Selective Deworming in Sheep and Goats: FAMACHA, Refugia and Resistance

By Dr Duncan Houston

Routine calendar deworming may feel like the safest way to protect lambs and goats from parasites. In reality, repeatedly treating every animal can rapidly select for worms that survive the available drugs.

Selective deworming takes a different approach. Animals are monitored individually, and only those showing evidence that parasites are compromising their health or performance are treated.

The approach can reduce drug use, preserve susceptible worms in refugia and identify animals that repeatedly struggle with parasites. However, selective treatment is more complicated than checking eyelid colour once a month and treating every animal with a score of 3.

FAMACHA© is valuable, but it detects anaemia associated mainly with Haemonchus contortus, the barber-pole worm. It does not identify every gastrointestinal parasite, confirm the cause of anaemia or tell you whether the selected dewormer still works.

Quick Answer

Selective deworming means treating only the sheep or goats that require treatment, while safely leaving healthier animals untreated. This preserves refugia and reduces unnecessary selection for anthelmintic resistance.

FAMACHA© scores of 4 or 5 generally require prompt treatment with an effective dewormer. A score of 3 is conditional and should be interpreted alongside age, lactation, body condition, weight change, bottle jaw, diarrhoea and local parasite risk. Faecal egg counts and post-treatment efficacy testing remain essential because FAMACHA© applies mainly to barber-pole worm anaemia. (Sheep 101)

Selective Parasite Control at a Glance

Tool	What it tells you	Main limitation
FAMACHA©	Degree of anaemia in an individual sheep or goat	Mainly useful for blood-feeding H. contortus
Five Point Check©	Anaemia, bottle jaw, condition, diarrhoea and nasal signs	Clinical signs are not specific to parasites
Faecal egg count	Egg shedding and pasture contamination	Does not perfectly equal adult worm burden or disease severity
Faecal egg count reduction test	Whether a dewormer is still effective on the farm	Requires correct sampling, dosing and interpretation
Weight and body-condition records	Whether an animal is performing as expected	One isolated measurement is much less useful than a trend
Larval culture or molecular testing	Which gastrointestinal nematodes are present	More specialised and may not be routinely available
Post-mortem worm count	Direct evidence of the parasite species and burden	Requires a suitable deceased or euthanased animal

An effective programme normally combines several of these tools rather than relying on one score or one pooled faecal sample.

What Is Selective Deworming?

Selective deworming, also called targeted selective treatment, means examining individual animals and treating only those that are clinically affected or likely to benefit.

Untreated animals continue carrying some parasites that have not been exposed to the drug. These susceptible parasites help dilute resistant genes when their offspring mix with the offspring of worms that survived treatment.

This is fundamentally different from:

• Treating every animal monthly

• Deworming solely because animals entered a new pasture

• Giving medication whenever faeces look abnormal

• Rotating drugs according to the calendar without testing efficacy

• Treating every animal after one high pooled faecal egg count

Targeted treatment must still protect welfare. Leaving a severely anaemic, underperforming or clinically ill animal untreated merely to preserve refugia is not sustainable parasite control. It is undertreatment. (wormx)

What Is Refugia?

Refugia is the proportion of the parasite population that is not exposed to an anthelmintic treatment.

It may include:

• Adult worms inside untreated animals

• Eggs and larvae already on pasture

• Immature stages not affected by a particular drug

• Worm populations in untreated management groups

These susceptible parasites are important because they reduce the proportion of the next generation that inherits resistance.

When every animal is treated and immediately moved onto a pasture with very few susceptible larvae, most of the eggs subsequently contaminating that pasture may come from resistant worms that survived treatment. Resistance then has a very tidy little breeding programme all to itself.

Selective treatment allows healthy animals to remain untreated, but the number safely left untreated depends on parasite species, climate, animal susceptibility, pasture contamination, production stage and the degree of resistance already present.

Why Does Blanket Deworming Drive Resistance?

Anthelmintics kill susceptible worms. Worms carrying resistance genes are more likely to survive, reproduce and pass those genes into the next generation.

