Tuesday, February 16, 2010

Tuesday, 2/16/10 - Veterinary Tale Chapter 3 - A Man of Few Words

Sorry for no post yesterday - internet and telephone service to my valley were out for 48 hours. A transformer burned out and a new one had to be shipped in from who knows where before service could be restored.  That's the bad news - the good news is today's post is the latest chapter in Veterinary Tales.  I hope you enjoy it.   In case you missed the first two Veterinary Tales, you can find them in the blog archives from January 31st, and February 4th.  More on vaccinations and the immune system on tomorrow's Vet Tip of the Day.

Veterinary Tale Chapter 3 - A Man of Few Words
I excel in emergency situations. Throughout my life I’ve espoused the theory that there are basically two types of people. The ones who step forward toward crisis, and the ones who step back. Years ago a horse trailer pulled up in front of the large animal clinic at the University of Georgia where I was the resident on duty accepting emergencies. The driver jumped out of the truck, shouting over her shoulder as she rushed to the back of the trailer.

“It’s a really bad colic, and I think he just went down,” she said as she opened the door of the stock trailer before I could stop her.

I was standing about 6 feet away and what I saw was this woman standing there holding the door with her right hand, facing the open trailer. In the trailer, inches away from her face, was a horse in the process of throwing itself over backwards, its head and flying front feet coming directly at the woman. Without hesitation I jumped forward, shoving the gal to the side with my right arm while reaching up with my left arm and grabbing the horse’s lead rope. The rope was sailing through the air just ahead of the horse’s nose, following the trajectory caused when it snapped loose from the tie ring at the front of the trailer. As the horse’s owner went stumbling off to the right, I yanked the lead rope as hard as I could to the left, lunging in the same direction. The horse came tumbling out the back of the trailer, all 4 feet flying in the air, and hit the pavement left shoulder first. The owner was unhurt, the horse scrambled to his feet, and without pausing I headed into the clinic leading the horse to get emergency treatment started. James Bond eat your heart out.

This is the kind of thing I’m really good at – acting during a crisis. But the mass I’d discovered in my dog Sticky’s mouth was another matter all together. This was something I had time to think about, worry about, plan about – something that wasn’t going to be over and done within a short time, something that wasn’t going to go away. So I acted accordingly: I ignored it, just blocked it out, and when I did think about it, tried to convince myself that the mass was scar tissue that had formed at a tooth extraction site. I knew it had not been present 4 months ago, because Sticky had had her teeth cleaned by Dr. Mark Altman, my local small animal veterinary buddy, and a tooth had been extracted at that time. My denial continued for 5 days, and then I realized I had to face the music.

Here’s the thing. I’m a veterinarian, and while I don’t treat small animals, I am board certified by the American College of Veterinary Internal Medicine, and I’ve been practicing medicine for 22 years. I’ve seen my fair share of neoplasia (cancer) in large animal species, and I knew that the horrible thing growing in my dog’s mouth was not benign. On day 6, when Fern arrived at the office in preparation for the day’s calls, I asked for her help.

“Hey, Fern, I think we need to biopsy this thing in Sticky’s mouth,” I said, sounding all unconcerned.

“I was wondering what you were doing about it. I didn’t want to say anything, but it looks pretty bad, don’t you think?” Fern asked. Bless her heart; Fern is the soul of discretion. She’d come to work for 5 days without mentioning Sticky’s condition, even though I knew she’d been as upset by the discovery as I had. All nineteen year olds should have a fraction of her maturity and compassion.

Fern’s been one of my assistants since she was fifteen. She’s never wanted to be anything but a veterinarian, and I’ve been taking care of her horses since I met her family when Fern was eight. She announced she was ready to begin working for me when she was ten, and her mother and I struggled to dissuade her, pledging that if she was patient, she could start working at fifteen. Her intention never wavered, and for the past four years she’d been with me every summer and on weekends during the school year. We knew each other well, and worked in easy companionship most of the time. After all, I taught Fern early on my number one rule for employees: whatever goes wrong, it’s their fault. Once they get this down, the road smoothes right out.

I looked at Fern and nodded, “My small animal medicine is pretty rusty, but I do remember that oral tumors in dogs tend to be aggressive and malignant. But before we make assumptions, we need to submit a biopsy to be sure. They did pull a tooth right where the mass arises, so we cannot rule out that it is a mass of granulation tissue and not neoplastic.”

