firm answer.

Fecal testing is often part of the workup. A Baermann fecal exam is commonly used to look for lungworm larvae, and herd-level sampling may be helpful if several sheep are affected. Your vet may also use standard fecal flotation, especially when checking for mixed parasite problems, because sheep with lungworm often have other internal parasites at the same time.

If breathing is more severe, your vet may also assess for pneumonia and dehydration, and may recommend treatment based on the whole clinical picture. Negative fecal results do not always rule lungworm out, particularly if shedding is low or timing is early, so diagnosis may involve combining test results with exam findings and flock response over time.

Treatment Options for Lungworm in Sheep

Spectrum of Care means you have options. Here are treatment tiers at different price points.

Budget-Conscious Care

$40–$90
Best for: Mild coughing sheep that are still eating, walking normally, and not in obvious respiratory distress, especially when several flockmates have similar signs.
  • Targeted veterinary exam or herd consultation
  • Weight-based deworming plan using an appropriate labeled or veterinary-directed product
  • Basic isolation or reduced-stress pen rest for affected sheep
  • Pasture review and short-term management changes to lower reinfection pressure
  • Monitoring for appetite, breathing rate, and worsening cough
Expected outcome: Often good when treated early and when reinfection pressure is addressed.
Consider: Lower upfront cost, but less diagnostic confirmation. This approach may miss pneumonia, resistance issues, or another cause of coughing if signs do not improve.
Most Common

Recommended Standard Treatment

$90–$180
Best for: Most sheep with persistent cough, reduced thrift, moderate breathing changes, or unclear diagnosis.
  • Full veterinary exam
  • Fecal testing such as Baermann and/or flotation
  • Weight-based deworming plan tailored to flock history and likely resistance patterns
  • Supportive care such as anti-inflammatory medication, fluids, or nursing care when needed
  • Treatment plan for concurrent pneumonia risk if your vet suspects secondary infection
  • Follow-up plan for recheck and pasture parasite control
Expected outcome: Good to fair, depending on parasite burden, age, body condition, and whether secondary pneumonia is present.
Consider: More cost than a treatment-only approach, but gives better information for choosing the right parasite-control plan and reducing repeat problems.

Advanced / Critical Care

$180–$350
Best for: Sheep with open-mouth breathing, marked respiratory effort, collapse, severe weakness, or suspected pneumonia on top of parasite disease.
  • Urgent veterinary assessment for severe breathing difficulty
  • Expanded diagnostics and close monitoring
  • Injectable or oral medications as directed by your vet for parasites and secondary complications
  • Oxygen support or intensive nursing care when available
  • Fluid therapy and nutritional support for weak or dehydrated sheep
  • Detailed flock-level prevention strategy after stabilization
Expected outcome: Guarded to fair in severe cases, but some sheep recover well with prompt care.
Consider: Highest cost and may not be available in every field setting, but it is the most appropriate option when breathing compromise is significant.

Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.

Questions to Ask Your Vet About Lungworm in Sheep

Bring these questions to your vet appointment to get the most out of your visit.

  1. You can ask your vet whether this cough pattern fits lungworm, pneumonia, or both.
  2. You can ask your vet which fecal test is most useful for my flock right now, including whether a Baermann exam makes sense.
  3. You can ask your vet which dewormer class is appropriate for sheep in my area and whether resistance is a concern.
  4. You can ask your vet how to dose by accurate body weight and what withdrawal times apply for meat or milk in my operation.
  5. You can ask your vet whether affected sheep should be separated from the flock and for how long.
  6. You can ask your vet what signs mean a sheep needs urgent recheck, such as faster breathing, fever, or poor appetite.
  7. You can ask your vet how to adjust pasture rotation, stocking density, and manure exposure to reduce reinfection.
  8. You can ask your vet whether lambs, thin sheep, or recently stressed animals need a different monitoring plan.

How to Prevent Lungworm in Sheep

Prevention starts with flock-level parasite control, not repeated routine deworming without a plan. Work with your vet to build a program based on your region, pasture use, age groups, and parasite history. Strategic fecal testing can help identify when treatment is truly needed and can reduce pressure for drug resistance.

Pasture management matters. Avoid overcrowding, reduce repeated grazing of heavily contaminated areas, and pay close attention to lamb groups, which are often more vulnerable. Good nutrition and low-stress handling also support normal immunity and recovery.

It is also important to use dewormers thoughtfully. In the United States, sheep have a limited number of approved dewormer options, and resistance is a growing concern. Your vet can help choose an appropriate product, dose accurately by body weight, and review withdrawal times. If coughing keeps returning after treatment, ask your vet to reassess the diagnosis and the flock parasite-control plan rather than repeating the same product automatically.

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