Lungworm Infection in Cattle: Hoose Symptoms and Treatment
- Lungworm infection in cattle, also called hoose or parasitic bronchitis, is usually caused by the parasite *Dictyocaulus viviparus*.
- Common signs include coughing, faster breathing, reduced weight gain, exercise intolerance, and in more serious cases open-mouth breathing or respiratory distress.
- See your vet promptly if multiple grazing cattle start coughing, especially in late summer or fall, because early treatment usually leads to a better outcome.
- Your vet may diagnose lungworm based on grazing history, herd pattern, fecal larval testing such as a Baermann exam, and response to treatment.
- Treatment often includes a dewormer chosen by your vet, plus anti-inflammatory care or antibiotics when secondary bacterial pneumonia is also present.
What Is Lungworm Infection in Cattle?
Lungworm infection in cattle is a parasitic disease of the lower airways, most often caused by Dictyocaulus viviparus. You may also hear it called hoose, husk, or parasitic bronchitis. The parasite lives in the bronchi and smaller airways, where it causes irritation, inflammation, coughing, and sometimes pneumonia.
This condition is most often seen in grazing cattle, especially in moist conditions that help infective larvae survive on pasture. Young cattle in their first grazing season are often affected, but older cattle can get sick too if immunity is weak or exposure is heavy. Outbreaks can move through a group quickly.
Some cattle show only a mild cough and slower growth. Others develop marked breathing trouble, poor body condition, and secondary bacterial pneumonia. Severe cases can become emergencies, so a herd-level response with your vet matters.
Symptoms of Lungworm Infection in Cattle
- Frequent cough, especially at pasture or after moving cattle
- Faster breathing rate at rest
- Reduced weight gain, poor thrift, or drop in milk production
- Exercise intolerance or lagging behind the group
- Harsh lung sounds or noisy breathing
- Nasal discharge or signs of secondary pneumonia
- Open-mouth breathing, marked distress, or head and neck extended to breathe
- Sudden death in advanced or complicated cases
A mild cough in grazing cattle can be easy to miss at first. Concern rises when coughing becomes widespread in a group, breathing rate increases, or cattle lose condition. See your vet immediately if any animal has labored breathing, open-mouth breathing, weakness, or signs that pneumonia may also be present.
What Causes Lungworm Infection in Cattle?
Cattle get hoose by swallowing infective lungworm larvae while grazing contaminated pasture. Dictyocaulus viviparus has a direct life cycle, which means it does not need an intermediate host. Adult worms in the airways produce eggs that hatch into larvae, the larvae are coughed up and swallowed, and then passed in manure. Under warm, moist conditions, infective larvae develop on pasture and are eaten by other cattle.
Risk is highest where pasture contamination builds up. That can happen with continuous grazing, high stocking density, wet weather, irrigation, or when susceptible cattle are moved onto contaminated fields. First-season grazers are often most vulnerable, but adult cattle can also develop disease if prior immunity has faded.
The worms damage the airways directly, but the bigger problem is often the inflammation they trigger. That airway injury can set cattle up for secondary bacterial pneumonia, which is one reason some animals stay sick even after the parasites are killed.
How Is Lungworm Infection in Cattle Diagnosed?
Your vet usually starts with the pattern in the herd: grazing history, season, age group affected, and the type of cough or breathing change present. Lungworm is often suspected when several cattle on pasture begin coughing and showing reduced performance, especially in moist grazing conditions.
Testing may include a Baermann fecal exam to look for lungworm larvae in manure. This can be very helpful, but timing matters. Early infections may test negative before larvae are being shed, and severe disease can still be present even when test results are not straightforward. In some cases, your vet may also use tracheal samples, postmortem findings, or herd response to treatment as part of the diagnosis.
Because coughing cattle can also have viral or bacterial respiratory disease, your vet may need to sort through other causes. Accurate diagnosis matters before treatment, both for animal welfare and for proper drug choice, dosing, and withdrawal planning.
Treatment Options for Lungworm Infection in Cattle
Spectrum of Care means you have options. Here are treatment tiers at different price points.
Budget-Conscious Care
- Herd exam and pasture-risk review with your vet
- Targeted deworming plan using a labeled anthelmintic selected by your vet
- Move cattle off the highest-risk pasture when practical
- Monitoring breathing rate, appetite, and response over the next several days
- Treatment records and withdrawal-time review
Recommended Standard Treatment
- Veterinary herd assessment and confirmation plan
- Fecal larval testing such as Baermann exam when indicated
- Dewormer chosen by your vet based on label, production class, and withdrawal needs
- Anti-inflammatory treatment when airway inflammation is contributing to breathing difficulty
- Antibiotics when your vet suspects secondary bacterial pneumonia
- Follow-up plan for retreatment, pasture management, and monitoring
Advanced / Critical Care
- Individual exam of severely affected cattle
- Urgent treatment for respiratory distress under your vet’s direction
- Injectable or oral parasite treatment selected for the case
- More intensive anti-inflammatory and antimicrobial support when complications are present
- Possible oxygen support, close nursing, or hospital-level care where available
- Postmortem evaluation of losses to guide whole-herd prevention
Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.
Questions to Ask Your Vet About Lungworm Infection in Cattle
Bring these questions to your vet appointment to get the most out of your visit.
- Does this herd pattern fit lungworm, pneumonia, or both?
- Which cattle should be treated right away, and should the whole group be treated?
- Do you recommend fecal larval testing or other diagnostics before treatment?
- Which dewormer fits these cattle best based on age, production class, and withdrawal times?
- Do any of these animals also need anti-inflammatory care or antibiotics for secondary pneumonia?
- Should we move this group to a different pasture now, or could that create other problems?
- How soon should coughing and breathing improve after treatment?
- What prevention plan makes sense for next grazing season on this farm?
How to Prevent Lungworm Infection in Cattle
Prevention starts with pasture and grazing management. Youngstock do best on lower-risk pasture when possible, such as fields with less recent cattle contamination. Heavy stocking, continuous grazing, and wet conditions can all increase exposure. A farm-specific plan with your vet is the most practical approach.
Strategic parasite control may also be part of prevention, but timing matters. Repeated deworming without a larger herd plan can reduce exposure in a way that also limits the development of natural immunity, so prevention is not always as simple as treating more often. Your vet can help balance parasite control, immunity, and resistance concerns.
Watch closely for early coughing in grazing cattle, especially in late summer and fall. Fast action is important because cattle may respond poorly once there is major lung damage or a large burden of dying worms in the airways. If your farm has had lungworm before, ask your vet to build a written prevention plan before turnout.