Fern gently held Sticky’s lip back while I took a scalpel blade and sliced off a small piece of the mass. My little PCD sat quietly, staring at me with absolute trust, without sedation or local anesthesia, as I performed the biopsy. She was just that kind of dog – she never made a big deal about anything. I knew the tumor would not have a nerve supply, so there would be no pain associated with the small biopsy, but most dogs would object to the restraint, especially around the mouth. But not Sticky, she didn’t move a muscle, just let Fern hold her lip back and wagged her tail slowly.

The biopsy safely stored in a submission jar filled with formalin, Sticky licked her bloody lips and jumped into the truck, ready to start the day. Fern and I looked at each other, hesitated a moment and then both burst out laughing.

“Sticky says, ‘come on you guys, let’s get going!’ “Fern said, her eyes shining with tears even as she smiled. “They just aren’t like us humans are they? No worries, just another day to live and enjoy. I don’t know, Dr. C, sometimes I’m just overwhelmed by how brave animals are.”

I climbed in and started the truck, motioning to Fern to join me. “I know, Fern, they teach us every day how to be better than ourselves, if we would just pay attention.” Sticky put her head in my lap, assuming her travel position. “Hand me a towel, will you – I’m going to have Sticky blood all over my pants for the rest of the day.”

“Here you go, Dr. C,” Fern said, handing me a blue surgical towel for my lap. “Maybe we should stop at the Frosty on the way to Roger & Barb’s and get her a soft cone – I bet that would feel good.”

“Good idea,” I agreed, “Today, whatever Sticky wants, Sticky gets.”

By the time we arrived at Roger Carlson’s cutting horse barn Sticky had lapped up her ice cream cone and was observing the world with her usual aura of ancient wisdom. Fern and I greeted Roger’s wife Barb and began preparations for the day’s procedure: castration of a two year old stallion.

Roger and Barb Carlson have been training cutting horses for over 30 years, almost as long as they’ve been married. They were high school sweet hearts, Barb the daughter of a local ranching family and Roger a Paiute Native American. They managed a training barn just over the California line, about 20 miles west of my office, in Sierra Valley. This was a picturesque area, located right at the transition elevation where desert and sage merged into aspen and pine stands peppering the steep Sierra Nevada foothills. I loved coming into this valley and had been excited about gaining the Carlson barn as an account. I inherited the work about a year previously from my friend Mark Altman when his small animal practice became so busy he no longer could provide adequate coverage to this area.

Mark was a real cowboy, a man’s man, a Deacon in the Church of the Latter Day Saints and one hell of an equine veterinarian. Guys like Roger Carlson and guys like Mark were born speaking the same language. When I first began working for the Carlson’s Roger’s wife Barb did all the talking, while Roger just watched me. I don’t think he said more than three consecutive words over the first year I came regularly to the barn. When he did finally begin talking to me, his dry humor and rare warm smile bowled me over. Roger had rich red skin, deep set dark eyes and a face etched by years riding outdoors in the high desert.

Today we were gelding one of his best young prospects. Roger brought the colt out into the center of the indoor arena and held him while I administered the first of two injections used for short term equine anesthesia. When my left hand closed around the colt’s neck to occlude the jugular vein I could feel his heart hammering through the skin against my thumb. I glanced at his eye to catch him glaring at me, his left ear cocked back and his expression saying loud and clear, “One wrong move and you are breakfast”. If only Sticky could talk to these young stallions and pass along some of her peaceful karma.

The first sedative successfully injected without incident, the colt began to relax, his head dropped, his lower lip drooped and he became wobbly. Ralph spoke to know one in particular,

“I guess this is the nicest colt I’ve ever raised.”

Silence.

“He certainly is a beauty, Roger,” I agreed. “Look at that hip, and the shoulder isn’t half bad either.” I added, thinking to myself – just lie down quietly and stay down until I’m done, you little monster.

Just as I pushed the plunger on the second syringe containing the ketamine that would cause the colt to drop, Ralph spoke again,

“You know when Dr. Mark used to do my colts he was done in no time at all.”

Silence.

“He’s quite a guy, that Dr. Mark” I mumbled, planning to wring his neck the next time I saw him.

