printStock Journal Technical Column, August 2022
Author: Chris van Dissel, PIRSA
Winter – Spring in Southeastern Australia is often associated with increased lameness in your flock. Damp ground and pasture, soft hooves and conditions favourable for infection are the main reasons for this increase in lameness.
Australia is currently experiencing and increased threat of exotic diseases such as Foot and Mouth disease (FMD), so it is now more important than ever to pay attention to lame sheep and accurately diagnose foot problems in your flock. Being vigilant and investigating lameness issues helps ensure the early detection of potential incursions of lameness causing exotic disease like FMD. An FMD outbreak in Australia could cost the livestock industry more than $80M.
Common endemic lameness causing diseases like footrot, will also cost you more, the longer they are present and undiagnosed in your flock. There are several common foot and hoof problems of sheep that you need to be aware of to ensure appropriate treatment and responsible trade-
Foot abscess- (Both heel and toe) are common when heavy sheep are grazing wet pastures. Moisture in the ground softens the hoof and allows penetration of sticks stones and other foreign bodies, that introduce the foot abscess bacteria from the ground to the hoof. The result is often a swollen fetlock joint or hoof claw, producing infection, heat, pain and pus. Paring the affected hoof can assist relieve the pressure of the pus, but antibiotics sourced through your vet are often required to completely resolve the issue.
Laminitis – Occurs when sheep are introduced to a high carbohydrate diet, such as good quality active growing pasture or grain. This dietary imbalance, whilst not associated with any infection, causes inflammation of the soft tissue underneath the hoof, can affect all four feet and is extremely painful. You will often feel heat in the hooves of affected sheep and may observe redness of the coronet (hair / hoof line). There are some in feed additives that can be used to prevent laminitis in sheep on grain diets and allowing access to hay that is high in fibre will assist in controlling the problem on lush pastures.
Strawberry Footrot – A different infection to footrot, is caused by the same bacteria that causes dermo’ in the fleece. Common in warm moist times of the year and more common on legume-based pastures, strawberry footrot causes rough red sores above the coronet (that resemble a strawberry). The causative bacteria is quite contagious, so many sheep can be affected through walking through the same pasture. Whilst the problem will go away as pastures dry, it can cause significant lameness and so treatment with antibiotics and segregation of affected animals may be needed to assist in controlling the problem.
Interdigital fibromas – These fibrous “skin type” lumps that grow between the claws of the hoof and continue to grow as sheep age can predispose sheep to conditions like footrot and foot abscess. The folds between the lump and the inside wall of the hoof can catch grass seeds and sticks and cause infection. They create an anaerobic (air free) environment in the hoof, which favours some of the lameness causing bacteria. Fibromas are a heritable trait, so breeding rams and ewes should be closely inspected for presence of these skin lumps and not used for breeding if they have them.
Footrot – This contagious notifiable disease is common in Springtime in the wetter areas of Southeastern Australia and can cause major economic impacts when established in a flock. Caused by a bacteria that favours warm wet conditions, the severity of a footrot infection can vary hugely, from just one or two lame sheep to over 90% of a mob limping. Footrot must be accurately diagnosed early to avoid the significant costs of establishment right through a flock. Footrot is often associated with other lameness causing problems, so thorough examination of many sheep is required to diagnose.
If you observe lameness in your sheep flock this year, first inspect the feet of the sheep and make some observations, if you see signs or symptoms you don’t recognise, seek advice from your local vet or Animal Health Adviser. Ignoring foot problems may not only cost you profit, but they could cost our entire livestock industry.