February 2009 Newsletter
Special Feature Article: Laminitis
The disease which has received the most research dollars over the past twenty years is laminitis. The term denotes inflammation: “-itis” of the laminae. Laminea are in the hoof and connect the hoof wall to the sides and sole of the coffin bone.
Their function to support the coffin bone in the hoof, and maintain body temperature. They are prone to pain due to the considerable numbers of sensory nerve fibers imbedded in the laminae.
The coffin bone is supported and attached to the hoof wall through the laminae. The laminae in the hoof wall interdigitate with the laminae around the sides and bottom of the coffin bone. The bond is tight and if greater strength is needed, an increase in the number of laminae, termed secondary and teritiary, will grow.
Although the adaptability of the laminae to need of the horse is great, there is a ‘breaking’ point when the laminae in the hoof wall no longer inter digitate or connect to the laminae on the coffin bone. In such cases, the coffin bone will rotate away from the hoof wall.
The second function is the unique presence of arterial/venous anastomoses or AVA’s. During vast changes in environmental temperatures, these open and close preventing blood flow in the foot temporarily for the purpose of maintaining a core body temperature during vast temperature changes in the environment. (This is why horses do not freeze in the winter.) They have great importance in laminitis because if they are closed too long, the lack of blood flow to the foot will decrease the production of enzymes which remodel the basement membrane, the tissue which allows the movement and growth of the hoof wall over the coffin bone. It will also allow separation between the laminae of the hoof wall and the coffin bone.
Causes of laminitis are in two categories: trauma or an abnormality in the body other than the foot. Traumatic causes occur if there is excessive or prolonged stretch to the laminae. For instance, horses which are not trimmed and the toe of the hoof wall elongates pulling on the laminae. Along the same lines, years of weight bearing on the hoof wall through shoeing can stretch the laminae downward and be very painful to horses. These horses need to be radiographed every 3 months to assure the trim of the hoof is in relationship to this constantly moving coffin bone. Traumatic laminitis also occurs in horses bearing all their weight on one foot as was the case of Barbero.
In the past decade the most common causes of laminitis are from internal causes. By far, the most common cause is a chronic or consistent, increased sugar in the blood from increased ingestion and decreased exercise. Increased sugar in the blood increases the fragility of the basement membrane of the hoof, thus resulting in separation of the laminae. Cushing’s disease and equine metabolic syndrome are the most common syndromes. Their frequent occurrence and importance causes need for intervention. They are the most common cause of laminitis and their specific causes and treatments will be discussed in depth in an upcoming H Magazine. The treatment of the feet, though, is the same as is outlined in this article.
Other causes which are very acute and severe are post foaling mares if the placenta is retained in the uterus, toxins released by the intestines during severe colic, severe pneumonia, and excessive amounts of grain ingestion. THESE CASES ARE EMERGENCIES AND NEED TO BE TREATED IMMEDIATELY!!! The feet are placed in buckets of ice for 24 hours or more. Use of anti-inflammatories and DMSO are also used. The foot is radiographed for evaluation and supported in 2 inch Styrofoam for comfort and to allow weight bearing on all parts of the hoof.
The success in treating the foot after laminitis has greatly improved in the last ten years. We now know and have the ability to treat all areas of the foot concurrently. The method of radiography is critical as now, when we use radio-opaque markers at the tip of the frog and on the hoof wall, we know how to trim tissue away which is interfering with healing and is causing pain. (Just to note, this technique was developed at Colorado Equine Clinic and is used throughout the world.)
We also know the depth of the sole and how to protect the coffin bone from pressure, and how much of the hoof wall at the heel can be cut down. After trimming, we take the weight off the injured tissue, the laminae, and put the weight on sound tissues, usually the frog and some parts of the sole. Four techniques are used to accomplish this. First, a shoe which angles inward to the ground to decrease the lever at the end of the hoof wall is used, then we assure weight is being born on the frog and perhaps the sole, third we assure there is no pressure on the tip of the coffin bone by screwing the pad to the toe of the shoe creating a concavity in the pad so it does not touch the sole, and fourth we elevate the heels to decrease excessive pull of the flexor tendon. ALL FOUR of these actions need to be done CONCURRENTLY in order to start the healing process. If one is missed, pain will stay in the foot preventing the re-establishment of blood flow. We use two different shoeing systems at CEC to accomplish these four steps, either the Stewart Clog, or the Equine Digit Support System.