The selection pressure becomes stronger when:

• Treatments are frequent

• Every animal is treated

• Animals are underdosed

• The same pasture receives mainly eggs from surviving resistant worms

• Ineffective drugs continue to be used

• New resistant parasites are introduced with purchased animals

• Long-acting drugs expose several generations of larvae to declining drug concentrations

Resistance does not develop because an individual sheep or goat becomes “used to” the medication. The parasite population changes genetically.

Selective treatment reduces how often worms are exposed while maintaining more susceptible parasites in refugia. It cannot reverse established resistance automatically, but it may slow further deterioration. (wormx)

What Does FAMACHA Actually Measure?

FAMACHA© compares the colour of the lower conjunctival mucous membrane with a standardised five-colour card.

The score estimates the degree of anaemia:

• Score 1: red

• Score 2: red-pink

• Score 3: pink

• Score 4: pink-white

• Score 5: nearly white

Its principal purpose is identifying anaemia caused by the blood-feeding barber-pole worm, Haemonchus contortus. It does not directly count worms, measure faecal egg shedding or determine which dewormer will work. (wormx)

How Should FAMACHA Scores Be Interpreted?

FAMACHA score	General interpretation	Typical response
1	Red, no visible anaemia	Do not treat solely on this score
2	Red-pink, acceptable	Usually leave untreated
3	Pink, borderline or moderate anaemia	Consider the entire animal and farm situation
4	Pink-white, marked anaemia	Treat promptly with an effective anthelmintic
5	White, severe anaemia	Urgent treatment and veterinary assessment

Animals with a score of 3 do not all need the same response.

Treatment becomes more appropriate when a score-3 animal is:

• A young lamb or kid

• A goat, particularly one with a history of rapid deterioration

• Pregnant or heavily lactating

• Losing weight or body condition

• Failing to achieve expected growth

• Showing bottle jaw

• Scouring

• Rough-coated or weak

• Progressing rapidly from a previous score of 1 or 2

• Grazing during a period of high barber-pole worm transmission

A strong, non-lactating adult with good weight gain, good body condition and no other abnormalities may be left untreated and rescored within approximately one week under an established farm protocol. (Sheep 101)

Is a FAMACHA Score of 5 an Emergency?

It can be.

A nearly white conjunctiva indicates severe anaemia, but the eyelid score does not show how well the animal’s circulation is compensating.

A score-5 animal that is standing, eating and responsive is still seriously affected. A score-5 animal that is weak, recumbent, breathing rapidly, cold or minimally responsive requires immediate veterinary treatment and supportive care.

Killing the worms does not instantly replace the blood already lost. Severely compromised animals may continue deteriorating after deworming unless dehydration, nutritional deficits, hypothermia and circulatory compromise are also addressed. (wormx)

How Do You Perform FAMACHA Correctly?

Producers should receive approved FAMACHA© training and use an authentic card. Printed internet copies and phone-screen colour charts are unreliable because colour reproduction changes between printers, screens and lighting conditions.

Correct technique includes:

1. Examine the animal in good natural daylight.

2. Cover the eye by rolling the upper eyelid over the eyeball.

3. Apply gentle pressure to the closed upper eyelid.

4. Pull the lower eyelid down so the conjunctival bed becomes visible.

5. Compare the conjunctiva directly with the card.

6. Check both eyes.

7. Use the higher score if the two eyes differ.

8. Round a borderline result upward rather than using half-scores.

Do not score only the thin inner surface of the lower lid or the third eyelid. Both may appear paler than the true conjunctival bed and can make the animal look more anaemic than it is. (wormx)

How Often Should Sheep and Goats Be Scored?

A fixed monthly schedule may be dangerously infrequent during peak barber-pole worm conditions.

As a practical starting point:

• Peak warm, moist transmission periods: score every 1 to 2 weeks.

• More than 10% of the group at scores 4 or 5: score at least weekly.

• Rapidly increasing scores or recent deaths: reassess the entire group immediately.

• Lower-risk periods: intervals may extend to approximately 3 to 4 weeks.

• Late pregnancy, lambing or kidding: increase monitoring because periparturient animals may become more susceptible.

• An untreated score-3 animal: recheck within approximately one week.

