Sheep Mastitis: Diagnosis, Ewe Treatment, and Lamb Nutrition Planning

At a Glance

Mastitis in ewes is inflammation of the mammary gland that reduces milk production, compromises lamb growth, and can lead to ewe mortality or culling. Clinical signs include a hot, swollen, painful udder, fever, and lameness. Subclinical mastitis is more prevalent than clinical disease and requires diagnostic testing such as the California Mastitis Test (CMT) or somatic cell count (SCC) measurement. Treatment involves antibiotics, non-steroidal anti-inflammatory drugs (NSAIDs), and frequent milk removal. Lambs from affected ewes require supplemental feeding and careful growth monitoring. The table below summarizes key decision points for managing mastitis in a sheep flock.

Clinical Presentation and Diagnosis

Recognizing Clinical Mastitis

Clinical mastitis in ewes presents with visible changes to the udder and the ewe's general condition. The affected gland becomes hot, swollen, and painful to touch. The ewe may show signs of systemic illness including fever, reduced appetite, and reluctance to move. Lameness on the hind leg on the affected side is common because the ewe shifts weight away from the painful udder. The milk appearance changes to clots, flakes, watery secretion, or blood-tinged fluid. In severe cases, the udder skin may become discolored blue or black, indicating gangrenous mastitis requiring immediate veterinary attention.

The Merck Veterinary Manual describes mastitis as inflammation of the mammary gland that can be caused by bacterial, mycoplasmal, or fungal infections. Clinical signs range from mild local inflammation to severe systemic disease. Early detection improves treatment success and reduces the risk of permanent udder damage.

Subclinical Mastitis Detection

Subclinical mastitis produces no visible changes in the udder or milk but reduces milk production and quality. It is more prevalent than clinical mastitis in most flocks. Detection requires diagnostic testing of milk samples.

The California Mastitis Test (CMT) is a practical on-farm screening tool. A study of New Zealand grazing dairy ewes found that a CMT score of 1 or higher in one or both glands occurred in 21.2% of ewes. The mean log10 SCC increased linearly with CMT score, but the correlation between the ewe's highest gland-level CMT score and SCC was moderate (Kendall's tau = 0.47). This means CMT is useful for screening but not perfectly predictive of SCC levels.

Somatic cell count (SCC) measurement provides a more quantitative assessment. In the same New Zealand study, the geometric mean SCC was 169,039 cells/mL, varying between farms and decreasing across lactation visits. A SCC threshold of approximately 400,000 cells/mL had the greatest Youden's index for diagnosing intramammary infection using a single SCC measurement. This threshold can guide decisions about which ewes need further investigation or treatment.

Milk culture remains the gold standard for identifying the causative organism. In the New Zealand study, bacteria were isolated from 9.9% of ewes, with the most common being non-aureus staphylococci (7.0% of glands) and Staphylococcus aureus (0.6% of glands). Knowing the pathogen helps select appropriate antibiotics and informs biosecurity measures.

Diagnostic Workup Steps

When investigating mastitis in a ewe, follow these steps:

1. Perform a complete physical examination including temperature, heart rate, respiratory rate, and udder palpation. Note any asymmetry, heat, swelling, or pain.
2. Collect a milk sample aseptically from each gland into a sterile container. Label clearly with ewe identification, date, and gland.
3. Perform a CMT on each gland using the test paddle and reagent. Score results as 0 (negative), trace, 1, 2, or 3 based on gel formation.
4. Submit milk samples for SCC measurement and bacterial culture if CMT is positive or if clinical signs are present.
5. Record all findings in the ewe's health record for tracking treatment response and identifying chronic cases.

Limitations of Diagnostic Methods

CMT is a subjective test with moderate correlation to SCC. False positives can occur in early lactation or with high milk protein content. False negatives are possible in late lactation or with low-grade infections. SCC thresholds for diagnosing intramammary infection vary between studies and farms. A single elevated SCC does not confirm infection, repeated testing improves accuracy. Milk culture requires 48 to 72 hours for results and may miss slow-growing or fastidious organisms. Proteomics-based biomarkers such as cathelicidin-1 and serum amyloid A show promise for earlier diagnosis but are not yet available as routine on-farm tests.