In conclusion, although too many horses still die from laminitis, there have been many horses in the last ten years who have healed from laminitis providing their owners feed them according to their needs, not human desires, and been persistent in caring for their feet.
Colorado Equine Clinic Wellness Program 2009
Spring is on the horizon, and Colorado Equine Clinic is excited about updates to our Wellness Program. Now is the time to start planning for your horse’s care in 2009.
CEC will be offering two types of Wellness Program’s based on type of dewormers. Research of recent literature and concern about parasite resistance have spurred us to review our current fecal analysis and deworming programs. CEC will now be using the McMaster’s Technique for fecal analysis (please refer to “Parasite Control” handout by Dr. Lana Groom) and will be basing type and frequency of deworming on fecal egg count.
Wellness Program Option 1 is designed for horses that are on the Strongid C2x daily dewormer and includes:
Wellness Program Option 2 is designed for horses with a low number of shed parasite eggs and includes:
Wellness Program Option 3 is designed for horses with a high number of shed parasite eggs and includes:
Purchasing one of these Equine Wellness Program options allows you the confidence of knowing you have covered your equine’s healthcare bases with one convenient program at one convenient price. These options also offer a cost-savings over purchasing care individually, something we all can appreciate in these tough economic times. Please feel free to call us with any questions. We are looking forward to caring for you and your horse at your next “Wellness” appointment!
**Please contact Colorado Equine Clinic after February 1st for further questions and prices on our Wellness Program options.**
Winter Care for Horses
Have you ever wondered how horses stay warm, or what it it would be like to stand in zero degree weather in the snow or rain. It’s no wonder that owners feel sorry for their horses and blanket them through out the winter.
Increasing the food intake is important during the winter months. Adding more protein and fiber is sufficient The horse’s metabolism along with the body goes through a series of physiological changes. The change in metabolism allows him to store more fat for insulation and for energy reserves. With this in mind the owner should slowly increase their food intake during the winter months. As you may notice the horses coat is thicker in the winter months so a blanket is not necessary unless he is clipped. Some owners choose to clip their horse for easier and faster cool out. The horse’s longer and thicker hair coat during the winter months can stand up on the skin to make a layer of insulation. If you choose not to blanket, it is very important to offer shelter or some kind of wind break.
A well fed horse can withstand temperatures well below zero, even 30-40 degrees below zero as long as there is no wind and stays dry. The horse’s best defense from the cold is his long coat and a layer of fat just beneath the skin. Horses rarely suffer from frostbite. The blood supply to their muzzle is very rich; therefore the nose does not suffer frostbite. The long nasal passage insulates the cold air before it reaches his lungs. A horse’s legs and feet can withstand extreme cold without much discomfort. Below the knees are mostly bone and tendons which does not require as much circulation as muscle.
The horse has several ways that enable him to deal with the cold weather. In extreme cold weather horses may stand in groups to block the wind and this also allows them to exchange body warmth.
With proper care and nutrition the horse can be quite comfortable and be happy through out the winter months. Please read up coming articles on more advice for winter care.
Happy Trails,
Monica Trantham
Geronimo – A Love Story
Have you ever loved a horse so much that you were willing to not only change your life for him but also change who you are? I have. Ten years ago I was a regionally ranked tennis player, high school teacher and tennis coach. I lived in a very nice condo in suburbia. Going to educational conferences, attending school activities and playing in tennis tournaments at plush country clubs was the life that I need and enjoyed. All of that changed when I saw a gangly little guy with mane and forelock standing straight up come out of the trailer after his mother. He was being led, or rather jerked and dragged down the ramp by a big man with bushy hair and a scruffy beard. It was obvious that he had no compassion or patience for this scared creature. “You had better beware of this one as he is wild and dangerous.” Dangerous? I think not. Once he had been reunited with his mother he eagerly looked for the comfort of her nipple and drank and drank and drank, becoming calmer with each gulp. I walked up to them and he allowed me to scratch behind his ears and under his neck. This is when I fell in love with a three month old white stud colt, named Geronimo.
As I was still living and working in the city I only managed to make it to my friends’ ranch on the weekends. It seemed that work days would drag on and on and that Friday would never arrive. But when it did, I was in my car racing off to see the cute little guy. The drive, although 45 minutes in length, never seemed long and it was always so exciting coming around the last bend on the bumpy dirt road that dipped down into Plum Creek Meadows. Soon the ranch was in sight and I would immediately search the pastures for that fluffy white guy with the long legs and mane and forelock standing straight up.
