There are many things that can cause lameness in cattle. One of the most common is the condition called interdigital necrobacillosis, or foot rot. (It is also known as foul, foul in the foot, infectious pododermatitis and interdigital phlegmon.)
Foot rot in cattle is caused by Fusobacterium necrophorum, which may act alone, or in concert with a few other bacteria, including Bacteroides melaninogenicus, Staphylococcus aureus, Escherichia Coli, Actinomyces pyogenes and the newly blamed Porphyromonas levii. Dichelobacter (Bacteroides) nodosus, the causative agent of the highly contagious foot rot seen in sheep, can cause a superficial surface inflammation in cattle, allowing the entrance of the pathologic F. necrophorum.
F. necrophorum is a normal commensal bacteria found in the intestines of healthy cattle, and generally does not penetrate dry, healthy skin. In addition to foot rot, it is the cause of necrotic stomatitis in calves, calf diphtheria and is isolated from liver abscesses in feeder cattle. It acts synergistically with other bacteria, such as the ones listed above, which decrease the dose of F. necrophorum necessary to cause illness. In the case of foot rot, diseased or injured skin is susceptible to infection, so anything that damages the interdigital area can predispose to it. High rainfall, wet, muddy feedlots, or even just standing in that puddle of urine cattle are so good at making and standing in to apparently cool their feet, can cause maceration of skin tissue and allow penetration of the causative organism. High temperatures and humidity may cause chapping and cracking of the skin, leaving it vulnerable to bacterial invasion. Injury caused by sharp pieces of stone, wood, thorns, frozen manure and even corn or alfalfa stubble can precipitate a case of foot rot. Once loss of skin integrity occurs, the bacteria gains entrance into the subcutaneous tissues and begins to rapidly multiply. With multiplication comes the production of toxins that further proliferate the infection and cause necrosis (death) or decay of the infected tissues. There exist conflicting reports on susceptibility due to age; some references claim the condition is usually seen in older cattle, others claim calves are more susceptible to infection. Based on my own experience, I would guess that sporadic cases are more likely in “older”cattle (weaning on up) but in cases of outbreaks and severe environmental contamination, calves may very well make up most of an outbreak. Regardless of age, acquired immunity appears to be poor.
Unlike foot rot in sheep, the disease in cattle is usually sporadic and while very infectious, it is not generally considered highly contagious, but it may affect larger numbers of cattle in outbreaks situations or in certain problem herds. Certainly, infected feet serve as a primary source of infection for other cattle by contaminating the environment with high levels of the organism, but predisposing factors must be present to cause disease. The bacteria have been estimated to live between 1 and 10 months outside the body, depending on conditions, so that high environmental levels may be present for an extended period of time. If a cluster of cases is seen during hot dry weather, then particular attention should be paid to the primary loafing area, often in a shady part of the pasture, where crowding of animals results in urine and manure ponds. Sometimes extremely wet weather can lead to a few cases, with more showing up later when everything appears dry. This is probably due to previous heavy contamination of these isolated wet loafing areas and trauma to the interdigital skin produced by dry stubble or sharp stones.
The first sign of foot rot is acute swelling of the tissue between the toes and swelling evenly distributed around the hairline of usually just one hoof. Often, the animal may be running a fever at this time. Acute foot rot appears to be exquisitely painful, the cattle are often dead lame on one foot, with reluctance to move, and increased recumbency. Calves are usually easy to diagnose from a distance, as their lighter body weight allows them to move about relatively well on three legs, rather than remaining recumbent. Also, their smaller, more delicate features may allow easier detection of the tell-tale swollen foot. Eventually, the interdigital skin cracks open, revealing a necrotic, vile-smelling core of dead tissue. Untreated, the infection may cause swelling to extend up the foot to the fetlock, or higher. More critical, severe cases may invade the deeper structures of the foot, including the bones, tendons and joints, resulting in permanent damage.
Other conditions that may resemble foot rot include interdigital dermatitis, sole abscesses, sole abrasions infected corns, fractures, joint infections (septic arthritis) and tendonitis. These conditions usually involve only a single claw of a single foot and not the areas of skin between the toes. Digital dermatitis (hairy heel warts) usually occurs on the back of the foot, just above the bulb of the heels and may progress up to the dewclaws. Large hairy heel warts are unmistakable in the peculiar, large horny “hairs” that grow from the chronically inflamed skin. They require only topical therapy, while foot rot, unless caught very early and a very mild case, requires systemic antibiotics.
Certainly many cases of foot rot heal on their own within 7-10 days, however due to the tendency to progress animals must be watched very closely to determine if in fact, healing is occurring and whether systemic treatment should be given. In range animals not under close observation, sustained duration of action is a must in any antibiotic chosen.
