The use of ultrasound technology is an essential diagnostic tool for the equine veterinarian. Each one of our equine veterinarians has been equiped with the latest in ultrasound technology allowing it to be used for a variety of day to day tasks.
Ultrasound as the name suggest uses sound waves that are emitted from a small hand held probe. The sound waves are extremely safe and cause no discomfort or audible noise. As sound waves are directed at various body tissues they are bounced back to the same probe. The amount the sound waves bounce back will vary with the density of the body tissue. The probe can then send this information to the macine via a cord. The machine instantly converts this signal to a black and white image which we can then interpret.
Our biggest use of ultrasound at Scenic Rim Vets is for the detailed examination of the reproductive tracts of mares during the breeding season, with any one of our vets performing up to 100 of these examinations each day. The technique involves the careful placement of the probe in the rectum of the mare which gives us a birds eye view of the uterus, ovaries and cervix. Another common usage for ultrasound is the examination of the tendons and ligaments of the horses lower limb.
Our vets can also use ultrasound to look at chests, abdomens, muscles and other soft tissues of the body. There are very few limitations to the use of ultrasound, it can only visualise the surface of bone and is not suitable for deeper boney structures (see section on radiography or x-ray).
Tendon and ligament injuries in the limbs of competitive horses are, unfortunately, very common. It is true that many owners and trainers of performance horses have regarded injuries to these structures as more threatening to an equine athlete’s future career than fractures.
It often seems that these injuries are becoming more common, and many believe there is a heritable component that breeders are allowing to be more prominent within the population. These injuries are more common in horses of poor conformation, horses that are competing when still reasonably immature and when performing at a higher level.
Usually horses with suspected tendon injuries are presented when an owner recognises swelling over the structures and the presence of mild lameness. The swelling is usually not present at the time of injury, but is more commonly noticed the following day. At this point, there are several questions that need to be answered.
- Is the inflammation within the tendon or ligament or is it in surrounding tissue?
- If it is in tendon/ligament – how severe is the damage?
If swelling is surrounding the tendon the prognosis is very good, and the horse only needs a very short period of rest before return to performance. If the damage is to tendon or ligament fibres themselves, then the prognosis and treatment change depending on the severity.
Assessment of tendon damage is best performed by a veterinarian experienced in the use of a quality ultrasound machine. For basic assessment of obvious lesions, examination with a portable machine on farm may be all that is required. For the detection of more subtle lesions and better assessment of the tendon fibres can be achieved at a dedicated surgical facility with an appropriate high end machine.
The factors that indicate severity that are usually assessed are
- cross sectional size of the tendon or ligament (Usually compared to either an ‘established normal’ size, or comparison against the opposite limb. It is important to remember that the opposite limb may also have been affected at some time, and therefore it may not represent a normal size for the use as a comparison). If the cross section size is increased by 20-30% it is rated as ‘moderate’ damage (obviously if it is <20% it is ‘mild’ and >30% it is ‘severe’.)
- if a core lesion (seen as a hole on ultrasound in the tendon) is present it should be measured. In this case, ‘moderate’ applies to core lesions of 15-30% of the tendon cross sectional area or if it extends 20 -30% of the length of the tendon.
- Chronicity (ie. Is this a re injury of a previous lesion?). If the tendon has been torn several times the prognosis for ongoing soundness is obviously reduced. Assessment of deposition of previous scar tissue is readily established with good ultrasonographic technique and will change the case management.
Some of the more common structures involved are the Superficial digital flexor tendon (SDFT), the Deep digital flexor tendon (DDFT), the Suspensory ligament origin (behind the knee and hock) and the Suspensory branches. Some of these structures more commonly form low grade ongoing tendonitis, while others tend to suffer acute severe tears.
Treatment options for these injuries are many and varied. The most important factor on healing is a graded exercise program, which prevents further damage and the slow introduction of exercise allows for realignment of healing tendon fibres. This is sometimes aided by use of an aqua walker if one is available.
An example of a regime for a moderate tear of the SDFT might be
- Stable confinement for 2 weeks and treat with anti inflamatories (usually phenylbutasone). At this point (usually the 5-10 day mark) you may consider intralesional treatments (i.e. injected into the tendon itself). These have been widely researched and used, with very variable results. Two of the most common currently in use are platelet rich plasma (PRP) and stem cells. These are both reasonably expensive therapies. Then..
