What's new and hot in veterinary medicine? What if you could get two of the world's foremost equine veterinarians to dig through the mountain of research that is published each year and tell you what is really significant for your and your horses or your practice? That describes the annual Kester News Hour at the American Association of Equine Practitioners Convention, held Dec. 3-7 this year in Seattle, Wash. Orthopedic surgery specialist Larry Bramlage, DVM, MS, Dipl. ACVS, of Rood and Riddle Equine Hospital in Lexington, Ky., and internal medicine specialist John Madigan, DVM, MS, Dipl. ACVIM, professor of medicine and epidemiology and section chief of equine medicine at the University of California, Davis, host this popular section each year to a full house.

No Added Benefit from Higher Bute Dosages
Bramlage began with an Oklahoma State paper on Bute dosages. He said, "Horsemen are fond of using the freshman chemistry formula--if a little is good, a lot is better. This paper proved that 4g of Bute was no better than 2g (in treating chronic lameness). We want to get the message to horsemen there's not an additive or a benefit when you keep upping the dose." (www.TheHorse.com/ViewArticle.aspx?ID=5769, J Am Vet Med Assoc. 2005 Feb 1;226(3):414-7.)

West Nile Virus
Madigan gave his usual West Nile virus (WNV) rundown, which he's done every year since 1999, when the disease first showed up in the Western Hemisphere. In this year's report, he reviewed the research study that showed infected mosquitoes can infect uninfected mosquitoes as they co-feed on an uninfected mouse (www.TheHorse.com/ViewArticle.aspx?ID=5955). He reviewed the spread of WNV across the United States and said most of the horses that died of WNV were not fully vaccinated for the disease. "The clients that aren't going to pursue the vaccine aren't going to treat the ataxic horse," said Madigan. "We put out a lot of information to educate these horse owners," and he believes it's helped.

"There were 847 human cases in California (this year)," he said. "This is suggesting something very important and affects how we look at West Nile in the horse. There's no vaccine for humans, and (the horses are) probably getting a lot of exposure, but the horses have built immunity and the cases are dropping as things have moved over to the left coast.

"In 2004, the numbers are dropping, which is really good," he continued. "There's very little doubt that the horse population was spared the full brunt of this disease by the rapid development of (WNV) vaccines by Fort Dodge and Merial. It's a lot of credit to our industry, as it certainly saved a lot of lives."

Bramlage added, "It's a bad disease, but good for veterinary medicine, because we can do something about it."

Electroacupuncture and Back Pain
Bramlage reported on a University of Florida study that showed electroacupuncture was effective in alleviating chronic back pain after three treatments (www.TheHorse.com/ViewArticle.aspx?ID=6293, J Am Vet Med Assoc. 2005 Jul 15;227(2):281-6.). "You'll be relatively futile if you don't get (solve) the primary lameness (that's causing the back pain), but if you do need something else to help with the back pain, (this study) was very well investigated," said Bramlage.

Amicar and Exercise-Induced Pulmonary Hemorrhage
Oregon State researchers showed that epsilon-aminocaproic acid (EACA, or Amicar), a fibrinolysis inhibitor, enhanced clot maintenance, stability, and diminished exercise-induced pulmonary hemorrhage in the clinically normal horse. "Even at a low dose, it lasts for five hours," said Bramlage. "This is a good stepping stone in looking to see if there's an EIPH protection effect of Amicar. It might be a second line of defense when Lasix is not effective anymore. We need that data because the racetrack medication and testing consortium is in the process of sorting out all these recommendations—what's good for the horse and what's not." (Am J Vet Res. 2005 Feb;66(2):313-8)

Catheter Problems
According to a University of Pennsylvania retrospective study, horses with endotoxemia (condition that occurs when toxins from Gram-negative bacteria escape from the intestine and into the bloodstream) are 18 times more likely to develop catheter-associated jugular thrombophlebitis (inflammation of the jugular vein) than horses without endotoxemia, described Madigan. A horse with salmonella is 68 times more likely to develop thrombophlebitis than a horse without salmonella. Additionally, horses with hypoproteinemia (low protein blood levels) are five times more likely to develop thrombophlebitis than horses without hypoproteinemia. For a horse in the medicine section of an equine hospital, the odds of developing thrombophlebitis were 16 times those for a similar horse in the surgery section. ("Horses are usually systemically healthy for orthopedic surgery," noted Bramlage.) Finally, Madigan said if a horse has received an anti-diarrheal or anti-ulcer medication, they are 31 times more likely to develop thrombophlebitis than horses that have not received these medications.