Treatment Protocols

Antibiotic Therapy

Antibiotic treatment for ovine mastitis should be based on milk culture and sensitivity results whenever possible. The choice of antibiotic depends on the identified pathogen, the ewe's withdrawal period requirements, and local regulations. Intramammary infusion of antibiotics is the standard route for lactating ewes, but systemic antibiotics may be needed for severe cases with systemic signs.

The Merck Veterinary Manual notes that treatment success depends on early intervention, complete course duration, and removal of infected milk. Antibiotics should be administered after the gland is milked out to improve distribution within the udder. Treatment typically continues for 3 to 5 days, but longer courses may be needed for chronic or severe infections.

Do not use antibiotics without a veterinary prescription. Withdrawal periods for milk and meat must be observed according to label instructions or veterinary directions. Record the product name, dose, route, frequency, duration, and withdrawal dates for each treated ewe.

Non-Steroidal Anti-Inflammatory Drugs

NSAIDs reduce inflammation, pain, and fever in ewes with mastitis. They improve the ewe's comfort and appetite, which supports recovery and milk production. Common NSAIDs used in sheep include flunixin meglumine and meloxicam. These drugs should be administered early in the treatment course, ideally at the first sign of clinical mastitis.

NSAIDs have withdrawal periods for meat and milk that must be followed. They should not be used in ewes with dehydration, kidney disease, or gastrointestinal ulcers. Veterinary guidance is essential for selecting the appropriate drug and dose.

Frequent Milk Removal

Removing infected milk from the gland is critical for treatment success. Milk the affected gland completely at least three to four times daily during the acute phase. This removes bacteria, inflammatory mediators, and toxins from the udder. It also reduces intramammary pressure and improves blood flow to the gland.

Hand milking is often necessary because the ewe may not tolerate machine milking due to pain. Gentle technique is important to avoid further tissue damage. Discard the milk from treated glands according to withdrawal periods. Do not feed this milk to lambs or other animals.

Supportive Care

Provide the ewe with clean, dry bedding and easy access to feed and water. Reduce stress by keeping her in a quiet area away from dominant flock members. Offer palatable feed to maintain body condition during the illness. Monitor temperature and appetite daily. If the ewe does not improve within 48 hours of starting treatment, re-evaluate the diagnosis and treatment plan with veterinary input.

Professional Escalation Criteria

Contact a veterinarian immediately if:

• The ewe shows signs of toxemia including depression, recumbency, or rapid breathing
• The udder skin becomes discolored blue, black, or purple (gangrenous mastitis)
• The ewe has a temperature above 41 degrees Celsius
• The ewe is unable to stand or shows neurological signs
• There is no improvement after 48 hours of treatment
• The ewe has recurrent mastitis in the same gland
• Multiple ewes develop mastitis within a short period, suggesting a flock problem

Impact on Lamb Nutrition and Growth

Milk Production Loss

Mastitis reduces milk production from the affected gland, and the reduction can persist even after clinical recovery. In ewes with unilateral mastitis, the healthy gland may partially compensate, but total milk yield is still lower than in unaffected ewes. Lambs nursing from ewes with mastitis receive less milk and may fail to gain weight adequately.

The reduction in milk production depends on the severity and duration of the infection. Chronic mastitis can cause permanent damage to the mammary tissue, leading to fibrosis and reduced functional capacity. Ewes with chronic mastitis may produce insufficient milk to support lamb growth, especially for twins or triplets.

Supplemental Feeding Strategies

Lambs from ewes with mastitis require supplemental nutrition to maintain growth. The choice of supplement depends on the lamb's age, the severity of milk loss, and the availability of alternative milk sources.

For newborn lambs (less than 24 hours old), colostrum is essential. If the ewe cannot provide colostrum due to mastitis, give colostrum from a healthy ewe on the farm or a commercial colostrum product. Aim for 200 mL of colostrum per kilogram of lamb body weight within the first 6 hours of life, divided into multiple feedings.

