Thursday, April 29, 2010

4/28/2010 Equine Melanoma

Vet tip of the Day: Equine Melanoma
Key Words: Melanoma, skin tumor, metastasis, cisplatin, cimetidine, laser

Many of you may have had experience over the years with melanoma in grey horses.  This form of melanoma, the dermal melanoma, is a very common skin tumor, usually slow growing, and usually confined to the site of origin.  Dermal melanomas are tumors of the black pigment cells, melanin cells, that are present in high numbers in the skin of grey horses.  The tumors typically are round, hard, and dense black when cut open.  They occur most frequently around the tail base and rectum, but also are seen in the throat latch region and at the base of the ear, where they most commonly arise in the parotid salivary gland.  While dermal melanomas often are solitary, some horses are afflicted with multiple tumors.  This condition is called dermal melanomatosis, and horses with multiple melanomas are more likely to have metastasis of tumors to remote locations, including lymph nodes, liver, spleen, and skeletal muscle.  Surgical removal of individual tumors in such horses may be locally curative, but the remaining tumors continue to grow and more tumors may develop.
There are two less common types of melanomas that occur in horses. The first is the melanocytic nevus, which is a benign tumor that occurs as a single, discrete, nodular mass in young horses. They may arise anywhere on the body and when removed surgically rarely recur.  At the other end of the spectrum are anaplastic malignant melanomas, which occur in older horses (usually over 20 years of age) of any color.  These tumors are uncommon, but usually metastasize to distant sites within a year and carry a poor prognosis.

While most horses with dermal melanomas tolerate them well, occasionally these tumors can be life threatening.  This happens most often when the tumors metastasize and grow in internal organs, or when they become so large that they cause mechanical obstruction to breathing in the throat region or impair defecation by obstructing the anus.

Dermal melanomas present an excellent example of how variable the behavior of tumors can be in different species.  As you probably are aware, melanoma in people often presents as a highly malignant tumor which may carry a poor prognosis for long term survival, even in the face of aggressive treatment.  Similarly, in dogs, oral melanoma is a malignant neoplastic process with a high fatality rate.  Many of you knew my wonderful dog Sticky, who died last year within three months of her diagnosis with malignant melanoma.  Luckily for our horses, this is NOT the case with equine dermal melanoma.  However, the common occurrence of melanoma in horses has made it a useful research tool for scientists investigating treatments for melanoma in other species.

One of the areas of intense investigation is the role of the immune system (immunomodulation) in treating melanomas in humans, dogs, and to a lesser degree, horses.  There is a melanoma vaccine currently under conditional license for malignant melanoma in dogs which I gave to Sticky during her treatment.  There also have been limited investigations using vaccines made directly from tumors removed from a particular horse then administered back to the same horse to control widespread melanomas. However, at this time there is no commercially available equine melanoma vaccine and the use of individual melanoma vaccines is not considered standard therapy.

There are many medications used for other purposes which exhibit immunomodulatory activity in addition to their primary mode of action.  One of these is cimetidine.  Cimetidine is an H2 histamine antagonist which reduces acid production in the stomach and is available over the counter as Tagamet, used in people and horses to treat gastric ulcers.  Cimetidine also acts in several complex ways to alter the body's immune  response to certain neoplastic (cancerous) processes.  It has been used with some success in the treatment of equine dermal melanoma at a dosage of 2.5 mg/kg given orally every 8 hours.  Unfortunately, after some promising initial studies, it appears that the activity of cimetidine against equine melanomas is very variable from horse to horse.  While the medication is unlikely to have adverse effects, its efficacy in each case is unpredictable, and therefore, it also no longer is widely used in the treatment of melanomas.

Dr. Robertson, a veterinarian at the Virginia Tech School of Veterinary Medicine did his PhD research on comparative melanoma (across species) and continues to conduct clinical research using Frankincense Oil as an immunomodulatory agent in the treatment of equine melanoma.  The oil is injected into the tumors and causes their regression.  The overall effectiveness of this treatment is not yet determined, but it is an interesting avenue holding promise for the future.  

In addition to immunomodulation, chemotherapy has been used in the treatment of equine melanoma. One chemotherapy agent used in horses is cisplatin, which is very effective in the treatment of squamous cell carcinoma (blog coming up on this soon).  Cisplatin has poor effectiveness against melanomas in dogs and people, but has been used with success in at least one clinical trial in horses.  In this study, 13/14 horses with melanoma had a positive response to the implantation of slow release cisplatin beads into the tumor mass.