Treatment is usually straightforward once the diagnosis has been confirmed. Probably length of treatment time is more critical than which antibiotic is used. A minimum of 3-5 days of antibiotic therapy will be necessary, and in severe or resistant cases, longer than that. A number of injectable antibiotics are usually highly effective against the foot rot organism. Treatment should always begin with cleaning and examination of the foot. If extremely mild and early, topical treatment with antibiotic ointment or soaks may suffice; however, close observation must continue to make sure the infection is responding to the treatment. Sometimes “flossing” between the toes with a clean rope or twine will help to remove some of the dead tissue. Injectable antibiotics are the mainstay of treatment for foot rot. They need to be used at a high enough dose for a long enough period of time to cure the infection. This will require adequate blood levels for a minimum of 3-5 days, and at least several days past apparent cure (the animal is sound, not limping, without swelling and without fever.)
Deep infection of the foot may occur as a result of untreated or severe cases of foot rot. Involvement of the joints, tendons or bones of the foot will not be correctable with foot trimming procedures and often will result in permanent lameness ultimately requiring slaughter. Unfortunately the dorsal pouch of the distal interphalangeal joint is very close to the interdigital skin, and can become infected due to foot rot. The disease is not to be taken lightly.
Affected animals should be kept in dry areas until healed. This accomplishes 2 things; speeds healing in the infected animals, and limits environment contamination. Foot rot that progresses to a severe infection that may require salvaging for slaughter, (carefully following drug withdrawal requirements) claw amputation, or in extremely valuable animals, claw salvaging surgical procedures.
Prevention of foot rot is of course, preferably to treatment. Effective preventative measures include minimizing the time cattle can stand in wet, contaminated areas, as well as minimizing exposure to clipped weeds, pasture or brush that has stubble high enough to injure the interdigital skin. Footbaths are impractical for most beef operations, although may be possible for small herds. Other preventative measures include the addition of zinc and/or organic iodine to the feed or mineral mixes, and vaccination. If cattle are moderately to severely deficient in zinc in the diet, supplemental zinc may reduce the incidence of foot rot. One study supported the use of 5.4 gms per day of zinc methionine in grazing steers. Historically, organic iodide (EDDI) has been added to salt mixes to aid in the prevention of foot rot. Vaccination with a killed F. necroforum bacterin (Fusoguard-Novartis) may reduce clinical signs of infection and should be considered if other control methods fail or a severe outbreak is anticipated. It requires an initial vaccination with a booster dose given 3 weeks later. Based on references citing the lack of good acquired immunity to natural disease, I do have to wonder about the efficacy of vaccination. While feed antibiotics would be convenient to treat foot rot, there are no feed-grade antibiotics approved for foot rot treatment in the
Sources of injury should be removed from pastures and feedlots. Mud holes should be filled and stagnant pools drained or fenced off. Manure should be removed frequently in confinement operations. Lanes and walkways should be kept well-graded and drained, avoiding low areas. Regular foot trimming will keep animals walking comfortably and prevent injury due to abnormal locomotion. Foot rot is a serious infection but with early intervention and vigorous treatment, most cases will have a favorable outcome.
Over-the-counter antibiotics labeled for foot rot include LA 200 and Biomycin, both containing oxytetracycline, Sustain III (sustained release sulfa boluses), and Tylan. All can be excellent treatment for foot rot if used at appropriate dosages. I have personally used Biomycin with excellent results at label dosages.
In addition to the above listed antibiotics, there are a number of excellent prescription antibiotics that effectively treat foot rot. Advantages of these prescription antibiotics include low volumes and/or extended duration of therapy. Generally cost of the drug will not be an advantage, as these products are usually more expensive than OTC meds, but if consideration is given to labor time and costs, they become extremely attractive options.
Any of the ceftiofur preparations are labeled and excellent for foot rot. Naxcel is a non-irritating, low volume and short withdrawal period form, that must be rehydrated prior to use, and given one time per day. Excenel is the same antibiotic (ceftiofur) in a ready to use formulation that may be administered every 1-2 days, at relatively low volume. Excede is a sustained release formula of Ceftiofur that maintains blood levels for up to 7 days; however, it can only be administered subcutaneously in the ear.
Micotil is another excellent antibiotic that is low volume with 7-10 day duration of activity. However, I do not use Micotil as it is highly toxic if accidentally injected into yourself or another human. There have been at least 13 deaths associated with human exposure to Micotil since 1995, some accidental and some apparent suicides.
Nuflor is another good antibiotic but a very thick solution that makes loading a syringe difficult, and requires relatively large volumes for a duration of 4 days.
Tetradure is an oxytetracycline antibiotic that has a 7 day duration of therapy, is relatively inexpensive, but is also very thick and difficult to syringe and requires large volumes for the average cow (60-80 cc*) which must be given in multiple sites as no more than 10 cc should be given in one location. I use Tetradure quite a bit, and like it despite its drawbacks. It has a tendency to cause considerable swelling at the site of injection.
The last prescription antibiotic I will mention is relatively new called Draxxin. It is in the same antibiotic class as Micotil, but doesn’t come with the same extreme human toxicity. It is very low volume, easy to syringe, with a 7-14 day duration of activity. It is extremely expensive but very effective. I like Draxxin very much despite its expense.
