Treating foot rot in livestock

Dear Prof McCrindle,

How common is hoof rot in livestock? What are the causes, prevention and treatment? Is it a highly contagious disease and how can it be controlled? Kind regards,

Alice

Dear Alice,

Foot rot in dairy cows is called digital dermatitis and is very common, especially in humid areas with high rainfall. It is currently becoming a serious problem in parts of South Africa due to very high daily temperatures and rainfall leading to high humidity and muddy pastures. Horses, goats and sometimes sheep also have a problem with foot rot when pastures are muddy and contaminated with manure.

Sadly, it is often the most valuable highproducing dairy cows or milch goats that have to be culled. This is because their systems are often more stressed and their resistance to bacterial infection is lower. In Holstein/Friesian cattle, the body weight of cows is also a problem. Often the cow goes down just after coming into parlour, as the transition from muddy pasture onto a hard concrete surface becomes very painful.

The coronary band is the name of the skin around the hoof. The interdigital area is between the two claws (or toes) on each foot. Foot rot begins as an irritated area, often between the toes, that is swollen, then becomes red and feels warm to the touch. All hooves may be infected at the same time, as the bacteria are proliferating in the slushy mix of mud and manure in grazing paddocks or uncleaned barns. Deep kikuyu pastures are an ideal place for these bacteria to multiply.

Once the skin is irritated, inflammatory cells migrate to the area and each foot becomes swollen to a degree that the blood supply is cut off. The skin becomes ulcerated, ‘necrotic’, and turns rotten. The hoof may even separate from the skin. After treatment the skin will start to heal, swelling will reduce and a scab will form. Only about half the cattle or goats in a herd will have all four feet infected.

Globally, the main cause of foot rot in cattle, sheep and goats is a bacterial spirochaete called Treponema. It is invasive and migrates deep into underlying tissues. Other bacteria then start multiplying in the ulcerated skin. These include Borrelia, Bacteroides, Mycoplasma species, Campylobacter, Candidatus and Amoebophilus.

Environmental hygiene and nutrition are very important. Acidosis in ruminants is also an important cause.

Treat by injecting tetracycline for three to five days. Each infected hoof must be washed off well using a hosepipe, then soaked in salt water (four level teaspoons salt per litre), or, preferably a 10% zinc sulphate solution, for 10 minutes. Then hydrogen peroxide (3%) can be poured over the underside of each hoof. Then, in turn, each affected hoof is sprayed with 1% iodine. Tetracycine wound spray is useful in milder cases. Oral or injectable anti-inflammatory medications will reduce lameness. Observe withdrawal times in dairy and meat animals. Prof Cheryl McCrindle

ȊȲSource: Fesseha H. ‘Ovine Footrot and Its Clinical Management’. Vet Med (Auckl). 2021 May 11;12:95-99. Visit pubmed.ncbi.nlm.nih.gov/34007821/.

Cheryl McCrindle is an emeritus full professor in the Faculty of Veterinary Science at the University of Pretoria, and has extensive experience in animal health. Email her at farmersweekly@caxton.co.za. Subject line: Ask our vet.