F460
Lameness Associated
with the Foot


footrot | hairy heel warts | abscesses and ulcers | fractures | laminitis


Footrot:

Introduction/Causative Agents: Footrot or foot rot is a serious disease of cattle that is sometimes difficult to cure. Studies show that Fusobacterium necrophorum is the main organism involved in these infections. Other organisms such as Bacteroides melaninogenicus and Bacteroides nodosus can also be involved in the infection and may make it so that a smaller amount of F. necrophorum is necessary to cause an infection. F. necrophorum is common in most cattle feces. It is very hardy and can almost always be found in every environment. Studies indicate that the organism can live for 1-10 months in the environment.

Disease Transmission: Footrot infections mainly occur in wet conditions when the tissue between the claws has been injured and allows infectious agents to enter the hoof tissues. Allowing excessive hoof growth to occur can also lead to a footrot problem.

Clinical Signs: Animals infected with footrot can be mildly to severely lame in one or more feet. The area between the claws (interdigital tissue) is inflamed and moist. The problem, if left untreated, will spread and can cause cracks and dead (necrotic) tissue to appear in the interdigital skin. A characteristic foul odor and some discharge are often noticed. Swelling may progress from the hair-line of the foot (coronary band) up the limb and in severe cases, invade the deeper structures of the foot such as the navicular bone, joints, and tendons. In these situations, the problem is very severe and requires immediate attention. Because of the potential rapid progression of this problem, some producers refer to these conditions as "super footrot."

 

 


Diagnosis:
Cases of footrot are often diagnosed based on clinical signs and evidence of damage to the hoof. Cultures of samples taken from problem areas can be used to identify the organisms causing the infection. Problems such as digital dermatitis (hairy heel warts), sole ulcers/abrasions, fractures, septic arthritis, fescue toxicity, laminitis, bluetongue, and foot-and-mouth disease may also have symptoms similar to footrot.

Treatment: When possible, trim and clean the feet of every affected animal in the herd. Lame animals or animals with obvious signs of footrot should have any problem areas of hard and soft hoof completely removed. Trimming removes cracks and areas for the bacteria to hide in and also allows medications to reach the bacteria. When small numbers of animals are infected and the infections are not severe, sprays and brushes can be used to apply topical medications such as antibiotics (tetracycline) or antiseptics (copper sulfate or zinc sulfate). Footbaths that contain copper sulfate - 10% or zinc sulfate - 10% can also be used. To prevent the potential spread of infection, remember to disinfect all hoof trimming equipment after trimming each animal’s feet.

After completely trimming all affected animals, treatments using antibiotics can also be given for the more severe cases. Penicillin and long-acting oxytetracycline are commonly used. Products such as Tylan 200, Naxcel, Micotil, and Albon can also be used. In situations where trimming and cleaning of the feet is not an option, antibiotics given as an injection or orally can be an adequate treatment.

Separate infected and non-infected animals, and when necessary, repeat the treatment on infected groups of animals one week later. Infected animals should receive additional treatments at 7-day intervals as needed and be re-examined on a regular basis. Severe infections that involve the deeper structures of the foot may never fully recover. It is often necessary to cull/sell these animals that are persistently lame. In very valuable animals, claw amputation or claw salvaging surgical procedures can be performed.

* No one method of treatment seems to be completely affective every time. This means that a combination of antibiotics, trimming feet, footbaths, and vaccinations should be part of every treatment program.

Prevention: Proper feet trimming, keeping animals out of wet, marshy areas, regular footbaths during the wet seasons, and routine culling of lame animals are all essential prevention measures. Feeding 500 mg of chlortetracycline per head per day, or using a dry footbath of 90% slaked lime and 10% copper sulfate has also been recommended. Never use equipment (trucks, hoof trimming tools, etc.) that could have been contaminated by infected animals. More recent studies have identified a possible nutritional link to the disease. As a result, adequate levels of zinc (30-40 ppm of the total diet), vitamins A & D, calcium, and phosphorus are essential.

Vaccines such as Volar (page C944) are also available that can be used to prevent footrot. There is some controversy on how well the vaccines work, so the prevention techniques mentioned previously are still essential. Some animals may develop injection site lesions due to these vaccines; this should be considered when administering them to show animals.

                                                                                             

Hairy Heel Warts (foot warts, strawberry foot, raspberry heel, or papillomatous digital dermatitis):

Causative Agent:
Hairy heel warts are caused by spirochetes (Treponema spp.), which are corkscrew-shaped bacteria. These organisms invade the outer layers of tissue in the foot region.

