Lameness in sheep: Why the correct diagnosis is vital

Estimated reading time: 4 minutes

Lameness in sheep and goats has a myriad causes, ranging from genetic defects, infections and nutritional deficiencies, to poisoning, parasites and injuries. It is therefore important to find out exactly what is causing the lameness before administering treatment.  

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If an animal has difficulty walking, first do the following: check whether one or more legs are affected, whether the animal is limping, is unbalanced, lies down and can’t get up again.    

According to well-known veterinarian Dr Faffa Malan, lameness is merely a clinical sign and not a diagnosis. Every claw, joint and bone must be clinically examined to determine the cause. For everything other than an injury, thorn or tick between the claws, the help of a veterinarian should be sought.   

What the veterinarian looks at 

If the joints are swollen, the veterinarian must collect some of the fluid or pus causing the swelling and test a smear or culture to verify which organism has infected the joint.  

As for genetic defects, be sure to check whether the lame animals all have the same sire. Defects can also be attributed to ewes that were treated with an attenuated vaccine (e.g. bluetongue) during pregnancy. 

Infections such as footrot, foot abscesses, foot-and-mouth disease, and the like are among the main causes of lameness in sheep. Lame animals tend to ingest less feed and water, their growth and reproduction are impaired, rams produce fewer spermatozoa and have trouble covering ewes or cannot do it at all, wool break occurs, and the flock is not as profitable.  

The causes of footrot 

Dichelobacter nodus is the bacterium responsible for footrot. It is highly contagious and can enter the claws through wounds, tick bites or other injuries. Heavier animals such as rams and highly pregnant ewes are more susceptible because their claws tend to splay while walking. This disease, which causes cracks in the claws, is the main culprit responsible for lameness in sheep, especially during the wet season. The organism thrives in hot and humid conditions, and can survive in the soil for up to two weeks. Animals can be long-time carriers. 

It only affects the claw, which smells bad, is hot, painful, dirty with a purulent discharge. The sheep will pull back its leg when touched or handled and stand on its knees when grazing. 

Sick sheep must be isolated and kept on a dry surface. Clip off the affected parts with a hoof trimmer, have the sheep walk through a footbath containing copper and zinc sulphate or a prescribed control agent daily, and treat the claw with a disinfectant. 

Proper nutrition will assist in managing the disease, as sheep in good condition are more resistant to infection. Provide dry kraals or pens, keep sheep out of wetlands and wet areas, and isolate sick animals to limit the spread of the disease. The bacteria have difficulty surviving in an alkaline environment, so be sure to treat the holding facilities with agricultural lime. 

Treatment of abscesses 

A foot abscess is a bacterial infection of the foot joint. The bacteria enter the skin or claw via small wounds caused by ticks, shrubs, stones, and the like. An abscess forms between or above the claws and often affects the fetlock joints. The bont-legged and heartwater ticks are the main culprits. The joint swells, causing the animal to limp. Older and heavier animals are often more affected. 

Lance the abscess, clean it, and administer antibiotics and an anti-inflammatory. 

Other causes 

• Strawberry footrot (lumpy wool): The coronary band of the claw is affected, probably due to the simultaneous infection by the lumpy wool organism and orf virus. 
• Acute mastitis (blue udder): A ewe with an infected udder will drag the leg when walking on the side of the infection. 
• Bluetongue: The coronary band of the hoof is inflamed, the sheep is stiff and has difficulty walking, and the leg may be so painful that the sheep will kneel on its knees. 
• Joint inflammation: Various organisms can cause joint inflammation, and the degree of lameness will depend on which joints are affected. 
• Chronic pulpy kidney: The toxin from the bacterium Clostridium perfringens type D causes paralysis in sheep. The animal will look as though it is in a coma. 
• Botulism is caused by the toxin from the bacterium, Clostridium botulinum. As the disease progresses, the animal becomes stiff and lies down. 
• Post-dipping lameness and joint inflammation: A bacterial infection that causes joint and coronary band inflammation and laminitis two to four days after dipping. 
• Posterior paralysis (sitsiekte): A bacterium enters the body through wounds such as tick bites. An abscess forms which presses on the spinal cord and paralyses the hind quarters. 
• Nutritional deficiencies, poisoning, parasites and injuries can also cause lameness and paralysis. – Andries Gouws, Stockfarm

For more information, contact Dr Faffa Malan on 082 908 8666 or email dokfaffa@gmail.com.