Lameness
Lameness Lameness is probably the number one reason for a vet having to see your horse other than routine vaccinations and teeth etc. There are many causes of lameness which all vary greatly in the ease of diagnosis and treatment. Some conditions, such as a foot abscess, can often be diagnosed and treated immediately, others require specialist diagnostic tools just to find the problem and some conditions often require months off work, e.g. tendon injuries. Horse owners must realise how complex a case of lameness can be and understand that even the most experienced of vet’s may not be able to give you all the answers immediately.
Identifying lameness An obvious lameness can often be seen at the walk and may cause the horse to stand awkwardly on the leg, however, most cases of lameness are only evident at the trot and this is usually the best gait to assess a lame horse. Lame in front: When trotting the horse’s head will nod when the sound leg hits the ground. Lame behind: The hindquarters will sink lower when the sound leg hits the ground.
Some lamenesses can be made worse by lunging on a circle or working on either soft or hard ground.
Vets will grade a lameness out of either 5 or 10. A 0 score is a sound horse, 1 a mild lameness at the trot and 5 or 10, unable to bear any weight on the lame leg, with others filling in the levels between.
What to do if your horse is lame Any lame horse should be placed on box rest, to prevent further damage, until a vet has examined the animal and said it is OK to do otherwise. A horse that is unable to bear any weight on the leg is an emergency and needs to be seen by a vet as soon as possible, this can be assessed by trying to lift the opposite leg to encourage the horse to stand on the lame one. Slight lameness can be often be reassessed after a few days of box rest and veterinary advice sought if there has been no improvement. Any lameness that is associated by a kick or wound will usually require veterinary attention.
Finding a diagnosis Initially the lame leg can be carefully examined for any areas of pain or swelling and the joints flexed to see if this is resented. Hoof testers should be used to assess foot pain as most lamenesses involve the feet. If there is an area of pain the shoe is normally removed and the foot thoroughly searched for an area of bruising or an abscess.
Nerve blocks In most instances the clinical examination is not able to identify the source of pain in the lame leg, therefore, nerve blocks are used. The aim of a nerve block is to remove all sensation from specific areas of the leg by injecting a small amount of local anaesthetic around the nerves. The sensation is usually abolished for approximately two hours. The vet will start nerve blocks low down on the leg and work upwards until the horse is sound after a block, ‘blocks out’. This indicates that the pain is between the level of this block and the previous one and further diagnostic tests can be carried out on this area.
Joint blocks If a joint, tendon sheath or bursa is slightly swollen or nerve blocks indicate that the pain may come from a particular joint, sheath or bursa, local anaesthetic can be injected into the structure to either confirm it or rule it out as the source of pain. To perform this procedure the area must be made sterile and the technique performed using sterile gloves and other equipment to prevent the joint, sheath or bursa from becoming infected.
Radiographs (X-rays) X-rays are produced from the x-ray machine and pass through the area you wish to image and onto a plate behind. The plate contains an x-ray film that is developed. Bone shows up white on the finished image as fewer x-rays were able to pass through it due it being thicker that the surrounding tissue. Because of this, x-rays are used mainly to assess the bones and joints and can be very useful in finding fractures, arthritis, bone cysts, etc. and are also very useful in assessing the conformation within the foot, especially in laminitics. For each area of the horse standard views are taken, often four needed, to fully assess the area.
Protective clothing is worn by the people present taking the x-rays to reduce exposure and anyone under the age of 18 or pregnant must not take part in the procedure.
A recent advance in x-ray technology is digital x-ray which allows the images to come straight up onto a computer screen where they can be easily manipulated. A protective gown must be worn when taking X-rays.
Ultrasound scanning Ultrasound scanning is used to look at soft tissues, muscles, tendons, tendon sheaths, bursas or ligaments, and only the bone surface can be seen. The requiring scanning must be clipped, cleansed and ultrasound gel applied. High energy sound waves are produced which hit the tissues are then rebounded back. The way these waves return gives us the image on the screen. Unlike with most radiographic machines this image is instant. Ultrasound scanning is mainly used to diagnose and monitor strain injuries of tendons and ligaments and to assess fluid build up.
Bone scanning Bone scanning detects areas of active bone remodeling ‘hot spots’ and can find problems that could not been find on radiographs or are in areas that cannot be x-rayed easily e.g. pelvis. Radioactive material is injected into the horse which binds to active bone. These areas can then be seen by a camera that picks up the gamma rays that are now being produced from the bone. After the scan horses must be quarantined for one to two days after injection due to the radioactive material.
MRI-Magnetic resonance imaging MRI is able to assess all tissues in one examination, however, is time consuming and expemsive and in some instances requires a general aneasthetic. Because of this MRI is used in cases where the area causing the pain is known, however, no abnormalities can be found using conventional tools, x-ray and ultrasound scanning. The most common cases for MRI tend to involve the feet as, due to the hoof wall, are very difficult to visualize the soft tissues using ultrasound scanning.
Key-hole surgery (arthroscopy, tenoscopy, bursoscopy) Surgery can be performed to look into joints (arthroscopy), tendon sheaths (tenoscopy) and bursas (bursoscopy) using a small camera. This technique requires a lot of skill and is particularly useful if a particular joint, sheath or bursa is found to be causing the lameness yet no abnormalitiy can be found using conventional diagnostic tools. This procedure requires a general anaesthetic and is the most expensive of all the diagnostic procedures available, however, in many cases the problem can be accurately diagnosed, attempts can be made to treat/improve the problem and an accurate prognosis can be given.