Clinical Signs: These warts usually cause the animal to be moderately lame and cause some swelling. The lesion is actually raised, bright red and fairly painful, usually located at the heel of the foot. Often there are small hair-like projections from the lesion itself.

Disease Transmission: The disease spreads rapidly and easily among susceptible animals. This is particularly true when the environment is wet, overcrowded, or contaminated with excessive amounts of urine and manure. Each animal becomes infected when the Treponema organisms invade the tissue of the foot.

Treatment: Topical application of oxytetracycline along with some type of wrap is recommended. (This can be accomplished by soaking a 4x4 gauze pad with tetracyclines, placing it directly over the wart and wrapping the foot with tape or vet wrap). The bandage should be changed every 3-5 days. Footbaths and hand sprayers containing oxytetracycline are also very effective. In order for the sprays, bandages, and footbaths to work, all the mud, manure and debris should be removed from the foot. Different solutions that seem to be effective include tetracycline, lincomycin, acidified copper solution, and acidified sodium chlorite. Residue warnings should be considered when using any of these products. Injectable antibiotics given in high doses can also be effective. Penicillin and ceftiofur (Naxcel) at extra-label doses for 3 days can be effective, but very expensive, especially when many animals are involved. Injectable antibiotics are often used in conjunction with topical treatments.

Prevention: One very controversial method of preventing hairy heel warts is vaccination. The reason for the debate is that some studies show that the vaccines really work, while other studies indicate that the vaccines seem to have no effect. The key to using vaccines for hairy heel warts is to determine if the vaccine is economically justified. To do this, producers will need to calculate the total cost of the vaccination protocol. This includes the vaccine itself, labor costs, etc. Realize also that the vaccine is not 100% effective and that a certain number of animals will have to be treated as described previously. These numbers should then be compared to the costs of not using the vaccine (decreased production, culling rates, etc.). Trep Shield (Novartis), a killed bacterin vaccine that specifically targets the spirochetes that cause hairy heel warts, is an example of a vaccine that could be used if vaccination is determined to be beneficial.

Ideas for Feed Lots and Dairy Producers:

Foot Sprayers: A common protocol used when spraying the feet is outlined as follows: "Mix one packet of Terramycin 343 (Pfizer) in one gallon of distilled or demineralized water (hard water will cause the tetracycline to precipitate.) Alternately, mix one packet of Lincomix soluble powder (Upjohn) in 2 quarts of distilled or demineralized water. Use these solutions as a topical spray at the rate of 10-20 cc per foot. Apply to the heels and between the toes while coating visible lesions. During the first week, treat all feet of all cows once daily for 5 to 7 consecutive days. In subsequent weeks, continue daily topical treatment of all cows with visible lesions only.*"

Footbaths: Footbaths can also be used to help prevent the problem as long as they are kept clean and manure free. A common protocol for footbaths is outlined as follows: "Foot baths with 5-10 percent copper sulfate or 1-10 gram/liter tetracycline have been moderately successful in controlling the disease. To achieve these concentrations, add 5-10 pounds of copper sulfate in 8.5 gallons of water or one packet of Terramycin 343 (Pfizer) in 25 gallons of water (1 gram/liter). Foot bath schedules range from daily soaks, to twice weekly, to each month for 3-4 days. It is recommended that the footbath be placed in the return alleys, not in parlor. The solution in the foot bath should be changed when grossly contaminated or after no more than 150 cows have passed through it.*"

* Wallace, Richard L. Hairy Heel warts: Fads and Fashions

 

                                                                                             

Abscesses and Ulcers: These are often discovered when inspecting the foot or using hoof testers and appear as pockets of infected material with abnormal coloration of surrounding hoof tissue. Often, this problem is associated with rough surfaces, nails, excessive toe growth, poor conformation, and problems with laminitis. Treatment for most abscesses involves cleaning/paring out the abscess to promote drainage and antibiotic treatment. Placing the unaffected claw on a block to prevent weight bearing on the affected claw can also help.

Fractures: The clinical signs include mild to severe lameness and swelling. In some cases, the animal may refuse to bear weight on the limb. Treatment depends on the location of the fracture and should involve a veterinarian.

Laminitis: This can be a common problem on a herd-wide basis. The cause of laminitis on a herdwide basis is usually a result of a diet high in carbohydrates and low in fiber. This causes a decrease in rumen pH and a potential laminitis problem. Laminitis on an individual animal basis can be caused by mastitis, rumenitis, grain overload, pneumonia, and retained placenta. Clinical signs include shifting leg lameness, tenderness, pink areas around the white line, and abnormal rings of hoof growth below the coronary band. Treatment involves the administration of anti-inflammatory agents and correcting the diet problems or individual animal diseases.