For lambs older than 24 hours, milk replacer is the primary supplement. Choose a lamb-specific milk replacer with 20 to 24 percent protein and 20 to 30 percent fat. Mix according to manufacturer instructions and feed at body temperature. Feed 150 to 200 mL per feeding, four times daily for the first week, then gradually reduce frequency as the lamb ages.

For lambs over 3 weeks old, introduce creep feed to supplement milk intake. Creep feed should contain 18 to 20 percent crude protein and be offered free-choice in a creep area that lambs can access but ewes cannot. Fresh water must always be available.

Weaning Decisions

Mastitis in the ewe may necessitate early weaning of lambs. The decision to wean depends on the lamb's age, weight, and ability to consume solid feed. Lambs can be weaned successfully at 6 to 8 weeks of age if they are eating at least 200 grams of creep feed per day for three consecutive days.

For lambs from ewes with chronic mastitis, early weaning reduces the nutritional demand on the ewe and allows her to recover body condition before the next breeding season. It also prevents lambs from nursing from a gland that may harbor infection.

Wean lambs gradually over 7 to 10 days to reduce stress. Move the ewe out of sight and hearing of the lambs. Provide the lambs with high-quality feed and fresh water in a clean, sheltered area. Monitor for signs of digestive upset such as diarrhea or bloat.

Growth Monitoring

Regular weighing of lambs is essential to detect growth problems early. Weigh lambs at birth, at 4 weeks, and at weaning. Compare weights to breed standards or farm targets. Lambs that fail to gain at least 200 grams per day in the first month of life may need additional supplementation.

Record lamb weights in a notebook or spreadsheet along with the ewe's mastitis history. This data helps identify ewes that consistently produce lambs with poor growth rates, indicating chronic udder problems that may warrant culling.

Prevention and Flock Health Management

Milking Hygiene

For dairy sheep operations, milking hygiene is critical for preventing mastitis. Clean and dry teats before milking using individual paper towels. Use a pre-milking teat dip with an effective disinfectant such as iodine or chlorhexidine. Allow contact time of 30 seconds before wiping dry.

Milking equipment should be maintained according to manufacturer specifications. Check vacuum levels and pulsation rates regularly. Replace rubber parts such as liners and hoses at recommended intervals. Clean and sanitize the milking system after each use.

For meat sheep operations where lambs nurse directly, udder health depends on lamb hygiene and ewe management. Keep lambing areas clean and dry. Remove soiled bedding regularly. Treat navel infections promptly to prevent spread to the udder.

Dry Ewe Therapy

Treating ewes with long-acting intramammary antibiotics at the end of lactation reduces the risk of mastitis in the next lactation. Dry ewe therapy is particularly useful for ewes with a history of mastitis or high SCC. The antibiotic remains in the udder during the dry period, eliminating existing infections and preventing new ones.

Consult a veterinarian for advice on which dry ewe therapy product to use. Withdrawal periods for meat must be observed after treatment. Record the product, dose, and treatment date for each ewe.

Culling Decisions

Ewes with chronic mastitis that does not respond to treatment should be culled. Signs of chronic mastitis include a hard, fibrotic udder, recurrent clinical episodes, and consistently high SCC. These ewes are unlikely to produce enough milk for lambs and may serve as a reservoir of infection for the flock.

Culling decisions should be based on records of mastitis episodes, treatment outcomes, and lamb growth data. Ewes that require treatment for mastitis more than once in a lactation are candidates for culling. Ewes whose lambs consistently fail to reach target weights due to poor milk production should also be considered for culling.

Biosecurity

Introducing new ewes to the flock is a risk factor for mastitis. Quarantine new arrivals for at least 30 days and test for mastitis using CMT or SCC before mixing with the main flock. Treat any infections before allowing the ewe to join the flock.

Separate ewes with clinical mastitis from the rest of the flock until treatment is complete. Use separate milking equipment or milk them last to avoid spreading infection. Practice good hand hygiene between handling affected and unaffected ewes.