“Why don’t you let me hold him while he goes down, Roger, “ I said, taking the lead rope into my left hand just as the youngster sank quietly to the ground with a deep groan. “How’s that for a smooth induction, oh Marvelous Mark?” I mentally complimented myself.

Fern moved in to tie up one hind leg, cover the colt’s eyes with a towel and scrub the scrotum while I gloved up and opened the emasculator and scalpel blade. I removed the first testicle and looked up to see where Sticky was. Don’t be too disgusted, but Sticky always knows when we are gelding a colt, and she is always sitting intently by the horse’s flank, waiting for her special treats. Soft ice cream cones are great, but they don’t compare to this. I spot her watchful eye and prepare to toss her the prize.

“Hold on there, doc!” Roger’s voice is actually raised a few notches, a new experience for me.

“I’m sorry Roger, I usually give these things to Sticky as a treat, but if you don’t want me too, that’s fine.”

“ I don’t care what happens to the damn things, but you move that dog up here by the colt’s head and throw ‘em forward to her – don’t you know that if you toss them over his head he’ll never look back?”

“Um, OK, no problem, come here Sticky,” I called, cursing Mark for not giving me a head’s up on this old western horseman’s tradition I’d certainly never heard before.

Sticky finished her hors d’oeuvres with relish, the colt recovered uneventfully from anesthesia, and Fern cleaned up and packed the truck while I stood with the now young gelding and Roger. More silence, but I figured I was better off saying nothing than trying to make conversation and sounding like an idiot. As I saw Fern finishing, I checked the colt’s incisions for bleeding and turned to Roger.

“Everything looks good Roger; he can go back to his stall now.”

Roger led the colt from the arena without a word and put him in his stall. I wrote up the bill and went out front to the travel trailer that served as an office to give it to Barb. We chatted as she wrote out the check and said thanks and good bye. I went out to the truck to leave. As I was pulling away from the barn Roger walked out. He spoke just loudly enough for me to hear.

“I guess Dr. Mark was right when he said you were OK.”

After a year, I was still thankful for small mercies.

Saturday, February 13, 2010

Sat. Feb 13, 2010: Vaccination Protocols

Vet tip of the Day: Selecting Appropriate Vaccines
Key Words: West Nile, Tetanus, Influenza, Rhinopeumonitis, Encephalitis, Rabies, Strep Equi

Diseases are like brush fires.  Some smolder for awhile and are easily extinguished, others flare up and have devastating effects.  Choosing vaccinations for your horse has a lot to do with the nature of each disease we are attempting to prevent.  Toward this goal, here are the answers to yesterday's questions.  

Note: The answers about likelihood of exposure are only pertinent to horses in Northern Nevada.  Consult your veterinarian for other geographic regions.

1.     How likely is it that this horse will be exposed to Disease A?
  • West Nile:  Likely
  • Tetanus: Unlikely
  • Influenza: Very Likely
  • Rhinopnuemonitis: Very Likely
  • Encephalitis: Very Unlikely
  • Rabies: Very Unlikely
  • Strangles: Likely
2.     Is Disease A a deadly disease, such as Tetanus? (this assesses risk to this horse)

  • West Nile: Yes, 40% mortality
  • Tetanus: Yes, 80+& mortality
  • Influenza: No
  • Rhinopneumonitis: No, but high risk abortion in pregnant mares
  • Encephalitis: Yes, 85+% mortality
  • Rabies: Yes, uniformly fatal
  • Stangles: No, 10% complication rate, with fatality uncommon
3.     Is Disease A highly contagious, such as Influenza? (this assesses risk to neighboring horses)

  • West Nile: No, is not transmitted horse to horse. Disease is transmitted from infected bird, to mosquito, to horse
  • Tetanus: No, is not transmitted horse to horse. Tetanus bacteria lives in soil and usually gains access to horse through deep puncture wound that creates an oxygen free environment where bacteria can proliferate.
  • Influenza: Yes! Transmitted directly horse to horse by aerosole (cough) and direct contact.
  • Rhinopneumonitis: Yes! As for influenza.
  • Encephalitis: Moderately, disease is not transmitted directly horse to horse, but is carried from horse to horse by a "vector", which for this disease is the mosquito.
  • Rabies: No, is not transmitted horse to horse
  • Stangles: Yes! Primarily transmitted by direct contact horse to horse AND by contact with contaminated "fomites": halters, lead ropes, hands, feet, water buckets, etc.
4.     Is the vaccine used to protect against Disease A highly effective?

