It is well-known digital dermatitis is the most widespread infectious disease causing lameness in our herds. The infection sets in as a result of weakening of the skin, an injury for example. The main agent responsible for digital dermatitis appears to have been isolated: Treponema SP.
This bacterium is anaerobic, i.e., it develops in the absence of oxygen. It likes a neutral pH as well as warm and humid temperatures. It even has the ability to encyst itself in the animal, which is to say it enters into a state of dormancy when the environment is not conducive to its development. It is not easy, if possible at all, to get rid of the problem. This is when the footbath comes into play.
Let’s be clear: The footbath is used as a preventive measure. It is, therefore, not a treatment. It must be used more or less frequently depending on the farm’s situation (hygiene, herd’s infection rate, type of installation, etc.). Some use it once a week successfully. For others, four passages or more a week are needed to help control the lameness problem.
Current products
Traditionally, two products have been and are still used for the footbath: copper sulfate and formaldehyde. These have been proven to be effective when used as part of a program to control digital dermatitis. However, over the past few years, toxicity problems have risen due to its intensive use.
- Copper sulfate is the most widely used product in Canada and elsewhere for digital dermatitis control. Copper is a heavy metal and is persistent in soils. Even if copper is essential to plant growth, plants only need a very small amount.
After several years of applying footbath drainage water to fields, copper may accumulate to reach toxic levels for crops and micro-organisms in soils. This is the situation in some states that have been using copper for a long time. A study conducted in Oregon on 30 dairy farms showed surprising results: 75 percent of the farms had very high rates of copper in the soil with an average of 6 parts per million.
According to the study, a rate of 2 parts per million is considered high. Therefore, continued use of copper sulfate may result in an environmental challenge.
- Formaldehyde is being used less and less. However, some people continue to prefer formaldehyde use in footbaths. It is economical and known for its bactericidal properties, but it should be used with caution as it is a toxic and allergenic product.
It is also considered to be carcinogenic to humans by the International Agency for Research on Cancer (IARC). Before using this product, think about your health, your employees’ health and your hoof trimmer’s health. Trimmers can be exposed to fumes coming from formaldehyde accumulation in the horn when they trim hooves.
An alternative product
Lactic acid is a compound found naturally in milk but also in fruit juices, wine, muscles and others. We know it more as an agent used for roughage preservation. Present in the cosmetic industry, it is considered to be an excellent disinfectant and a gentle skin exfoliator.
It is also gaining more and more importance in the detergent industry as an antibacterial agent. It’s an organic acid, therefore degradable. It is gaining interest by manufacturers for use in footbath solutions.
Field tests have shown lactic acid is just as effective as the traditional footbath solutions, namely copper sulfate and formaldehyde, when used as part of a program to control lameness. Used in a footbath, lactic acid will reduce the pH of the water to a level not conducive to bacteria development.
The solution is effective as long as the footbath’s pH remains low. Footbath contamination will come from manure and other organic materials brought by the cows, which contribute to elevating the pH level of the solution, hence reducing effectiveness.
Generally, every 200 liters of footbath solution will allow 100 to 200 cows to be treated. Remember, there is no definite rule, and each situation is different. A 180-liter footbath is different than a 310-liter footbath. The choice of the product, cleanliness of the legs, volume of the footbath and even its location are elements that can affect the number of passages.
The interest behind lactic acid is the fact one can accurately measure the effectiveness of the solution by measuring its pH using a pH meter. Make sure you use the manufacturer’s recommended dosage. Also ensure the solution is replaced as needed and promote frequency rather than dosage.
In a 12-foot-long footbath, the cow will need three steps to walk through it. In a 16-foot-long footbath, the cow will need four steps to walk through it. A shorter footbath will contain less footbath solution, will allow fewer passages and will need to be changed more often.
A footbath located at the end of the barn, where animals are pushed through in groups by the producer, will have a tendency to stay cleaner longer compared to a bath located at the parlor exit. Every situation is different.
In general, dairy producers can plan to spend $30 to $40 per cow per year on footbath products; however, this certainly varies by farm and situation.
Cleanliness of the legs
A good number of studies have demonstrated the relationship between the number of digital dermatitis cases in a herd and the cleanliness of the alleys and the stalls. A direct relationship between the prevalence of the disease and the cleanliness of the legs was also clearly demonstrated.
A herd with dirty legs will have a greater risk of finding digital dermatitis cases. Maintaining cleaner alleys and crossings will contribute to a better leg hygiene. Cleaner legs also represent less organic material brought into the bath; therefore, farms could achieve more passages with the same solution. The frequency at which the animals walk through the footbath will also promote better leg cleanliness.
Effective, gentle to the skin and non-corrosive on steel, lactic acid is an interesting alternative compared to traditional footbath solutions. This organic acid will not contribute to the accumulation of heavy metals in fields or cause a risk to human health. As far as the use of the footbath, there is no miracle recipe.
Animal observation, regular hoof trimming and the footbath are all part of a series of operations that will help prevent and control lameness problems in herds. The control must be spread to the whole herd; don’t forget the heifers and dry cows. Are you buying new animals? Watch them closely and greet them with a good footbath. 
References have been omitted but are available upon request. Click here to email an editor.
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Francois Léveillée
- Sales Support Specialist
- DeLaval North America
- Email Francois Léveillée
