Footrot - Cattle

Synonyms

Foul in the foot, infectious pododermatitis, interdigital necrobacillosis, interdigital phlegmon, hoof rot.

Introduction

Foot rot in cattle is caused by the anaerobic bacteria Fusobacterium necrophorum. Fusobacterium necrophorum is ubiquitous in the environment of cattle as it is a normal inhabitant of the intestine of cattle (Kanoe et al., 1975) and is, therefore, shed into the environment. It can remain dormant in the soil for several months (Tulasne and Béguin, 1982) particularly in dried faeces. The organism contaminates areas where cattle congregate, such as tracks, areas around drinking sources, in gateways, in muddy corrals, or in the slurry of barns and loose houses.
Foot rot has been reported from many countries. The disease is particularly prevalent in temperate climates with a moderate rainfall and relatively high cattle population density.

Foot rot in cattle should not be confused with foot rot in sheep. The two diseases are different and cross infection between the two species is not believed to occur. Foot rot in sheep requires not only a virulent strain of Dichelobacter nodosus to be present, but also Fusobacterium necrophorum to be present.

F. necrophorum is consistently isolated from foot lesions along with other organisms. It is believed that most cases of foot rot result from the organisms entering the subcutaneous tissue through interdigital skin. It has been assumed that this occurs as the result of traumatic damage or the action of noxious agents in slurry. Another commonly held opinion is that the skin is made vulnerable by the action of various organisms frequently found on the skin of the digit.
Once F. necrophorum has entered the interdigital space, extensive cellulitis develops. The inflammatory oedema between the claws pushes them apart, stretching the interdigital ligaments and causing considerable pain. The skin between the claws fissures and sloughs away. A common complication is septic arthritis of the distal interphalangeal joint.

The incidence of foot rot has been reported nationally and it is thought to be the cause of lameness in around 5% of lame animals. Choquette-Levy et al. (1985) recorded a prevalence of 7.3% in Quebec, Canada and Russel et al(1982) found that in 40 veterinary practices in the UK, 15.8% of lame cows had been treated for foot rot.

Signalment

Any breed, age or sex of cattle are affected by this condition.

Clinical Signs

Signs include sudden onset generalised lameness in varying degrees such as stiffness or limping. The leg will appear swollen and erythrematous. The animal may be noted to be shifting its weight from one leg to another and if chronic, there may be evidence of disuse atrophy in the affected limb. The animal may have reduced weight gain or weight loss and have a decreased milk yield. The animals will usually be pyrexic.
On closer examination of the foot, it will appear hot, moist, erytrematous and have a foul odour. There may be skin necrosis and sloughing of the affected area and a purulent discharge may be present. The swelling may have caused the two digits to separate, and the cleft between the claws will appear to be larger than normal.

Diagnosis

Clinical signs plus physical examination of the foot will lead to a presumptive diagnosis of the disease.
Radiography is not useful in most instances, but is essential in cases failing to respond to treatment and when either septic pedal arthritis or a retroarticular abscess is suspected.
The organism can be isolated and cultured in a labortatory, but this is not usually required for diagnosis and would be more a research procedure.
Exclusion of differential diagnoses such as retroarticular abscessed is important. The characteristic of this condition is that swelling occurs around one digit only, which is different to foot rot. Severe diseases such as Foot and Mouth should also be eliminated as this is a notifiable disease.

Treatment and Control

If treated, most cases respond very rapidly, usually with very little after effect. Recurrence will occur occasionally. Natural immunity appears to inhibit reinfection for at least six months.
Suitable antibiotics for treatment of the condition include penicillin G, oxytetracycline, sulfadiazine/trimetroprim, sulfadimethoxine and tylosin. All should be given by injection as topical therapy is not strong enough to be curative. The injections should be given for three consecutive days. It should be noted that there are milk withdrawal periods on these medications.
Intravenous infusion via the digital vein with a suitable antibiotic is the most effective way to treat the most advanced, unresponsive, and/or acute cases. This procedure is best undertaken by a veterinarian. A tourniquet is applied above the swollen region and the injection is made into one of the veins. The tourniquet can be left in place for 20 min. If the tourniquet is applied for longer, tissue damage will occur. The tourniquet is released slowly to ensure that the antibiotic does not flood into the body too rapidly.
If the skin of the interdigital space has sloughed, topical treatment is essential. This is particularly important if a secondary lesion appears to be starting in the dorsal region of the interdigital skin. The wound should first be cleansed with soapy water, then thoroughly dried. A generous amount of a topical dressing such as an antibiotic paste should be applied. The lesion must then be protected at least for a few days. A cloth bandage has the disadvantage of acting as a wick when immersed in slurry. The affected foot may be enveloped in a stout freezer bag and protected from wear with duct tape. A lift is sometimes helpful or a Shoof (Shoof International, New Zealand, http://www.shoof.co.nz/index.cfm) may provide the best protection. If treatment fails to produce an early resolution, the case should be rechecked for complications or an alternate diagnosis.

Control measures include footbathing of animals with 5% copper sulpahte or formalin. Zinc methionine and paraformaldehyde have also been used.
Propriety vaccines are available but it is, at present, questionable if they are cost effective. Two injections are required one month apart, but the immunity that develops only reduces the incidence of the disease and does not eliminate the risk completely. The use of autogenous vaccines has proved to be very effective with deer (Chirino-Trejo et al., 2003). Nevertheless, vaccinating bulls twice each year is strongly recommended. When a bull suffers from foot rot, the fertility of the animal drops immediately and is slow to recover.
Once a case has become ‘open’, the discharge of the causal organisms into the environment causes contamination of those areas in which the traffic of cattle is heaviest. The reduction of slurry is extremely important. Good drainage around drinking and feeding areas is important. The isolation of cows (or the use of a protective boot) during the early infectious stages of the disease is strongly recommended. Very early, adequate treatment is essential.

References

Blowey RW, 1994. Interdigital causes of lameness. Proceedings of the 8th Symposium of Disorders of the Ruminant Digit, Banff, Canada, 142-154.
Chirino-Trejo M, Woodbury MR, Huang F, 2003. Antibiotic sensitivity and biochemical characterization of Fusobacterium spp. and Arcanobacterium pyogenes isolated from farmed white-tail deer (Odocoileus virginianus) with necrobacillosis. Journal of Zoo and Wildlife Medicine, 34:202-268.
Choquette-Lévy L, Baril J, Lévy M, St-Pierre H, 1985. A study of foot disease of dairy cattle in Quebec. Canadian Veterinary Journal, 26(9):278-281; 19 ref.
Eddy RG, Scott CP, 1980. Some observations on the incidence of lameness in dairy cattle in Somerset. Veterinary Record, 106:140-144.
Kanoe M, Imagawa H, Toda M, 1975. Distribution of Fusobacterium necrophorum in bovine alimentary tracts. Bulletin of the Faculty of Agriculture, Yamaguti University, Japan, 26:161-172.
Russell AM, Rowlands GJ, Shaw SR, Weaver AD, 1982. Survey of lameness in British dairy cattle. Veterinary Record, 111:155-160.
Tulasne JJ, Béguin JC, 1982. Ovine Footrot: General report. Proceedings of the 4th International Symposium on disorders of the ruminant digit, Paris, France.