The definitive treatment for melanomas is wide surgical excision.  With the advent of surgical lasers, it has become possible to remove larger tumors in challenging anatomic locations, such as the parotid salivary gland.
Traditionally, many veterinarians do not recommend the removal of small melanomas when they are first detected.  I disagree with this approach.  Melanomas tend to be very well isolated and complete surgical excision is often possible when the tumors are addressed early and are relatively small.  While excision does not prevent the development of new tumors at other sites, in my experience recurrence of the tumor at the site of excision is rare.

In summary, if you have a grey horse with melanomas, ask your veterinarian to evaluate them. I strongly recommend early surgical removal.  Consider cimetidine as an adjunctive therapy because it is safe, and may be effective.  Cimetidine can be obtained from reputable compounding pharmacies at a reasonable price.   For more advanced tumors, discuss the options of laser surgery and/or cisplatin bead implantation and consider seeking the opinion of a  veterinary specialist, an ACVS boarded surgeon and/or ACVIM boarded large animal internist.

I believe that education is the key to evolution. I believe that animals are the key to compassion. I believe the learning never stops.

Sunday, April 25, 2010

4/25/2010 Euthanasia Part III: Making the Decision

 Vet tip of the Day: When is it the right time for euthanasia?

In this final entry concerning the difficult topic of euthanasia, I would like to share with you my views as a veterinarian on the hardest part of the decision for euthanasia: when is the appropriate time?

First and foremost, I respect the right of a horse's owner to use their own judgement in deciding what they believe is best for their horse.  Horses legally are considered property, they do not have legal rights.  There are governing bodies in every state to respond to situations of animal cruelty to protect horses from abuse situations, but elective euthanasia is not considered abuse. I do not agree with every decision for euthansia, and I have refused to perform euthansia in rare cases.  However, the vast majority of owners who come to the decision to end their horse's life do so after careful and painful deliberation, and are acting in the best interest of their cherished animal.

I am frequently asked by clients to help them in making the decision to end a horse's life.  Usually this is in the case of geriatric horses, or chronically lame horses.  I would love to be able to tell you that it is always clear to me when a horse is suffering inhumanely, but it isn't.  The question of quality of life is engulfed in a huge grey cloud. Two things that I offer as factors to consider when you are trying to determine the quality of a debilitated or geriatric horse's life are: 1) progressive weight loss in the face of an excellent plane of nutrition and 2) prolonged periods of recumbency (lying down) to the point that pressure points such as hips develop non-healing sores, and the horse has pronounced difficulty rising.

The subject of euthanasia for practical reasons is really problematic.  Horses live a long time and they are very expensive to care for.  As horses age they typically require more calories and special dietary considerations, as well as nutritional supplements and sometimes medication (such as pergolide for Cushings horses, or anti-inflammtories for musculoskeletal problems) which increase the cost of upkeep for an animal that may no longer be rideable.  I stick very firmly to my respect for each horse owner's individual right to make decisions for such horses.

On the other end of the spectrum are owners who simply do not believe in euthanasia, and feel very strongly that all living beings should die a natural death.  Again, I respect this perspective, as long as the owner is able to provide adequate nursing care and pain medication to support their horse through the process of dying.  I always remember a foal I treated back at the University of Georgia when I was a resident.  The owner had lost a son to a long battle with cancer and absolutely would not consider euthanasia an option for this foal.  The foal suffered from neonatal septicemia, a bacterial infection that circulated throughout the body, seeding infections in multiple sites.  The foal had bacterial endocarditis (a vegetative bacterial growth on a heart valve), pneumonia, an infected umbilical cord, and an infection of the growth plate adjacent to one of the hind fetlock joints.  The bacteria responsible for all these infections was resistant to virtually every antibiotic available.  Statistically the foal's chance of survival was way below 10%, he was extremely lame, had dramatically reduced exercise capacity due to his enlarged heart and leaky mitral valve, as well as the severe pnuemonia.

Despite my repeated explanations of the foal's condition and poor quality of life, the owner refused to consider euthanasia, and instructed me to continue treating the foal, regardless of cost or prognosis.  Well guess what?  That foal lived to race as a 3 year old - he only raced once, and not very well, but he managed to overcome his heart infection, and although he never was sound, he was retired after his one race and lived out his life in a beautiful pasture. It is not our place to judge the decisions of others regarding their horses, unless cruelty or neglect are evident.

