Foot rot, or infectious pododermatitis is a hoof infection that is commonly found in sheep, goat, and cattle. As the name suggests, it rots away the foot of the animal, more specifically the area between the two toes of the affected animal. It is extremely painful and contagious. It can be treated with a series of medications but if not treated the whole herd can become infected. The cause of the infection in cattle is two anaerobic bacteria(bacteria that can grow without oxygen), Fusobacterium necrophorum and Bacteroides m e laninogenicus. Both bacteria are common to the environment that cattle live in and Fusobacterium is present in the rumen and fecal matter of the cattle. Usually there is an injury to the skin between the hooves that allows the bacteria to infect the animal. Another cause of foot rot may be high temperatures or humidity causing the skin between the hooves to crack and let the bacteria infect the foot. This is one of the reasons that foot rot is such a major problem in the summer. Foot rot is easily identifiable by its appearance and foul odor. Treatment is usually with an antibiotic medication, and preventing injury to the feet is the best way to prevent foot rot.
·
[edit] Signs of Infection
The first sign of a foot rot infection is when the skin between the claws of the hoof begins to swell. Swelling usually appears twenty-four hours after infection. The skin between the toes may be very red and tender and the toes may separate because of all the swelling. This is very painful to the animal and can cause lameness. A crack can develop along the infected part and is yellow in color. The foot will have a foul odor. Another sign of infection is that the infected animal may lose a large amount of weight rapidly. It is critical to treat the problem immediately or the bones, tendons, and joints in the area can become infected which is much harder to treat. There is a condition known as super foot rot that is seen in some animals. Super foot rot is just like normal foot rot only infection occurs much faster and is usually much more severe. Most normal foot rot treatments will not cure this foot rot and a veterinarian should be contacted immediately.
[edit] Treatment
The best way to treat foot rot is to catch it as early as possible. The infected animals should be separated away from the herd as soon as possible to prevent the infection from spreading and allow the animal a better environment for healing. The first treatment is to clean the foot thoroughly and examine the foot to determine that it is definitely foot rot that is causing the infection. Keeping the wound clean and using an antibiotic ointment may help reduce the spread of infection. Foot rot is usually treated with an antimicrobial product. Penicillin, tetracycline, and other antibacterial medicines are often used to treat normal cases of foot rot. Usually the antimicrobial product is non-prescription but sometimes a veterinarian may choose to use a prescription medication. It is critical to closely monitor the animals to make sure they are responding to treatment. The infected animals should be kept dry until the healing has occurred. If the animal is showing no signs of recovery after three to four days the bacteria could have infected the other tissues of the foot and along with a veterinarian the owner should decide whether to amputate the bad foot or to put the animal down
(edit) Prevention
The infected animals can serve as the source of infection for the whole herd because they will spread the bacteria throughout the environment. The bacteriacan live without a host for one to ten months. Once another animal gets a cut or crack in the soft tissue between their toes the bacteria can infect the animal. This is why infected animals must be kept away from the rest. A good way to prevent foot rot is to keep any foreign objects that may cut or damage the foot out of the environment. This should be a practice regardless of whether a herd has foot rot or not. The cuts are what allow the bacteria to enter the foot tissue and cause the infection. Some cattle feeders add zincto the feed mixes and may vaccinate the animals for foot rot. Zinc is important to maintaining the skin and hooves of cattle. Cattle deficient in zinc will become infected easier than cattle with adequate zinc in their diet.
Clinical Signs and Diagnosis
The earliest and most obvious clinical sign of foot rot is lameness, which increases in severity as the disease progresses. Once the infectious organisms become established, they cause inflammation and necrosis of tissue, resulting in slight to severe swelling and pain. The swelling is usually more evident in the interdigital space and around the coronet (or skin horn junction). The swelling is usually sufficient to cause separation of the digits. A break or fissure in the interdigital space develops which may extend from the front of the foot to the bulbs of the heel. These lesions are sometimes difficult to see unless the foot is elevated and properly restrained for examination. The interdigital lesion is often necrotic along its edges and has a characteristic fetid or foul odor, hence the name foul-in-the-foot.
