What is the cause and what are the symptoms of foot rot?
Foot rot is a sudden and severe inflammation between the toes, most likely caused by the Fusobacterium necrophorum bacterium. This necro-bacillus (a germ that causes necrosis – meaning death of tissue) is always present in the environment.
It is commonly assumed that, under certain conditions, bacteria are able to penetrate the skin between the toes, often through a small weakness or injury in the skin. The result is a reactive inflammation, often with a very rapid and severe onset.
The swelling is centered above the claws and frequently on one foot only. It is not unusual to have more than one animal affected at the same time. Proper and immediate treatment is essential to stop the infection process at this stage.
Often a second stage develops in which also the interdigital space (the skin between the two claws) becomes inflamed with necrosis and pus. This causes a foul smell and results in a deep wound between the claws.
As this deep type of wound heals, it will lead to excess growth, often referred to as a tyloma or corn. A secondary symptom can be separation or detaching from the horn, like an “ingrown nail” and we then enter another stage. This irritation will cause more swelling and inflammation and before you know it, the P3 bone or pedal joint will be irreversibly damaged.
All of the above might seem rather overwhelming, but as a positive point, I’d like to add that foot rot doesn’t need to be a serious dairy farm problem. Before pointing out the treatment procedures, I would like to discuss the following questions with you:
How can I distinguish foot rot from other hoof disorders?
If your cow is lame for a long period of time, the cause most likely is not foot rot. The foot may smell and look “rotten,” but the inflammation is quite probably not caused by foot rot and we’re dealing with another cause of lameness.
(If it was foot rot, this would be the point where it has gone into a secondary stage and now is affecting more areas of the foot or leg. In this case, we have a mess that is not easily reversed. I’ll get to that later in this article.)
Early recognition and action is the key for proper diagnosing. I would like to mention the other hoof diseases and their differentiating factors:
• A (complicated) sole ulcer, double sole and white line defect are confusing and prone to be misdiagnosed as foot rot. Holding onto the symptoms of foot rot: rapid onset (12-20 hours), the “centered” swelling above the foot, combined with a slight fever and an often noticeable production drop, will help you in your judgment.
• Heel erosion, where the heel bulb or ball horn is being undermined and deep grooves are appearing in the rear of the foot, can also cause some misdiagnosis.
There is often a foul smell, but the onset of lameness occurs over an obviously much longer period and the lameness may not appear as severe. This defect affects the claws themselves, whereas foot rot appears “above” the claws, within the foot.
• Hairy heel warts are also confused with foot rot, mainly because of the severity of lameness and the strong foul odor. Still, when compared to foot rot, this condition only affects the outer skin, primarily in the heel area.
The “centered” swelling might not be as obvious, but when you have a close look, you’ll find that the heel warts have an open “skin” problem and a “ring” of hairs on the outer circle. As a side note, I’d like to add that I’ve observed more than once that a hairy heel wart will cause the foot to be “weaker” and less resistant, making it more prone to foot rot.
• Foreign objects can often cause major swelling in a short time. I’ve seen o-rings, baler twine, five-inch nails, electrical staples, wraps that are overdue, etc. All of these will cause swelling, foul odor and sometimes “self-amputation” and are not classified under foot rot.
How do I treat and take care of the animal when foot rot is diagnosed?
It is important to know our field of expertise. As a hoof trimmer, I have to take a step back here and refer you to your veterinarian to prescribe the proper drugs to use on your farm. It is very important that you take quick action because of the deep tissues involved and the severity of this disease.
Some practical pointers that I would like to share with you are:
• If possible, separate the animal from the rest of the herd and give her soft bedding. This will help her to get around. With a sore foot, it is easier to stand on a straw pack than in a tight freestall on slippery floors.
• Give her easy access to feed. I have seen cases where foot rot caused such a significant setback in the animal’s eating habits that she ended up with a displaced abdomen or even abortion.
• In the later stage of foot rot, I have seen a loosening of the inner walls of the two claws. This results in an “ingrown nail” effect and causes irritation. This irritating horn has to be removed with a sharp hoof knife and a local anesthetic is recommended.
• In my years of serving the dairy industry as a hoof trimmer, I have come across some great additions and alternatives to medications. One of my favorites is the “claw-bag,” which is applied to the affected foot for 30-minute intervals, twice a day, for three to four days. Add warm water to the bag, together with Epsom salts or Tetra powder.
There are commercial bags available, but these are too narrow when we have a severe problem. For these cases, I take a tire inner tube from a vehicle and cut a third out of it off, to give a “banana” shaped tube with two open ends.
Next, you fold the “banana” in half, bringing the open ends together. Take three “layers” in one hand, one layer in the other and you have made a hoof bag. To hold the bag in place, I usually make some holes on the top and string a rope through it. Try it, you’ll love it.
• A great aid and alternative to antibiotics is a hoof gel containing chelated zinc, copper, and aloe vera. It should be used under a hoof wrap to help the healing process. For foot rot cases, I recommend removing the wrap no later than one day after application. The foot needs to “drain” and you do not want to put a “plug” on it. The hoof gel is available from your local dairy supplier.
• It is also very important to have regular checkups to ensure proper healing. Foot rot is usually under control in three to four days, but you should contact your veterinarian if problems persist.
It is possible that you might have missed the correct diagnosis, but don’t worry – you’ll get better at it over time and it is sometimes hard to distinguish the differences in foot problems.
What preventive steps can I take to eliminate foot rot?
• Proper cleaning of the facilities is always a must, not only for hoof defects but also for other health issues. In particular, foot rot will not spread as rapidly between animals when the environment is clean. “Weakening” factors, as described before, such as hairy heel warts and heel erosion, are also kept under better control in a clean barn.
• Timely control and treatment of an affected animal and removing her from the herd are great ways of preventing the spread of disease to her herdmates.
• I’ve seen dry lime or other commercial drying powders spread around the water troughs as a preventive measure. This is not a proven method, but it has some merit due to the fact that it dries the feet and controls the bacteria count in the area.
• Clearing up “messy” areas with a lot of obstacles (rocks, nails, glass and frozen dirt) is recommended to avoid injuries to the skin that can allow bacteria to enter the foot.
• Finally, the use of a footbath as a preventive method is an option to control not only foot rot, but a lot of other hoof diseases. Copper sulfate and formalin are still used on a lot of dairies, but these products are not environment-friendly and cause pollution. Formalin is also known as a cancer-causing substance and should be avoided.
I have noticed that more producers are turning to other alternatives. I have seen some results with antibiotic baths, but these are limited by the fact that there is a resistance buildup and no response after prolonged use.
For foot baths, I prefer to use a 5 percent hoof gel solution, which contains chelated copper and zinc. Check out a footbath solution which has a triple-purpose construction: a dividing grill to eliminate some manure pollution, a smaller volume that allows 30 percent less product to be used, and an extra step to allow more “dips” for each foot.
This article is meant as a quick guide for producers and I have tried to avoid difficult terms and explanations. Much has been written about hoof diseases and there are many books available for the producer who would like to delve into this further.
I also have developed a website where producers can find help and solutions to their specific lameness issues, which can be found at www.diamondhoofcare.com PD