So when is it appropriate to choose euthanasia for your horse?  Only you can make that decision.  Listen to your veterinarian's assessment of your horse's condition and prognosis, then search your heart and mind and make your decision based on your own personal ethical code.  It is never easy, and it never gets easier, but it is part of the responsibility of horse ownership. 

I believe that education is the key to evolution. 
I believe that animals are the key to compassion.
I believe the learning never stops.

Thursday, April 22, 2010

4/22/2010 The mechanics of euthansia

Vet tip of the Day: Euthanasia - What really happens
Key Words: Barbiturate, gunshot, cerebral cortex
Yesterday's euthanasia stories came straight from the heart.  Today I'd like to take a step back and discuss this difficult topic from a more detached perspective. Much of what will be included in todays' blog was taken directly from the American Veterinary Medical Association Guidelines on Euthanasia published in 2000.  If you want to read them in more detail, they are available on line.

The word euthanasia is derived from two Greek words.  The first, "eu" means "good" and the second, "thanatos" means "death".  Thus the word means "good death" or the act of inducing humane death in an animal.  One of the greatest concerns expressed by owners with respect to euthanasia is their animal's state of consciousness during the transition from life to death.  The AVMA makes it very clear that any appropriate form of euthanasia should result in a rapid loss of consciousness and that the loss of consciousness should occur before, or simultaneously with, loss of motor control.  In most cases, equine euthanasia is performed with an injectable barbiturate, usually sodium pentobarbital.  This drug acts very rapidly, causing central nervous system depression beginning in the cerebral cortex.  The cortex is the center of consciousness, so the first thing that happens when a horse receives a large dose of sodium pentobarbital is an immediate loss of awareness.  The drug then rapidly depresses the lower brain centers, resulting in apnea, or failure to breathe, and cardiac arrest. 

The horse may sink quietly to the ground after the euthanasia injection is administered, but this cannot be guaranteed.  Sometimes the animal becomes rigid and may even fall over backwards.  It can be very disturbing to watch such a large animal hit the ground, but REMEMBER THAT THE HORSE IS UNCONSCIOUS AND UNAWARE.  The physical process of dying may include several gasping breaths, muscle trembling, and voiding.  These activities are natural physical processes that accompany the shutting down of body systems and even though they involve motor activity, or physical movement, they occur AFTER the cortex has stopped functioning and the animal has lost consciousness.

Sometimes owners request that their horse be sedated prior to euthanasia.  If the horse is extremely excited or difficult to handle, this is appropriate.  However, in general I try to avoid sedation if possible.  Sedatives slow the heart rate and decrease cardiac output, thereby slowing the delivery of barbiturate to the brain.  Euthanasia is most often performed on very sick or very old horses, which may already have impaired cardiovascular function.  The goal is to get the largest amount of barbiturate into the horse's brain as quickly as possible to achieve immediate and complete loss of consciousness.  Sedation can compromise this process.

Finally I'd like to address the issue of using firearms to perform euthanasia.  The following is quoted directly from the AVMA Guidelines on Euthanasia (note the term "physical methods" includes firearms and captive bolt pistols):

"When properly used by skilled personnel with well-maintained equipment, physical methods of euthanasia may result in less fear and anxiety and be more rapid, painless, humane and practical than other forms of euthanasia.  Some consider physical methods of euthanasia aesthetically displeasing.  There are occasions, however, when what is perceived as aesthetic and what is most humane are in conflict."

The term "physical methods" includes captive bolt pistols and gunshot.  Most of us have a natural fear of guns and are very upset by the violence associated with the act of shooting an animal, especially one we have loved and cared for. Horses do not share this aversion.  When performed safely and correctly, death by a bullet into the brain is instantaneous and therefore, painless.  It should never be considered unless the person handling the firearm is skilled not only with the weapon, but also absolutely understands the anatomy of the horse's head and how the shot should be placed. 

These are difficult things to think about, but I believe that understanding the process is an important part of making the decision to end a life.  This decision, when you face it, is about the quality of your horse's life.  It is painful, and sad, but it also is part of the responsibility of owning animals.  Now that we have examined the physical realities of euthanasia, tomorrow I will conclude this topic with some more philosophical thoughts on reaching the decision for euthanasia of your horse.

I believe that education is the key to evolution.
I believe that animals are the key to compassion.
I believe the learning never stops.