Local rainfall, temperature, pasture use and previous farm history should determine the schedule. Barber-pole worm outbreaks can develop far more quickly than the next date conveniently highlighted on the wall calendar. (wormx)

What Can FAMACHA Not Tell You?

FAMACHA© should not be used as the sole parasite-management tool.

It Does Not Detect Every Worm

Several important gastrointestinal nematodes do not feed heavily on blood and may cause disease without obvious conjunctival pallor.

These include parasites associated with:

• Diarrhoea

• Reduced appetite

• Poor weight gain

• Protein loss

• Reduced milk production

• General unthriftiness

Examples include Teladorsagia, Trichostrongylus and Nematodirus. Animals affected by these parasites may remain at FAMACHA scores 1 or 2 while performance deteriorates. (Sheep 101)

It Does Not Diagnose the Cause of Anaemia

A pale eyelid is evidence of anaemia, not proof of barber-pole worm infection.

Other possibilities include:

• Liver fluke

• Sucking lice

• Coccidiosis with intestinal blood loss

• Chronic inflammatory disease

• Johne’s disease

• External or internal bleeding

• Severe nutritional deficiency

• Concurrent disease affecting red-cell production

A persistently poor FAMACHA© score after apparently effective treatment should trigger reassessment rather than an immediate repeat of the same dewormer. (wormx)

It Does Not Measure Egg Shedding

An animal may remain clinically well and have an excellent FAMACHA© score while shedding large numbers of parasite eggs onto pasture.

That animal is resilient, meaning it tolerates infection without becoming clinically ill. It is not necessarily resistant, which would mean it carries fewer worms and sheds fewer eggs.

Faecal egg counts are required to distinguish animals that remain healthy despite infection from those that genuinely carry lower worm burdens. (wormx)

What Is the Five Point Check?

The Five Point Check© expands clinical assessment beyond anaemia.

It evaluates:

1. Eye: FAMACHA© score for anaemia

2. Jaw: bottle jaw or submandibular oedema

3. Back: body condition

4. Tail: faecal soiling or diarrhoea

5. Nose: nasal discharge, including possible nasal bots

For goats, coat quality may provide additional information.

This helps identify animals that may need treatment despite a reasonable FAMACHA© score and guides decisions for borderline score-3 animals.

For example, a score-3 animal with falling body condition, bottle jaw or marked faecal soiling is more concerning than a score-3 animal maintaining normal growth and condition. (Sheep 101)

The Five Point Check© is still not a definitive diagnosis. Poor condition may reflect inadequate nutrition, dental disease or chronic infection. Diarrhoea may be caused by diet, coccidiosis, bacteria or toxins rather than nematodes. Clinical signs must be interpreted with farm history and diagnostic testing.

What Is the Role of Faecal Egg Counts?

Faecal egg counts can help answer three different questions.

How Much Pasture Contamination Is the Group Producing?

A pooled or group mean count provides an estimate of egg output and pasture contamination.

It is not a perfect measurement of disease severity. Different parasite species produce different numbers of eggs, and immature parasites can cause disease before egg laying begins.

Which Animals Are More Resistant?

Individual counts can identify persistent high and low egg shedders.

This is useful for:

• Breeding selection

• Identifying susceptible animals

• Deciding which replacements to retain

• Understanding which animals contribute most heavily to pasture contamination

A relatively small proportion of animals frequently contributes a disproportionately large percentage of the eggs contaminating pasture. (wormx)

Did the Dewormer Work?

A faecal egg count reduction test compares counts before and after treatment in the same animals.

Current WAAVP guidance provides a formal framework for detecting resistance. Simpler field protocols commonly compare pre-treatment samples with samples collected approximately 10 to 14 days later, although the ideal timing varies by active ingredient and regional protocol. A reduction below the expected efficacy, traditionally around 95%, raises concern and should be interpreted with confidence intervals, egg counts, dose accuracy and parasite identification. (waavp)

Testing one animal tells you whether that animal appeared to respond. It does not establish the resistance status of the farm. A properly designed test generally requires a suitable group of animals and professional interpretation.

What Did the Three-Year Lamb and Goat Study Actually Show?