Records and Measurements

Individual Ewe Records

Maintain a health record for each ewe that includes:

• Ewe identification number
• Date of each mastitis episode
• Affected gland (left, right, or both)
• Clinical signs observed
• CMT score and SCC result
• Milk culture results and pathogen identified
• Treatment given (product, dose, route, frequency, duration)
• Withdrawal dates for milk and meat
• Treatment outcome (recovered, chronic, culled)
• Lamb growth data for the current lactation

These records help identify ewes with recurrent problems and track the effectiveness of treatment protocols. They also support culling decisions and provide data for veterinary investigations.

Flock-Level Monitoring

Monitor flock mastitis prevalence by testing a sample of ewes at each lactation stage. The New Zealand study found that SCC and CMT results varied between farms and across lactation visits, so repeated testing provides more useful information than a single test.

Calculate the percentage of ewes with CMT scores of 1 or higher and the percentage with positive milk cultures. Track these metrics over time to detect changes in mastitis prevalence. Investigate any increase promptly to identify the cause and implement control measures.

Record the number of clinical mastitis cases per lactation and the number of ewes culled for udder problems. These data help evaluate the effectiveness of prevention programs and identify areas for improvement.

Common Failure Patterns

Delayed Treatment

Waiting too long to start treatment is a common cause of treatment failure. Mastitis progresses rapidly, and the window for effective treatment is narrow. Examine ewes daily during lambing and early lactation for signs of udder problems. Treat any ewe with a hot, swollen, or painful udder immediately.

Incomplete Treatment Course

Stopping antibiotics early because the ewe appears improved is a common mistake. Incomplete treatment allows surviving bacteria to multiply and may lead to relapse or antibiotic resistance. Complete the full course of antibiotics as prescribed, even if the ewe looks normal.

Inadequate Milk Removal

Failing to milk out the affected gland frequently enough reduces treatment effectiveness. Infected milk accumulates in the gland, diluting the antibiotic and providing a medium for bacterial growth. Milk the affected gland at least three to four times daily during treatment.

Ignoring Subclinical Mastitis

Subclinical mastitis is often overlooked because it causes no visible signs. However, it reduces milk production and can progress to clinical mastitis. Test ewes regularly using CMT or SCC and treat positive cases according to veterinary advice.

Poor Hygiene During Treatment

Introducing bacteria into the udder during intramammary infusion can cause new infections or worsen existing ones. Clean the teat end thoroughly with alcohol before inserting the infusion cannula. Use a new cannula for each gland and avoid touching the tip.

Welfare and Safety Context

Pain Management

Mastitis is a painful condition that compromises ewe welfare. Pain causes stress, reduces feed intake, and delays recovery. NSAIDs are essential for pain relief in clinical mastitis. Do not rely on antibiotics alone to manage the ewe's discomfort.

Ewes with severe mastitis may be unable to stand or move normally. Provide soft bedding and ensure they can reach feed and water without difficulty. Euthanasia should be considered for ewes with gangrenous mastitis or those that do not respond to treatment and are suffering.

Withdrawal Periods

Antibiotics and NSAIDs used to treat mastitis have withdrawal periods for milk and meat. These periods must be observed to prevent drug residues entering the food chain. Record the treatment date and calculate the withdrawal date for each product used.

Withdrawal periods vary between products and countries. Follow the label instructions or veterinary advice. Do not use milk from treated ewes for human consumption or for feeding lambs during the withdrawal period.

Zoonotic Risks

Some bacteria that cause mastitis in ewes can infect humans. Staphylococcus aureus can cause skin infections and food poisoning. Escherichia coli can cause gastrointestinal illness. Practice good hygiene when handling affected ewes and their milk. Wear gloves when milking or treating mastitis cases. Wash hands thoroughly after contact.

Decision Framework for Managing Mastitis Cases: A Triage and Treatment Protocol

Triage Categories Based on Clinical Severity

When a ewe presents with suspected mastitis, the first decision is to classify the case into one of three severity categories. This triage determines the urgency of intervention, the treatment setting, and the prognosis for recovery. The categories are based on physical examination findings, not on the duration of signs, because early aggressive treatment improves outcomes.

