ENVIRONMENTAL CONDITIONS CAN INCREASE HOOF ISSUES

by: Stephen B. Blezinger
Ph.D, PAS

It has only been recently that much of the cattleman's concerns focused on drought and widespread lack of moisture needed to grow pastures and forages. These conditions remain in many parts of the country. However, other areas including widespread parts of the southern US have “enjoyed” substantial if not excessive rainfalls over recent weeks and months. While this greatly improves forage growing conditions in these areas, a host of other problems develop with the high, sustained moisture levels. These include dealing with mud, inability to harvest hay meadows and a personal favorite, increased incidence in foot rot and other hoof conditions. While the problem itself is created by infection of hoof/foot tissues by a specific organism, continuously wet pasture conditions serve to increase or accentuate the issue. This is further compounded by wet conditions making it more difficult to check on cattle and certainly treat those affected. Under normal conditions it's almost impossible to estimate the countless dollars lost annually by cattle producers in terms of labor, medicine cost, performance and even animal loss. Foot rot is typically sporadic in occurrence, but the disease incidence has been reported as high as 25 percent in high-intensity beef or dairy production units. These levels are elevated under adverse environmental conditions

What we are dealing with

Foot rot is a sub acute or acute necrotic (decaying, rotting) infectious disease of cattle, causing swelling and lameness in at least one of the feet. The disease can become chronic (recurring in initially infected animals), with a lower likelihood of recovery if treatment is delayed. Waiting to treat the condition results in more extensive tissue infections and deeper structures of the toe affected. The causes will vary but normally starts with an injury of some type. There is a softening and thinning of the interdigital (between the toes) skin by continuous exposure to wet conditions as seen at this time but also common in spring and late fall. These situations increase entrance points for infectious agents. A common bacteria, known as Fusobacterium necrophorum is the organism most often isolated from infected feet, but can also be found in non-diseased, interdigital skin. The majority of F. necrophorum isolated belong to one of two types (types A or B) which produce toxins that cause necrosis (death) or decay of the infected tissues. This organism is also known to be the cause of liver abscess in feedlot cattle.

Regardless of the source, once loss of skin integrity occurs, bacteria gain entrance into subcutaneous tissues and begin rapid multiplication and production of toxins that stimulate further continued bacterial multiplication and penetration of infection into the deeper structures of the foot.

Spread of the Disease

Feet infected with F. necrophorum serve as the primary source of infection for other cattle by contaminating the environment. Researchers and veterinarians disagree on the length of time F. necrophorum can survive off of the animal, but estimates range from one to ten months. This means that the condition can crop up again in a given area even after no cattle or no observed cases appear for a period of time.

Signs, Symptoms, Related Problems

While this foot disease occurs in all ages and classes of cattle, as discussed, increased incidence is commonly observed during wet. When case incidence increases in hot and dry conditions, attention must be directed to areas where cattle gather, which are often crowded and may be wet from urine and feces deposited in shaded areas.

The first signs, after a growth and development period of the organism for five to seven days, include lameness, swelling of interdigital tissues, and swelling evenly distributed around the hairline of the hoof. Left unattended, eventually the interdigital skin cracks open, revealing a foul-smelling, necrotic, core-like material. Untreated, the swelling may progress up the foot to the fetlock or higher up the leg. More importantly, the swelling may invade the deeper structures of the foot such as the navicular bone, coffin joint, coffin bone, and tendons.

Where the issue becomes complicated is that there are other conditions that can cause lameness in cattle that can be mistaken for foot rot and require different treatment. Included: interdigital dermatitis, sole ulcers, abscesses and abrasions, infected corns, fractures, septic arthritis, and inflamed or infected tendons and tendon sheaths, etc. One defining factor is that these all generally only involve one claw of the foot and not the areas of skin or soft tissues between the toes or claws.

Digital dermatitis (hairy heel warts) is often confused with foot rot because of foot swelling and severity of lameness. Digital dermatitis affects only the skin, beginning in the area of the heel bulbs and progressing up to the area of the dewclaws. This is compared to foot rot lesions which occur in the interdigital area and invade the subcutaneous tissues.

In certain areas, cattle grazing endophyte infected fescue pastures that develop fescue toxicity, causing loss of blood circulation to the feet and subsequent lameness, are sometimes mistaken as having foot rot.