Wednesday, April 21, 2010

4/21/2010 Euthanasia

 Vet tip of the Day: Thinking about Euthanasia
I would like to introduce the topic of euthanasia with a few stories.  The first is one about an experience I had as a resident, and the second is about PipSqueak, a wonderful patient of mine

I completed a large animal internal medicine residency at the University of Georgia School of Veterinary Medicine.  I was on call to receive emergency patients into the hospital every 3rd weeknight and every other weekend for 5 consecutive years.  That's a lot of emergency admissions.  The sad reality of referral equine medicine is that we see a lot of very sick horses and many of them don't make it out of the hospital.

One weekend early in the first year of my residency I didn't sleep for 48 hours.  During that time I received 8 emergency patients.  Four of them were critically ill and over the course of two days I administered a lethal dose of sodium pentobarbital (euthanasia) to all four when it became clear that they had no hope of survival. Right there you come up against one of the more difficult concepts in the decision for euthanasia: no hope.  We all know that there always is hope, we just choose under certain circumstances to consider that hope too small to warrant the continued suffering of the really sick or the really old.  And let's face it, economic concerns and practical concerns influence the decision to end animal's lives as well.

That particular weekend in 1989 when I was a resident was very difficult for me. In the five subsequent years I never had to face the death of some many horses in such a short period of time.  I was exhausted, I was a new resident and I didn't have a lot of experience coping with the grief, guilt and confusion often experienced by owners when making the decision for euthanasia of an animal they love. At that stage of my career I also didn't have a lot of experience pushing the plunger on the syringe of "blue juice" that ends an animal's life.  I don't really remember all the details of that weekend.  I do remember that moment, just before performing each injection, when I wondered if perhaps there was hope, if perhaps I had misinformed the clients, if in fact the horse might survive if I could just do one more thing to turn its condition around, if I was making a terrible mistake.  None of these things was true, but the thoughts ran through my head nevertheless.  And I remember on Sunday afternoon, after I had humanely destroyed the fourth horse, sitting on the floor of the recovery stall outside the equine surgery suite and thinking, if one more horse comes in and requires euthanasia before tomorrow morning, someone else is going to have to push the plunger, I just can't take any more life today.

The second story is about PipSqueak.  PipSqueak was a grey arabian gelding who I took care of for 13 years, from the time he was 14 until his death.  Over these years PipSqueak belonged to 4 different owners, all of whom he taught the skill of riding after hounds, or foxhunting.  PipSqueak was a remarkable horse, an outstanding athlete, and a very wise soul.  Toward the last years of his life he was retired and turned out to pasture by his then owner.  His care was not adequate and he lost weight and began to have trouble getting up.  One of his previous owners, who by now was a teenage girl, saw PipSqueak's condition and reclaimed him.  She had owned PipSqueak when she was 8-12 years old and had ridden him all over the desert of Northern Nevada.  Now 15 years old, she brought PipSqueak home and fattened him up and took great care of him for another 9 months.

Although he was back in great body condition, PipSqueak's degenerative joint disease progressed to the point that he sometimes struggled for as long as 20 minutes attempting to rise, raising himself on his front legs but unable to lift his hind end to a standing position.  He was treated with joint supplements and anti-inflammatories, his hocks were injected, he was put on special footing and had special foot care, but his condition continued to deteriorate.  Finally his owner's grandmother called me one day to schedule an appointment for PipSqueak's elective euthanasia.

I arrived at the appointed time to find the entire family waiting with PipSqueak.  The horse had been bathed, his mane and tail brushed to a shimmering white, hoof dressing applied to all four feet, and he wore a beautiful new halter.  We all walked out with PipSqueak to the area where he was to be buried.  PipSqueak walked comfortably because his owner had given him one last whopping dose of bute that morning along with a bucket of grain so that he would be comfortable and feel especially spoiled in his final hours.  As we walked we shared stories of PipSqeak's many exploits over the years.

PipSqueak stood patiently while everyone said their goodbyes.  As I injected the sodium pentobarbital PipSqueak's family stood close by, speaking to him gently.  As soon as he fell to the ground we followed his descent, everyone keeping a hand somewhere on his neck or head.  We were very quiet,  his young owner began to cry and arms encircled her in her grief.  PipSqueak passed from life to death very swiftly, in the company of humans who loved and respected him, and who took the responsibility of ending his life squarely on their own shoulders, with compassion and grace.

I find the topic of euthanasia very complex, and will discuss it in more theoretical, and practical terms, over the next few days.  Please feel free to comment on this blog entry with your own thoughts and experiences concerning this topic.

I believe that education is the key to evolution.
I believe that learning never stops.