  • West Nile: Yes, Intervet DNA vaccine extremely safe and effective with minimal side effects
  • Tetanus: Yes, killed vaccine 95+% safe and effective
  • Influenza: Vaccines against influenza currently available are moderately effective, with relatively short lasting immunity provided. 
  • Rhinopneumonitis/Equine Herpes type I and IV: There are 2 main Equine herpes viruses that cause upper respiratory disease in horses. They are also responsible for abortion and a neurologic disease which can be fatal.  Currently available vaccines are very effective in preventing abortion, moderately effective in preventing upper respiratory disease, and of questionable efficacy against the neurologic form of herpes virus.  More discussion on this in a later vet tip post.
  • Encephalitis: Yes, killed vaccine very safe and effective
  • Rabies: Yes, killed vaccine very safe and effective
  • Stangles: The intranasal vaccine against Strep equi bacteria is moderately effective, and of all the vaccines discussed here has the highest complication rate.  We will discuss Strangles in more depth in a later vet tip post.


5.     What is the cost vs. effectiveness vs. safety value of the vaccine for Disease A?

  • West Nile: Excellent
  • Tetanus: Excellent
  • Influenza: Moderate
  • Rhinopneumonitis: Moderate, except very good against Equine Herpes induced abortion
  • Encephalitis: Very Good
  • Rabies: Excellent
  • Stangles: Fair

 With this information, consider the following:
Your horse's age: the young and the old are always more susceptible to disease
Your horse's lifestyle: travel, stress of competition, and exposure to other horses always increase the risk of disease


Now decide which vaccines you think are appropriate for your horse.


More on Monday.  Have a wonderful weekend.


Chrysann



Friday, February 12, 2010

Friday, Feb 12, 2010 - Vaccination

Vet Tip of the Day: Vaccination
Key Words/Phrases: Immunity, West Nile Virus, Influenza, Encephalitis, Veterinary Consultation

It is mid-February, almost time to begin gearing up for spring, which means administration of spring vaccinations.  For the next few vet tips, I would like to discuss some of the theory behind the practice of vaccination, in order to give you the tools to make informed decisions about appropriate vaccination strategies for your particular horses.  Rule #1: never be afraid to ask your veterinarian the basis for choosing your horse's vaccination program.  You deserve this attention.  However, I am as guilty as anyone else in this regard - the words "hectic" and "springtime" are virtually synonymous for equine practicioners.  We are usually scrambling to keep our heads above water during the months of March, April and May, from gelding colts, to getting mares in foal, to welcoming new babies into the world, to preparing performance horses for upcoming show seasons our days (and nights!) are already full, so we tend to be on the go when it comes time to administer routine vaccinations.

You may want to try this strategy: avoid trying to slow your veterinarian down to talk in the spring when they are most likely to be distracted.  Instead, talk to your veterinarian about routine health strategies such as vaccination during the quiet winter months.  Schedule a consultation appointment and let your vet know the topics you would like to discuss ahead of time.  This approach allows your veterinarian to sit down and focus on your questions in a relaxed fashion that will lead to a more thorough, rewarding information exchange.

To begin our discussion of vaccination strategies, let's determine how we decide whether a horse should receive a certain vaccine.  Consider vaccinating a horse against Disease A.  I ask myself the following questions:
1.     How likely is it that this horse will be exposed to Disease A?
2.     Is Disease A a deadly disease, such as Tetanus? (this assesses risk to this horse)
3.     Is Disease A highly contagious, such as Influenza? (this assesses risk to neighboring horses)
4.     Is the vaccine used to protect against Disease A highly effective?
5.     What is the cost vs. effectiveness vs. safety value of the vaccine for Disease A?

With these questions answered, I then can make an informed decision whether or not to recommend vaccinating this horse against Disease A.

The diseases against which we routinely vaccinate horses in the Western United States are listed below.  Test your own knowledge and try to answer the questions above for each of them - I will post the answers in tomorrow's Vet Tip of the Day.

