2006 Kester News Hour Research Highlights

For the past 10 years, the Kester News Hour has been a crowd-pleasing presentation at the annual American Association of Equine Practitioners (AAEP). At the 2006 convention, held in San Antonio, Texas, from December 2 to 6, Kester presenters Larry Bramlage, DVM, and John Madigan, DVM, summarized some of the most interesting scientific and veterinary research of the year during a special two-hour session.

The research papers discussed were pulled from a variety of sources not included in the official convention proceedings. Here are some of the highlights from the 2006 Kester News Hour:

• Research from the University of Missouri suggests the risks associated with stacking flunixin meglumine and phenylbutazone probably outweigh any benefits for routine treatment. Researchers studied 13 horses given both bute and banamine, and then bute alone. Blood samples collected at the beginning and conclusion of the study revealed a significant drop in protein levels among horses given bute and banamine together. One horse from the study group died from what the researchers suspect was NSAID toxicity.

Reference: “Effects of phenylbutazone alone or in combination with flunixin meglumine on blood protein concentrations in horses,” American Journal of Veterinary Research, vol 67, no 3.

• An Oklahoma State University force-plate study showed no significant increase in analgesic effect when bute and banamine were administered together to treat horses with navicular pain. The researchers concluded that there is little advantage to administering the two drugs together and doing so may lead to an increased risk of toxicosis.

Reference: “Evaluation of Phenylbutazone and Flunixin Meglumine in Combination in Horses with Navicular Syndrome Using Force Plate Analysis,” American College of Veterinary Internal Medicine, 2006.

• University of Saskatchewan researchers reported that ethyl alcohol may help hock joints fuse with minimal pain. The researchers injected ethyl alcohol into the hock joints of eight healthy horses, then monitored the joints through lameness exams and postmortem exams. The horses showed no signs of pain during the fusion process and radiography revealed that eight of 16 joints were fused within four months of treatment. All but one joint had fused after 12 months. This treatment would only apply to low motion joints, such as the hock.

Reference: “Use of intra-articular administration of ethyl alcohol for arthrodesis of the tarsometatarsal joint in healthy horses,” American Journal of Veterinary Research, May 2006, vol 67, no 5.

• A Texas A&M study showed that abnormal radiographic findings in yearlings are not correlated with poor performance later in life. Researchers reviewed the radiographs from 348 sale yearlings and recorded any abnormal radiographic findings attributed to developmental orthopedic disorders. When performance records from the end of each horse’s second and third year were reviewed, no association was found between abnormal radiograph findings and performance deficits. However the researchers did find a connection between radiographic findings and reduced sales prices. They, caution however, that the low number of individual lesions of any one type may account for the lack of statistical associations..

Reference: “Association of Racing Performance with Specific Abnormal Radiographic Findings in Thoroughbred Yearlings Sold in Texas”, Journal of Equine Veterinary Science, vol 26, no 10.

• University of Utrecht researchers found that the use of microcurrent electrical tissue (MET) stimulation on cells cultured from the equine superficial digital flexor tendon initially resulted in cell proliferation, but multiple applications led to accelerated cell death. The researchers conclude that scientific findings are far from conclusive with respect to the use of METS to promote tendon healing in horses.

Reference: “Effect of microcurrent electrical tissue stimulation on equine tenocytes in culture”, American Journal of Veterinary Research, vol 67, no 2.

• In a University of Guelph study, methicillin-resistant staphylococcus aureas (MRSA) was found in 120 of 2,283 horses admitted to the Ontario Veterinary College Veterinary Teaching Hospital. Sixty-one of the horses were colonized with the bacteria at admission; 53 horses during the hospital stay; and in six horses the origins of colonization were unknown. The researchers found clinical infections attributable to MRSA were present or developed in 14 of 120 horses, and the horses colonized at admission were more likely to develop clinical infection.

Reference: “Methicillin-resistant Staphylococcus Aureus in Horses at a Veterinary Teaching Hospital: Frequency, Characterization and Association with Clinical Disease,” Journal of Veterinary Internal Medicine, 2006, vol 20, no 1.

• In 2005, University of Guelph researchers screened 417 attendees at an international veterinary conference held in Baltimore, Md., for MRSA. Researchers isolated the bacteria from the nostrils of 27 people (6.5 percent of those tested). Of those screened, large animal practitioners were more likely to carry MRSA (15 people of 96 swabbed) compared to small animal personnel (12 people out of 271 swabbed). The researchers conclude that MRSA colonization may be an occupational hazard for veterinary professionals.

Reference: “Methicillin-resistant Staphylococcus aureus colonization in veterinary personnel,” Emerging Infectious Diseases, December 2006, vol 12, no 12.

• A 2005 Michigan State University study of draft horses used in pulling and hitch competition revealed a high incidence of laryngeal dysfunction. More than one-third of 183 draft horses examined using video endoscopy had idiopathic left laryngeal hemiplegia (ILH). Forty-two percent of the Belgians, 31 percent of the Percherons and 17 percent of the Clydesdales examined had ILH. The researchers also noted that horses with ILH were more likely to have increased tracheal mucus. The researchers speculate that selective breeding for larger, taller, longer-necked horses may have contributed to the comparatively high incidence of ILH amongst competitive draft horses.

Reference: “The Prevalence of Laryngeal Disease in a Large Population of Competition Draft Horses”, Veterinary Surgery, August 2006.

