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Code of Recommendations and Minimum Standards for the Welfare of Sheep

Diseases and their Control

Every sheep farmer should have an animal health programme which incorporates preventive measures to guard against internal and external parasitism, diseases of the feet and trace element deficiencies. It should include appropriate vaccinations against endemic diseases.

All sheep in which injury or disease is or seems likely to be causing severe or persistent pain, or distress, severe malaise or emaciation must be treated. If the appropriate treatment is not known or not available, a veterinarian must be consulted or the sheep humanely destroyed without delay.

Internal and External Parasitism

Internal Parasitism

Control of gastrointestinal parasitism is essential to ensure good health, production and welfare.

Sheep in their first year of life are particularly susceptible and generally require regular drenching with an effective drench. Thereafter an age-related resistance tends to develop, but parasitism may still occur.

Care must be taken to avoid damage of the throat by rough handling and drench guns with rough or damaged nozzles should not be used.

External Parasitism

Parasites such as lice, keds, ticks and blowflies can distress sheep by causing irritation and itchiness. They can also limit production while severe infestation by blowfly larvae can be fatal. Lice tend to build up over autumn and winter.

Sheep should be regularly inspected and any early infestations of external parasites treated promptly. Sheep should be kept as calm as possible during treatment.

Pour-ons are less stressful than plunge dips and saturation shower dips.

Sheep must not be plunge-dipped if they are panting. There must be at least one stock handler beside the plunge bath to supervise sheep as they are put through to ensure that no sheep is distressed unnecessarily.

Insecticides should be used according to the manufacturer’s instructions.


Flystrike can cause sheep extreme suffering. This may lead to reduced appetite, weight loss and sometimes death. Flystrike can occur at any time of the year but generally summer/early autumn is the period of highest risk.

Reasonable steps must be taken to control flystrike.

(Dipping technique recommendations can be found in the publication Fly and Lice: Numbering their Days, which you can order from Meat and Wool Innovation)

Trace Element Deficiencies

Many of New Zealand’s soils and pastures are deficient in the vital nutrients cobalt, selenium and/or copper. Farmers should monitor the trace element status of their sheep and provide supplements as appropriate.

Diseases Related to Feeding

The metabolic diseases milk fever (hypocalcaemia) and sleepy sickness (pregnancy toxaemia or acetonaemia) are diseases which occur in late pregnancy. Milk fever may occasionally occur during lactation. Grass staggers (hypomagnesaemia) can occur in ewes in early lactation. To detect early cases, stock should be observed closely for abnormal behaviour such as dullness or agitation. To be effective, treatment should be administered as soon as possible.

Many crops provide good nutrition in the short-term; however, with some of them there is a risk that nutritional deficiencies may occur or harmful amounts of damaging substances may be eaten. Among the diseases that can occur are brassica redwater, brassica white muscle disease, brassica goitre in neonatal lambs, rape scald and, on a variety of green feeds, nitrate poisoning.

Silage should be of good quality with a pH of less than 5 otherwise there is a risk of circling disease (cerebral listeriosis) and possibly abortions. Silage and hay should not be mouldy.

Digestive disorders can result from over consumption of any new feed particularly high energy feeds such as concentrates and grain (see Feed).

If there is any doubt about how to prevent, detect or treat diseases associated with feeding, advice should be obtained from a veterinarian or other animal health consultant.

Diseases of the Feet

Lameness can be a significant animal welfare issue. There are a variety of causes including arthritis, but most frequently the site of lameness is the foot. Arthritis may occur in newborn or recently docked lambs.

Footscald and footrot are common causes of lameness. If footrot is left untreated, arthritis in the foot joints or foot abscesses may develop and these are very difficult to treat effectively.

Sheep which are persistently lame should be treated or humanely destroyed.

Tooth Faults

Tooth faults may be a cause of or may contribute to ill-thrift in sheep and examination of the incisors should be included in investigations of ill-thrift.

Mechanical grinding of teeth to reduce their length must not be carried out.

Facial Eczema

With the exception of the southern part of the South Island, facial eczema occurs in much of New Zealand.

Facial eczema is caused by a fungus in the pasture. Toxins in the spores damage the liver and predispose the sheep to an exaggerated form of sunburn called facial eczema.

In summer and autumn, habitats known to favour high spore counts such as north-facing slopes, ridges and near hedges should be avoided.

If there is any doubts about prevention and treatment of the disease, advice should be obtained from a veterinarian or agricultural consultant.

Ryegrass Staggers

This disease is common in summer and autumn in all but the southern part of the South Island. It is caused by a fungal endophyte in ryegrass.

The signs are tremor of the head then the rest of the body, staggery gait and unco-ordination.

Affected animals usually recover spontaneously when no longer exposed to the toxin.

Bearings and Bearing Retention

Vaginal prolapses (“bearings”) may occur in ewes in late pregnancy. Predisposing factors include lush feed, a full rumen, pregnancy especially with two or more lambs in utero, overfatness, lack of exercise and hilly ground. Avoiding as many of these factors as possible will reduce the risk of bearings. Food intake should be moderate and regular.

Early action is essential if treatment is to be successful. Sutures and pins used to retain bearings must be removed when lambing is imminent. Whatever method is used to prevent vaginal prolapses, every effort must be made to minimise any additional pain or discomfort caused by their use and if there is any doubt about the method or technique, a veterinarian should be consulted.

Ewes must be destroyed humanely if the bearing has dried out, if it has been badly damaged or if it is not successfully retained.

Johne’s Disease

Johne’s disease is a bacterial disease which impairs digestion in the intestine. Affected sheep progressively lose weight even if treated until they become emaciated and die. Prevention by vaccination is an option on problem farms. Veterinary advice should be obtained regarding diagnosis and control. Affected sheep should be euthanased as early as possible both for welfare reasons and to help reduce the spread of infection.

Plant Poisoning

A variety of native and introduced plant species have the potential to poison sheep. Some appear to cause considerable distress and pain and may be fatal. Sheep should not be given garden plants or garden trimmings unless it is certain that the plants are not poisonous. Sheep should not be allowed access to native shrubs and trees unless the shepherd is confident that there are no poisonous species present.


A number of infectious diseases can be prevented by vaccination. These diseases include some clostridial diseases such as pulpy kidney disease, blackleg, black disease and tetanus. Other diseases are toxoplasmosis abortion, Campylobacter abortion, scabby mouth, salmonellosis, Johne’s disease and footrot. The vaccination programme for each farm should be devised in consultation with a veterinarian.

To reduce the risk of infection at the injection site, farmers should follow the vaccine manufacturer’s instructions carefully when vaccinating sheep as injection site lesions, if found at slaughter, may cause carcase downgrading or rejection.

Diseases in Organic Farming Systems

Successful organic farming systems require high levels of husbandry to avoid the stock health and welfare problems that can occur without the regular use of conventional vaccines and other animal remedies.

Veterinary and other appropriate expert advice should be obtained if organic remedies are ineffective in relieving pain and distress caused by disease or injury.

Breeding for Resistance to Disease

The susceptibility to many diseases may be partly hereditary. Gastrointestinal parasitism, facial eczema and footrot are among the most common diseases in New Zealand and susceptibility to these diseases can be reduced by selective breeding.


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