- Small yard for 4 weeks.
- Larger yard for 6 weeks. At this point introduce hand walking (or on a rotary walker) for 10 minutes per day. Then add 5 mins extra walking per day each week for the next 6 weeks (i.e. till you reach 40 mins walking per day).
- 3mth post injury. Re evaluate with ultrasound.Horse may remain in yard or be turned into paddock. At this time the horse should have 5 minutes extra of its walk removed and replaced with ridden trot each week.
- 6mth post injury. At this time the tendon should be re evaluated with ultrasound, and if healing is progressing well the horse can begin work at a canter.
- 8mth post injury full work (but not at racing speed)
- 10mth post injury re evaluate then back into competition
The average rehab program for a SDFT tear is approximately 4-5 months for a mild tear, 8-10 months for a moderate tear and 12-18 months for a severe tear. The success rates of tendon therapy (measured by successful return to multiple racing starts) are often difficult to accurately report as individuals and companies frequently exaggerate claims of their own success. As a guide (from a large study in University of California Davis) the percentages were approximately 70% for mild tears, 60 % for moderate tears and 40% for severe tears when treated with a graded exercise program. Big claims of success are also made by the manufacturers of some of the intralesional therapies available, but clinical observation doesn’t always reflect them. The important thing to remember is that no treatment or regime is capable of returning the tendon to the strength it had prior to original injury. Thus it is necessary to maximise the strength of the healing as described above, but it is also absolutely essential to take all measures to correct any mechanical imbalances in the foot to help prevent re injury.
Several specialised shoes are commercially available for reducing stress on different tendinous and ligamentous structures, and are a vital tool to an astute vet/farrier team in supporting these horses.
Although controlled exercise requires time, effort, and money, if coupled with the accurate interpretation of regular clinical and ultrasonographic examinations, it provides the best opportunity for a successful resolution of tendon injury.
Case Study – Hind limb tendon injury
These images are from a thoroughbred racehorse that had traumatised both its hind superficial flexor tendons with a wound 1 year previously. The picture above shows the near hind leg with a severely enlarged Superficial digital flexor tendon labelled SF. It has extensive scaring and loss of fibre pattern. As this is a hind limb, and the damage was from a wound rather than a tear, they usually hold a better prognosis. This tendon had not caused lameness and the horse had been working for the preceding year.
However, when the horse became lame in the off hind it was assumed that the pain was associated with the previous SF damage. This turned out not to be the case, with a new and painful lesion developing in the Deep flexor tendon as seen in the images above (a longitudinal view, looking along the tendon) and below (transverse view, looking across the tendon). The darker area within the DF is the core lesion. PS labels the proximal sesamoid bones at the back of the fetlock. These findings obviously change the horse’s treatment and prognosis significantly.
Your horse’s teeth can often be overlooked when it comes to horse care.
There are many reasons for having your horse’s teeth checked on a regular basis.
A general rule is to have them checked annually unless you have been advised otherwise, with some horses requiring 3 to 6 monthly assessments.
Sharp teeth can be a source of pain and in turn lead to a difficulty in eating and loss of weight. Sharp teeth can also lead to a reluctance to accept the bit and cause a horse to misbehave whilst being ridden.
Horse feed is often expensive, so to maximise the efficiency of feeding it is vital that your horse be able to use its teeth to reduce feed to a size that the gut can process effectively.
Equine dentistry is a rapidly expanding area of horse care. There are many different people offering this care. In Queensland equine dentistry is not restricted to vets only. However, the use of sedatives and pain relief is restrcted by law to veterinary surgeons only. Further to this, insured horses are not normally covered for any accidental damage sustained whilst having teeth done by dentists who are not veterinary surgeons.
At Scenic Rim Vet Service we are able to provide a full range of dental services for horses, with access to specialists for even the most advanced procedures.
Our equipment includes a “Powerfloat” which is the latest in motorised dental tools. Such equipment is designed to improve the efficiency of equine dentistry and correct problems without prolonging the time your horse needs to stand with its mouth open.