Category 1: Mild Local Mastitis

The ewe is bright and alert with a normal temperature below 40 degrees Celsius. The udder shows mild swelling and heat in one gland, but the ewe is not lame and continues to eat and drink. Milk appears slightly abnormal with a few clots or slightly watery consistency. The ewe can remain with the flock if separated by a temporary pen, but she should be monitored twice daily. Treatment can begin with NSAIDs and frequent milk removal while awaiting culture results. Antibiotics may be started empirically based on the farm's common pathogens, but culture-guided therapy is preferred.

Category 2: Moderate Mastitis with Systemic Signs

The ewe has a temperature between 40 and 41 degrees Celsius, reduced appetite, and mild depression. The affected gland is hot, swollen, and painful. The ewe is lame on the affected side and may lie down more than usual. Milk is visibly abnormal with clots, flakes, or watery secretion. The ewe should be moved to a hospital pen with clean bedding, easy access to feed and water, and shelter from weather. Treatment must begin immediately with NSAIDs and antibiotics. Milk the affected gland completely before each antibiotic infusion. Monitor temperature and appetite twice daily. If the ewe does not show improvement within 48 hours, escalate to veterinary consultation.

Category 3: Severe or Gangrenous Mastitis

The ewe is depressed, recumbent, or shows signs of toxemia including rapid breathing, weak pulse, or cold extremities. Temperature may be above 41 degrees Celsius or below normal in terminal cases. The udder skin is discolored blue, black, or purple, indicating tissue death. The gland may feel cold instead of hot due to compromised blood supply. This is an emergency requiring immediate veterinary attention. Do not attempt to treat gangrenous mastitis on farm without veterinary guidance. The ewe may need intravenous fluids, systemic antibiotics, and surgical drainage or amputation of the necrotic gland. In many cases, euthanasia is the most humane option.

Decision Tree for Antibiotic Selection

The choice of antibiotic should be guided by milk culture results whenever possible. However, treatment often begins before culture results are available. The following decision tree helps select an initial antibiotic based on the farm's historical pathogen profile and the ewe's clinical presentation.

Step 1: Review farm records for common pathogens

If the farm has previously identified Staphylococcus aureus as a common cause of mastitis, choose an antibiotic effective against gram-positive bacteria such as cloxacillin or cephalexin. If Escherichia coli or other gram-negative bacteria have been isolated, choose an antibiotic with gram-negative activity such as amoxicillin-clavulanic acid or a third-generation cephalosporin. If no farm history is available, choose a broad-spectrum antibiotic that covers both gram-positive and gram-negative bacteria.

Step 2: Consider the ewe's treatment history

If the ewe has been treated for mastitis within the same lactation, avoid using the same antibiotic class. Bacteria may have developed resistance. Choose a different class of antibiotic or request sensitivity testing from the laboratory.

Step 3: Administer the first dose after milking out the gland

Milking out the gland removes bacteria, inflammatory debris, and toxins. It also reduces intramammary pressure, allowing the antibiotic to distribute more evenly within the gland. Infuse the antibiotic using aseptic technique. Clean the teat end with an alcohol swab and allow it to dry before inserting the cannula. Use a new cannula for each gland.

Step 4: Re-evaluate at 48 hours

If the ewe shows significant improvement with reduced swelling, lower temperature, and improved appetite, continue the same antibiotic for the full course. If there is no improvement or the condition worsens, collect another milk sample for culture and sensitivity, and consult a veterinarian for a change in antibiotic.

Criteria for Switching from Intramammary to Systemic Antibiotics

Intramammary infusion is the standard route for lactating ewes with mastitis. However, systemic antibiotics may be needed in certain situations. The decision to switch routes should be based on the following criteria.

When to use systemic antibiotics:

• The ewe has a temperature above 40.5 degrees Celsius, indicating systemic infection
• The udder is severely swollen with edema extending up the abdominal wall
• The ewe is depressed, anorexic, or recumbent
• The ewe has gangrenous mastitis with tissue necrosis
• The ewe has recurrent mastitis in the same gland despite intramammary treatment
• The ewe has mastitis in both glands simultaneously

Systemic antibiotics such as oxytetracycline, amoxicillin, or ceftiofur can be administered intramuscularly or intravenously. They reach the udder through the bloodstream and may be more effective when tissue penetration is poor due to swelling or fibrosis. Combine systemic antibiotics with intramammary treatment for severe cases. Always follow veterinary guidance for systemic antibiotic use and observe withdrawal periods.