West Nile Virus
Influenza, Rhinopneumonitis
Eastern & Western Encephalitis
Strep Equi (Strangles)
Rabies

Our new and improved website if coming on line.  It is like a fledgling chick pecking its way out of the egg - if you want to watch it emerge, then keep checking in over the next week or so.  If you'd rather just see the final product, wait a couple of weeks and then look.  Either way, you can now get to this blog through the website - it's an easier address to remember and the link to the blog is on the home page.  Just log on to HighDesertEquine.com


There is quite a bit of information on the website as well for your education. 


Finally, for my local clients, the spring vaccination clinic schedule will be posted by Monday, February 15th.

Enjoy,
Chrysann

Wednesday, February 10, 2010

Wednesday, Feb 10, 2010 Face Lacerations

Vet Tip of the Day: Facial Lacerations
Key Words/Phrases: Wound healing, primary closure, golden period


We've been hammering limb anatomy and lameness for over a week, so I think it's time to take a break and look at something entirely different. Facial lacerations are a relaxing break out topic because while they often start with a horrified horse owner and a gaping wound such as this one, they are simple to treat and usually end with an excellent outcome.

The tissues of the face have a tremendous blood supply, and because blood is what carries all the magical factors necessary for wound healing to the site of injury, lacerations on the face have a healing advantage not present in other areas of the body.

The first six hours after a skin laceration occurs is called the "golden period" in wound healing.   In general, sutures placed in a wound more than 6 hours after its occurrence are likely to fail, no matter how carefully the wound is prepared and how correctly the sutures are placed.  With every minute that passes after a laceration is sustained, exposure to external factors increases the risk of infection while at the same time the lack of blood supply to exposed tissues decreases the chance that tissue will remain alive and reattach when sutured.  The one anatomical exception to the "golden period" rule applies to facial lacerations, where wounds often heal uneventfully when sutured 24 hours or more after they occur.  Even large wounds filled with debris that involve skin flaps with wide areas of exposed underlying bone usually heal well, due to the excellent blood supply to tissues of the face.

The horse pictured here sustained a high impact injury involving a rigid metal object. Following sedation with 10 mg of intravenous detomidine, and subcutaneous placement of a local anesthetic around the wound margins, this horse's wound was carefully cleaned with dilute betadine, then flushed copiously with sterile saline.   Skin staples were used to hold the skin flap back in position.  The staples were removed 14 days later and as you can see, the wound healed without any skin loss.  Even if you find a severe face laceration that is over 12 hours old (the thunderstorm during the night is a classic for this), don't despair - primary closure may still be possible and successful.

Horses that sustain lacerations to the face and have concurrent nose bleeds should always receive antibiotics.  The presence of bleeding at the nose indicates that the concussive force may have been severe enough to cause bleeding into one of the sinuses that underlie much of the space beneath your horse's forehead and nose.  Because the sinus cavities communicate with the nasal passages, bacteria in the nasal passages can gain access to the sinus.  If there are broken blood vessels in the sinus, bacterial infection (sinusitis) can set up housekeeping in the sinus cavity.  Treating a well established bacterial sinusitis is difficult, and the need to do so can be avoided by initiating antibiotic treatment at the time of facial trauma.  So don't forget - face lacerations accompanied by nose bleeds should be seen by your veterinarian, even if the laceration itself is not severe.

I'm late writing the Veterinary Tale for this week, so it may not get posted tomorrow, but I'll do my best to get it to you soon.  The practice website is being updated this week.  I really like the new look and will let you know as soon as it is on line so you can check it out and give us your opinion.

The sun was out today in Reno - halleluiah! We used to take it for granted, but after this winter, no longer.

Enjoy,
Chrysann

Tuesday, February 9, 2010

February 9, 2010 - Injectable Joint Therapies

Vet Tip of the Day: Injectable Joint Therapies
Key Words: Adequan, Legend, PSGAG, Hyaluronic Acid

To finish our segment on the hock, here is a brief discussion of the two FDA licensed injectable agents to improve joint health.  The first, Adequan, is used more commonly for osteoarthritis of the hock (bone spavin).  Adequan is a large molecule with the chemical name polysulfated glycosaminoglycan (PSGAG) which cannot be absorbed when given orally and so is administered by intramuscular injection.  Adequan has been shown repeatedly in controlled clinical trials to improve lameness associated with chronic degenerative joint disease, however, on an individual animal basis, it's effectiveness is quite variable.   Its mechanism of action is similar to chondroitin and glucosamine.  Remember that these oral supplements are building blocks used by the body in the construction of cartilage.  Adequan is a very large molecule, more complex than either chondroitin or glucosamine, and is further along the construction pathway in the formation of cartilage matrix.  The PSGAG molecule is incorporated into cartilage, giving it elasticity and shock abosorbing capacity.