The study behind the original article followed six grazing groups over three years. Each group contained six Suffolk lambs, six Katahdin lambs and six meat-goat kids. Three groups received whole cottonseed at 0.5% of body weight, while three groups did not receive the supplement. Animals were monitored using FAMACHA© scores, faecal egg counts and blood measurements. (Results Verification System)

Finding 1: Selective Treatment Reduced Dewormer Use

Using FAMACHA© to guide retreatment reduced the number of dewormer doses by approximately 54% to 56% compared with the theoretical practice of dosing every animal monthly. (ARS)

That is the most practically important finding.

It demonstrates that many animals could remain untreated for longer periods without simply dosing the entire flock or herd by calendar.

Finding 2: Katahdin Lambs Had Lower Parasite Measures

Katahdin lambs had:

• Lower faecal egg counts

• Better albumin and globulin patterns

• Lower FAMACHA© scores

• Longer intervals before retreatment

The average time from the initial treatment to the next required treatment was approximately:

• 77 days for Katahdin lambs

• 67 days for Suffolk lambs

• 33 days for goat kids

The goat kids required the most frequent treatment and had the highest FAMACHA© scores within this particular study. (ARS)

These findings support genetic and species differences, but they do not mean every Katahdin is resistant or every goat will perform poorly. Individual variation remains substantial.

Finding 3: Whole Cottonseed Did Not Reduce Egg Counts

Whole cottonseed did not reduce faecal egg counts and did not improve FAMACHA© scores at the tested inclusion level. Supplemented animals generally gained weight faster, but their egg counts tended to be as high as or higher than those of unsupplemented animals. (ARS)

This suggests improved resilience rather than improved resistance.

The animals may have coped with infection and grown more successfully, but the supplement did not reliably reduce infection or pasture egg contamination.

A newer goat study similarly found that cottonseed supplementation at the tested level did not significantly control H. contortus infection, although changes in physiology and rumen microbiology remained scientifically interesting. (PubMed Central (PMC))

Does Protein Supplementation Help With Parasites?

Adequate protein and energy support:

• Red-cell production

• Immune function

• Repair of gastrointestinal tissue

• Maintenance of albumin

• Growth

• Lactation

• Recovery from blood loss

• General resilience against infection

Young animals, late-pregnant females, lactating females and animals grazing poor-quality forage may be unable to meet both production and immune demands without nutritional support. (wormx)

This does not mean protein is a dewormer.

Nutrition can help an animal tolerate parasite challenge and recover after treatment. It will not reliably remove an established Haemonchus burden, correct severe anaemia overnight or restore the efficacy of a drug to which the farm’s worms are resistant.

A ration should be balanced according to:

• Forage analysis

• Energy requirements

• Protein requirements

• Mineral status

• Age

• Pregnancy or lactation

• Growth targets

• Existing body condition

• Other feeds already supplied

Should Whole Cottonseed Be Used?

Whole cottonseed can provide protein, energy and fibre. Its suitability depends on price, availability, the rest of the ration and the class of stock being fed.

It should not be added specifically as an assumed antiparasitic treatment.

Cottonseed also contains gossypol. Excessive long-term exposure may cause:

• Cardiac injury

• Anaemia

• Liver damage

• Reduced sperm production

• Reproductive problems

• Weakness

• Sudden death in severe toxicosis

Immature ruminants and animals with incompletely developed rumens are more vulnerable, and goats may be more sensitive than cattle. Any cottonseed ration should therefore be formulated rather than estimated with a bucket and optimism. (Merck Veterinary Manual)

Do Breed Differences Matter?

Yes, but breed is only one part of the picture.

Hair-sheep breeds such as Katahdins often demonstrate better parasite resistance or resilience than many traditional wool breeds. Resistant native and hair-sheep populations have also contributed useful genetics to low-input production systems.

Within any breed, however, there are:

• High egg shedders

• Low egg shedders

• Animals that remain productive despite infection

• Animals that repeatedly become anaemic

• Families that require more treatments than others

Goats generally develop less effective acquired immunity against gastrointestinal nematodes than sheep and may require closer monitoring, particularly during growth, lactation and periods of high pasture challenge.