Tuesday, April 20, 2010

4/20/2010 Spring Breeding - the Transitional Period

Vet tip of the Day: The Mare's Transitional Period

It's the time of year when I get lots of calls regarding breeding mares.  In the past week I've also had several  about performance mares exhibiting unusual behavior and brood mares showing irregular heat cycles.  Both of these problems are related to the seasonal nature of mare's reproductive cycle, and may be particularly evident this year because of our unusual weather patterns. Today I am going to briefly review the mare's estrous cycle with emphasis on the transitional period that affects many mare's between January and April.

Seasonal variation in the duration of daylight has a profound influence on mare reproductive performance.  The horse is a seasonal breeder - increasing daylight improves the mare's reproductive efficiency while shortened days results in poor reproductive regulation.  Daylight is believed to act by stimulating the production of melatonin by the pineal gland, located within the brain.  This melatonin in turn causes the hypothalamus to release GnRH (gonadotropin releasing hormone).  GnRH acts on the pituitary, causing production of FSH (follicle stimulating hormone) and LH (luteinizing hormone) which influence the ovaries to develop and release follicles. In order for successful conception to occur, a mature follicle, or egg, must be fertilized by healthy sperm and then arrive in a uterus which is ready to accept and nourish it as it develops into a budding embryo. 

The transition from the short days of winter when most mares stop cycling all together, to the long days of June, when fertility is at its highest, is a gradual, progressive process.  During the spring and fall, mares enter a period of anovulatory receptivity, or the transitional period.  At this time, they often exhibit erratic estrus behavior, and while they appear to be in standing heat and accept a stallion, there often is not an associated ovulation of a mature follicle.  Even if a transitional mare does ovulate appropriately, it is also likely that the hormonal sequence necessary to maintain the early critical days of pregnancy will not be in place and the conceptus is lost.  Particularly in the spring, this transitional period is characterized by long, erratic heat cycles without ovulation. 

During the transition period performance horses often exhibit irritable behavior and are difficult to train.  It is during this time that trainers are often looking for ways to suppress reproductive activity so that their mares will behave appropriately in the show ring.  There are many oral supplements available over the counter which claim to improve the demeanor of irritable mares. The effectiveness of these supplements is debatable.  The only way to know if one will help your cranky mare is to try.  For years people have used cattle subcutaneous hormonal implants to control mare's heat cycles, but multiple research trials have been performed using these implants and no one has ever been able to show that they have any real effect on the mare's hormonal regulation.  Injectable progesterone in olive oil can be used intramuscularly to prevent mare's from cycling during the transitional period with variable success.  The only truly reliable means of controlling a mare's reproductive system and preventing cycling is the daily administration of  oral Regumate liquid (a synthetic progesterone).

Once the transitional period is over and mare's are cycling regularly, reproductive efficiency rapidly improves.  The "normal" mare has a 21 day heat cycle.  She is not receptive for 14-15 days (diestrus), then comes into heat for 4-7 days (estrus), ovulating 12-24 hours before behavioral signs of estrus disappear. Regarding performance horses, some mares continue to be difficult during the days close to ovulation, but in general the number of days when undesirable behavior is exhibited are markedly reduced, and can be predicted based on following the heat cycle.

So, when your mare is acting like a maniac and its February or March, remember that part of her behavior may be attributed to the "raging hormone" condition that we all recognize in each other from time to time.  Mares, just like people, are very individual in their reaction to their own internal chemistry.  Some have placid dispositions and do not seem affected by the ups and downs of hormonal transitions while others are truly distressed during these transitional phases and should not be punished when they are at the mercy of Mother Nature's nasty tricks.  If you own a mare you are trying to breed in the early spring, or a performance horse with seasonal behavior problems, speak with your veterinarian about management practices that may improve your breeding success or help your mare's disposition. 

I believe that education is the key to evolution.
I believe that animals are the key to compassion.
I believe the learning never stops.

Saturday, April 17, 2010

Prepurchase Exam III: Diagnostic tests

Vet tip of the Day: Prepurchase Part III - Additional Diagnostics
Key Words: Radiographs, ultrasound, endoscopy, blood work 

Today we will discuss the final aspect of a prepurchase examination: the decision to pursue further diagnostic tests.  Radiographs are commonly utilized to aid the veterinarian's evaluation of your prospective purchase.  In some cases, ultrasound, upper airway endoscopy, and blood work also may come into play.  Let's look at each individually.

