EquineSite.com

January 18, 2011

 by

Cara McNamee, DVM

Horses’ hooves are strong, made up of tough layers of keratin, the same material in our fingernails.  However, the hooves also protects crucial structures such as the navicular bursa, deep digital flexor tendon, coffin bone, and also synvia structures like the coffin joit and the navicular bursa.  When there is a penetrating injury to the foot, injury to these structures can be career-ending or even life-threatening.  Early recognition and treatment is therefore imperative to the best possible outcome.

The most common injury to the sole of the foot usually involves stepping on a sharp object, such as a nail.  They frequently cause significant lameness, even if no deeper structures have been affected.  Non-weight bearing lameness is not uncommon, with increased digital pulses present in the foot as well as possible swelling in the distal limb.  If the object is still present embedded in the foot, DO NOT REMOVE IT, and call your veterinarian immediately!  It is necessary for your veterinarian to see the object’s location as well as take radiographs with it in place to determine the depth of the wound and use his anatomical knowledge to determine the structures at risk.

Your vet will clean the foot thoroughly and examine the wound thoroughly with a probe in order to determine the depth of the tract.  The wound may be dissected sharply with a hoof knife or bone curette to examine the tract for foreign material and establish drainage. If none of the synovial structures is affected, local debridement and cleaning of the wound, and antibiotics, along with wrapping the foot for a few days will likely take care of it.

If the foreign body is at risk of having penetrated any of the vital structures, he ill likely be referred to a hospital. Your horse should be vaccinated against tetatnus yearly, and a booster may be indicated because the organism tends to be found in dirt and rust. He will likely be started on antibiotics as well.

Either at the hospital or at the farm, the veterinarian will evaluate all the synovial structures: the coffin joint, navicular bursa, and tendon sheath should be tapped and the fluid tested for presence of bacteria or increased cell count, indicative of inflammation.

If it is the case, surgery and aggressive antibiotic therapy (Intravenous antibiotics, regional limb perfusions, intrasynovial antibiotic delivery) will be needed as this kind of injury is life threatening.

In closing, if your horse comes in from the field lame and you suspect injury to the sole, call your veterinarian immediately.  Do not remove any foreign object from the sole.  Puncture wounds to the foot can threaten your horse’s career, so the earlier you seek treatment, the better. 

Please contact your veterinarian or any of the veterinarians at New England Equine Medical & Surgical Center if you have any questions.

     (By Dr Rachel Roemer and Dr Omar Maher)

Nuclear scintigraphy, also known as a bone scan, can be a useful diagnostic tool in many difficult lameness cases. Nuclear scintigraphy helps identify areas of inflammation and changes in physiologic bone activity. This is particularly useful in cases when the lameness cannot be adequately localized with local nerve blocks or seems to be caused by pain high in the limbs or in the neck or spine. It can also be helpful when there may be more than one area of inflammation or if there are radiographic changes that may or may not be the cause of the lameness. 
 
Nuclear scintigraphy units are located at many veterinary schools and private referral practices. The bone scan process is an inpatient procedure and the horse is kept in the hospital at least overnight. An intravenous catheter is placed in the horse’s neck and a radioactive isotope, technetium-99m (99mTc), bound to a molecule with a high affinity for bone, is injected into the horse. The 99mTc emits gamma-rays, which are picked up by a specialized sensor to produce an image of the 99mTc uptake in the body. The more 99mTc that is located in a single area, the more gamma-rays will be emitted from that location. Within the first 1-2 minutes after injection the 99mTc remains within the vessels (known as the vascular phase) and images to compare blood flow to the distal limbs can be obtained. At about 3-10 minutes post-injection blood flow to soft tissues can be evaluated (soft tissue phase). Increased uptake during the soft tissue phase is indicative of edema or inflammation. Several hours later, the 99mTc distributes to bone (bone phase), particularly to areas of active boney turnover where bone is being broken down and replaced or where boney inflammation is present. If a horse has active bone disease, such as degenerative joint disease, boney sclerosis (increased bone density), septic arthritis, etc., the affected area will “light up” on the image. Typically, only the soft tissue and bone phases are imaged, unless there is a suspicion of compromised blood flow.
 
Nuclear scintigraphy is quite safe for the horse as 99mTc has a relatively short half-life of about 6 hours, so it breaks down quite quickly. About half of the radioactive material is excreted in urine within hours of injection. During the bone scan process the technicians working with the horse and obtaining the images wear protective clothing similar to that warn when taking radiographs (x-rays). The horse must be kept isolated for at least 24 hours after the bone scan when it is excreting radioactive urine. Radioactivity levels are monitored using a Geiger counter and once the levels are back within a safe range the horse is allowed to be handled and transported as needed. Bone scans also allow veterinarians to collect important information without having to anesthetize the horse, which eliminates a host of potential risks. Bone scans cannot replace the lameness exam, diagnostic nerve blocks, or radiographs. However, in certain cases nuclear scintigraphy is extremely useful finally identifying the specific cause of lameness.

Bone bruising, fractures that are not obvious on radiographs (including stress fractures on race horses, pelvic fractures), back issues and sacro-iliac disease, cervical pathology (neck arthritis), pedal osteitis.

New Hampshire’s beautiful country settings are drawing many persons to move into or

travel those areas to enjoy the countryside. Our rural neighborhoods still have farm

animals, and horses are a common sight in pastures and back yards. You are likely to see

these horses ridden or driven down New Hampshire roads attributing to the country

setting that others are seeking.

NH Horse Council wishes to remind motorists about NH RSA 265:104 Approaching

Horses. “Every person having control or charge of a vehicle shall, whenever upon any

way and approaching any horse, drive, manage, and control such vehicle in such a

manner as to exercise every reasonable precaution to prevent the frightening of such

horse, and insure the safety and protection of any person riding or driving the same.”

NH Horse Council advises to, “please slow down and pass wide, and allow as much room

as feasible between the horse and the vehicle. Slowing down allows the horse and rider

(driver) enough time to realize a vehicle is approaching and to make sure the horse is

prepared for the vehicle to pass. When approaching a horse from the rear, it is important

to know that the horse and rider (driver) is going to be less aware of your presence, so

please be cautious. Never sound the horn or create loud noises, as this might cause the

horse to spook.”

If a rider (driver) is moving a hand up and down with the palm down, he/she is asking

you to slow down more. If the arm is out with palm toward you, he/she is asking you to

stop so the horse can be moved to a safer spot so you may pass. These gestures help to

communicate with motorists when additional caution is needed.

Motorcyclists, box trucks or vehicles with trailers should be especially aware of how

easily they can startle a horse. All motorists should be alert to the actions of the horse and

rider (driver) and be sure to slow down and pass wide. Please help with safety when

sharing the road.

Horse owners do appreciate all motorists who show awareness, courtesy and

respectfulness with sharing the road! WE THANK YOU ALL! Remember we are your

neighbors whom you pass on your town roads. Let’s slow down and give each other a

friendly wave.

From NH Horse Council “Thank You Again for your courtesy”!

(please feel free to repost this NHHC article and submit to local papers)