Madigan suggested keeping these study results in mind when advising a client about the chances of complications in a hospitalized horse. (J Am Vet Med Assoc. 2005 Oct 1;227(7):1134-41)

Bone Growth and Lesions
Bramlage discussed one study of transplanted rabbit growth plates that found they closed at the rate of the donor aging, not the recipient. "The theory is that the chondrocyte (cartilage-producing cell) DNA ages with each round of replication, and the growth plates close when calcification overtakes the rate of cell proliferation," he said. "Functional closure occurs before radiographic closure, and the maturation of bone is influenced hormonally--estrogen promotes earlier closure, so fillies close earlier than colts. Also, there is a period of catch-up growth in the plates after inhibition from disease or surgery; they will try to catch up to those numbers of divisions they've missed out on. Chondrocytes multiply very quickly."

Performance Wins
He also discussed a study of the effects of selection of Hanoverian warmblood breeding stock for orthopedic health and performance. The horses were used for dressage and jumping, and the researchers found it was possible to reduce orthopedic lesions by breeding selection. However, breeding value followed ability, not prevalence of lesions.

"We breeders and veterinarians sometimes get blamed for causing these lesions, but everyone wants good horses and are willing to put up with lesions if we can treat them," he commented. "Even if you know which horses have fewer lesions, human nature is to breed for the one that will win." (Am J Vet Res. 2005 Aug;66(8):1371-9.)

About the AAEP
Part of the Kester News Hour is always a brief report of AAEP member demographics and other statistics. Bramlage noted that there are currently 7,212 regular members and 1,953 student members, for a total of 9,165. Men comprise 64% of the membership, and 83.5% of the members reside in the United States, while 5.9% are Canadians and 11% are from other countries. Almost half practice mostly on horses.

As for types of practice, 57% say they handle mostly performance and pleasure horses, while 14.5% handle mostly racehorses, and 13.9% focus on reproduction.

Nearly 28% graduated from veterinary school more than 25 years ago, and 21% graduated less than four years ago. "That's the second-largest group now," Bramlage noted. As for length of membership, 44.2% have been members for less than 10 years.
"We're really growing, so our job now is to make sure we're really relevant to that (new) group; we have been very successful in bringing them in," said Bramlage. "For the first time, 52% of new members are female, and vet students are about 80% female. Thirty percent of new members work in a 100% equine practice, as do 13% of international members.

He also noted that while equine practice veterinarians make almost 9% less money right out of school than small animal practitioners, this is because equine graduates are not as productive right out of school. "Small animal vets find it much easier to be productive soon after graduation because the owners are usually not as highly educated or critical as equine owners," Bramlage said. "We need to keep pushing up our internship salaries because some graduates are not looking long enough range to come into equine practice, but later their salaries accelerate and pass those of small animal vets. The internship salary is part of your education. After an internship you can do better work faster, and you can service more clients in a certain period of time. (AAEP data)

Joints--Injections and Injury
While it might be attractive to inject one lower hock joint in order to treat two, Bramlage said he will stick with injecting both after reviewing a study of the concentrations of methylprednisolone in the centrodistal joint after giving methylprednisolone acetate (MPA) in the tarsometatarsal joint. He reported that one sees therapeutic concentrations in both joints, but not nearly as high levels (50 times less) or as much anti-inflammatory action in the centrodistal joint as when it is injected directly (Equine Vet J. 2005, 37(2):172-4).

HA Protective?
A study evaluated whether sodium hyaluronate might offer a protective effect to cartilage, which can be depleted with MPA use. The study found that it did not offer protection in that instance (Am J Vet Res. 2005 Jan;66(1):48-53).

Lameness Model
He discussed another study exploring whether injecting a horse's blood into his fetlock was a good model of temporary, reversible lameness. Researchers found significant lameness (four on a five-point scale) peaking at two to four hours after injection, but horses were sound again 24 hours later even with no treatment. "This doesn't work really well as a (research) model because it's too short-lived," he commented.

"But we've all seen horses come back from training with hemorrhage into the joint," Bramlage said. "They're often so lame they take them off the track in an ambulance, but they're fine in 24 hours. The message here is that lameness from hemorrhage disappears within 24 hours. If it doesn't, look for infection." (Am J Vet Res. 2005 Jun; 66(6):1084-9).

