Age affected: Gits, Sows
Causes: Piglets not sucking; mismanagement; subclinical mastitis, stress
Effects: No milk after farrowing; neonatal deaths; sow not ill.
Agalactia is the failure of the sow to produce milk. Failure may be on the maternal side (production or let down) or on the side of the piglet (failure to suck). Agalactia can follow blockage of the teat for congenital reasons and may be associated with blind teats, inverted nipples, absence of teats or the total absence of mammary tissue. Scarring and non-function of the teats may follow teat necrosis when a piglet damages the teat or it may be damaged as an adult. Transient agalactia may occur after farrowing, particularly if pigs are born prematurely. Agalactia may result from water deprivation, particularly if drinkers do not deliver at a sufficient rate, are blocked, if water is unpalatable or in hot weather. Milk production may be suboptimal in thin or underfed sows. Infection is a major cause of agalactia and may occur in one or more mammary glands without causing obvious illness in the sow. Infection of the uterus (metritis) is also commonly associated with agalactia. Milk let down may not occur when the young gilt is frightened by her litter or when she is disturbed for other reasons. Agalactia rapidly develops if piglets are unable to suck and unsucked individual glands rapidly dry up.
Mode of transmission
Most forms of agalactia are non-infectious, but it may occur in groups of sows and gilts exposed to a common factor, such as water deprivation or teat damage as piglets, sometimes in successive batches. Hereditary factors may be transmitted vertically, from sow to female offspring. Infectious causes of agalactia are transmitted by the routes associated with the causal infection. Agalactia resulting from reduction in sucking by piglets may result from infectious disease in the litter.
The most obvious and consistent sign of agalactia in pigs is the effect on the litter. Sucking piglets require milk on an hourly basis, and if it is not available, the piglets are restless, continue to nurse, and may grunt and squeak in dissatisfaction instead of leaving the sow and lying down in the creep area. If agalactia continues, the piglets begin to lose condition and their hair coat may become erect. Weaker individual develop hypoglycaemia, convulsions, go into a coma and die. The behaviour of the litter draws attention to the sow. In some cases, illness in the litter is the cause of the agalactia, and close examination of the litter itself can confirm this.
Sows with agalactia may be normal or inappetent, reluctant to rise and may have fever or abnormal vulval discharge. The udder may be swollen where mastitis, milk let down or failure to suck are the cause of agalactia and after farrowing in glands with blocked teats. Back-pressure soon acts to reduce secretion and the swelling soon subsides. The udder is not swollen where there is immaturity of the gland, some kind of teat abnormality, water deprivation or long term reduction in sucking. Abnormalities of the teats may be visible. Expressed milk may be abnormal in appearance or present in small amounts. Careful examination of the affected animal can determine the presence of one or more of these causes of agalactia
Inspection of the teats should reveal physical factors such as teat necrosis and blind teats. Milk quantity and quality can only be studied following oxytocin injection as milk let down is under voluntary control. The presence of mastitis can be confirmed by laboratory means such as cell counts and bacteriology, but the quantity of milk available is more difficult to estimate. Observation and a subjective assessment may be the only way to determine whether gilt behaviour is preventing let down or piglet approach. Failure of milk production can be determined by udder examination. The most important cause of this is poor water supply and the capacity of the drinkers to deliver adequate water should be checked. Sow condition is obvious from clinical examination, but the development of agalactia associated with premature farrowing requires consultation of the records.
Most causes of agalactia in sows and gilts can be identified in the live animal, and post-mortem examination is rarely carried out. The teats are easily examined post-mortem and the presence of mastitis can be confirmed by laboratory means (microscopic examination of the glands or bacterial culture of milk) and these techniques can also be used to examine non-functioning glands for the absence of mature milk-forming tissue.
Treatment and prevention
Treatment of agalactia centres on making milk available to the piglet as soon as possible. Where mastitis or milk let down is a problem, injection of oxytocin to release retained milk is the first step. If this treatment does not provide adequate milk for the piglets, or if let down is not the primary problem, water should be provided in piglet drinkers and freshly prepared sow milk substitute should be provided. Young piglets should receive colostrum for their first feed and may need to be fed by stomach tube. Where mastitis or metritis is responsible for agalactia, an antimicrobial may be given by injection along with the oxytocin. Water must be made freely available. Adequate feeding will correct nutritional underproduction of milk by affected sows if given during pregnancy, and may benefit milk secretion and let-down after farrowing. Where correction of agalactia is not possible, piglets should be reared artificially or fostered. Agalactia may be prevented or reduced in a herd by careful examination of the udders of sows and gilts prior to service for unserviceable teats, clean housing with adequate drainage to reduce infection, reducing udder damage using soft floorings or by clipping piglets' teeth where allowed, adequate feeding in pregnancy and lactation, the provision of adequate water supplies, prompt treatment of mastitis and other diseases and encouragement of milk let down by tranquilising frightened gilts.
Agalactia can be present on any farm, and even small reductions in milk output can reduce the viability of a young litter.