Sunday, March 27, 2011

My Thoughts from 'Along The Way'

I hope you enjoyed reviewing the assorted collection of images that I have acquired over the past several weeks. As promised, here are some of my thoughts about them.

What's wrong with this picuture? This is way too much ice for the end of March!

I realize the picture quality is not very good on these next two images. I'm not a very good photographer(if you have seen the pictures I take Coggins testing, you already know that). If you look very carefully at the pupils (the black circles in the center of the eye) you would see that this horse looks like he has two pupils in each eye. This is the result of an underdeveloped iris. The condition is called an iris coloboma. It is not really a disease process, but rather a congenital malformation. It occurs with much greater frequency in eyes that have very little pigment (i.e. blue eyes). It is not a painful condition for the horse, but sometimes they have a little diffiulty controlling the amount of light that enters the eye, since the iris cannot function normally. There is no treatment for this condition.

Somewhere down this trail you can't go any futher, but it's a long way away...miles and miles.

Complaint: "I took my horse out for the first ride of the year, and he acted terrible. He kept tossing his head and wouldn't do anything I wanted, so I just decided to put him away. Any ideas?"
If you look carefully at this picture, you will see that the bit has been put on this bridle backwards. The shank portion of the bit is attached to tthe headstall and the reigns are attached to where the headstall is supposed to go. The chin strap is installed as a nose band.

I realize it might be a little difficult to get your orientation with this next picture. Let me explain. This is a view of the inside of a horses mouth (speculum in place holding the mouth open). You are seeing the set of teeth on the upper left side of the horse. This is very old horse. The first tooth, toward the front, is pretty much worn down to nothing. There is just a little stump of it remaining. The next tooth back is still present. The third tooth back is extremely loose and desperately wants to fall out. The forth tooth back is missing, thus just some gum there. The last tooth back, that you can see, is worn down to the gum and does not have any enamel left.

This is what the third tooth back looked like after I 'helped' it fall out. As you can see, there is virtually no living tissue left associated with this tooth. It was just a source of irritation and infection to the horse.

It's definitely not hot, it's not a tin roof, but it is a cat.

This is an 'under the tail' view of a horse with fairly extensive melanomas. In horses these tumors are usually benign (not cancerous) but they can become fairly extensive, as in this case. This is almost exclusively a grey horse disease. There are a number of different options for dealing with these. Again, this is a topic worthy of its own blog posting at some future date...stay tuned.

This is a lateral (side view) x-ray of a horses foot. This horse has, and has had laminitis. The dense white line on the front of the hoof is barium past. We put that on the hoof before we take the x-ray so that we can clearly see where the hoof wall is on the radiograph. Some people use a nail or wire for this purpose, but I firmly believe that barium paste is a far superior hoof wall marker. The nice thing about barium is that it conforms perfectly to the hoof wall, so you can see dishes or changes in countour that would be missed with a rigid wire. Note is this projection the amount of coronary band swelling. You can see it where the barium bulges out at the very top of the hoof (i.e. the coronary band). The front side of the bone inside the hoof (coffin bone)should be parallel to the hoof wall (or barium paste). As you can see in this image they are not. The coffin bone has shifted within the hoof capusule due to a break down of the attachment of the bone to the hoof wall. The bone has shifted as a result of all of the other forces acting upon it. Under normal situations, the laminae work to oppose the force of the deep digital flexor tendon. In horses with laminitis the laminae 'loose their grip,' so the pull of the deep digital flexor tendon 'wins.' This is perhaps an over simplification of the process, but it is in essence what happens.

This is one view from a venogram on a horse that had a very mild case of laminitis. Venograms are definitely a topic worthy of their own posting at some future time. They are an excellent way to visualize the integrity of the live tissues in the horses hoof and to assess how they are being influenced by load and pressure. A diagnosis of laminitis would have been very difficult to make in this horse without a venogram. But because it was identified early, before any rotation or displacement occured, we were able to intervene to take some of the load off of the laminae while they healed. The idea here is to keep the horse from developing any displacement of the coffin bone, rather than come back in a month and see the rotation after it has taken place and at that time say 'yup, he had laminitis.' Early intevention is crucial to sucessful treatment of this disease.

Here is another case of laminitis. The shoes placed on this horse are designed to significantly decrease the pressure tthat the deep digital flexor tendon exerts on the coffin bone and thus greatly reduce the chance for further rotation. They are also ridiculously effective at promoting sole growth. One of the caveats to using these shoes is that it is absolutely imperative that they be applied correctly. Without good radiographs it is not possible to know if they are being used properly or not. This set of radiographs demostrates that quite well. It is very important that the bottom of the coffin bone not be more than 5 degree off of parallel with the bottom of this shoe. The bottom of the coffin bone of most horses is 3 to 5 degrees off of parallel with the ground surface. When horses rotate, the angle the bone makes with the ground surface increases. In horses with a significant amount of coffin bone rotation it can be a challenge to get the alignement just right.

This radiograph is the same hoof after the shoe has been properly aligned to the coffin bone. As you can see in this x-ray the bottom of the coffin bone is now just about parallel with the hoof contact side of the shoe.