Cartilage Healing
Bramlage briefly discussed another study of cartilage healing in horses with naturally occurring osteochondrosis and others with experimentally induced fractures. There was no observable difference, leading researchers to conclude that the repair/response process is the same for both insults (Am J Vet Res. 2005 Nov; 66(11):1881-90).

Dorsal Displacement of the Soft Palate
Bramlage discussed a Rood and Riddle study of the efficacy of three surgeries combined (sternothyroideus myotomy, staphylectomy, and oral caudal soft palate photothermoplasty) in correcting dorsal displacement of the soft palate, or DDSP. Performance improved in 63% of the horses after surgery, all of which were available for follow-up.  (Vet Surg. 2005 Jan-Feb;34(1):5-10).

Tie-Forward
He also covered a report of a new surgery for DDSP that ties the larynx forward to the hyoid apparatus, effectively pulling the larynx up over the soft palate rather than trying to make the palate stiffer as some other treatments do. Ninety-eight of 116 horses were available for follow-up; 73% raced again and 82% had improved performance and earnings.
"Generally if they're lost to follow-up, they did not race," Bramlage commented. "If the horse raced, there is a record of it somewhere. I don't think 'lost to follow-up' is appropriate in a racing paper" (Equine Vet J. 2005 Sep;37(5):418-23).

Magnets

"Do magnets reduce pain?" Bramlage asked the audience. "No magnet tested to this point (not counting electromagnets) has enough field strength to penetrate the skin when applied topically. But they do work on those who believe in them via the placebo effect."
He explained that the mechanism described to work is that magnets attract red blood cells via the iron they contain, bringing blood flow to the area of the magnet. "But blood isn't magnetic; if so we'd explode when we had magnetic resonance imaging," he said (Bone and Joint Oct 2005; 9(9)).

More Magnets
Another study looked at the effects of low-level "electromagnetic field" modification on egg laying hens. Bramlage noted that daily egg production increased 4.96% over the breed average and 1.33% over controls. Hen daily mortality rate was 36.9% less than the breed average, and 47.6% less than controls. "So they live longer and are happier?" he suggested.

"There is a lot of anecdotal belief that (magnets) work," he added. "The belief that they work is a potent improver of health in people. Most of our treatment breakthroughs start out as anecdotes" (Am J Vet Res. 2005 Aug;66(8):1425-9).

Toe Grabs
Bramlage also discussed a study of toe grabs where racehorses' hoof accelerations were measures both with toe grabs and three days later after the grabs were ground off. "Toe grabs affect different horses to different degrees, with the maximum force peaks up to 170G (170 times the force of gravity) seen on deceleration (when the hoof lands and comes to a stop after an initial sliding deceleration), not weight bearing," he reported. "We always thought the grabs helped create more force on pushoff, but there is actually more force on deceleration when stopping the foot" (ACVS Symposium Equine and Small Animal Proceedings, October 27, 2005).

No Added Benefit from Higher Bute Dosages
Bramlage began with an Oklahoma State University paper on Bute dosages. He said, "Horsemen are fond of using the freshman chemistry formula--if a little is good, a lot is better. This paper proved that 4 g of Bute was no better than 2 g (in treating chronic lameness). We want to get the message to horsemen there's not an additive or a benefit when you keep upping the dose." (www.TheHorse.com/ViewArticle.aspx?ID=5769, J Am Vet Med Assoc. 2005 Feb 1;226(3):414-7.)

Indwelling Nasogastric Tubes and Gastric Emptying
Madigan reported on a Texas A&M study in which researchers found that having a nasogastric tube in place for 18 hours did not delay the rate of gastric emptying, which is a concern in colicking horses. (Am J Vet Res. 2005 Apr; 66(4):642-5.)

West Nile Virus
Madigan gave his annual West Nile virus (WNV) rundown, which he's done every year since 1999, when the disease first showed up in the Western Hemisphere. In this year's report, he reviewed the research study that showed infected mosquitoes can infect uninfected mosquitoes as they co-feed on an uninfected mouse (www.TheHorse.com/ViewArticle.aspx?ID=5955). He reviewed the spread of WNV across the United States and said most of the horses that died of WNV were not fully vaccinated for the disease. "The clients that aren't going to pursue the vaccine aren't going to treat the ataxic or down horse," said Madigan. "We put out a lot of information to educate these horse owners," and he believes it's helped.