I enjoyed many hours of being around him, kissing his eyes, scratching his butt and under his chin. Quickly he grew used to me and when he saw me would come running, managing to come to a fast stop just inches from me looking for a treat and a scratch under the chin. Weeks turned into months into a year and then one day a marvelous thing happened. It was my 50th birthday and I was gifted with Geronimo! Can you believe it? A 50 year old city girl, tennis player, tennis coach and soon to be retired teacher was just given the present of her life! I jetted to the pasture to tell Geronimo the news. Now I had read somewhere that the Native Americans would breathe into the nostrils of their horses to show them that they belonged together. So what the heck. Why not? I lifted his face close to mine and breathed into his nose. And then that sweet air coming back, caressing my face brought tears to my eyes. We were now one.
Soon dress clothes and shoes were replaced with jeans and boots. I gave up my racquet for a halter and lead rope and tennis matches disappeared as I was now mucking stalls, moving hay and repairing fencing. As I knew nothing about this life I learned something new everyday. Leaving the city and moving to the ranch was the last step as I willingly left my old life behind and dedicated myself to Geronimo.
Over the next ten years Geronimo and I did it all. We learned and grew together, trusting each other completely. I slowly evolved into a decent horsewoman and a darn good ranch hand. We rode in parades and performed with a drill team at state fairs and expos, Competition in shows was always stressful for me but Geronimo would take charge and all I had to do was sit in the saddle and enjoy the ride! We herded cattle, rode along side buffalo and always ran flat out through rivers and streams. Geronimo loved the water and we never missed an opportunity to splash. I had never been happier.
And then one day I discovered some strange lesions. A nasty very aggressive squamous cell carcinoma had begun to attack my boy. With the help of wonderful vets Geronimo fought valiantly. Always kind and patient, he allowed himself to be poked, injected, evacuated, debrided and catheterized over and over. Although he was losing weight and seemed tired he never minded a visit from me and a short ride. In fact the last time we rode together we managed to find a nice little patch of water which we raced through back and forth over and over until we were both drenched but happy. Oh please, I need more time. But it was becoming obvious that he was losing the fight and the inevitable decision had to be made. I brought him home from the clinic and prepared for our last goodbye. With the vets standing by I softly called his name. He lifted his head, ears pressed forward listening. I told him that it was all okay. He was not going to have to fight anymore. He looked at me with those wonderfully soft eyes as if to say that it was time for both us to move on. And then he was gone. Also gone was half of my heart.
Although I am still grieving I am thankful for Geronimo. I am thankful that I had as many years as I did with such an amazing horse. He changed me into this new person and I also know that he has prepared me for the next adventure with a new little guy who is waiting out there somewhere…just waiting to be loved.
FEBRUARY CASE STUDY
CUTANEOUS LYMPHOMA (LYMPHOSARCOMA)
A 7 year old Warmblood mare was presented to our clinic to have her teeth floated. The owner had noticed that the mare had lost some weight. The owner had noticed some masses that waxed and waned in size over the last year. They were suspected to be related to insect bites.
A complete physical exam was performed. Significant physical findings include: enlarged pre-scapular (i.e.shoulder) lymph nodes; rough hair coat, thin – body score 3/9; multiple haired and hairless nodules/masses perivulvar (vulva area) which extended between and inside the hind limbs. There was also a firm mass located in the girth area. The nodules ranged from 1 cm to 8 cm in diameter.
Two of the nodules located below the vulva were biopsied. These biopsies were sent to Colorado State University Diagnostic Laboratory. The diagnosis came back as Cutaneous malignant lymphoma.
The most common type of neoplasia (cancer) to involve the equine hemolymphatic system is lymphosarcoma. There are 4 forms that have been described – generalized, intestinal, mediastinal, and cutaneous. The disease is usually found in adult horses from 5-10 years of age, with a range from birth to over 20 years.
The cause of lymphosarcoma is not known. There has not been any documentation of a viral cause, although viruslike particles were described in a lymph node from a foal that had died shortly after birth. (Haley, PJ et al.)
The most common clinical signs of lymphosarcoma are chronic weight loss, depression, ventral edema on the abdomen, and enlarged lymph nodes. Other clinical signs are variable depending on the organs involved and the duration of the disease. Other associated clinical signs are fever, anemia, mild colic, or diarrhea. Most clinical signs are progressive over weeks or months, although they may have a sudden onset.