There are two reasons to take x-rays.  First, to obtain further information about a specific anatomic region because of abnormal findings during the clinical portion of the exam.  A very common example would be a horse demonstrating a mild to moderate positive response to upper hind limb flexion, but no other signs of lameness.  Degenerative joint disease (djd) of the lower hock joints is very common in athletic horses (search blog entries for "hock" to review this subject) and often is quite manageable with appropriate medical therapy.  Therefore, hock radiographs are one of the most commonly obtained diagnostic series during prepurchase exams.

The second reason to obtain radiographs of the horse you are considering is to look proactively for radiographic abnormalities which may cause lameness problems in the future, or affect your ability to resell this horse, even though they are not causing clinical problems at this time. The most common anatomic areas investigated for these reasons are feet and stifles, but may also include fetlocks and carpi (front knees).

So how do you decide whether to request radiographs?  If your intended use for your new horse is pleasure riding or light competition, the horse is in full work and has a complete history, and the clinical examination of the horse is normal, you may choose to forego radiographic evaluation.  On the other hand, if you are buying a high level performance horse, if you are planning to re-sell the horse in the near future, if the horse has not been in full work prior to the prepurchase evaluation, or if there are any questions which arise after the horse's clinical evaluation, then you should seriously consider additional diagnostic tests based on consultation with the veterinarian conducting the examination.

One final word on radiographs: they sometimes open a can of worms that may be confusing to you.  While some radiographic abnormalities are straightforward, many are open to various interpretations.  If the horse you are looking at has abnormal radiographic findings in the absence of a corresponding clinical unsoundness, the veterinarian must give you their best professional opinion on the significance of the x-ray findings, but remember: they don't have a crystal ball! Once again, this brings up the importance of having a good performance record on your prospective purchase to help the veterinarian performing the evaluation interpret the significance of radiographic findings.

Ultrasound of the soft tissues of the distal limb, specifically suspensory ligament, superficial and deep flexor tendons, may be considered in higher level performance horses.  However, ultrasound imaging has not been standardized to the same extent as radiography, and ultrasound actually is not a sensitive tool for determining subtle changes in soft tissues.  I do not recommend ultrasound as part of a routine prepurchase examination.

Upper airway endoscopy usually is reserved for upper level performance horses such as race horses and upper level endurance horses.  During the exercise phase of the clinical evaluation, the veterinarian will ask the horse to canter long enough to elevate both heart rate and respiratory rate and will evaluate these systems immediately after exercise to look for any indication of upper airway problems indicating a need for endoscopic evaluation.

Blood work is not a bad idea.  Although very unusual, it is possible for a horse to be harboring a chronic inflammatory or infectious condition without showing outward clinical signs.  A complete blood count and chemistry screen can rule out the possibility of an underlying problem.  A toxicology screen testing for sedatives, analgesics (pain killers), or other behavior modifying drugs may be indicated in certain situations.  If you request a "tox" screen, be sure to ask the veterinarian what how long it will take to get results of this test - it may be up to a week, and thus you must factor this delay into your negotiation with the seller.

So that's the story on prepurchase examinations.  I strongly recommend you have a veterinarian conduct at least a full physical examination and basic lameness evaluation on any horse you plan to purchase.  There are  many problems that may not be apparent to either the seller or buyer that a vet can identify for you and help you understand before you make the decision to bring a new horse into your life.

I believe that education is the key to evolution.
I believe that animals are the key to compassion.
I believe the learning never stops.

Friday, April 16, 2010

4/16/2010 Prepurchase Exam II

Vet tip of the Day: What to Expect in Your Prepurchase Exam 
Key Words: Lameness, Conformation, Physical Examination, Suitability

Before I begin, let me apologize for the gap in my blog entries.  Spring is here and as much as I enjoy writing, my clinical practice takes first priority and it has been consuming my energy lately.  Also, in all honesty, I've been focusing on my young jumper in preparation for his first horse show of the season, and putting him ahead of writing time as well over the past week.

Back to the prepurchase exam.  What should you expect to see happen when a veterinarian is evaluating a horse for you?  First, a complete physical examination from head to toe, including an eye exam with ophthalmascope, careful ausculatation of heart, lungs and gastrointestinal tract with a stethoscope, a brief oral exam and careful palpation of the entire horse will  take place. We are mentally running through a check list of body systems as we perform this initial examination.  Before diving into the musculoskeletal portion of the examination we are checking skin, lymph nodes, circulation, heart and lungs, intestinal tract.  We get a sense of the horse's systemic well-being based on heart rate, respiratory rate, rectal temperature, body condition, and oral mucous membrane color and moisture.  Having completed the overall systemic exam, the musculoskeletal portion of the exam begins.

