OCALA EQUINE CONFERENCE

The 26th annual Ocala Equine Confer- ence was held at Ocala, Florida, on October 31 and November 1, 1987. The conference was well attended by Florida equine practi- tioners, as well as practitioners from neigh- boring states, who heard lectures concentrat- ing on anesthesia and lameness.

Anesthesia Dr. John Benson from the University of

Illinois discussed the many sedatives and tranquilizers used in the field. He felt it was important to know the animal's weight in order to calculate a proper dose. A useful method to estimate weight is to measure the circumference around the girth and over the withers in inches. Square this value and multiply it by the length of the horse and then divide this value by 300. The above equation will give you an approximate weight for the horse in question.

Commenting on sedation, Dr. Benson felt that chloral hydrate combined with xylazine is very useful for long standing pro- cedures, such as a recto-vaginal fistula. Chlo- ral hydrate is given at a dosage of 15 mg/Ib of the 2 percent solution and could be prolonged with 20cc increments; xylazine is used at 1.5 mg/lb IM. Local analgesia is added to the above combination.

Benson felt xylazine was an excellent pre-med for general anesthesia at the dosage of 0.25-0.5 mg/lb. The same dosage could be used for sedation of foals. He warned against the use of xylazine in wobblers and discussed the inadvertent injection of xylazine in the carotid artery. Carotid injection is not lethal and the convulsions can be controlled with Valium at .025 mg/lb. Rough recovery from general anesthesia also can be smoothed out by using xylazine at the dose of 0.15-0.30 mg/lb. Adverse effects of Rompun are re- versible using tolazoline at a dose of 2.5-5.0 rag/lb. This product is available through Sigma Corporation in powder form.

Because the onset of action of acepro- mazine is 15-30 minutes, it should be noted that when the popular combination of ace- promazine/xylazine is injected, the useful effect of the xylazine is finished just as the effects of the Acepromazine are beginning.

Rompun combined with a tranquilizer. Dr. Benson spoke about a combination of

guaifenesin, ketamine, and xylazine that could be used in the field for general anesthe- sia in foals. For example, it could be used when flushing septic joints in a foal, where prolonged anesthesia may be necessary.

500 ml 5% guaifenesin 500 mg ketamine 250 mg xylazine Induction: 0.35-0.5 ml/lb Maintenance: 1.0 ml/lb/hr 15 drops -- 1 ml 15 x BW (lb)/60 -- drops/minute

Back Pain Dr. Bill Moyer from the University of

Pennsylvania presented his views on back pain. He felt it was necessary to rule out conditions of the hind limb, such as painful hocks, that will cause secondary back pain.

Rest is always useful, but the client is not always willing to take the horse out of work. Dr. Moyer identifies the painful areas with digital palpation and injects these areas with a combination of'carbocaine and depo- medrol (50 ml carbocaine to which 5 ml depo-medrol is added) using a 3.5 inch spinal needle. He inserts the full length of the needle and then injects 6-8 ml of the solution as the needle is withdrawn. This relieves the spasm and deposits an anti-inflammatory in the painful area. The horse is then sent home on a regimen of Butazolidin, hot hydrotherapy using a Water Pic shower head, free longe in a paddock and then a saddle is put on and the horse is walked for 5-10 minutes before start- ing exercise. Dr. Moyer felt acupuncture also has a place in therapy.

Laminitis Factors that complicate the successful

outcome of laminitis are the multitude of causes, the pathophysiology of the disease not being fully understood, and lastly, all the degrees of lameness that can be seen with the syndrome. Causes include Potomac fever, endotoxemia, possible allergic reactions, severe infections, digestive tract disorders, and trauma to the feel Clinical signs some- times can be deceiving. Any bilateral or quadralateral lameness should be treated as laminitis until proved differently and it con- stitutes a veterinary emergency.