Breeding decisions should therefore use individual records, including:

• Faecal egg counts

• FAMACHA© trends

• Treatment frequency

• Growth

• Body condition

• Reproductive status

• Comparable management groups

A breed label is useful context. It is not a laboratory result. (ARS)

How Worried Should You Be?

Lower Risk

The animal has:

• FAMACHA© score 1 or 2

• Normal appetite

• Expected growth or stable weight

• Normal body condition

• No bottle jaw

• No diarrhoea

• Normal activity

Action: Leave untreated unless another diagnostic finding indicates treatment. Continue scheduled monitoring and record the result.

Moderate Risk

The animal has:

• FAMACHA© score 3

• Mildly reduced growth

• Early loss of body condition

• A rough coat

• Mild faecal soiling

• A high-risk age or production stage

• A worsening score compared with the previous check

Action: Assess the full Five Point Check©, recent weight trend, group egg counts and local risk. Treat vulnerable or deteriorating animals. If the animal remains untreated, reassess within approximately one week.

High Risk

The animal has:

• FAMACHA© score 4

• Bottle jaw

• Marked weight loss

• Reduced appetite

• Significant diarrhoea

• Weakness

• Poor milk production

• Rapid worsening over several days

Action: Treat promptly with an anthelmintic known or expected to be effective on that farm. Move the animal to a low-stress area with easy access to feed and water. Arrange veterinary assessment if weakness, dehydration or significant protein loss is present.

Critical

The animal has:

• FAMACHA© score 5

• Inability to stand

• Collapse

• Severe weakness

• Rapid or laboured breathing

• Marked tachycardia

• Cold extremities or hypothermia

• Minimal responsiveness

• Severe dehydration

• A rapid rise in deaths across the group

Action: Seek immediate veterinary treatment. Deworming alone may not be enough. Circulatory support, fluids, nutritional support and other emergency treatment may be required. (wormx)

What Else Can Look Like a Worm Problem?

Finding	Important alternative explanations
Pale eyelids	Liver fluke, blood loss, sucking lice, coccidiosis, chronic disease or nutritional deficiency
Bottle jaw	Barber-pole worm, liver fluke, severe protein loss, Johne’s disease or malnutrition
Diarrhoea	Other nematodes, coccidiosis, dietary change, bacterial enteritis or toxins
Poor body condition	Inadequate nutrition, dental disease, chronic infection, lameness or social competition
Rough coat	Parasites, poor nutrition, trace-mineral imbalance or chronic disease
Poor growth	Parasites, coccidiosis, inadequate milk or feed, respiratory disease or genetic limitations
Treatment failure	Resistance, underdosing, wrong drug, reinfection, incorrect diagnosis or poor administration

Repeatedly deworming an animal that remains anaemic or unthrifty can delay the correct diagnosis while adding further resistance pressure. (wormx)

When Is This an Emergency?

Seek immediate veterinary help when a sheep or goat has:

• Nearly white conjunctiva

• Collapse

• Recumbency

• Severe weakness

• Open-mouth or markedly laboured breathing

• A very rapid heart rate

• Inability to eat or drink

• Severe dehydration

• Marked bottle jaw with weakness

• Sudden deterioration after apparently successful treatment

• Multiple deaths or down animals within the group

A severe barber-pole worm burden can remove blood faster than the animal can replace it. The animal may die from anaemia and circulatory compromise even after the worms have been killed.

The most compromised animals should be protected from weather, long walking distances, competition and additional pasture exposure while receiving direct veterinary care. (wormx)

What To Do Right Now

1. Determine Whether Barber-Pole Worm Is Actually the Main Risk

Review:

• Climate and rainfall

• Season

• Previous larval cultures or molecular testing

• Necropsy findings

• Faecal egg counts

• Previous history of anaemia

• Local veterinary advice

FAMACHA© is most useful where H. contortus is an important component of the parasite population.

2. Obtain Proper FAMACHA Training

Use an authentic card and train every person who will score animals.

Different staff members should periodically score the same animals to check consistency.