The veterinarian will look at the horse carefully from front, back and each side before beginning the hands on exam.The horse will be examined for conformational defects, musculoskeletal symmetry, body condition and mobility of large muscle groups such as the neck and back.  Each limb will be carefully palpated and manipulated and hoof testers applied to the feet.  As we feel each limb, there are specific anatomic structures being evaluated systematically by palpation and visual assessment.  Each joint is assessed for fluid filling and mobility.  Tendons and ligaments are palpated for painful responses and palpable swellings or irregularities.    After a thorough examination of the horse at rest, he will be observed in motion.

The gait evaluation portion of the examination will vary depending on the intended use of the horse, the horse's age and training, and the facility where the exam takes place.  For performance horses, even lower level athletes, minimum evaluation includes observation on a longe line at walk, trot and canter on at least two surfaces: once in deeper footing and once on hard ground.  In some cases the horse will be observed under saddle as well.  After evaluating the horse on the longe line it will be observed in hand at a walk and trot in a straight line.  Various full limb flexion tests will be performed to see whether these stress tests produce any alteration in the horse's gait.

Flexion tests are theoretically intended to reveal subtle discomfort in joints or soft tissue structures (tendons & ligaments) that may not cause overt lameness at the time of the examination.  When a horse trots off lame after a flexion test, it may indicate the need for further diagnostic evaluation such as radiographs (x-ray) or ultrasound.  The interpretation of flexion tests is controversial.  There is considerable debate among veterinarians concerning the significance of flexion tests.  The problem is the wide variation from horse to horse in the response to flexion and variations of technique in performing flexion tests between veterinarians.  This is one of the many areas where an experienced trainer, and a veterinarian you know and trust, can be of great assistance in helping you interpret the findings of a prepurchase examination.

I put a lot of effort into trying to make explanations of my findings clear yet thorough when speaking to a prospective buyer during a prepurchase exam.  However, I'll be honest with you,  it is challenging to condense years of knowledge and experience of the anatomy, pathophysiology, and demands of a performance horse's life into simple formulas that adequately explain the implications of every abnormality revealed during a prepurchase examination.  And that is what we are trying to do, both for the benefit of the buyer and the horse.  Therefore, it is important that you ask questions until you feel comfortable in your understanding of the significance of the veterinarian's findings with respect to YOUR needs for THIS particular horse.  Finally, you must understand that as veterinarians, we are asked to look at a horse once, over the course of 45 minutes to a couple of hours, and determine whether it is going to stay sound and healthy for years to come.  Obviously this isn't possible, but remember from the last blog post, you are most likely to have a positive outcome if the horse you are looking at has a complete history and is in full work at a performance level close to its intended use for you.

In tomorrow's blog (and I PROMISE to write an entry tomorrow) we will discuss ancillary tests, such as x-rays, ultrasound, and blood work which may be part of your pre-purchase examination.  Until then, enjoy the sunshine and warmer weather!

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I believe that education is the key to evolution.
I believe that animals are the key to compassion.
I believe the learning never stops.

Friday, April 2, 2010

4/2/2010 - The Prepurchase Exam

Vet tip of the Day: The Prepurchase Examination
Key Words: Intended Use, Physical examination, X-rays
 Today I am going to discuss some theoretical considerations regarding prepurchase examinations.  Tomorrow I will go over the nuts and bolts of the prepurchase exam including what you should expect your veterinarian to do during the exam, and how to determine if x-rays or blood work are indicated.  Right now let's begin with a look at the issue of suitability.

Today I completed a prepurchase examination on a 15 year old arabian endurance horse.  The horse was experienced, with 5,000 competition miles and no history of lameness problems.  The buyers were looking for a safe, experienced horse to do 25 to 50  mile endurance rides, but not at a highly competitive level.  The horse had not been competing for the past two years, but had been consistently ridden as an athletic trail horse.

I share this information with you, and chose this picture of the little cowgirl riding her barrel patterns on what appears to be a very wise old mare, for a reason.  The arabian gelding I saw today, and the old quarter horse poking around the barrel are two very different horses, but each is appropriate for their rider's needs.

A prepurchase exam is a veterinarian's evaluation of a horse's physical well being based on a single evaluation which takes from 45 minutes to a couple of hours to complete. While a tremendous amount of valuable information can be gathered based on a thorough physical examination, lameness evaluation, and diagnostic imaging, even the most rigorous prepurchase exam cannot replace a good history on a horse's past performance record and a buyer's solid understanding of their goals in purchasing this horse.  Obviously the little cowgirl's horse needn't demonstrate the same athletic ability as the 15 year old endurance horse.

