scald

May 062013
 

Best foot forward

Lambing time is an exhausting roller coaster of highs and lows, you go through the lambing process and come out the other end (sleep deprived) and breath a huge sigh as your last ewe and lamb goes out into the field.  Time to get back to normal……..But do not make the mistake of thinking that this is you finished.  Young lambs are very vulnerable to a range of factors that if not dealt with can impact on the welfare, and weight gain of the lamb.  However, if you keep an eye out you can spot an issue and deal with it quickly, saving you and the animal a lot of pain and expense.

 One problem that can occur is a lame lamb who may limp, lie down a lot, or be seen on its knees.  This lameness can be caused by a range of factors, from the physical (mud ball in the hoof, thorns, injury to the legs) to bacterial (footrot and scald) and viral (orf).  I would always recommend that you discuss with your vet in the first instance before attempting any self-diagnosis and/or treatment.

“Sheep that remain lame despite treatment and a period for recovery do not have a life worth living.  Sheep that are lame for one week or longer lose body condition and, as a result of lameness, they are debilitated and less productive. Lame lambs do not thrive and can lose body condition.”

There is no magic bullet or one vaccine that will prevent all the problems.  Prevention and prompt action are crucial.  Here are a few things that we have experienced over the years:

Orf (scabs and sores on mouth) in lambs

Orf is spread by direct contact.  It  is a zoonotic disease, which means that it is easily transmitted from animals to humans. SO BE CAREFUL. Outbreaks occur more frequently during periods of extreme temperatures such as late summer and winter.  Or infection can be caused by scratches from thistles of both growing and felled plants. Symptoms of Orf include scabs and sores on the lips and muzzle, and less commonly in the mouth of young lambs and on the eyelids, feet, and teats of ewes. The lesions progress to thick crusts which may bleed and cause secondary infections. Orf in the mouths of lambs may prevent suckling and cause weight loss, and can infect the udder of the mother ewe, thus potentially leading to mastitis. Sheep are prone to reinfection. Occasionally the infection can be extensive and persistent if the animal does not produce an immune response.

The virus is epitheliotropic, which means that it has an affinity for the skin. The period of incubation is relatively short. Susceptible animals usually develop the first signs of the disease 4 to 7 days after exposure that persists for 1 to 2 weeks or for longer periods. The disease affects sheep and goats.

“Extensive lesions on the feet can lead to lameness in adults and young animals.”

The infection is spread by direct and indirect contact from infected animals or by contact with infected tissue or saliva containing the virus. Lesions can be treated with a single application of 3 percent iodine solution. In severe cases of secondary bacterial infection, the usage of a systemic antibiotic is recommended.

Young animals are the most susceptible to contracting the disease. Lambs can contract orf after a few weeks of birth.
However, outbreaks in young animals are most frequent during postweaning.  Smallholders can help by applying antibiotic sprays on to large scabs, ensuring infected lambs receive sufficient milk and separating out the infected stock to slow down cross-transmission to healthy animals. It is advisable for those handling infected animals to wear disposable gloves to prevent cross-infection and self-infection. Vets need to be contacted if there is a risk of mis-diagnosis with other, more serious conditions.

Joint ill in lambs

Infectious polyarthritis (joint ill) is acquired during the first few days of life with lameness visible from five to 10 days-old. Typically only one joint is affected in approximately half of lambs with 2 to 4 joints in the remainder. The affected joint(s) are swollen, hot, and painful. Infection causes considerable muscle wastage.  You need to catch the lame lamb and treat it immediately with antibiotics.  Penicillin once daily for at least five consecutive days administered during the early stages of lameness effects a good cure rate in many infections.  Lambs with joint ill that continue to show moderate to severe lameness after two courses of antibiotic therapy do not grow well and represent a major welfare concern and you should consider having them culled.

  To prevent or reduce the incidence of joint ill, ensure that ewes are lambed in a clean, dry environment and that lambs take in adequate amounts of protective colostrum within six hours of birth. Dipping navels and providing clean lambing pens or dry lambing fields also help to protect lambs.

 

Scald or footrot

This was a hard lesson for us to learn.  If you do not identify and treat scald it can lead to foot rot which can then lead to fly strike.  These are issues you do not want to have to deal with and can cause severe health and welfare problems for the lambs.
“Scald is the most common cause of lameness in sheep
and is most prevalent when conditions underfoot are wet.”
 
Scald can be a precursor to some other more severe causes of lameness so needs to be treated promptly. It can affect all age groups but is more prevalent in lambs than ewes. Foot scald (interdigital dematitis) is an infection and is not contagious. Foot scald causes lameness, frequently on the front feet, and lesions are found between the hooves. The tissue between the toes of a sheep with foot scald are generally blanched and white, or red and swollen. Foot scald is much easier to treat than foot rot. Footrot is a very common condition, it is extremely painful and very contagious. Affected feet have a very characteristic foul smell and may be fly-struck.
 
It is recommended that you do not breed or buy replacements from sheep that have had scald or footrot, and that susceptibility to footrot can be inherited. However the plus side of this is that you can breed for improved resistance.  I know this is hard for smallholders when you pet lamb or favourite ewe is the one that you have the most issues with, but try to tough about this for the welfare of the flock.   Some breeds do fare better than others,  we keep a range of breeds and it is my experience that the more primitive or historic breeds are more resistant.

When treating, and YOU MUST DO SOMETHING, use an isolation pen for sheep with scald or footrot.  Move them immediately (for example to a pen) and consider using hydrated builders’ lime (or purchased from an agricultural merchant)  around water troughs and feed areas.

 Footrot is probably what will happen if you ignore the scald.  It is a highly contagious disease, caused by dual infection with the bacteria Dichelobacter nodosus and Fusobacterium necrophorum (which also causes scald). F.necrophorum is widely found in the environment, especially in dung. D. nodosus survives primarily in infected sheep, although the duration of its survival on the pasture is not clear, probably a number of weeks. These two bacteria are closely connected and thrive on the by-products of each other.
 
Sheep that have been infected with or exposed to footrot do not develop any significant natural immunity or resistance. Short term immunity can be achieved using vaccines.  Spread is primarily from foot to foot via pasture or mud. Goats, cattle and possibly vehicles can act as carriers. However moist pastures, laneways and muddy yards are the main areas where footrot is spread.
 
“Older ewes, ewes rearing twins and male lambs are at higher risk of footrot.”
 
Affected feet have a characteristic foul smell and a grey ‘ooze’ may be seen. It causes extreme discomfort to the sheep and leaves the animal highly vulnerable to blowfly strike in the foot or along the flank where the sheep tucks its foot when it lies down.  The most effective footrot control were using an injectable antibiotic plus an antibiotic foot spray and treating a sheep as soon as lameness became evident. I is also recommended not to trim or footbath feet at this time as there is the strong risk that you will make the damage worse and transfer it to other sheep.  Leave the trimming until the lameness has gone.
 
Footrot bacteria are readily killed by dry heat, sunlight, cold, dry environment and a number of different chemicals. It is said that most domestic disinfectants will destroy D. nodosus but are not registered or recommended for treating sheep as they are easily de-activated by dirt contamination. Zinc Sulphate, “Radicate” and formalin (Formalin, Formol) are the chemicals currently registered for the treatment of footrot in footbaths.
 

Other lameness causes in lambs

Although we have no direct experience of the following – here are some other causes of lameness in lambs.

Erysipelas is caused by a bacterium present in soil. It is an uncommon condition in sheep but can cause outbreaks of lameness in lambs; if left untreated, lambs become severely debilitated and should be euthanised promptly.

Interesting related articles:

%d bloggers like this: