Look how far we've come

I stumbled across this video that I think you would enjoy. It's really just a quick overview of some of the advances in equine veterinary medicine in recent years. Click here for the link, or go to http://www.myvnn.com/page.asp?id=39&media_type=11&story_id=127

Along the way...

I realize it has been a while since I've made time for a post. This is my best attempt at playing catchup. These are some images I've acquired in my recent travels, that I hope you will enjoy.

Further evidence that veterinarians never know what they will encounter in the course of the day.

This was a large ulcer in the cornea, as demonstrated by the large green area in the center of the cornea. The green area is a stain that we put in the eye that gets taken up by the cornea when the superficial layers of the cornea have been disrupted. You can tell this has been going on for quite a while because of the blood vessels that you can see starting to migrate from the margin of the cornea. The blue haze on the left side of the eye is the result of edema within the cornea. This horse has an unstable tear film which made this a very difficult case to manage.

This is a pair of ultrasound images from a fetal gender determination. This is an incredibly reliable method of determining the gender of a fetus, in utero. It is best done between 60 and 70 days of pregnancy. At this stage of pregnancy gender can be determined by the location of the genital tubercle (labled as GT in these images). In this case the GT is immediately behind the umbilical cord. It can also be seen in the image all the way to the left between the hind legs. This fetus is a colt. If it were a filly the GT would be up under the base of the tail.

The owner of this establishment is presumably is an Appaloosa breeder.

One of the joys of getting up early in the morning is the ability to appreciate the handiwork of God. Note the symmetry in the clouds.

This was a case of cellulitis I saw the other day. The skin was leaking serum, giving the leg a wet, shiny appearance. What looks like wounds are actually areas where the skin is trying to die. This horse responded well to therapy, and is well on his way to a full recovery.

This is an image of a horse's hoof 2 weeks after a hoof wall resection. The severity of this case required that a portion of hoof wall be removed. After removal of the hoof wall, the tissue will fairly quickly keratinize, which is what you see now at the site of the resection. This is a very interesting case that is ongoing. At some point in the future this case will be worthy of its own post. Stay tuned.

"I'm the king of the mountain."

Further evidence of the limitless creativity of horses to incessantly find new and exciting ways to injure themselves.

This is what the wound above looked like after it was put back together.

I love this picture. Count the number of locks on the door. A couple of days before I was at this farm, I was out at another farm at 10:PM treating 5 horses for grain overload. A well secured feed room door represents a significant cost saving over seeing me at 10:PM.

What is your diagnosis? When I arrived at this farm the pony was out on pasture. This was the first thing I saw when I looked in the stall. Notice all of the saliva mixed with chewed up feed. Horses produce an incredible amount of saliva. When the esophagus (the tube that goes from the mouth to the stomach) becomes obstructed, as in a 'choke,' feed and saliva are no longer able to be swallowed. As a result large amounts of saliva and feed will pour out of the mouth. In such cases, a veterinarian should be called immediately.

One of the challenges of dealing with wounds in the summer months is baby flies (otherwise known as maggots).

Baby horses are a lot cuter than baby flies.

Wolf Teeth

The picture to the right is of the right upper dental arcade. The small little tooth at the very front is a wolf tooth. These small little teeth do not serve any known function, other than to get in the way of the bit. For this reason they are typically removed before a young horse goes into training. Occasionally we will encounter an older horse with bit related issues as a result of a wolf tooth left in place.

They can be highly variable in their eruption pattern. Most are about the size of the one in this picture, but they can also be larger or smaller. Most horses have upper wolf teeth, some only have one, and yet some horses never develop them at all. Very rarely will they appear on the lower jaw. They are almost exclusively only on the upper jaw.

Many people get wolf teeth confused with canine teeth. The wolf tooth is technically the first premolar. They sit just in front of the second premolar, which is a very large tooth, and the first major cheek tooth in the dental arcade. The canines sit quite a bit further forward in the mouth, much closer to the incisors. Canine teeth do not appear in the mouth until 4 or 5 years of age. Another difference from wolf teeth is that they are present on both the upper and lower jaws. A properly placed bit would sit behind the canines, but just in front of the wolf teeth. Most mares do not develop canines, but if they do, they are typically quite a bit smaller than what their male counterparts would have. Canine teeth are considerably large than wolf teeth. They are extremely difficult to extract. Canine teeth are only removed if they are diseased. We do not remove healthy canine teeth.

Because wolf teeth do not serve any known function and because they only serve to be a source of irritation in the bitted mouth, we typically removed them prior to a young horse going into training. The picture to the right is the same horse pictured above, except now the wolf tooth has been removed. To extract the tooth we first numb up the area, cut the gum around the tooth and then gradually work to slide it out with an elevator. The small hole left heals over quickly and uneventfully.

Here is what the tooth looks like out of the mouth. You can see that while they have a very small crown, there is a very long root present.

EHV Outbreak: Update

Here is a link to the latest situation report by USDA of the ongoing outbreak of EHV-1. The exciting thing is that in the past week there have been no new cases on any premise that is not under quarantine. It would appear that this latest outbreak is being brought under control.

USDA's EHV-1 Situation Report (June 8)

Barbaro, Laminitis & 5 yrs.

How can you not remember Barbaro. Can you believe it has been 5 years since he defeated the field in the Kentucky Derby. He brought the world along on his journey through a catostrophic racing injury. However, that is not what ultimately led to his demise. It was laminitis in the other limb that they were not able to get under control which became the last hurdle he could not clear. Check out this video that USA Today put together about Barbaro and the ongoing war on laminitis.

Neuro Herpes Outbreak Update

Here is a link to the USDA's most recent update on the ongoing EHV-1 outbreak. In includes lots of interesting statistics, with breakdowns by state.

http://www.aphis.usda.gov/vs/nahss/equine/ehv/ehv_2011_sitrep_060211.pdf

For more details on the neuro form of EHV-1 see the posting on this blog from May 25.

How Many?

I had a 4-H leader ask me the other day how many teeth do horses have? Sounds like a simple enough question, but the answer is not. It is influenced by several different variables such as age, gender, if any have ever been removed, and if there are any extra ones present. Let me explain.

Let’s start with the basic dentition pattern of the horse. The major teeth of the horse are the incisors, canines, premolars and molars. There should be 6 incisors top and bottom. These are the teeth at the very front of the mouth that are very easy to see. There are 4 canine teeth, two on the top and two on the bottom (one on each side of the mouth). These teeth sit behind the incisors, but in front of the premolars. The bit sits in the space behind the canines, but in front of the pre-molars. The typical adult horse has 12 premolars and 12 molars. They are oriented in a straight row, front to back, top and bottom, on each side of the mouth, with the 3 premolars in front of the 3 molars. With the two top rows, one row on each side, and the two bottom rows all of 6 each, we end up with 24 cheek teeth in all. So in the normal adult male horse we should have 24 cheek teeth (12 molars and 12 premolars), 4 canines, and 12 incisors for a total of 40 teeth. But that is not the whole story.

How many teeth a given horse is influenced by his/her age. The canine teeth do not usually erupt until 4-6 years of age. The last molar does not come in until about 3.5 years of age. The last ‘baby tooth’ is replaced by an adult tooth around 4 years of age.

Gender plays a role in all of this as well, primarily because most mares usually do not develop canine teeth. If they are one of the 28% of mares that have them, they are usually much smaller than those in a stallion or gelding.

Wolf teeth are typically removed at a very young age. They are technically a rudimentary first premolar and can vary tremendously in their eruption pattern. Some horses never get them, some have only one, but most have 2 (one on each side). They are almost always just on the top. It is rare to see wolf teeth on the lower jaw. They do not serve any function for eating or chewing. They often cause bit related problems due to their location and small size. If present, they will sit just in front of the cheek teeth, but well behind the canines. This is the same place that the bit rests in the mouth. We occasionally see them in older adult horses, but most horses have them removed when they are young.

On rare occasion we will encounter a horse with a supernumerary tooth (an extra one). Here is a picture of one I saw just yesterday. It is hard to tell from the picture, but the really long tooth way in the back is actually the seventh tooth back (remember there are only supposed to be 6). Since there is not a seventh tooth on the bottom the upper one just keeps growing and growing. This tooth was an otherwise normal appearing tooth, so we just shortened it with the aid of a motorized burr so that it is no longer rubbing on the opposing gum. This tooth will have to be maintained throughout this horse’s life because it will continue to grow.

So there is the long answer to how many teeth a horse has. The short answer is 36 to 44 in an adult, depending on if canine and wolf teeth are present. If you really want to know exactly how many teeth your horse has, ask your vet next time your horse’s teeth are done and they can give you the exact count for your horse. Of course, that may not be the answer your 4-H judge is looking for.