Treatment

Treatment can be successful, particularly when caught and started early. Always consult your veterinarian but normal treatment should include:

1) Cleaning and examining the foot to establish that lameness is actually due to foot rot and not one of the other conditions discussed.

2) Apply a topical treatment should be applied. Some very mild cases will respond to topical therapy.

3) Give an injection of an approved, recommended systemic antimicrobial/antibiotic therapy. There a number of antibiotic products on the market that can be useful. Consult your veterinarian for his recommendation. Since many of these now require a prescription he can provide this as well. Be sure to document which antibiotic is used, how much and the animal treated for your records.

4) If at all possible, keep affected animals should be kept in dry areas until healed.

5) If improvement is not evident within three to four days, it may mean the infection has invaded the deeper tissues and may need to be evaluated by your veterinarian and may require repeated or more extensive treatment.

With the value of cattle in today's market, it makes sense to take necessary measures to deal with the problem quickly and appropriately to conserve performance and in many cases to save the animal itself.

Nothing Beats Prevention

Preventive measures are focused on the prevention of mechanical damage to the foot as caused by frozen or dried mud, shredded weeds or brush (resulting in stubble), and minimizing the time cattle must spend standing in wet areas. Additionally, make sure pastures are clean and free from trash or other materials that can cause injury to the foot if stepped on.

A solid, well designed mineral program is critical to off setting foot rot. In areas where it is a problem feeding a mineral which includes elevated Zinc and Iodine can significantly reduce incidences of foot rot and other foot infections. Research has shown that supplemental zinc may reduce the incidence of foot rot. Improvements have been seen in foot health even when zinc is not deficient in the diet when highly available sources are included and overall zinc concentrations in supplements are increased. Zinc is important in maintaining skin and hoof integrity. Adequate dietary zinc should be provided to help minimize foot rot and other types of lameness. As an example, in a three-year study in Kansas, zinc methionine added to a free-choice mineral supplement reduced the incidence of foot rot and improved daily weight gain in steers grazing early summer pasture as seen in Table 1.

Additionally, feeding of organic sources of iodine has been shown to also be effective in this type of program. Iodine from EDDI (ethylene diamine dihydriodide), an organic source, is believed to be effective in preventing foot rot although it should not be routinely fed at elevated levels year-round. Studies have reported that organic iodine fed at a rate of 10 to 15 mg per head per day was helpful in the control of foot rot on some farms.

Some other preventative measures can include:

Feeding low levels of chlortetracycline (CTC). This can also be added to a free-choice mineral product. Consult your veterinarian and nutritionist for proper feeding levels. Low level feeding of chlortetracycline (CTC) is labeled and approved through the Food and Drug Administration for beef cattle, for the reduction of liver abscesses at 70 mg per head per day. F. necrophorum is the major infective agent in both liver abscesses and foot rot in cattle as discussed previously. CTC is labeled at 350 mg per head per day (at least 0.5 mg per lb. of body weight per day) in beef cattle under 700 lbs., and 0.5 mg per lb. per day in cattle over 700 lbs. Consequently, many mineral mixes and commercial supplements are formulated to provide 350 mg per head per day, to control those diseases listed on the CTC label. Since foot rot is caused by the same organism as liver abscesses, some control of foot rot should occur at the 350 mg per head per day level.

Injection with a trace mineral product such as MultiMin® (prescription required). Evidence has shown that the use of injectable trace mineral solutions containing significant levels of organic zinc as well as manganese, selenium and copper, may increase zinc status in the animal and subsequent reductions in the incidence of foot rot have been observed.

Conclusions

Foot rot is one of many conditions of the foot that cause lameness in cattle. For treatment to be effective it must be started early in the course of the disease. It is normally necessary to have a break in skin integrity for foot rot to occur. The most important preventive measures are centered on the protection of interdigital skin health. All this said, however, solid preventative measures such as feeding a properly designed mineral supplement as well as other nutritional applications can dramatically reduce if not prevent the expense of a foot rot outbreak and in general may be the most cost-effective method available to the cattleman.

Copyright 2015 – Dr. Stephen B. Blezinger. Dr. Steve Blezinger is nutritional and management consultant with an office in Sulphur Springs, Texas. He can be reached by phone at (903) 352-3475 or by e-mail at sblez@verizon.net. For more information please visit www.facebook.com/reveillelivestockconcepts.







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