"There were 847 human cases in California (this year)," he said. "This is suggesting something very important and affects how we look at West Nile in the horse. There's no vaccine for humans, yet the number of human cases in areas that experienced West Nile infection in previous years is decreasing.  This suggests that likewise in horses, there is probably a lot of subclinical exposure and horses have built immunity, and the number of new cases is dropping as the disease has moved across the country and over to the left (West) coast.

"In 2004, the overall numbers are dropping, which is really good," he continued, following the virus data over the past several years. "There's very little doubt that the horse population was spared the full brunt of this disease by the rapid development of (WNV) vaccines by Fort Dodge and Merial. It's a lot of credit to our industry, as it certainly saved a lot of lives."

Bramlage added, "It's a bad disease, but good for veterinary medicine, because we can do something about it."

Electroacupuncture and Back Pain
Bramlage reported on a University of Florida study that showed electroacupuncture was effective in alleviating chronic back pain after three treatments. "You'll be relatively futile if you don't get (solve) the primary lameness (that's causing the back pain), but if you do need something else to help with the back pain, (this study) was very well investigated," said Bramlage (www.TheHorse.com/ViewArticle.aspx?ID=6293, JAVMA vol 227, no. 2 Jul 15).

Legal Classification of Animals
"Wisconsin, Massachusetts, Arkansas, Rhode Island, and several cities characterize those residents having animals as animal guardians instead of owners," said Madigan, who believes the trend is disturbing. If horse owners were to be considered animal guardians, it could limit what veterinarians can  or cannot choose to do to treat health problems and expand legal ramifications of veterinary and animal husbandry choices . (For more information, see "More Than a War of Words," www.thehorse.com/ViewArticle.aspx?ID=5152.)

Equine Influenza
Madigan talked about the 2005 report on equine influenza virus jumping into racing Greyhounds (www.TheHorse.com/ViewArticle.aspx?ID=6364 and www.TheHorse.com/ViewArticle.aspx?ID=6391).

Currently, the main concern with the circulating flu viruses are small, irreparable changes in the viruses' makeup (antigenic drift), which make the viruses look new to the immune system. Thus, immunity against previous strains does not protect against the new virus. Another concern is recombination between different flu strains, or exchanging of genetic material, to create new subtypes, such as the Hong Kong Flu.

"If humans are infected with a normal human flu strain and are around fowl with different strains, the viruses then might recombine and you have a shift. That's the worry," said Madigan. He also discussed a new system for making flu vaccines based on reverse genetics using monkey kidney cells, which he said is much faster to produce than the older, possibly antiquated, method using eggs.

Economic Impact of the Horse Industry
Madigan reviewed the American Horse Council's study that showed the horse industry has a $39-billion impact on the U.S. economy (www.TheHorse.com/ViewArticle.aspx?ID=5856).

Google Earth
"Anyone can take a closer look at any part of the world, get driving directions, find restaurants, hotels, ATMs, etc. using a visual satellite-like zoom of the area of interest with the relatively new program called Google Earth," said Madigan, who recommended it to the AAEP membership (free online at http://earth.google.com/).

Tips of the Hat
Madigan offered the annual Kester "Tips of the Hat" to Travis C. McGuire Jr., DVM, PhD, professor in the Department of Veterinary Microbiology and Pathology at Washington State University, and C. Wayne McIlwraith, BVSc, PhD, DSc, FRCVS, Dipl. ACVS, director of orthopaedic research at Colorado State University's College of Veterinary Medicine. Both men were inducted into the Equine Research Hall of Fame in October 2005 (www.TheHorse.com/ViewArticle.aspx?ID=6238).

Next, he showed a slide show of photos from the various relief efforts after Hurricane Katrina devastated the Gulf Coasts of Louisiana and Mississippi, giving a tip of the hat to "the exceptional efforts by many, the AAEP, the AVMA-VMAT (veterinary medical assistance teams), the National Veterinary Response Team, HSUS (Humane Society of the United States), and many others.\

"The list of folks (that helped post-Katrina) is long," he said, but he reviewed the response of Louisiana State University's Equine Health Studies Program to horse owners impacted by the hurricane (www.TheHorse.com/ViewArticle.aspx?ID=6314 and www.TheHorse.com/ViewArticle.aspx?ID=6152).

Additionally, he commended volunteers at Texas A&M University's large animal hospital who responded during Hurricane Rita by setting up a hospital for nearly 700 human patients (www.TheHorse.com/ViewArticle.aspx?ID=6222).

