See related information under Foot abscess, Lameness
This is a loosely defined term given to swelling of one or more legs seen in cattle at sea. Swollen legs are generally the result of accidental injury with or without secondary bacterial infection. Swollen legs and lameness represent one of the most common conditions affecting cattle during export voyages.
Animals may be injured as a result of accidents during transport or loading, being stepped on by a pen mate, or from abrasion of the feet or lower limbs from contact with the deck or other hard surfaces. Anatomical areas that are commonly affected and where initial swelling will be seen if detected early, are the fetlock, pastern or coronet region of the lower legs.
Deck surfaces can be rough and abrasive. As the voyage progresses and there is increased accumulation of faecal matter on the floor, abrasions and minor wounds or injuries of the feet or lower limbs may easily become infected.
Cattle recumbent in crowded pens are always at risk of injury from being stepped on, especially the legs. All legs are at risk, but especially the hind legs as they may be less likely to be tucked under a recumbent animal than the front legs. The number of swollen legs from this cause increases when pens are crowded with nervous, tired cattle.
Initial injuries may be small and innocuous, but over time there is a risk of mild injuries being exacerbated through repeated insult, and contaminated from exposure to faeces on the floor. A localised cellulitis may develop and result in swelling and lameness. Infection may involve distal joints depending on the site and extent of initial abrasion or injury. If the cellulitis progresses, the swelling becomes extensive, there is incapacitating lameness or toxaemia and the animal dies or must be euthanased.
Lame animals may have difficulty standing and moving and this in turn can lead to dehrydration and inappetance and may predispose animals to a range of other conditions including heat stress.
Complications from swollen legs are one of the major causes of losses at sea, either directly as a result of the condition causing death or resulting in euthanasia, or indirectly by contributing to animals then succumbing from another condition. It can also result in rejection during health inspections at destination.
During pen inspections, inspection of lower legs will detect enlargement of the coronet, pastern and fetlock regions when compared to other legs. Lameness is usually absent unless swelling is severe. Lacerations are often not visible unless the skin is scrubbed clean and then they may be very small.
Swelling of the coronary band and pastern may occur with diseases of the claw such as excessive wearing of the sole, sole bruising, toe abscess, sole abscess and white line disease; or disease of the interdigital space such as foot rot. However, these conditions are accompanied by moderate to severe lameness and the claws are spread.
At necropsy there is oedema and dark, mixed discolouration of subcutaneous tissues in the area of the swelling. A discharging skin wound may be present.
Minor lacerations or swelling affecting legs of export cattle should not be ignored or treated lightly. Recovery without treatment is possible but unpredictable. Without early treatment, uncontainable or irreversible cellulitis may occur.
Administer a course of antibiotics (procaine penicillin, oxytetracycline, or ceftiofur) and non-steroidal anti-inflammatory drugs (flunixin meglumine, ketoprofen, meloxicam, or tolfenamic acid) and once finished, recheck the animal for relapse. Avoid long-acting penicillins and glucocorticosteroids.
Avoid overcrowding during transport or in pens. Avoid situations where penned animals may rush and step on recumbent animals. Move quietly around the cattle decks when cattle are settling in to life on board, and make sure all cattle in a pen are standing before feed is put out into troughs.
Because early intervention saves lives, inspect cattle as soon as possible after loading and isolate and treat any animals that have lower leg wounds or swelling. During the voyage, all lower legs should be systematically scanned twice daily. This is best done immediately before or soon after feeding has commenced when most cattle will be standing up. Swollen legs are most easily detected after deck washing - ensure a scan of legs occurs immediately after deck washing and before spreading of sawdust when cattle will start to lie down.