Moyer commented that many horses that

served when pressure is applie& (~omnary band swelling may be seen without radio- graphic changes. Radiographs may not re- veal rotation acutely, but one can measure the distance from the dorsal aspect of the coffin bone to the dorsal aspect of the hoof wall. The distance for most Thoroughbreds is less than 15-16ram. If the distance is increased, it would indicate lamina swelling and, usually, problems forthcoming.

In treating laminitis, Moyer felt it was important to counsel the owner with regard to severity of condition, the economics of ther- apy, and the long term commitment required.

When treating these cases, Moyer tries to determine and treat the cause. He gives them 4 gms of Butazolidin IV and then maintains them on a daily dose of 3 glns orally. B anam- ine is used for the first three days and he uses promazine (Sparine) at haft the normal dose to lower blood pressure. Moyer will use nerve blocks in the acute stage, but does not walk the animal. He may repeat the nerve block one time. If the horse is well shod, Dr. Moyer bandages the foot with extra padding under the frog. He described a frog pad that was being developed by Dr. Ric Redden. He does not advocate applying shoes in the acute stage. These animals are re-evaluated in 72 hours and treatment is changed if necessary.

Radiographic evidence of a seroma is indication for immediate hoofwallresection. Fluid pressure will cut off blood supply fur- ther, promote rotation, and cause mechanical separation within the hoof wall. Dr. Moyer performs his resections with a rasp as de- scribed by Dr. Ric Redden. Completed resec- tions are packed with 2% iodine and ban- daged with combine roll.

Navicular Disease vs Foot Brulslng

Dr. Moyer ended the series by describing a number of horses that were diagnosed as classic navicular cases. These horses were subjected to post-mortem examination that revealed no bony damage or tendon problem in the navicular region. Dr. Moyer feels that navicular disease is certainly over-diag- nosed.

Foot bruising may show the same clinical signs as navicular disease; for example, the horse may move the same way, the response to hoof testers is the same, the horse is ren- dered sound after a P-D nerve block and may

80 EQUINE VETERINARY SCIENCE

or may not show radiographic changes. Bruises may be hard to spot, especially in a dark foot. What is bruised is the interface of the coffin bone and sensitive sole. The bruise is seen when sufficient leakage of blood enters into the sole. Horses with flat feet can continuously bruise and therefore become chronic. Causes of foot bruising are narrow shoes, unbalanced feet, a long-toe-low-heel foot, and tight medial branches of the shoe.

Dr. Moyer treats these cases by balancing the feet, applying wide-web shoes with the sole surface of the shoe well concaved using agrinder. He tries to extend the useful surface of the foot as far back as possible by using bar shoes. Recent work completed in different studies is proving that isoxsuprine at the rec- ommended dose is ineffective as a vasodila- tor. (By Steve O'Grady, DVM)

SAFETY

Safety should always be a part of all educational programs for horse owners, adult and youth. This includes both safety for the rider or handler as well as for the horse. We all love horses, and horse riding is an excel- lent sport for people of all ages. However, we often become careless. Safety should be a constant consideration. Horseback riding is indeed a relatively dangerous activity. Horses are not pets, they do not reason or think like humans,and they are not machines.

Safety rules for working around, riding, hauling, training, breeding, etc. must always be a part of any management or educational program. More people, adult and youth, than ever before are using safety helmets. We should always stress suitability of the horse to the rider. Most young riders and even beginning or novice adult riders need older, stable, well-broke, and "bomb proof type" horses or ponies.

Many excellent horse safety guidelines are available. Safety should be a priority for all horse owners - - read, study, demonstrate and practice safety at all times. Prevention of injury to rider or horse is the final goal; however, most people under even the best of conditions or preparation, will eventually be involved in accidents. This is a given that should be understood by everyone involved. Sooner or later all riders do fall off, are thrown or become involved in a riding or handling accident. Riders and handlers should be well versed in safety and in first aid for both the rider and the horse. These steps should not diminish the desire to ride or the thrill but everyone involved should keep the sport in perspective. (By Dr. Arden N. Huff)

WINTER MANAGEMENT

Feeding and management programs for horses are critical during the cold winter months. More feed energy is required for maintenance during extreme cold weather. Horses need regular daily care and observa- tion. Exercise is important, especially for stabled horses. Feet should be inspected and picked out on a regular basis. Mud and ice balls accumulate on the hoof and/or fetlocks and should be removed. Shoes need to be reset or replaced at least every six to eight weeks. During cold weather, horse owners should check the daily water supply to be sure that it is adequate and not "bone chill- ing" cold. Water in buckets sitting overnight will freeze or be much colder than freshly drawn water. Horses need an access to shel- ter.