Monitoring Treatment Response Using a Scoring System

A standardized scoring system helps track treatment response objectively and identify cases that are not improving. Score the ewe daily on the following parameters.

Temperature score:

• 0: Normal temperature below 39.5 degrees Celsius
• 1: Mild fever 39.5 to 40.0 degrees Celsius
• 2: Moderate fever 40.0 to 41.0 degrees Celsius
• 3: Severe fever above 41.0 degrees Celsius or hypothermia below 38.0 degrees Celsius

Udder swelling score:

• 0: No swelling, gland soft and pliable
• 1: Mild swelling, gland slightly firmer than normal
• 2: Moderate swelling, gland noticeably enlarged and firm
• 3: Severe swelling, gland hard, tense, and painful

Milk appearance score:

• 0: Normal milk, no visible abnormalities
• 1: Slight abnormality, a few clots or slightly watery
• 2: Moderate abnormality, many clots, flakes, or watery secretion
• 3: Severe abnormality, blood-tinged, purulent, or no milk obtainable

Ewe demeanor score:

• 0: Bright, alert, eating and drinking normally
• 1: Mildly depressed, reduced appetite but still eating
• 2: Moderately depressed, not eating, drinking less
• 3: Severely depressed, recumbent, unable to stand

Add the scores from all four parameters to get a total daily score. A total score of 0 to 4 indicates mild disease that is likely to respond to treatment. A score of 5 to 8 indicates moderate disease requiring continued treatment and close monitoring. A score of 9 to 12 indicates severe disease that may require veterinary intervention. A score that does not decrease by at least 2 points within 48 hours of starting treatment indicates treatment failure and warrants re-evaluation.

Record System for Mastitis Treatment and Outcomes

A structured record system allows you to track individual ewe responses and identify patterns across the flock. Use a notebook or spreadsheet with the following columns for each mastitis case.

Ewe identification and case details:

• Ewe ID number
• Date of diagnosis
• Affected gland (left, right, or both)
• Triage category (1, 2, or 3)
• Initial total score from the monitoring system

Diagnostic results:

• CMT score for each gland
• SCC result if available
• Milk culture result and pathogen identified
• Antibiotic sensitivity pattern

Treatment details:

• Antibiotic product name and dose
• Route of administration (intramammary, systemic, or both)
• Frequency of administration
• Duration of treatment
• NSAID product name and dose
• Frequency of milk removal

Outcome tracking:

• Daily total score for the first 5 days of treatment
• Date of clinical recovery (total score of 0 for 2 consecutive days)
• Date of milk return to normal appearance
• Any adverse reactions to treatment
• Final outcome: recovered, chronic mastitis, culled, or died

Lamb management:

• Lamb ID numbers
• Lamb age at time of ewe's mastitis diagnosis
• Lamb weight at diagnosis
• Supplemental feeding type and amount
• Lamb weight at weaning
• Lamb weaning age

Review these records at the end of each lactation to identify ewes that should be culled and to evaluate the effectiveness of treatment protocols. If more than 20 percent of treated cases result in chronic mastitis or culling, review the treatment protocol with a veterinarian.

Troubleshooting Common Treatment Failures

When a ewe does not respond to treatment within 48 hours, investigate the following potential causes.

Incorrect diagnosis:

The swelling may not be mastitis. Udder edema in early lactation can mimic mastitis but does not respond to antibiotics. Abscesses in the udder tissue may require surgical drainage instead of antibiotics. Trauma from lamb nursing or fighting can cause swelling and pain without infection. Re-examine the ewe and collect a milk sample for culture to confirm infection.

Inappropriate antibiotic selection:

The antibiotic may not be effective against the causative bacteria. Staphylococcus aureus, for example, is often resistant to penicillin. Mycoplasma species do not respond to beta-lactam antibiotics. Request sensitivity testing from the laboratory and change the antibiotic based on results.

