This fact sheet has been compiled to answer frequently asked questions about wounds involving joints and tendon sheaths in the horse, and also to give background information on the diagnosis and treatment of such cases which require surgical intervention. If you have any specific questions about the information which it contains, please email us on eqhosp@rvc.ac.uk
There are a number of factors which need to be taken into account in determining whether a wound should be regarded as serious, or whether it is a minor problem which will heal without any long term consequences. The size of the wound is the most obvious, but equally important is its location. A large skin wound, over the top of a large muscle mass, may lead to an unsightly scar, but it is unlikely to cause permanent lameness problems. In contrast, a tiny wound which has penetrated the tendons, or gone into a joint, can result in permanent lameness and even loss of the horse, if it is not appropriately handled. Therefore, a puncture wound in the fetlock or pastern region should always be taken seriously, particularly if the horse quickly becomes markedly lame. Infections of a tendon sheath, or a joint, can be very persistent, once they have become established, and the longer bacteria are present, stimulating an inflammatory reaction, the more likely the tissues of the joint are to be damaged, leading to permanent arthritis.
In most cases, when the joint or tendon sheath has been penetrated by a sharp object, it is contaminated with bacteria. For about 6-8 hours, these bacteria will remain relatively dormant, before they start to multiply in the tissues. It is at this point that the wound can be regarded as infected. This lag phase is sometimes known as the "golden period", and the defence mechanisms of the body may manage to clear the bacteria at that stage. If these mechanisms are supplemented by veterinary intervention, in the form of decontamination and early antibiotic therapy, this gives the best chance of the tissue resisting infection and healing in a straightforward manner.
The best treatment for such wounds involves a thorough investigation under general anaesthesia. The damage to the cartilage, bone, ligaments and tendons can be assessed, allowing an immediate conclusion on the degree of lameness a horse may be left with in the future, and any dead tissue which might harbour infection, and dirt and debris which would prevent wound healing, can be removed. We have found pieces of grit, metal, wood and leaf all rammed into the tissues, acting as foci for the subsequent infection. At this stage, the joint can be flushed with large volumes of sterile fluids, and, ideally, closed to promote rapid healing. If there is any danger of the stitches breaking down in the repaired wound, the leg can be put in a cast, to protect the wound and keep it sealed.
If you have ever taken antibiotics yourself, you will be aware that there are different types of antibiotic available for different types of bacteria, and that the length of the course of an antibiotic varies according to the condition being treated. The same is true of the use of antibiotics in animals. For a small cut that has only just gone through the skin, a single injection into the muscle might be all that is needed. In the case of contamination of a joint, the best way of preventing or treating infection is to put antibiotics directly into the joint, as well as giving antibiotics into one of the horse’s veins, several times a day, to keep up a high level of the antibiotic in the bloodstream. At least two antibiotics are normally given, as many different types of bacteria will be introduced into a dirty wound, and it is necessary to ensure that all of these are likely to be killed by the antibiotics used.
We have conducted a survey of the cases which we have treated, in the past, to see what factors determine the success rate. Where a wound to a joint has been present for less than 7 days, the infection can be controlled, in 9 out of 10 cases, with virtually all these animals returning to soundness. If the wound into the joint has been present for more than a week, infection can only be controlled in about 8 out of 10 horses, and only four of these animals will become sound. The likelihood of a horse returning to soundness is obviously considerably decreased if there is substantial damage to the bone, ligaments or tendons around a joint, as well as infection of the joint. It is still possible to control the infection in about 8 out of 10 animals, but only about two of these will end up sound.
The clear conclusion is that early, aggressive treatment saves the vast majority of animals, and those successfully saved return to their original work. If the treatment is delayed, although it may be possible to save an animal, the likelihood of it returning to work will be less than 50%.
Each case is different, so no two bills are alike. However, the UK range, in 2001, would be £2,500-£5,000, with £3,000 being the average. £2,000 would cover a straightforward case, where the infection is quickly controlled, the horse needs very few drugs after surgery, and goes home after about a week. Horses which are hospitalised for longer periods, and require a greater range of drugs during any operation, and in the post-operative period, incur correspondingly higher bills.
If you are insured for veterinary fees, this would normally cover up to the limit set for each incident. Always read the small print carefully. Some policies purport to offer thousands of pounds of cover but the maximum for a single problem may only be a few hundred pounds. Insurance for an incident costing up to £3,000 will cover the bulk of the fees in most cases of this type, but, in 2001, £2,000 is really too little cover. Most insurance companies do not cover livery while the horse is staying at a hospital, and there is usually an "excess" on the policy which means that you are liable for the first £50-£100 of the bill.
You will be given specific instructions, when your horse returns home, on the appropriate management. This may involve a period of rest in the stable, followed by a gradual return to work. The length of any lay-off period is determined by a number of factors, such as how long the infection went untreated, the speed with which it was controlled, and complications such as chip fractures of joints and damage to tendons and ligaments. You can be reassured that all advice will be tailored to the individual needs of your horse or pony.