With the cutaneous form, the subcutaneous nodules may appear suddenly, frequently regress, and then reappear. Other lymph nodes may become involved. Internal organ involvement can occur, but does not occur frequently. Horses may live and function well for many years with this form of lymphosarcoma.
The mediastinal form is usually seen in adult horses. The clinical signs associated with the mediastinal form are respiratory signs, pleural effusion, edema of the ventral chest area, and enlarged lymph nodes.
The intestinal/alimentary form is most often seen in horses less than 5 yrs of age. Clinical signs seen with this form include: poor body condition, intestinal malabsorption, mild recurrent colic and/or recurrent fevers. Exterior lymph nodes are generally not enlarged, but intestinal lymph nodes may be enlarged and your veterinarian may be able to feel them while performing a rectal examination.
The generalized/multicentric form usually present with severe depression, poor body condition, enlarged lymph nodes and ventral edema. Other clinical signs may be present and are usually associated with internal organ involvement and dysfunction.
Treatment
The cutaneous form of lymphosarcoma may be responsive to corticosteroid and progestin therapy. (Littlewood JD et al) Unfortunately, if the corticosteroids are stopped or treatment was not long enough, the cutaneous lesions may reoccur in a more aggressive form. Horses that have the cutaneous form may live and function for many years with or without treatment. Horses with the cutaneous form, generally have longer survival times then the horses with the other forms (mediastinal, generalized or intestinal).
With the other 3 forms of lymphosarcoma, the horses are often debilitated greatly by the time of diagnosis. It has been reported that transient improvement of the generalized form has occurred following use of cytotoxic drugs, immunomodulators, and corticosteroids. (Rebhun WC et al and McConnel S et al). The prognosis for the generalized, intestinal or mediastinal form is grave. Most horses die or are humanely euthanized within 6 months of the onset of signs.
UNDERSTANDING THE HORSE’S MIND
The Instinct to Flee
We are fascinated with horses, but sometimes their actions confuse, hurt, or irritate us. The horse embodies the same range of abstract and intangible personality characteristics we have as humans, yet as prey animals, they instinctively deal differently with fears than we do. A better understanding of the instincts and thus actions of the horse will improve our relationship and bond with them.
There are ten traits every horse inherits: Flight, perception, response time, rapid desensitization, learning, memory, dominance hierarchy, control of movement, body language, and precocity. Each H magazine I will review one of these inherited characteristics of the horse to assist our communication and time with our horses. This article will deal with flight.
Ever wonder why it is difficult for a horse to stand still? Why does a horse want to walk over us? Every animal has a method for primary defense and has even developed anatomy specific to that defense. The horse is the only domestic animal whose primary defense is flight. During the dinosaur age, the horse had three toes and anatomy similar to the dog. All of the dinosaurs and other mammals became extinct during that time except the horse. Several adaptations were made by the horse, to enable it to flea predators and well it did as we still have our beloved horse! An increase in the number of joints in the limb would logically increase the stride length and thus speed of travel. Over time, the horse became to have one toe and thus one more joint. The other toes are now called chestnuts, one at the back of the fetlock, one inside the forearm or hock. There are at least ten additional anatomical differences in the horse in the hind limb alone which assist in moving a body weight of 1000 pounds at a speed of 40 miles an hours in an instant!
What was helpful for the horse to survive in the wild can be problematic to us if not understood. The horse is a perceptive, flighty, timid creature whose primary defense is to run away from anything it interprets as a possible danger. Common dangers are sounds not previously heard such as downshifting of truck engines, threatening movements such as plastic blowing in the wind, unfamiliar odor such as medication added to food, or the sight of unfamiliar objects such as deer jumping out of the brush. By understand the nature of horses, when such dangers as listed above happen we can expect our horse to move suddenly. We will then understand our horse, as opposed to being angry with their sudden movement which is just their protection. Why doesn’t our horse always run from the unfamiliar? He will, if we do not 1) understand their instinct to flee and 2) communicate WITH them in ways they can understand. This great recipe works for people too!
How do we communicate with horses to ease their fears? First is to feel calm and relaxed within ourselves, second is to speak to the horse in quiet, soft tones. A soft touch on the side of the neck can be calming to the horse. If the horse still wants to move and run, we can move the horses feet by walking the horse in circles or move the horse forward or backward. Can the horse’s primal instinct of running from fears be overcome? Yes. The horse learns fast and forgets nothing. What we teach them, they learn. It is our responsibility to teach them well as they do not forget.