Serum Testing and Colic
Madigan began, "Quiz: In a horse with colic, is there any blood test that might suggest, in conjunction with the physical exam, that the horse has a specific kind of (intestinal) displacement?" He answered the question with study results from Cornell University that showed serum gamma glutamyl transferase (GGT, an enzyme) activity rose above reference range in 18 of 37 horses (49%) with right dorsal displacement of the large colon (RDDLC) and in one of 48 horses (2%) with left dorsal displacement of the large colon. The positioning of the colon in horses with RDDLC results in compression of the bile duct, which can obstruct the duct and cause an elevation in serum GGT activity (J Vet Intern Med. 2005 Sep-Oct;19(5):761-4).

Catheter Problems
According to a University of Pennsylvania retrospective study, horses with endotoxemia (condition that occurs when toxins from Gram-negative bacteria escape from the intestine and into the bloodstream) are 18 times more likely to develop catheter-associated jugular thrombophlebitis (inflammation of the jugular vein) than horses without endotoxemia, said Madigan. A horse with salmonella is 68 times more likely to develop thrombophlebitis than a horse without salmonella. Additionally, horses with hypoproteinemia (low protein blood levels) are five times more likely to develop thrombophlebitis than horses without hypoproteinemia. For a horse in the medicine section of an equine hospital, the odds of developing thrombophlebitis were 16 times those for a similar horse in the surgery section. ("Horses are usually systemically healthy for orthopedic surgery," noted Bramlage.) Finally, Madigan said if a horse has received an anti-diarrheal or anti-ulcer medication, he is 31 times more likely to develop thrombophlebitis than horses that have not received these medications.

Madigan suggested keeping these study results in mind when advising a client about the chances of complications in a hospitalized horse (J Am Vet Med Assoc. 2005 Oct 1;227(7):1134-41).

Gastric Ulcers and Recreational Horses
Madigan reviewed the results of an Iowa State University study that showed horses could get ulcers from recreational use and trailering (www.TheHorse.com/ViewArticle.aspx?ID=6179).

Managing Head Trauma Cases
Veterinarians are always trying to figure out better ways to treat head trauma cases--Madigan said horses that have flipped over and hit their heads are brought into veterinary hospitals on a regular basis. "We want to reduce brain swelling, decrease intracranial pressure, maintain normal cerebral blood flow, maintain tissue oxygenation, prevent further injury, and prevent infection," he said.
"In brain trauma, there's no benefit whatsoever with corticosteroids," he continued. "You may also have the risk of infection, laminitis, elevated blood sugar, etc."

He reported on a human study published on Emedicine.com that showed the following:

  • Methylprednisolone succinate is not recommended for brain trauma, but it can be used for spinal trauma if administration is started within six to eight hours of injury. He noted that the improvement over no treatment was not immediately apparent, but the outcome was better at four to six months;
  • Mannitol is good for head trauma because it decreases intracranial pressure by a variety of mechanisms, regulates cerebral blood flow, and carries less risk of electrolyte imbalance than furosemide;
  • IV fluids are controversial, but he concludes you shouldn't restrict use of fluids. Use of hypertonic saline has also been reported to be of initial benefit. 

He also recommended maintaining normal blood pressure in affected horses and elevating the head 30 degrees if the horse is down.

Cloning
In 2005, England government officials said they would allow equine cloning for research purposes. Madigan reported on the April 2005 birth of the clone of champion Arabian endurance horse Pieraz, which was the first successful commercial cloning and the first cloning of a gelding (www.TheHorse.com/ViewArticle.aspx?ID=5772).

In the case of Dolly the cloned sheep, "cloning was not thought to be practical because she aged so fast," said Madigan. "It will be interesting to see if the horse does the same thing."

Seasonal Allergens and Recurrent Airway Obstruction
"What we used to do with a horse with COPD (chronic obstructive pulmonary disease, now called recurrent airway obstruction or RAO) is get him outside and use a little Ventipulmin," Madigan said. But a recent study suggests the change to an outdoor atmosphere might not be the best arrangement for all RAO horses.

Madigan explained, "Ward and Couetil (of Purdue University) found a significant correlation between outdoor mold and pollen counts and the prevalence of COPD (RAO) in horses admitted to North American veterinary teaching hospitals between 1990 and 1999." In other words, if you put an RAO horse out in the field and his clinical signs recur or get worse, he could be allergic to something outside (J Am Vet Med Assoc. 2003 Dec 1;223(11):1645-50).

By Stephanie L. Church and Christy West

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