One of the best ways to save feed and keep horses in good shape is to have a good internal parasite control and prevention pro- gram. A regulated and balanced feeding program is critical during the winter. It is best to manage and feed horses by age groups or to separate young horses from older horses.

Horses have to be fed as individuals and there are no rigid guidelines. Horses should be kept in good shape - - not thin and cer- tainly not obese, this is critical for breeding horses. As a guide, horses will need 1/2 to 1 1/2 pounds of grain and 1 to 1 1/2 pounds of hay per hundred pounds bodyweight per day.

Idle mature horses can be maintained on a hay ration. Other horses will need grain and protein according to age, work or use. All horses should have access to trace mineral- ized salt. A simple free choice mineral mix- ture is also provided by many owners. Young horses require higher quality feeds and pro- rein supplements. All mares kept for breed- ing should be kept in good flesh throughout the year. Fleshy (ribs not showing) mares out perform thin mares in all areas of reproduc- tive efficiency.

Nutrition for the pregnant mare should be of high quality and gradually increased for the last 90 days of pregnancy and then the early stages of lactation willrequire the high- est plane of nutrition. Increased feeding in this process may also have a "flushing" ef- fect, of value in re-breeding. Protein levels may be suggested as a percentage of ration dry matter, a young foal requires about 19% protein, ayearling needs about 12% orhigher and mature idle horses can do well on 9 to 10%. Lactating mares will need 13 to 15% protein. Most high quality balanced rations will provide adequate supplies of vitamins; however, specific supplementation may be required under some conditions. Calcium

and phosphorus nutrition is i~aportant, espe- cially for young horses. This includes the proper levels and ratios. The minimum cal- cium to phosphorus ratio should be 1.1 to 1.

Basic stable management should in- elude ftre prevention programs and rodent control. Rats and mice can destroy a lot of feed. Moisture is one of the biggest problems in horse housing. Horses produce heat and moisture. The moisture must be removed from the building to preventodorbuildup and condensation. Ventilation of one type or another is the technique for removal of mois- ture and odors. (By Dr. Arden N. Hufl)

HORSE BORN THROUGH NEW FERTILIZATION TECHNIQUE

The world's first horse conceived through a new equine fertilization technique has been born at Colorado State University.

The friendly chestnut colt, named Gift, was born through the technique called heterogeneous fertilization. The technique consists of an egg being removed from a mare's follicle before ovulation, surgically transferred to a recipient mare's oviduct and fertilized.

Not only was this the first use of this technique, it also was the first time that a foal has been born following surgical transfer of an egg into the oviduct of a recipient mare.

The new technique is expected to be a boon for equine research and members of the horse industry who want to obtain foals from valuable mares that are infertile.

Such a mare is incapable of carrying an embrytr---an egg that already has been fertil- i zed- to maturity or to the point where it can be transferred to a recipient mare through embryo recovery and transfer methods. Those methods, standard procedures now, were pioneered several years ago at Colorado State.

However, the embryo recovery and transfer methods have faced difficulties. Embryos can be recovered from a fertile donor at a rate of 60% to 70% per cycle, but expected embryo recovery from an infertile donor mare is less than 30%.

"This new fertilization technique elimi- nates problems with embryo recovery from infertile mares," said Angus McKinnon, veterinarian in charge of the projecL '~I'o date, it is the only practical way to provide pregnancies from infertile mares that fail to provide embryos by standard recovery pro- cedures."

"Its use is expected to be limited to mares valuable enough to warrant a proce-

Volume 8, Number 1, 1988 81