This disease affects breeding age sows. The key clinical signs include inappetence at farrowing; swollen teats; fever.
calendar icon 8 November 2018
clock icon 9 minute read

Background and history

Mastitis denotes inflammation and infection of the mammary glands. It is a common condition that occurs sporadically in individual sows or sometimes as herd outbreaks. It is primarily a condition seen in the lactating sow. Nevertheless it can be a problem in the dry period with new cases occurring within two days of weaning.

It starts around farrowing and becomes clinically evident up to 12 hours later. It can arise because bacteria have gained entry to one or more mammary glands for the first time, or it may be a flare-up of a long-standing sub-clinical latent infection. It sometimes arises as a sequel to udder oedema possibly due to poor milk flow.

The route of entry of the bacteria is probably the teat orifice but it may be from the blood stream or by injection on piglets' teeth. It also commonly occurs at weaning time.

If left untreated it can become chronic with thick fibrous scar tissue and large lumps which ultimately may ulcerate to the surface. Chronic mastitis may occur at weaning time when the udder is dried off, the gland having become infected in lactation.

The bacteria that cause mastitis in the sow can be grouped into three broad categories: coliform bacteria, staphylococci and streptococci, and miscellaneous bacteria. Limited surveys suggest that coliform mastitis is the most common and usually most serious, staphylococcal and streptococcal mastitis fairly common and usually less serious, and miscellaneous bacteria uncommon and varying in seriousness in the individual sow.

Coliform mastitis

Coliform bacteria are related to E. coli, the commonest being E. coli itself and klebsiella. They produce a severe acute mastitis which results in reduced milk yield, a very ill sow and poor piglets.

Herd problems can develop because the organisms are present in faeces and may also be in sows' urine. Consequently, they may be everywhere in a piggery. Coliform mastitis may thus be regarded as environmental in origin.

Staphylococcal and streptococcal mastitis

These are usually less acute and less severe than coliform mastitis. They tend to occur sporadically in individual sows in one or more glands and usually do not make the sow ill. The exception is an acute severe staphylococcal infection, usually in a single gland, which becomes swollen, hard and discoloured and makes the sow toxic.

Unlike coliform bacteria the source of these organisms is not usually the contaminated environment but the skin and possibly orifices of the sow herself. There is some evidence to suggest that as in the dairy cow and sheep some of these bacteria may persist sub-clinically in the udder and then flare up at or after farrowing

Miscellaneous bacteria

These include organisms such as pseudomonas which can produce a serious mastitis and toxaemia and which are often resistant to antibiotic treatment. Fortunately such infections are rare.

Clinical signs

These are seen within 2 to 4 days of weaning.

  • Inappetence at farrowing or before if mastitis is already developing.
  • Obviously ill.
  • Will not suckle.
  • Fever – temperature range from 40–42ºC (104–107ºF).
  • Mucous membrane of her eyes are brick red.
  • Affected glands swollen, red colour and painful.
  • Discoloration of the ears and the whole of the udder, but particularly over the affected glands.
  • Blue skin.
  • Mammary tissue is infiltrated with hard lumps that are usually not painful when palpated.
  • They may ulcerate to the surface and become a potential source of infection to other sows.
  • In severe infections toxins are produced and sows may die within 24 hours.


Piglets of a sow with mastitis will be hungry, thin and squealing due to lack of milk.

The clinical signs are usually sufficient to diagnose mastitis. It is very important that mastitis is diagnosed early and that prompt treatment is given.

The sow's udder should be examined routinely at two days after weaning and also while the sow stands at mating, to look and feel for chronic mastitis.

If there is a herd problem with a number of sows affected, you should examine all animals clinically at farrowing and again at weaning, to determine the starting point of the mastitis. A sample of the secretions from the infected quarters should be submitted to a laboratory for examination. This is carried out by wiping the teat end with cotton wool soaked in surgical spirit, injecting the sow with 0.5ml of oxytocin and once there is a good flow squirt the milk on to a sterile swab. The swab should be immersed in a transport medium.

If the prevalence is more than two percent of the dry sow population then an investigation should be carried out to assess the reasons why and to determine where the mastitis is starting. This could be in the immediate post farrowing period, during lactation or at weaning time.


  • The continual use of farrowing houses.
  • Poor farrowing pen hygiene, bad drainage, inadequate and poor quality bedding.
  • The use of saw dust or shavings for bedding that become soaked in water or urine.
  • A warm temperature for the organisms to multiply.
  • Worn pitted farrowing house floors.
  • Wet farrowing house floors.
  • Contaminated drinking water.
  • Adverse temperatures, draughts and poor ventilation in the farrowing houses.
  • Klebsiella in the water system.
  • A build-up of faeces behind the sow associated with shortage of labour or failure to carry out normal hygienic tasks. Faeces behind the sow in the crate should be removed every day.
  • Occasionally mastitis will arise from a blood borne infection associated with the farrowing process.


There are two fundamental requirements for the development of mastitis. The first is the presence of the causal organism and secondly an ideal environment at the teat end for the organism to multiply and gain access to the mammary gland. As such, the following activities can help to prevent mastitis:

  • Give long-acting injections of either penicillin, oxytetracycline or amoxycillin on the day of weaning.
  • Clean and disinfect weaning accommodation regularly.
  • Address hygiene issues.
  • If a klebsiella infection is the cause of a herd outbreak it may be necessary to clean out the watering system.
  • If floor surfaces are poor these can be improved by brushing them with lime wash containing approximately 1oz to the gallon of a phenolic disinfectant. This should be allowed to dry for 48 hours or so before the sow enters the crate to farrow.
  • The udder can be sprayed daily with an iodine based dairy teat dip, commencing 24 hours before expected farrowing. This spraying should continue once a day for the first two days post-farrowing.
  • If a specific organism is identified and its antibiotic sensitivity is known, the sows feed can be top-dressed from day of entry into the farrowing houses until three days post-farrowing with the appropriate in-feed antibiotic or injections of appropriate long-acting antibiotics at farrowing.
  • Cull chronic infected sows.


Treatment should consist of the following:

  • Oxytocin to let milk down (0.5ml).
  • Antibiotics as prescribed by your veterinarian depending on the organism and its sensitivity. In very severe cases the sow should be injected twice daily. The following could be used:
    • OTC;
    • penicillin and streptomycin;
    • trimethoprim/sulpha;
    • semi-synthetic penicillins such as amoxycillin;
    • framycetin, tylosin, enrofloxacin and ceftiofur.

If the sow is toxic an injection of flunixin could be given.Corticosteroids may also be prescribed.In severe outbreaks the sow can be injected 12 hours prior to farrowing with an appropriate long-acting injection.If sever ulceration on the udder, the animal should be culled.

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