One remark on the use of Procaine penicillin G; (Pen-G, Agricillin, Crysticillin, Pen-Aqeous) Pen-G is a wonderful antibiotic when used for the right type of infections and at appropriate dosages. Foot rot falls into the right type of infection, but the dosage listed on the label is, in my opinion, totally worthless. I would not give an injection of penicillin G at the labeled dosage for any reason in cattle. However, Pen-G is a very popular OTC antibiotic that everybody seems to keep in their barn or tack box.. LA 200, Biomycin or sulfa boluses are all excellent antibiotics and much better choices at label dosages for OTC (over-the counter) uses in cattle.
Using Systemic Antibiotics for the Treatment of Foot Rot in Cattle
AMDUCA- Animal Medicinal Drug Use Clarification Act: this act allows veterinarians to prescribe extra-label uses of certain approved animal or human medicinal products for animals under certain circumstances. Extralabel use refers to the use of a drug in a manner not listed on its label. The Act specifies that the extra-label use of any animal medicinal drug must be by or on the order of (prescription) by a veterinarian for that specific extra-label use, within the context of a valid veterinarian/client/patient relationship. This includes both prescription and OTC drugs.
It is illegal to use OTC antibiotics for any purpose or at any dosage not listed on the label unless prescribed specifically by a veterinarian for the animal(s). Needless to say, prescription antibiotics always require a prescription, regardless of use.
OTC Antibiotics commonly used to treat Foot rot.
If accompanied by a * indicates Extra-Label Dose, prescription required. All costs figured on 1/2009 internet prices, assuming prescription available from your veterinarian and you purchased the largest bottle available. Expect to pay more per treatment if your veterinarian dispenses the drug in just the volume you require.
Liquamycin LA 200 or Biomycin 200: dose 4.5 cc/100lbs body weight IM or SC (repeat in 72 hours)* 1200# cow requires 54cc sc in 6 locations. Repeating in 72 hours* for a total duration of therapy of 6 days, costs approximately $12.00. I find Biomycin a little less irritating than LA 200 and have used it with great success.
Sustain III boluses: 1 bolus per 200 # body weight; repeat in 72 hours. Approximate cost for a 1200# cow is about $9.00. Restraint for injections may be easier than restraint for oral boluses, particularly in horned cattle.
Tylan 300: dose 4 ml/100# IM once per day for 3-5 days. 1200# cow will need 48 cc in 5 different locations once per day for 5 days costing about 20.00 for treatment, and a lot of grief for the cow and the owner.
Procaine Penicillin G (Crysticillin, Pen-Aqeous, Agricillin): Label use is 3000 units/pound IM. This amounts to 12cc once a day for a 1200# cow. It sounds very attractive and inexpensive. I have no use for Pen G at this dose. If you want it to work, the dosage should be in the range of 20,000-30,000 units/ # * IM or SC once or twice per day. That puts the drug up in the range of 40-80cc once or twice a day. This will cost $4-8.00 per day, depending on how much you give. This, number one, makes Pen-G look not nearly as cheap, and number two, not nearly as convenient (see Tylan remarks.) But it will work at this dose.
Prescription antibiotics: some of these dosages are extra-label but they require a prescription from your veterinarian in all cases anyway.
Tetradure 300 (same active ingredient as LA 200 and Biomycin, longer duration of therapy): Dose is 4.5cc/100# and gives about 7-8 days duration of therapy. 54 cc should cost about 15.00 and will require 6 injection sites.
Excede: 1.5 cc/100# once SC in the ear. Total cost for our cow getting 18 cc is about 30.00. Single injection site is an advantage, however, chronic inflammatory changes can occur to the ear, depending on volume and location. Draining tracts may develop with larger volumes. I wouldn’t recommend this for show cattle.
Micotil: 1.5 cc/100# SC: don’t inject yourself!!! 18 cc (2 sites) for our cow should be about 25.00.
Nuflor: 6cc/100# SC, for about 4 days of therapy. 72cc (8 sites) costs about 35.00.
Excenel: dose specifically for foot rot is 1-2cc/100# sc for up to 5 days. Amounts to 24 cc (2 sites) once a day for 5days and would cost about $78.00: this would be my first choice for a particularly bad case of foot rot. Extralabel doses of 12-24 cc every 2 days would be substantially cheaper, but I would only use these for milder forms of the disease.
Naxcel: 1-2 cc/100# SC or IM once per day for up to five days. Same active ingredient as Excede and Excenel, but must be reconstituted with sterile water, and used within 12 hours at room temperature or 1 week if refrigerated. Can be frozen one time for up to 8 weeks once reconstituted. Will be more a little more expensive and a bigger hassle than Excenel, so I see no advantage to it over Excenel.
Draxxin: dose is 1.1 cc per 100# one time (duration of therapy 7-14 days) Dose for our cow is 13.2 cc (two sites) SC and costs about 50.00. A 250 ml bottle of Draxxin can be purchased for about $890.00 on the Internet. It is not much less when I buy a bottle.
2 excellent antibiotics for use in cattle are Pfizer’s A180 (danofloxacin) and Bayer’s Baytril (enrofloxacin). However, these are labeled for the treatment of respiratory disease only. It is illegal to use this class of antibiotics (fluoroquinolones) for any other purpose and at any other than listed doses in food producing animals.