3. Set a Risk-Based Monitoring Interval

Do not default to one check per month.

Increase monitoring during:

• Warm, wet weather

• Rapid pasture contamination

• Weaning

• Late pregnancy

• Early lactation

• Group outbreaks

• Periods when scores are worsening

4. Record Individual Results

Record:

• Animal identification

• FAMACHA© score

• Body condition

• Weight

• Faecal-soiling score

• Bottle jaw

• Treatment

• Dose

• Drug class

• Response

• Date of next assessment

Records reveal the animals that repeatedly need treatment and help distinguish a genuine outbreak from one chronically susceptible individual.

5. Treat the Animal, Not Just the Score

A score of 3 needs context.

A score of 4 or 5 requires prompt action, but severe illness also requires supportive care.

6. Weigh Before Dosing

Underdosing selects for resistance and may leave clinically important worms alive.

Use accurate scales and:

• Dose according to the current product instructions

• Weigh rather than estimate

• Split groups when body weights vary widely

• Calibrate the drench gun

• Check that the full dose is swallowed

• Follow species-specific veterinary advice

• Observe meat and milk withdrawal requirements

Goat dosing and legal product use vary between drugs and jurisdictions. Do not automatically copy a sheep dose or use an off-label regimen without veterinary direction. (SCOPS)

7. Confirm That the Treatment Worked

Perform a post-treatment faecal egg count or formal reduction test according to the selected drug and laboratory protocol.

If an animal remains pale after treatment, consider:

• Severe anaemia requiring time to recover

• Poor nutrition

• Immediate reinfection

• Anthelmintic resistance

• Incorrect dosing

• Liver fluke

• Coccidiosis

• Sucking lice

• Another chronic disease

8. Preserve Refugia Safely

Leave clinically healthy, well-performing animals untreated when the farm protocol supports doing so.

Do not leave:

• Score-4 or score-5 animals untreated

• Young animals with rapid decline untreated

• Animals with bottle jaw or major performance loss untreated

• Entire vulnerable groups unmonitored

9. Reduce Pasture Exposure

Infective larvae are concentrated mainly within the lower several inches of forage.

Useful strategies include:

• Avoid grazing below approximately 4 inches

• Maintain appropriate stocking density

• Provide browse and taller forage

• Use low-risk paddocks for lambs, kids and lactating females

• Harvest contaminated paddocks for hay where practical

• Alternate with cattle or horses

• Rest pasture for a climate-appropriate period

• Keep animals away from persistently wet congregation areas

Simple pasture rotation does not automatically solve the problem. If animals return while infective larvae remain alive, they may encounter the same burden waiting politely for their return. (wormx)

10. Improve Nutrition

Use forage testing and ration formulation to meet energy, protein and mineral requirements.

Nutrition should support immunity and recovery without being marketed as a replacement for effective parasite treatment.

Should Dewormer Classes Be Rotated?

Routine calendar rotation is no longer considered a reliable strategy for preventing resistance.

Moving from one drug to another without knowing their efficacy may mean rotating from a partially effective treatment to one that works even less well.

Farm-specific combination treatment may improve efficacy and delay further resistance when:

• Different active classes are selected appropriately

• Each retains useful activity

• Full doses are given

• Products are administered correctly

• The combination is legal

• Withdrawal periods are observed

• Efficacy is subsequently tested

Do not mix different commercial products into the same container or drench gun unless the combination is specifically formulated and licensed that way. Sequential products should be administered according to professional advice. (wormx)

The best drug programme is based on farm efficacy data, parasite species and local regulation, not a universal list copied from another producer.

Common Selective Deworming Mistakes

Treating Every FAMACHA Score of 3 Automatically

Score 3 is a decision point, not an automatic prescription.

Using FAMACHA for Every Parasite

It mainly detects anaemia from barber-pole worm. Animals can have severe non-blood-feeding parasite disease with red eyelids.

Scoring Only Once a Month in Peak Season

A susceptible kid or lamb can deteriorate rapidly during warm, wet conditions.

Using a Printed Internet Card

Printer and screen colours are not reliable enough for clinical scoring.

Scoring Under Artificial Light

Lighting changes perceived conjunctival colour.