The signs of foot rot in cattle include lameness with holding or raising a foot, reluctance to move, impaired locomotion, loss of appetite, weight loss, low-grade fever and reduction in milk yield for lactating cows. Hind feet are affected most often and cattle tend to stand and walk on their toes. If left untreated, lameness becomes increasingly severe with infection extending to the distal and proximal interphalangeal joints and other deeper structures of the foot.
Diagnosis of foot rot is made by observation of the animal and physical examination of the foot for the characteristic gross lesions. Cattle producers often diagnose any lameness associated with foot swelling as foot rot, but a more careful examination may reveal other causes of the swelling and lameness.
Introduction
Ovine foot rot was first reported in 1869. It is an infectious, contagious disease of sheep that causes severe lameness and economic loss from decreased flock production. In a Virginia survey, approximately 21 percent of the producers considered foot rot to be a serious health problem in their flocks. With current understanding of the disease, and aided by drugs and vaccines, control and elimination of the disease should be the goal of all sheep producers.
Ovine foot rot is caused by an interaction of two anaerobic (without oxygen), Gram (-) bacteria, Bacteroides nodosus (formerly Fusiformis nodosus) and Fusobacterium necrophorum (formerly Sphaerophorus necrophorus). Fusobacterium necrophorum is a normal inhabitant of the ruminant digestive tract and in wet weather may interact with another bacteria, Corynebacterium pyogenes, to produce foot scald, an infection of the skin between the toes. This infection sets up the foot for invasion by Bacteroides nodosus, which, working in conjunction with the Fusobacterium, produces the condition referred to as foot rot. Since Bacteroides can only live in the hoof of an infected animal or in the soil for no more than 10-14 days, it is possible, through careful management procedures, to keep from introducing foot rot into a flock and to successfully control and/or eliminate the disease if the flock is infected. See Figure for a diagram of the predisposing factors for infection.
Return to Table of Contents
Diagnosis
Lameness is usually the major sign of an infected animal, although sheep with an early infection may not exhibit lameness. The area between the toes first becomes moist and reddened. Then the infection invades the sole of the hoof, undermining and causing separation of the horny tissues. The infection causes a characteristic foul odor and may infect one or more feet at the same time. Not all lame sheep have foot rot. Before undertaking an eradication, treatment, or control program, it is best to consult a veterinarian for a positive diagnosis and advice. Other diseases that may be confused with foot rot are foot abscesses, foot scald, laminitis or founder, corns, traumatic injuries, and foreign bodies lodged between the toes.
Return to Table of Contents
Transmission
The bacteria that causes foot rot, Bacteriodes nodosus, is spread from infected sheep to the ground, manure, bedding, etc., where it is then picked up by noninfected sheep. Foot rot is introduced by purchase of an infected animal or by simply using facilities or trucks that have been contaminated by infected sheep. Spread occurs best when temperatures are from 40-70 degrees F and the environment is wet. Since the organism doesn't survive long in the environment (< 2 wks), carriers in the flock will continue to reinfect the flock unless the animal is either culled or the organism is eliminated by proper treatment.
Return to Table of Contents
Prevention
It is always easier and less expensive to prevent foot rot than to treat it after it has become established. To remain disease free, there are five management principles that will help keep foot rot from being introduced into a clean flock.
1. Never buy sheep with foot rot or from a flock infected with foot rot, even if the animal(s) appear unaffected.
2. Avoid buying sheep at sale yards or livestock markets where clean and infected sheep may have been commingled or run through the same area.
3. Avoid using facilities (trails, corrals, dipping areas) where infected sheep may have been in the last two weeks.
4. Never transport sheep in a vehicle that has not been properly cleaned and disinfected.
5. Trim and treat the feet of all new arrivals, then re-examine them periodically during the 30-day isolation period.
Return to Table of Contents
No comments:
Post a Comment