Parasite Control Updated: It’s All About the Eggs
Once upon a time, when wild horses roamed the plains, they had parasite control pretty well worked out. Since there was lots of space to graze, they never picked up too many parasite eggs or larvae (immature parasites). The parasite burden they did carry in the GI tracts remained in check due to the horses’ immune systems. Those unfortunate horses whose immune system failed to fight off these parasites probably did poorly and generally didn’t survive to pass on these genes.
Now enter the modern day horse. These horses are often kept in small pastures contaminated with plenty of parasite eggs and larvae. They may have the added disadvantage of not having an immune system that is very good at recognizing these GI parasites. This sets up the situation for horses to become overly burdened with parasites, which could cause poor health, colic, and even death.
Thankfully, effective dewormers entered the market about 40 years ago. Since that time, deworming horses has been a fairly regimented procedure. Initially, the veterinarian came out twice a year and wrestled with your horse(s) to stick a tube down their nose and then pour some foul looking liquid into their stomach. Life got much easier (for your horse as well as your veterinarian!) when paste dewormers came out and all you had to do was figure out what products you needed to rotate and when. Most of you have been great at following your veterinarian’s eight-week deworming schedule. Some over achievers have even taken to deworming their horses every four weeks or whenever their farrier comes out.
Unfortunately, all this enthusiastic deworming has caused the parasites to become resistant to these chemicals. Of the three classes of chemicals, the benzimidazoles, which include fenbendizole (Panacur), oxibendizole (Anthelcide), and oxfendazole have seen the most widespread resistance. Pyrantal salts, (most commonly known as Strongid) has also seen resistance occur. The newest class of drugs, ivermectin and moxidectin (Quest), have had sporadic resistance by ascarids. As resistance increases, our ability to use these dewormers to effectively protect our horses decreases.
The Strategic Plan
So what’s a responsible horse owner to do? The goal should be to keep our horses as healthy as possible by deworming them only when necessary. Unfortunately, this takes a little more planning then following a rotational deworming schedule. What we need to do is deworm our horses strategically. The true goal should be keeping our horses from becoming infected by large number of parasites. This is important, since the parasites that can cause some of the biggest health problems are the larval stages of strongyles (large and small). Our other main parasites for adult horses, tapeworms and bots, will be controlled with our new strategy.
Here is some additional information on the background of this program. Because 20-30% of horses don’t have an immune system that is very good at recognizing GI parasites, these horses are the ones that should be getting dewormed most frequently. The reasons for this:
The rest of the horses will either be fairly good at resisting a high parasite burden (20-50%), or very good (30-50%). By using fecal egg counts on individual horses, we will be able to identify which horses carry the heaviest parasite burden, and therefore, need the most frequent deworming. On the other hand, most of your horses need only be dewormed 2-3 times a year. Use of the fecal egg counts (FEC) will, over the next year, determine which of these categories your horses fit.
Other variables that determine how often your horses need deworming will depend on the stocking rate of your pastures and weather conditions, e.g. strongyle larvaie do not survive on pastures at temperatures above 85˚F.
One last factor may help make more sense of our new program: the different classes of drugs each have different intervals when eggs are again being passed in manure. This is known as the egg reappearance period (ERP). Benzimidazoles and pyrantals ERP is 4 weeks, ivermectin, 8 weeks, and moxidectin at least 12 weeks.
Remember, this is not a one size fits all situation; please ask us to help you in designing the best program for your horses(s).
Still hesitant about this program? We plan to have updates on how the new program is working for the next year. Stay tuned!
Fecal Testing at Colorado Equine Clinic
Several techniques are available to evaluate the parasite load of horses. At Colorado Equine Clinic we will be using the McMaster modified egg count. In order to perform this diagnostic test our veterinarians or clients need to collect fecal samples.
When collecting samples for testing it is best to follow these simple guidelines:
The following is a brief explanation of the McMaster modified egg count.
The McMaster modified egg count allows the veterinarian to determine the presence or absence of strongyle and ascarid eggs expressed as eggs per gram of feces. This procedure is used as a rough indication of the number of parasites present within a host. A known amount of feces is combined with solution to quantify eggs per gram of feces. Owners and veterinarians must take into consideration the fact that various species of parasites produce different number of eggs. In addition, egg production is sporadic and may not correlate with the number of parasites present. Each horse will then be classified as a High Shedder (>500 eggs per gram of feces) OR a Low Shedder (<200 eggs per gram of feces). An adult High Shedder would then be dewormed 5-6 times per year. The adult Low Shedder would be dewormed 3 times per year.