Inadequate dose or frequency:

The antibiotic dose may be too low to achieve therapeutic concentrations in the udder. Check the label instructions and ensure the dose is appropriate for the ewe's weight. Intramammary infusions may need to be given more frequently in severe cases, such as every 12 hours instead of every 24 hours.

Poor distribution of antibiotic:

Fibrosis or abscesses within the udder can prevent the antibiotic from reaching all infected tissue. Massage the gland gently after infusion to help distribute the antibiotic. In chronic cases, systemic antibiotics may reach areas that intramammary infusions cannot.

Reinfection during treatment:

Poor hygiene during intramammary infusion can introduce new bacteria into the udder. Review your aseptic technique. Use a new cannula for each infusion and clean the teat end thoroughly. If the ewe is housed in a dirty environment, move her to a clean pen.

Underlying immunosuppression:

Ewes that are underweight, parasitized, or stressed may not mount an effective immune response. Check the ewe's body condition score and treat any concurrent health problems. Provide high-quality feed and reduce stress by housing the ewe in a quiet area.

When to Discontinue Treatment and Consider Culling

Not all mastitis cases are treatable. Continuing treatment in a ewe that will not recover wastes time and money and prolongs the ewe's suffering. Consider culling in the following situations.

Gangrenous mastitis:

Once the udder tissue has died, it cannot be restored. The ewe will require ongoing care for a non-functional gland and is at risk of toxemia and death. Euthanasia is the most humane option for gangrenous mastitis.

No improvement after 5 days of treatment:

If the ewe's total score has not decreased after 5 days of appropriate treatment, the infection is unlikely to resolve. The ewe will likely develop chronic mastitis with permanent udder damage.

Recurrent mastitis in the same gland:

Ewes that develop mastitis in the same gland more than once in a lactation are unlikely to produce enough milk for lambs in future lactations. The gland may have structural damage that predisposes it to infection.

Bilateral mastitis:

Mastitis in both glands severely reduces milk production and makes it difficult to rear lambs. Even if the ewe recovers, she may not produce enough milk for twins or triplets.

Chronic mastitis with fibrosis:

A hard, fibrotic gland that does not soften after treatment will never produce normal milk. The ewe will be a poor milker and may serve as a reservoir of infection for the flock.

Poor lamb growth despite treatment:

If lambs from a ewe with mastitis consistently fail to reach target weights, the ewe's milk production is inadequate. Culling the ewe and focusing on ewes that produce healthy lambs improves flock productivity.

Professional Escalation Criteria for Flock Outbreaks

When multiple ewes develop mastitis within a short period, the problem may extend beyond individual cases. Contact a veterinarian if any of the following occur.

• More than 5 percent of the lactating flock develops clinical mastitis within a 2-week period
• Mastitis occurs in ewes that have no history of udder problems
• Mastitis occurs in ewes that were treated with dry ewe therapy
• The same pathogen is isolated from multiple ewes, suggesting a contagious source
• Mastitis occurs in ewes that have recently lambed, suggesting a problem with lambing hygiene
• Mastitis occurs in ewes that were milked with the same equipment, suggesting a milking machine problem

The veterinarian can investigate the cause by reviewing farm records, examining the milking system, collecting samples from the environment, and testing bulk tank milk. Control measures may include changes to milking hygiene, dry ewe therapy protocols, vaccination, or culling of carrier ewes.

Practical Implementation Steps for the Decision Framework

To implement this decision framework on your farm, follow these steps.

1. Print the triage categories and monitoring score sheet and keep them in the treatment area.
2. Train all staff who handle ewes to recognize the signs of mastitis and assign a triage category.
3. Designate a hospital pen for ewes with moderate or severe mastitis.
4. Stock the treatment area with NSAIDs, antibiotics, sterile infusion cannulas, alcohol swabs, and gloves.
5. Establish a relationship with a veterinarian who can provide guidance on antibiotic selection and treatment protocols.
6. Keep a record book or spreadsheet for mastitis cases and review it at the end of each lactation.
7. Set a threshold for culling based on your farm's goals. For example, cull any ewe that requires treatment for mastitis more than once in a lactation or that has a total score above 8 at the time of diagnosis.