As a veterinarian, one of the most challenging situations when performing a prepurchase examination is trying to evaluate a horse with an unknown history which is not performing the job for which it is intended.  For example, last fall I was asked to evaluate a 9 year old thoroughbred mare being purchased as a children's show jumper.  The mare had done some showing as a 5 and 6 year old, and then for an unknown reason had become a brood mare.  She had 2 foals then didn't conceive last year and now was for sale. 

Evaluating a horse like this is really difficult.  She has not been in any kind of exercise program for 3 years and there is no explanation for her change from performance horse to brood mare.  She may have a perfect prepurchase examination on the day I look at her.  She may be sound, have good conformation and pass all my flexion tests and limb palpations with flying colors.  She may have normal x-rays of her hocks, and front feet.  From my perspective, she is a sound horse.  However, I always caution buyers of such animals that the horse is not performing at the level of intended use and has an incomplete history therefore it is impossible for me to have great confidence in assessing the horse's long term prospects for continued soundness.   In fact, when this mare was put back in regular work and began jumping she developed a hind limb lameness that was attributed to a suspensory injury, which very possibly had been the reason she became a brood mare in the first place.

The moral of the story is this:  when purchasing a horse, always look for an animal that is in work, and performing at least close to the level at which you intend to use it.  It is then much more likely that your veterinarian will be able to accurately identify issues of concern and discuss them with you.  Make every effort to obtain a history of the horse's past performance and ask the seller why the horse is for sale.

A prepurchase examination is a very important part of making a wise investment.  Often I identify problems during a prepurchase exam about which the seller was unaware - that is why we subject the horse to unusually rigorous conditions during the examination such as trotting small circles on very hard and very soft surfaces.  But at the end of the day, the ethical horse seller with a complete history on their horse can be equally as valuable as your veterinarian's assessment.  Tomorrow I will discuss in detail what you should expect from your veterinarian during a prepurchase examination.

The wind is howling - Mother Nature has been very restless throughout March and appears to be continuing her mood right into April.  Keep your head down and your spirits high.

Thursday, April 1, 2010

4/1/2010 Protecting our Ecology

Vet tip of the Day: Homeostasis- Support the Water Wars
Today's vet tip isn't strictly about veterinary medicine, but it is about the most important concept behind practicing good medicine: Homeostasis.

Whenever I am treating a very sick horse, foremost in my mind is the concept of homeostasis, which is the natural balance of all the elements in the body which when present, produces a healthy organism.

This morning I received a call from a client who has been deeply involved in a fight in the area where I live to stop the exportation of dangerous amounts of water out of our delicate watershed by a land development consortium.  She asked me to post the following message on the blog on behalf of the Northern Nevada Citizens for Water Conservation.  For many of us, riding our horses in the exquisite high desert environment of Northern Nevada nourishes our souls in a manner that defies expression.  The exportation of water proposed by these developers threatens the homeostasis of this delicate ecological system.  Please read Helen's message and do anything you can to support NNCWC in their fight for our precious native ecology.

You are all probably aware that RRR LLC have filed an appeal to the

Nevada Supreme Court with regards to the Washoe County Commission's
decision not to allow them to export water from our valley.
RRR LLC has been denied this on three different occasions; at the
Community Advisory Board, Washoe County Commission, and most recently
in their request for a Judicial Review.
Northern Nevada Citizens for Water Conservation has organized and funded this
fight. We hired an attorney when the Judicial Review was requested, by
doing so we were allowed to have our testimony and concerns heard.
Legal fees have pretty much exhausted our funds. How far we have gotten
in our cause, on fundraisers and donations is remarkable.

NNCWC is working for everyone's water. We need money for round number
four, it's that simple. Please put your donation in perspective with
what you are at stake to lose; if your well levels drop and you are
forced to drill deeper, (hoping to find the diminishing water table);
how that will affect your property value or even your ability to
exist here...

One more thing, be aware that the State Water Engineer has been
severely chastised by the courts for allowing excessive water
exportation permits to the potential devastation of environments and
small rural communities. The message being that their interests are not
necessarily yours, nor are they looking out for you. Please help. Send
contributions to: NNCWC 448 Hill St Reno, Nv 89501.

To learn more about water issues in the West, log on to

Thank you,
Helen Mooney

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