Treating Without Knowing Whether the Drug Works

A perfectly selected animal still receives no benefit from an ineffective dewormer.

Estimating Body Weight

Underdosing increases the probability that resistant worms survive.

Rotating Drug Classes Blindly

Rotation without efficacy testing does not prevent resistance.

Assuming Whole Cottonseed Is Antiparasitic

The key three-year study found no reduction in faecal egg counts or improvement in FAMACHA© scores.

Treating the Entire Group and Immediately Moving to a Clean Pasture

This may leave the new pasture to be contaminated predominantly by resistant survivors.

Using Breed Alone To Make Treatment Decisions

Katahdins may perform better on average, but susceptible individuals exist in every breed.

How Can Parasite Control Become More Sustainable?

A strong programme combines:

1. Risk-based FAMACHA© monitoring

2. Five Point Check© assessment

3. Individual weight and body-condition records

4. Faecal egg counting

5. Routine testing of dewormer efficacy

6. Accurate dosing

7. Refugia

8. Appropriate pasture management

9. Good protein, energy and mineral nutrition

10. Genetic selection for lower egg counts and fewer treatments

11. Quarantine and testing of new animals

12. Rapid necropsy or worm counts during unexplained outbreaks

The goal is not to eliminate every parasite from every animal. That is rarely realistic and would create intense resistance pressure.

The goal is to prevent clinical disease and production loss while retaining effective treatments for the animals that genuinely need them.

Frequently Asked Questions

Does every FAMACHA score of 3 need deworming?

No. Score 3 should be interpreted with age, lactation, body condition, weight trend, bottle jaw, diarrhoea and parasite risk. Vulnerable or deteriorating animals are usually treated, while a strong adult may be monitored and rescored within about one week.

Can FAMACHA replace faecal egg counts?

No. FAMACHA identifies anaemia, mainly from barber-pole worm. Faecal egg counts help assess egg shedding, pasture contamination, individual resistance and drug efficacy.

Did whole cottonseed reduce parasites in the lamb and goat study?

No. Whole cottonseed did not reduce faecal egg counts or improve FAMACHA© scores at the tested level. It improved weight gain, which may indicate greater resilience rather than lower infection. (ARS)

Should dewormers be rotated every few months?

Not simply to prevent resistance. Drug choice should be based on farm-specific efficacy testing. Carefully selected combinations may be appropriate, but they require correct full dosing and veterinary oversight.

How soon should animals be checked after treatment?

Clinically anaemic animals should be observed daily and rescored over the following one to two weeks. Dewormer efficacy testing is commonly performed within approximately 7 to 14 days depending on the active ingredient and protocol.

Final Thoughts

Selective deworming is one of the most useful tools available for protecting small-ruminant health while slowing anthelmintic resistance.

The important distinctions are:

1. FAMACHA© measures anaemia, not total parasite burden.

2. It is mainly useful for Haemonchus contortus.

3. Scores 4 and 5 require prompt treatment.

4. Score 3 requires clinical judgement.

5. Young, lactating and poorly conditioned animals deserve a lower treatment threshold.

6. Faecal egg counts identify egg shedding and help select resistant animals.

7. Post-treatment testing determines whether a dewormer still works.

8. Refugia helps dilute resistant parasite genes.

9. Accurate dosing is essential.

10. Routine calendar rotation does not solve resistance.

11. Protein and energy support resilience but do not replace deworming.

12. Whole cottonseed did not reduce parasite egg counts in the key three-year study.

13. Genetics matter, but individual records matter more than breed labels.

14. Severe anaemia requires more than an injection of dewormer.

15. Parasite control must integrate animals, pasture, nutrition, diagnostics and treatment.

The mistake that costs producers the most is waiting until deworming stops working before testing whether it works. Build the programme around evidence while effective options remain available.

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ASK A VET™ can help organise FAMACHA© records, body weights, treatment frequency, faecal egg counts, efficacy-test results and pasture history while producers work directly with their livestock veterinarian. A sheep or goat with white eyelids, collapse, severe weakness or breathing difficulty still requires immediate hands-on veterinary care.