This decision framework provides a structured approach to managing mastitis cases from diagnosis through treatment and outcome evaluation. It helps ensure that each ewe receives appropriate care based on the severity of her condition and that treatment failures are identified early. By tracking outcomes and reviewing records, you can continuously improve your mastitis management program and reduce the impact of this disease on your flock.

Frequently Asked Questions

How can I tell if a ewe has mastitis without a CMT kit?

Look for visible signs including a hot, swollen, or painful udder. The ewe may be lame on the hind leg on the affected side. Check the milk for clots, flakes, or watery appearance. Take the ewe's temperature, a fever above 40 degrees Celsius suggests infection. Compare both glands for symmetry and firmness. Any difference between glands warrants further investigation.

Can mastitis in ewes be treated without antibiotics?

Mild cases of mastitis may resolve with frequent milk removal and NSAIDs alone, but antibiotics are usually needed to eliminate the bacterial infection. Without antibiotics, the infection may become chronic or spread to other glands. Always consult a veterinarian before deciding to withhold antibiotics.

How long does it take for a ewe to recover from mastitis?

Clinical signs often improve within 24 to 48 hours of starting treatment. Complete recovery of milk production may take 1 to 2 weeks. Some ewes never regain full milk production in the affected gland. Chronic mastitis can persist for the remainder of the lactation.

What should I feed lambs if the ewe has mastitis?

For newborn lambs, provide colostrum from a healthy ewe or commercial colostrum within the first 6 hours. For older lambs, use lamb milk replacer fed at body temperature. Introduce creep feed from 3 weeks of age. Ensure fresh water is always available.

Can I milk a ewe with mastitis and feed the milk to lambs?

Do not feed milk from a ewe with mastitis to lambs. The milk contains bacteria, inflammatory cells, and toxins that can cause illness in lambs. It may also contain antibiotic residues if the ewe is being treated. Discard the milk or use it only for non-food purposes.

How do I prevent mastitis from spreading to other ewes?

Isolate affected ewes from the rest of the flock. Use separate milking equipment or milk affected ewes last. Practice good hand hygiene between handling ewes. Clean and disinfect any equipment that contacts the udder. Treat all clinical cases promptly to reduce the bacterial load in the environment.

When should I cull a ewe for mastitis?

Cull ewes that have recurrent mastitis episodes in the same gland, chronic mastitis that does not respond to treatment, or consistently produce lambs with poor growth rates due to low milk production. Ewes with severe udder damage such as fibrosis or abscesses should also be culled.

Is mastitis in ewes contagious to other livestock?

Some bacteria that cause mastitis in ewes can infect other species. Staphylococcus aureus can spread between sheep, goats, and cattle. Mycoplasma species may be species-specific. Practice biosecurity measures when moving animals between species groups. Consult a veterinarian for advice on specific pathogens on your farm.

Related Veterinary Guides

• Sheep Foot Health And Lameness Prevention
• Dairy Sheep Production Systems Breeds Milking And Flock Management
• Sheep Farming Flock Nutrition Grazing Lambing Parasite Risk And Welfare
• Beef Cow Pregnancy Diagnosis Records
• Dairy Cattle Farming Nutrition Housing Health Signals And Herd Management

References and Further Reading

• www.acvim.org
• Merck Veterinary Manual. Merck Veterinary Manual.
• Animal Health and Welfare. World Organisation for Animal Health.
• Sheep embryonic stem-like cells engrafted into sheep femoral condyle osteochondral defects: 4-year follow-up.. BMC veterinary research, 2018.
• Diagnosis of clinical or subclinical mastitis in ewes. 2014.
• Subclinical mastitis in New Zealand grazing dairy ewes 2: Relationships among somatic cell count, California Mastitis Test, and milk culture, and risk factors for elevated aerobic plate count.. Journal of Dairy Science, 2025.
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This article is educational and is not a substitute for veterinary diagnosis or treatment. Contact a veterinarian for advice about an individual animal.