• A Colorado State University study compared the efficacy of different footwear hygiene protocols, including various combinations of overboots, saturated mats and footbaths. The data revealed that overboots had little effect on the number of bacteria found on the floor surface, and use of antiseptic on shoes made less of a difference than was expected. The researchers conclude that further study is needed to evaluate the usefulness of various footwear hygiene measures in reducing the risk of hospital-acquired infections in horses.

Reference: “Evaluation of the effects of footwear hygiene protocols on nonspecific bacterial contamination of floor surfaces in an equine hospital”, Journal of the American Veterinary Medical Association, vol 228, no 7.

• University of Minnesota researchers report that intravenous lidocaine is a safe and effective treatment for horses with ileus. Their study was based on 32 horses with postoperative ileus or enteritis that had refluxed more than 20 liters in the previous 24 hours. The horses were given an intravenous lidocaine bolus followed by an infusion for 24 hours. Reflux stopped in 65 percent of treated horses within 30 hours; only 27 percent of saline-treated control horses stopped in that time. The researchers conclude that intravenous lidocaine should be considered for the treatment of equine ileus.

Reference: “Intravenous Continuous Infusion of Lidocaine for Treatment of Equine Ileus”, Veterinary Surgery, vol 3, no 1.

• Researchers from the University of Utrecht utilized a global positioning system to quantify the spontaneous locomotor activity of 59 foals. The observed activity broke down as follows:
  
  34.8 percent standing

  10.7 percent walking

  .02 percent trotting

  0.5 percent cantering

  32 percent grazing

  21.6 percent lying down
  The researchers also noted that compensatory locomotion activity allotted to foals stabled for a portion of each day was probably insufficient to reach the exercise level of foals kept continually outside.

Reference: “Quantification of spontaneous locomotion activity in foals kept in pastures under various management conditions”, American Journal of Veterinary Research, vol 67, no 7.

• In a University of Zurich study, magnetic resonance imaging (MRI) proved to be useful in investigating lameness caused by proximal metacarpal and metatarsal pain. The researchers compared the ultrasound and MRI appearance of the origin of the suspensory ligament in fore and hind limbs of six sound horses to post mortem MRI images and histology. They found that in several areas of concern, the MRI provided more detailed information than ultrasonography and correlated well with histology.

Reference: “Magnetic resonance imaging, ultrasonography and histology of the suspensory ligament origin: a comparative study of normal anatomy of Warmblood horses”, Equine Veterinary Journal, vol 38, no 6.

• A University of Guelph study supports the possibility of interspecies transmission of the bacteria Clostridium difficile, which can cause diarrhea and severe colitis. Using PCR technology, the researchers tested 133 isolates of C. difficile from dogs, horses and humans, plus one from a cat and one from a calf. They found 35 percent of the isolates from humans were indistinguishable from isolates from one or more animal species.

Reference: “PCR ribotyping of Clostridium difficile isolates originating from human and animal sources”, Journal of Medical Microbiology, February 2005.

• A Oklahoma State University study raises questions about the therapeutic benefit of oral administration of acyclovir in treating equine herpesvirus (EHV). When horses received oral doses of 20 mg/kg, the researchers found poor bioavailability of the drug, adding that inhibition of EHV has been reported to require significantly higher acyclovir concentrations than the ones achieved in the study.

Reference: “Pharmacokinetics of acyclovir after single intravenous and oral administration to adult horses”, Journal of Veterinary Internal Medicine, vol 20, no 3.

• In a University of Pennsylvania study, transdermal fentanyl patches failed to deliver blood concentrations sufficient to provide analgesia in one-third of study horses. The researchers measured plasma concentrations of fentanyl periodically for the 72 hours after patches were placed on six adult horses and then 12 hours after patches were removed. The fentanyl concentrations peaked about 12 hours after application, but with much individual variation. No adverse effects were noted.

Reference: “Pharmacokinetics of fentanyl delivered transdermally in healthy adult horses — variability among horses and its clinical implications”, Journal of Veterinary Pharmacology and Therapeutics, December 2006.

Other studies mentioned during the Kester News Hour include:

Effects of hyperbaric oxygen on full-thickness sheet grafts applied to fresh and granulating wounds of horses. American College of Veterinary Surgeons Symposium Oct, 5-7, 2006.

Delayed phase nuclear scintigraphic changes associated with osteochondritis dissecans and subchonral bone cysts in the horse. American College of Veterinary Surgeons Symposium, Oct 5-7, 2006.

Racing performance after arthroscopic removal of apical sesamoid fracture fragments in Thoroughbred horses ages 2 years and older: 84 cases (1989-2002). American College of Veterinary Surgeons Symposium, Oct 5-7, 2006.

Effects of extracorporeal shockwave therapy on healing in collagenase-induced desmitis of the inferior check ligament of the deep digital flexor tendon in the horse. American College of Veterinary Surgeons Symposium, Oct 5-7, 2006.

Racing performance after arthroscopic removal of apical sesamoid fracture fragments in immature Thoroughbred horses, less than 2 years of age: 151 Cases. American College of Veterinary Surgeons Symposium, Oct 5-7, 2006.

“Cricothyroid muscle function and vocal fold stability”. Veterinary Surgery, No. 35, 495.

“Histomorphologic evaluation of extracorporeal shock wave therapy of the fourth metatarsal bone and the origin of the suspensory ligament in horses without lameness”. American Journal of Veterinary Research, vol 67, no 4.

“The evaluation of extracorporeal shock wave therapy on collagenase induced superficial digital flexor tendonitis”. Veterinary Comparative Orthopedics and Traumatology, vol 19, 99-105.

“Ultrasongraphic technique and normal anatomic features of the sacroiliac region in horses”. Veterinary Radiology and Ultrasound, vol 47, no 4.