New Product: Protazil

Protazil (diclazuril) was just released this month for the treatment and/or prevention of EPM (Equine Protozoal Myelitis) in horses. EPM is a disease that has been has been around for several decades. The disease is caused by a protozoa, called Sarcocystis neurona. It primarily causes neurologic deficits, which are sometimes vague and non-specific. This is not the first or only drug available for the treatment of this disease. It has actually been around for a while. Prior to its adaptation to the horse it was used to treat protozoal infections in chickens. While it is nice to have another weapon in the war on EPM, this drug is not going to cure every horse. According to the information submitted to the FDA for approval, only 67% of affected horses improved one neurologic grade (graded on a scale of 1-5) or no longer tested positive. That means that a horse that has grade 3 neurologic deficits has a 67% chance of improving to a grade 2. Meaning the horse still has neurologic deficits, they just might not be as bad. One of the challenges with this data is that they only looked at the horses a month after treatment stopped. They likely continued to improve beyond that time frame. The neurologic system is very slow to heal, to the extent that it can. Neurologic deficits associated with EPM can be caused by direct damage of the protozoa to the spinal cord and by the inflammation associated with their presence. Killing the protozoa does nothing to fix the damage that the protozoa did prior to starting treatment. Thus, at least so far, all the medications currently used to treat EPM, while they may be effective at killing the protozoa, do not always result in complete resolution of the symptoms. Initiating treatment as soon as possible, while any neurologic deficits are mild, will result in the best clinical outcomes. If treatment is not started until the horse has severe neurologic deficits, the deficits may improve, but in the end the horse will be less likely to experience a complete resolution of symptoms. Like most new drugs, this stuff is not cheap. A 28 day course of treatment will cost somewhere around $850.

You can read more technical information at: http://www.fda.gov/downloads/AnimalVeterinary/Products/ApprovedAnimalDrugProducts/FOIADrugSummaries/ucm062320.pdf

New Product: Sucromate

SucroMate (deslorelin) is another “new” drug to hit the market in the past month. SucroMate is indicated for the induction of ovulation in mares. It is given while the mare is in heat to induce her to ovulate. This greatly simplifies the use of shipped cooled or frozen semen for breeding because we can reliably time insemination with ovulation. The active incredient in this injectable solution is deslorelin. The reason I put “new” in quotes is that deslorelin has actually been around and widely used for some time now. It initially came on the market probably around 15 years ago under the name of Ovuplant. Ovuplant was deslorelin in a sustained released implant that was placed under the skin. It was taken off the market several years ago. Deslorelin has continued to be used as a compounded product since then. Compounding is when a pharmacist formulates a product in their own pharmacy. The FDA allows us to use compounded medications when an FDA approved product is not available. The problem with compounding is that quality control is left to the sole discretion of the person doing the compounding. That almost always means that there is no quality control. There have been numerous studies that have shown that compound medications may vary widely from what is put on the label. While it may be better than nothing, it is certainly not ideal either. SucroMate is the first FDA approved product available, since Ovuplant, for the induction of ovulation in mares. From a cost perspective, it will cost less than the compounded product we had been using.

New Product: Equioxx Injectable

Equioxx (firocoxib) injectable in a newer product I wanted to make sure you were aware of. An oral form of Equioxx has been available for over a year now, but it now comes in an injectable form, as well. Equioxx is used for the treatment of osteoarthritis in horses. Clinically we end up using it similarly to phenylbutazone (bute). The primary advantage of Equioxx is that is has a significantly less potential for some of the side effects that bute can cause. Bute can be a little harsh on the stomach, so in horses who are under a lot of stress (in training) or who have a predisposition to stomach ulcers or gastritis, Equioxx might be a good option for them. The other advantage to Equioxx is that it only needs to be dosed once daily. The injectable form allows us to achieve a therapeutic blood level much faster than the oral paste. Equioxx is similar in cost to Banamine.

COW: Strangulating Lipoma

It has been a while since I posted a case of the week (maybe at the rate I’m going it should be case of the month—but then the acronym COM just isn’t as nice as COW). This was an older horse I saw on emergency last week. The history was a sudden onset (less than 2 hrs) very severe colic. In fact when I arrived, the horse was down, in shock and unable to get up. With the assistance of lots of good drugs we were able to get the horse comfortable enough to stand just long enough to do a rectal exam. Rectal exams are probably the single best diagnostic aid we have in sorting out colic’s. On rectal, a very tight band could be felt. This almost always means that something is twisted or displaced.

As it turned out, the cause of this horse’s colic was what is called a strangulating lipoma. They are called that because it is a lipoma that ‘strangles’ off a portion of the intestine. Lipomas are benign tumors of fat. In horses, they tend to form in a very thin membrane, referred to as the mesentery. Lipomas really do not cause a significant problem for the horse until they somehow get wrapped around a loop of intestine- almost always the small intestine. Once they wrap around a loop of intestine, the horse VERY quickly becomes extremely painful. The only way to fix the problem is surgery. Often they wrap tight enough around the intestines that they also occlude the blood flow to that section of intestine. If the circulation to the affected loops is significantly compromised then the intestine quickly begins to die, in which case at surgery the strangulated loop of intestine would have to be surgically removed. That is why, if surgery is to going to be pursued, it needs to happen ASAP. Even if surgery is elected for, sometimes you just cannot get the horse on the surgery table fast enough to save the intestine. On average about half of horses treated surgically survive in the long term.

