Mastitis is inflammation of the mammary gland (udder) often associated with bacterial or fungal infection.
Lactating and heavily pregnant cattle are usually excluded from the live export process. However, sometimes on long haul voyages, non-pregnant and early pregnant cattle will develop swollen udders and some of these will commence lactation, evident by dripping or spraying milk. The condition has been termed premature lactation or spontaneous lactation. Some of these will develop mastitis.
Affected animals will generally show heat, swelling, redness and pain in one or more quarters, with associated asymmetry of the udder. If milk can be stripped from the affected quarter the presence of clots further confirms the presence of mastitis. Mild inflammatory disease may not be detected clinically. More severe cases of mastitis may be associated with lameness or changes in gait, and systemic signs such as fever, inappetence, and depression.
Laboratory identification of pathogens including sensitivity testing to antibiotics requires 20 mL of milk collected aseptically into a sterile container prior to antibiotic treatment. The samples should be frozen if there is likely to be any delay before processing, or chilled if they are processed quickly.
Prepartum udder oedema may be mistaken for mastitis. Oedema occurs in the third trimester of pregnancy, and presents as symmetrical swelling over the mammary gland and extending anteriorly along the ventral abdomen. The swelling is not hot or painful and will pit if a finger is pushed into it.
Mastitis in prepartum heifers is difficult to treat and the prognosis for later milk production may be adversely affected. Administration of parenteral antibiotics (florfenicol, oxytetracycline, erythromycin, trimethoprim sulpha, or tylosin) simultaneously with commercial intramammary preparations is recommended. At sea, there may be difficulty in restraining animals sufficiently to insert intramammary antibiotics aseptically. In prepartum heifers, the teats and teat canals are often underdeveloped adding to the difficulty of inserting intramammary antibiotics. Non-steroidal anti-inflammatory drugs (flunixin meglumine, ketoprofen, meloxicam, or tolfenamic acid) may assist to reduce pain, swelling and toxaemia in serious cases.
Stripping out of mastitic milk may be beneficial if time and facilities are available. Normal quarters should not be stripped. Animals with systemic disease associated with mastitis may require intensive therapies to combat septicaemia (intravenous fluids, antibiotics and anti-inflammatories).
To prevent mastitis in the export process, measures must be directed at preventing premature lactation and providing a relatively clean dry environment should lactation occur.
The risk of premature lactation may be reduced by increasing the roughage component of the diet (more hay and less pellets), and by careful selection of animals (non-pregnant animals instead of pregnant, Friesians may have lower risk than Jerseys).
A relatively clean dry environment is created by having ample sawdust, conservative stocking rates, and well managed watering and drainage systems on cattle decks.
The application of long acting teat dip preparations to individual animals pre-embarkation, or spraying iodine-based teat dips on swollen udders during the voyage (using a backpack pressure sprayer and wand) is probably not practical or effective.
The administration of Teatseal ™, a non-antibiotic paraffin-based compound, has been tried. It is introduced into the teat canal and cistern to provide a physical barrier to entry of pathogens during the period of non-lactation. However, application may be associated with slow processing times in facilities at assembly points, difficulty in achieving adequate disinfection of the teat end in those facilities, and lack of patency or sufficient size of teat canals in some heifers to allow administration. In addition, if lactation does commence the sealant is removed and the animal is then susceptible to entry of pathogens and development of mastitis.
Because subclinical infections may have established in cattle developing swollen udders or premature lactation during a voyage, farm managers at destinations receiving these cattle may need training in detection and treatment of mastitis at calving.