Reducing lameness in your sheep flock
Jack Friar, CAFRE Beef & Sheep Adviser, Armagh
Lameness is a common and persistent problem in some sheep flocks. Lameness is a serious health and welfare issue causing pain and discomfort. As well as effecting ewe health it can also impact on the financial side of the business in terms of time and money spent on products for treatment and prevention. Poor mobility can have negative effects on production, fertility and longevity. It has been estimated that the cost of lameness can range from anywhere between £4/ewe up to £14/ewe depending on the severity of the problem. To minimise the impact of lameness on the health of the ewes and reduce the costs to the business, timely and effective management and treatment and prevention strategies should be implemented, to keep the number of lame sheep below 2% of the flock.
Common causes of lameness in sheep
The most common causes are infectious such as scald, footrot and Contagious Ovine Digital Dermatitis (CODD). Other forms of lameness include non-infectious causes such as toe granuloma, toe abscesses and shelly hoof.
Scald and footrot
These two are the most common causes of lameness and the primary source is the bacteria Dichelobacter nodosus.
Scald causes inflammation to the skin between the claws resulting in a red/pink infection with loss of hair. Transmission between sheep is primarily via soil with warm wet weather also contributing to the spread. Other causes include dry, stony ground or long tough grass which cause trauma to the feet that allows bacteria to penetrate the skin.
Footrot is a more severe presentation and occurs where scald is already established as the bacteria progresses to the hoof and causes more damage. Footrot can be identified by its characteristic foul smell due to infection forming when the sole and hoof wall separate. Treat cases early to ensure a chance of an effective treatment. Footrot can also cause other problems by attracting flies, especially with the current warm conditions.
CODD starts with ulcers at the coronary band (where the hoof and the hair meet) and the infection progresses down the hoof towards the toe and may result in the whole hoof capsule falling off. As the name suggest it is contagious and can spread quickly through a flock, therefore early identification, separation and treatment is essential. To ensure the correct diagnosis seek help and advice from your Private Veterinary Practitioner (PVP) as it can be difficult to differentiate CODD from footrot. Your vet will also provide the correct treatment protocol for CODD.
Five key points to remember to control lameness.
Ensure quick identification and treatment of any lameness case. For individual cases of scald, these are often treated using oxytetracycline aerosols or foot-bathing where several sheep are affected. Afterwards these sheep should be turned out to clean pasture to reduce reinfection as infective bacteria can survive for 10 to 14 days on pasture. For footrot, treatment is usually injection with a long lasting/acting oxytetracycline and use of an aerosol spray. This should be discussed with your PVP and remember to use antibiotics responsibly and only under veterinary supervision. The treatment of scald by foot bathing should ideally be done with a walk through bath with sheep walking through at a slow pace. When treating footrot, a longer contact time will be required between the hoof and the solution. This allows the solution to penetrate the hooves and kill any infective bacteria. The footbath should be a minimum of 6 metres in length and the solution 5cm in depth to ensure proper coverage of the hoof. Most foot bathing chemicals need to dry on the feet for them to be effective. This means leaving sheep to stand for at least 30 minutes on a hard, clean concrete standing before returning to the field. Always follow manufacturer and veterinary advice when using these products.
Infective bacteria linked with lameness spread easily in areas associated with heavy traffic such as wet and muddy handling facilities, around water troughs, creep feeders and gateways. If possible, try to avoid spreading within these areas by moving creep feeders regularly and using hydrated lime. Also, again leave fields that sheep were in before treatment free for a couple of weeks to reduce the chances of reinfection or spreading of infective bacteria. Susceptibility to scald and footrot can be inherited therefore avoid breeding from rams and ewes that have had previous cases. Research has also suggested that routine hoof trimming is no longer advisable as an appropriate management technique and therefore should be avoided as it can increase levels of lameness. It has also been shown on lame sheep to lengthen the time it takes hooves to heal and therefore it is only recommended in some particular cases of lameness such as shelly hoof.
Now is a good time to remove persistent offenders (when sound) after weaning as lame sheep are sources of infection to others in the flock. Persistent offenders can be categorised as those who always have mis-shapen feet and also sheep that have been lame more than once during the season and not responding to treatment. Those not responding to treatment will be a constant source of re-infection for the rest of the flock.
Replacement breeding ewes and/or rams will be purchased shortly especially for early season lambers, therefore remember all incoming stock must be quarantined for at least 28 days to avoid the introduction of a different and perhaps more infectious strains of footrot or CODD. All incoming stock should have their feet examined and footbath treatments must be used during this period. Also treat all stock that are returning on farm from out-wintered or grazing on neighbouring land the same as newly purchased stock when it comes to quarantine protocols.
There is a vaccine available that can be used to treat and prevent footrot. Best results are achieved with a whole flock vaccination programme, including rams and should be timed to coincide with high risk times on the farm e.g. pre-tupping and housing. Vaccination protocols can differ on each farm, therefore seek advice from your vet and always read the product data sheet carefully.
- Identify, separate and treat lame sheep as quickly as possible.
- Ensure correct diagnosis to enable correct treatment.
- Keep good records and cull persistent offenders.
- Never, ever purchase and introduce lame sheep into your flock.
- Remember the main source of infection is from lame sheep.
- Seek and follow veterinary advice when using any antimicrobial products to control disease.