As I mentioned previously, this is embryo is 7 days old (the egg was fertilized 7 days ago). I am still awed by the fact that this microscopic structure is a horse. It may not look like one right now, but in 11 months it will running around a pasture.

Thursday, March 24, 2011

Along the way..

Here are some images I've collected over the past couple of weeks. See if you can decide what's wrong with each of these. Feel free to post your thoughts under 'comments.' I post my thoughts at a later date, so check back.

The right eye.

The left eye.

This is a venogram. The blood vessels in the foot have been filled with contrast material, so that the live tissues can be better assessed within the hoof capsule.

The last two images (below) don't really have anything wrong with them, I just wanted to share.
This is what an equine embryo looks like at 7 days, post fertilization. That is the embryo age that we typically aim to transfer them from one mare to another. Embryo transfers are worthy of their own blog post- hopefully at some future date. These are a 'through the microscope' view. In actual size, they are barely visible with the naked eye. They look about the size of a speck of dust. The first one is the embryo in a search dish.

Here is an up close view of the embryo.

The last image is of what a 14 day pregancy looks like with ultrasound. The pregancy is the black circle in the middle. You can also see the urinary bladder, full of urine, taking up the lower two-thirds of the image. It is incredible how an embryo can go from bareley visible to about 1.5cm in 7 days!

Wednesday, March 16, 2011


If there is someone in your life interested in a career in veterinary medicine than you need to know about this. This upcoming Saturday, March 19, the veterinary school and Michigan State is hosting their annual open house. This is a tremendous opportunity to explore the debths of veterinary medicine. Click here for all of the details.

Saturday, March 5, 2011

Strangling Strangles

We have encountered some isolated cases of Strangles at a couple of different barns already this year. Strangles is a highly contagious bacterial respiratory infection that affects horses. Affected horses can get quite sick, usually with fevers above 103F, depression, nasal discharge, cough, and greatly enlarged lymph nodes under the jaw or at the base of the neck which usually go on to rupture and drain. The disease is so named because the lymph node swelling can become so severe that it impinges on the air passages. Though affected horses become quite ill, the disease is rarely fatal.

The most significant issue surrounding cases of Strangles is the highly contagious nature of this bug. The disease is transmitted from horse to horse primarily through nose to nose contact or through shared water sources. It is also possible for the bacteria to be spread by handlers, shared tack or grooming equipment, barn cleaning supplies, etc. For these reasons it is best to isolate affected horses. This can become a real challenge as most barns do not have an isolation facility or housing separate from the rest of the horses. In such circumstances, we recommend moving affected horses to one end of the barn, close to an outside door (so the horse does not have to walk through the rest of the barn to go outside). There should not be any opportunity for direct nose to nose contact with other horses. It is imperative that water buckets not be shared. Affected horses should be fed and handled last. Stock tanks should be emptied, thoroughly sanitized and allowed to dry. Pastures that have housed infected horses should be left unused for 30 days before they are put back in use.

One of the frustrating aspects of Strangles infections in populations is that the first horse to become infected is rarely the source of the infection. The disease is usually brought in by new horses to the barn that are, unbeknownst to anyone, shedding the causative organism. Often the horses shedding the bacteria are no longer ill and otherwise seem healthy. The only way to identify asymptomatic shedders is to submit samples from each horse for either culture or PCR (polymerase chain reaction). PCR testing is a very good way to identify horses shedding the bug. The PCR test identifies the DNA from the causative bacteria, however, the test does not tell us if the bacteria are alive or dead, just that their DNA is present. For that reason, culturing is often done concurrently with PCR testing.

It is very difficult to know for certain that there is no longer any risk for infection at a barn that has had a recent case. The generally accepted recommendation is to not bring any new horses into or out of the barn for one month beyond the last clinical case. The first clinical signs are usually seen 2-6 days after exposure, but there are reports of it taking up to 2 weeks before symptoms take hold. An additional consideration is that recovered horses may continue to shed bacteria for many weeks, even though they are no longer ill. Because of all of these variables, in the absence of testing every horse, the general recommendation of a one month quarantine from the last clinical case is often made.

Strangles is certainly one of those diseases that is much better to prevent than to have to deal with. There are a couple of different vaccines available for Strangles. They each have their advantages and disadvantages. Talk to your veterinarian about specific vaccine recommendations for your individual situation. Strangles is not one of the core vaccines that we always recommend every horse have every year. However if your horse is considered 'at risk', it certainly makes sense to vaccinate. We generally recommend vaccinating if your horse is stabled with horses of unknown background or if you are taking your horse into barns or herds where there are other horses that also get out and have exposure to other horses in other places. Generally, if you do not travel with your horse and they do not have significant exposure to other horses of unknown background, then vaccination may not be necessary. Good hygiene and common sense go a long way in preventing and limiting the spread of this disease. New horses coming into a barn should be isolated from the rest of the herd for 14 days. Do not share water buckets or let them drink from stock tanks at shows or barns you may visit. When travelling with your horse, do your best to limit nose to nose contact with other horses. Unfortunately, even when good precautions are taken occasional flare ups of this disease still occur.

The best source of information about specific recommendations for the prevention and management of Strangles cases is still your regular veterinarian. The impact of and the stigmas attached to this disease make it very worthwhile to implement good prevention strategies.