Footrot in Sheep and Goats

Barry Whitworth, DVM, MPH | Senior Extension Specialist | Department of Animal & Food Sciences | Ferguson College of Agriculture | Oklahoma State University

Foot issues are a common finding in sheep and goat operations. According to a 2011 Sheep Study conducted by the United States Department of Agriculture, footrot was found in 37.3% sheep operations. In the 2009 Goat Study, “symptoms of sores on hoof area with foul odor” were found in 6.6% of all the operations. Some studies indicate the issue increases with herd size.  

Several factors contribute to the disease, but the main bacterium involved is Dichelobacter nodosus. The bacterium is contagious and does not survive long outside the host. However, the bacterium will live for years in the feet of sheep and goats. The bacterium has many strains. In general, they can be classified as benign or virulent. Virulent strains are able to destroy the horn. Benign strains do little or no damage to the horn.

Two other bacteria may play a role in footrot. Fusobacterium necrophorum, which causes foot scald, is a common inhabitant of the digestive tract of ruminants. It does not appear to be contagious. This bacterium usually contributes to the development of footrot. Some experts believe that foot scald is a precursor to footrot. One other bacterium that may contribute to the development of footrot or footscald is Trueperella pyogenes. This bacterium may increase the susceptibility of the hoof to the other two bacteria. This bacterium is found in the environment and is associated with foot abscesses. 

The first sign of foot scald is usually lameness. In foot scald, the space between the claws may appear red, hairless, swollen, and moist. No odor is present, and the condition tends to improve with dry weather.  

In comparison, footrot will have the same clinical signs as foot scald but the signs will be more severe. The space between the claws will be necrotic and the hoof will be affected. The foot will have a foul odor. In severe infection, the hoof wall will separate from the pedal bone. The condition is highly contagious and will spread rapidly through the flock.

Both footrot and foot scald are usually diagnosed on clinical signs. The presence of a foul odor is important to separate footrot from foot scald. A definitive diagnosis is based on culturing the bacteria from the foot.

Several management tools need to be used when dealing with footrot. Studies show a significant improvement in overall herd lameness when lame animals were separated from the flock. Sheep infected with Dichelobacter nodosus that causes footrot continue to shed the organism for a period of time after treatment. If left in the herd, these animals contaminate pastures and facilities which contribute to the spread of bacteria. Lame animals need to be isolated until they are healed.

Research has demonstrated that there is a benefit to early identification and prompt treatment of lame sheep. Sheep need to be observed daily for health issues. Studies show that treatment should be initiated within 3 days of lameness. Any animal found to be lame needs to be treated promptly with a long-acting antibiotic and topical antibiotic. Their feet should not be trimmed at this time. Trimming infected feet delays healing.

Another management tool is the use of foot baths. Using a foot bath during a footrot outbreak has been found to reduce lameness. Copper sulfate, formalin, and zinc sulfate may be used in foot baths, but a 10% zinc sulfate solution is preferred. 

Lastly, significant improvement in a flock can be made by culling lame sheep. Sheep requiring 2 or more treatments should be culled. Removing chronically infected sheep from the flock reduces a significant source of the bacteria which should lower the spread of the disease. Culling will improve the economics of the flock by decreasing labor time and money associated with treating footrot. It is also recommended not to keep lambs from culled ewes with footrot for replacement ewes.

Preventing footrot begins with proper nutrition. Hoof health is influenced by minerals and vitamins. Special emphasis should be placed on ensuring adequate amounts of selenium, biotin, zinc, Vitamin A, and Vitamin E. Hooves should not be allowed to over grow. Routine trimming and examination will ensure a healthy foot. Facility and pasture management play an important role in controlling lameness as well. It was found in a study conducted in the United Kingdom that allowing pastures to rest 2 or more weeks had a high impact in reducing lameness in sheep. Facilities need to be kept clean and dry. Lambing pens need to be cleaned and disinfected between uses. Fences need to be maintained. This prevents neighboring animals from entering the farm which could contaminate the pasture with unwanted bacteria.

Footrot can be a frustrating disease. However, following the above practices should improve foot health. For more information about footrot in sheep and goat enterprises, producers should consult with their veterinarian or the Oklahoma State University County Cooperative Extension Service Agriculture Educator.

References

Reilly, L. A., Baird, A. N., & Pugh D., G. (2002). Diseases of the foot. In D.G. Pugh(Ed.), Sheep & Goat Medicine (pp. 225-227). W.B. Saunders Company

Witt J, Green L. Development and assessment of management practices in a flock-specific lameness control plan: A stepped-wedge trial on 44 English sheep flocks. Prev Vet Med. 2018;157:125-133.