There are three main types of mastitis in sows: 1, acute agalactia, which often involves the udder, in the early post-partum period, see more below, 2, acute clinical mastitis during lactation usually affects separate udders and 3, in the dry period a chronic mastitis, often manifested as abscesses, appear. All three are caused by bacteria but therapy differs.
The older term agalactia in sows refers to a syndrome in the early post-partum period where the more modern “postpartum dysgalactia syndrome” (PPDS ), or “mastitis, metritis and agalactia” (MMA) are used today. Early symptoms are anorexia in the sow and hunger in the piglets. The sow often gets an elevated temperature, >40°C, and affected general condition. On palpation of the udder one or more swollen and warm udder glands are often identified. A discharge from the vulva is often present as metritis is part of the disease complex.
In cases of mastitis the etiology is often E. coli. Bacteria in the environment are believed to enter the udder through the teat canals and cause an acute inflamma- tory response. Streptococci and staphylococci have also been isolated from the udder.
Mastitis later in lactation and at drying off usually affects single udder glands without systemic symptoms. Streptococci and staphylococci are often present, but also other bacteria, aerobic as well as anaerobic, have been found.
The chronic case of mastitis often manifests itself as an abscessed udder. Actinosis or actinomycosis as well as streptococci and staphylococci are part of the etiology. Diagnosis is made by palpating the udder. The abscess may involve all of one udder gland or it may appear as a sub-cutaneous bunch of grapes.
Early diagnosis and ditto therapy are important when handling cases of PPDS. The first measure should be to inject the sow with oxytocin to stimulate milk let- down so that the piglets can suckle. Systemic administration of NSAID may ease the sows pain and discomfort.
Treatment with antibiotics generally is not necessary in mild cases of PPDS. If, however, general condition is affected and rectal temperature elevated therapy with antibiotics and/or NSAID are indicated. T/S is the drug of choice. If T/S fails BPP would be the logical alternative, but other drugs may be used on indication from bacterial cultures and tests of sensitivity.Mastitis in the latter part of lactation and after drying-off generally does not affect temperature or general condition of the sow. BPP is the drug of choice since the bacteria involved generally are sensitive to penicillin.
Sows with udder abscesses should not be treated with antibiotics as the bacteria are sequestered and cannot be reached. Sows with udder abscesses should be sent to slaughter. If this for some reason is not possible they must be isolated until farrowing and during the next lactation.
The incidence of PPDS in Swedish pig herds is normally around 10 % of farrowings. Hygiene in the farrowing box as well as good feed and water hygiene are important to keep incidence low. Amount and composition of feed also play a role. An elevated incidence of diarrheas in piglets may indicate problems with subclinical PPDS.
If incidence rises above 10 % the herd veterinarian should initiate a herd health analysis to identify underlying causes and, in dialogue with the farmer/owner, arrive at measures to improve the situation.
Mastitis later in lactation and at drying-off is prevented by treating sows with damaged teats and udders promptly before lesions develop into chronic forms. Poor milk production may be second to subclinical mastitis, which in turn makes the piglets hungry and more violent as they try to suckle. It is also important that the sows, and especially the young sows, do not lose too much weight during lactation and that they are kept in good condition.
Good hygiene and intra-herd prevention of infections are of major importance to reduce incidence of abscessed udders. Post-weaning the sows are sensitive for infections as unmilked udders may be infected via the teat canals. Since the
sows often are mixed at weaning a palpation of all sows udders should be done to identify which animals that should not be mixed with the healthy ones. Udder palpations should be repeated at insemination and heat checks when the dried-up udder is softer and abscesses easier to feel. Affected sows should be sent to slaughter if at all possible or at least kept separate from other animals.