Strangulating lipomas are so devastating, in large part, because they strike out of nowhere. There is nothing that can be done to prevent them and the only effective treatment is surgery. It is virtually impossible to detect these tumors until they cause a strangulation. The only thing that may lessen the development of these benign fat tumors is to keep your horse from getting too fat. Because it takes quite a bit of time for these tumors to form, they usually do not develop to a sufficient size to cause a problem until the horse is in its late teens or twenties. For reasons we do not yet fully understand, geldings and ponies tend to be at a greater risk for developing lipomas. The only effective treatment for a strangulating lipoma is surgery. Current estimates for an uncomplicated surgical colic are in the $5-7000 range. This type of colic is at a higher risk for post-surgical complications, so they can easily cost in excess of $7,000 to fix.

Here are the life lessons from this case: 1. With any severe, sudden onset colic, a veterinarian should be consulted immediately. In these cases, banamine is rarely ever powerful enough to suppress the severe level of pain. 2. Keep banamine on hand. Banamine is a medication that is quite effective in suppressing pain originating from the abdomen. Often a mild colic can be managed with this medication alone. If the pain does not resolve within 45-60 minutes of an oral dose of banamine, then a veterinarian should definitely be consulted. 3. Surgical costs are expensive and are almost always unexpected. It is wise to have some funds set aside in an emergency fund or have colic insurance. 4. Lipomas are just one more reason to add to the long list of reasons to keep your horse from getting overweight. Even if you do, as in this case, strangulating lipomas can and do still occur.

Here are some pictures of what they actually look like. The picture below is of the lipoma (after being unwrapped from the small intestine). Also notice the congested blood vessels to the small intestine as a result of the lipoma inhibiting the normal flow of blood.

Here is a picture of the distended loops of small intestine that develop as a result of the inability for ingesta to move through.

Merry Christmas

Don't Forget to Leave The Lights On

I am not referring to those coming home for Christmas. It is your broodmare that I am concerned about. As you know, mares generally do not cycle through the winter months. Their ovarian cycle is influenced more by day length, then by ambient temperature. As the day length becomes longer in the spring, it triggers the mare to resume normal cycling. Since getting the mare cycling is the first step in getting her bred, now is the time to start "tricking" your mare into thinking the days are longer than they really are. The trick is to provided a total of 16 hours of light every day. If the mare is turned out during the day, then she needs to be stalled at night with the lights left on long enough to give her 16 total hours of light.

As a word of caution, it does not work well to just leave the lights on all the time. Some period of darkness is still necessary. Also, the light has to be fairly bright. The easiest way to assess if there is adequate light is to grab a newspaper and try to read the print in the darkest part of the stall. If you can not, then you either need a higher watt bulb or additional light sources.

It takes, on average, 70 days for a mare to have a breedable cycle after starting exposure to prolonged light. Mares will typically start to shed some of their hair with 30 to 60 days of starting lights. If you plan to breed your mare in February, she should already be on lights. If you do not care how early the foal is born, you do not have to mess with artificial lighting. Most mares will start cycling on their own by late March or early April.

As mares go from not cycling in the winter to having normal cycles in the spring, they go through a period of transition. During this period of transition they may have very irregular, non-fertile heats. If necessary, we can encourage them out of transiton more quickly with the use of certain medications.

If you intend to breed your mare early in 2011, make sure that right now she is seeing at least 16 hours of light every day.

Welfare Reform

I spent most of this past week in Baltimore attending the 56th Annual Convention of the American Association of Equine Practitioners (www.aaep.org). This meeting brings together some 5,000 equine health professionals and has evolved into the premier source of the latest advances in equine veterinary medicine. I hope to share some of the highlights from this meeting with you over the next couple of weeks.

The conference opened with a talk about the latest buzzword: welfare. The continually growing issue of unwanted horses is bringing a significant amount of attention to how we can provide for the welfare of these horses. A recent survey attributed the rapid increase in ‘unwanted’ horses to the closing of horse slaughter facilities, a crippled economy, euthanasia costs and indiscriminate breeding.

Since the ban on horse slaughter a couple of years ago, the ‘unwanted horse’ problem has become a significant issue. Despite the work of some legislatures, it appears unlikely that horse slaughter will ever return to the U.S. While very little horse meat is consumed in the U.S., worldwide the demand for horse meat is at an all time high. Every year there are approximately 5 million horses processed for meat. That is a 28% increase from 1990.

So what are the solutions to the problem? That is the problem, currently there are not any easy ones. Current suggestions are to re-open domestic slaughter facilities (seems unlikely that will ever happen), increase the number (and funding) of horse sanctuaries and educate the public on responsible horse ownership. Some would like to see an increase in the number of adoption facilities, but nationwide only about half of the horses that enter an adoption facility are every adopted out. So it does not take long for an adoption facility to turn into a sanctuary.

Our views of animal welfare are conditioned by our personal knowledge base and life experiences. People view welfare in different perspectives: what is the healthiest for the animal vs. what allows the animal to ‘feel’ the best, or have the least amount of stress vs. what the natural behavior of the animal is. As the public has become progressively more disengaged in animal agriculture their personal knowledge base and life experiences have shifted which one of these perspectives they value most. In the end, if society perceives something is wrong, science and logic are unlikely to change that perception.