Dry cows (and infected heifers) should be included in the footbathing routine.
Permanent, concrete footbaths may measure 3 m (10 ft) long and 0.2–0.6 m (8–24 in.) wide. The sides of the bath should not slope inward and should be 15–25 cm (6–9 in.) deep. Cows prefer to use footbaths that have a bottom close to floor level; therefore, a built-up block "rounded lip" could be considered in the design. The medicated solution should be a minimum of 8–10 cm (3–4 in.) deep. Drainage from the bath should be provided to ensure the foot can be properly cleansed. To avoid blockage, the drain hole should be 10–20 cm in diameter and located at the lowest point of the bath.
Footbaths should be located in relation to the exit from the milking parlor in a frost-free environment with, ideally, an area suitable to drain chemicals from the feet to avoid contaminating the bedding. At all costs, deviation from the normal free flow of cow progression should be avoided.
Prewashing the feet before entering the footbath has been increasing in popularity. Ideally, the wash bath should be located before the cows enter the milking parlor. This allows time for washing fluid to drain before cows enter the chemical bath. The dimensions should be similar to those of the medication bath.
Use of a footbath is not a substitute for either good hygiene or claw trimming. However, if digital dermatitis is endemic on a farm, regular use of a footbath is mandatory.
Plastic, fiberglass, or metal portable footbaths should be avoided. A hoof mat, consisting of a sheet of foam plastic encased in a perforated plastic cover, is also available. The foam is soaked in medication that squirts up between the claws when the cow walks on the mat. There are no recent reports on the effectiveness of this device.
Fully automated power spray washers are claimed to be extremely economical in the use of water, and they require no operator. They deliver soapy water, and some users believe this device alone reduces the incidence of foot disease.
Chemical Agents for Footbaths:
Formalin 4% is the least expensive footbath solution for the control of interdigital phlegmon (footrot). Some cows will refuse to enter a formalin footbath if the solution is stronger than 4%. Formalin has been found of value to control digital dermatitis. The solution should be changed after the passage of ~200 cows, more frequently if the bath is heavily contaminated with manure. Formalin has good bacteriostatic activity and some potential to harden the epidermis. However, it is ineffective at temperatures <13°C.
Formalin generates strong fumes that irritate the lungs of milkers and can taint milk. It should never be used in baths located near the milking parlor.
The stronger the formalin solution used, the more effective it is, but the danger of a chemical burn on the cow’s skin is also greater. If the hair on the foot appears to be standing on end or the skin is pink, bathing should be suspended. Normally, cows can tolerate twice daily baths for 3 days using a 3% solution. The treatment should be repeated every 3 wk. Higher concentrations should only be used for the most resistant conditions.
Formalin is regarded as a hazardous waste, and land disposal restrictions should be checked and followed. Formalin must never be released into sewer systems, because sewer treatment plants may have problems and contaminated drinking water could be released. However, formalin is said to break down in 7 days in sludge or slurry; even then, it is wise to wait until it is diluted to one part formalin in three parts sludge before spreading it on arable land. Preferably, the land selected should not have a high water table. Unused formaldehyde concentrate should be returned to the vendor.
Footbathing with a 5% solution of copper or zinc sulfate controls interdigital dermatitis and is of some value in controlling footrot (interdigital phlegmon). There are two grades of copper sulfate, and the pentahydrate grade should be used. The solution must be prepared 5 hours before use. Prewashing of the cow’s feet is advised, and the solution should be changed after the passage of ~200 cows.
Copper has a strong affinity to be bound by soil, the organic matter in manure, and soil minerals. Hence, much of the copper found in soil is unavailable for plant uptake. Once the copper reaches a high level in the soil, the process cannot be reversed. Therefore, plants stunted by high levels of copper have a lower nutritional value to cattle. Copper sulfate footbath solutions may be tagged to slurry at the highest practical dilution and spread widely on the land.
The sulfates are quite rapidly deactivated by combining with the proteins in manure.
The use of antibiotics in footbaths has been a popular past strategy for the treatment, control, and prevention of digital dermatitis. Few reports on the use of antibiotics in footbaths appear in the current literature. Antibiotics are expensive and deteriorate in contaminated solutions. The type of antibiotic used in footbaths should be changed at intervals of ~6 mo to avoid development of resistant strains of the causal organisms. However, treatment may be given for 2–3 days and repeated once after 7 days. Formalin footbaths may be used alternately if more aggressive treatment is necessary. Antibiotics used in footbaths do not result in detectable levels of drug in the bloodstream or milk. Antibiotic sprays or powders are still used for topical treatments.
A new generation of chemical agents has been developed for use in footbaths, but claims of effectiveness have not yet been adequately substantiated in controlled trials. Foams are also available but the cost of associated equipment is considerable. Foams keep the chemical agent in contact with lesions better than liquid products.