I use the brand name Adequan, although there are generic PSGAG products available, as well as compounded products.  However, as with oral supplements, the molecular construction of the generics and compounded products are not necessarily equivalent to Adequan, and have not stood the test of clinical or experimental study.  In fact, Luitpold Pharmaceuticals, the manufacturer of Adequan, has spent quite a bit of money conducting quality research on their product, and in the comparison studies performed to date, Adequan has outperformed generics.  Once again, you get what you pay for.

Legend is injectable hyaluronic acid (HA).  And yes, just like PSGAG,  hyaluronic acid comes in many molecular weights and qualities, and so far, for intravenous administration, Legend is the gold standard.  While Adequan is used most commonly for hock arthritis, it is not uncommon to combine Adequan and Legend as joint therapies.  In the joint environment, hyaluronic acid and PSGAG have complex actions.  In addition to acting as structural components of joint fluid and cartilage, both HA and PSGAG have anti-inflammatory effects within the joint.  On top of that, when used together, each component enhances the activity of the other, so 1+1=3!  Therefore, in performance horses with joint issues, it may be advisable to use combination therapy. 

There is a standard protocol for initiation of Adquan therapy, established by the manufacturer.  The recommendation is to give 1 vial every 4 days for 28 days followed by one vial every 2-4 weeks thereafter. Legend is often given once monthly intravenously as maintenance therapy, with additional doses given around the time of competition.

Oral and injectable chondroprotectant agents are widely used in treating osteoarthritis of the hocks.  They often are used in conjunction with intra-articular (directly into the joint space) injections of similar products in combination with corticosteroids, as well as oral adminstration of non-steroidal anti-inflammatories such as phenylbutazone.  Finally, a topical anti-inflammatory cream is now available which provides local, temporary pain relief and can be effective to control hock pain during exercise.  This product is Surpass, or diclofenac acid.

We've covered a lot of information on the hock.  If you are interested in learning more,  use the key words provided as Search words in Google and you will find LOTS more to read.

Have a great day,
Chrysann

Monday, February 8, 2010

Monday, Feb 8 2010 - Winding up the Hock

Vet Tip of the Day: Oral Joint Supplements
Key words: chondroprotectant, synovial fluid, cartilage, joint capsule

Osteoarthritis is only one of many conditions that affect the hock; in the future we will come back and discuss other disease processes that affect tarsal joints.  But to conclude this introduction to hock anatomy and bone spavin, the most common cause of hock lameness, there will be two final Vet Tips of the Day: today we will look at oral joint supplements, how they work, and IF they work.  Tomorrow we will consider injectables.

It is important to distinguish between oral and injectable agents administered as chondroprotectants.  "Chondro" refers to cartilage, "protectant" is self-explanatory.  Chondroprotectant joint supplements are substances which claim to enhance the health of joints by improving the the quality of joint fluid and joint cartilage.  Cartilage is the spongey substance which lines the surface of bones within joints.  The cartilage is bathed in synovial fluid, or joint fluid, which is contained within the joint space by the joint capsule.  The joint capsule is lined by synovium, the site of joint fluid production.  In the simplest terms, the joint fluid and cartilage act as shock absorbers to diminish the force transmitted to bones when joints are compressed by weight bearing.

You've almost certainly heard of glucosamine and chondroitin.  These are two of the most common ingredients in oral chondroprotective joint supplements.  These substances are two of the primary building blocks the body uses in the construction of cartilage.  Theoretically, by increasing the amount and quality of glucosamine and chondroitin in the diet, the body is better able to produce and maintain healthy cartilage.  There are three major problems with this theory.  First, there are many structural varieties of glucosamine and chondroitin, and their absorption across the gut wall is widely variable.  Second, and perhaps more importantly, there are few government regulations regarding the manufacture of oral joint supplements, which are considered "neutraceuticals".  Therefore, the amount and quality of ingredients listed on the label vary widely from product to product, and there is not even any guarantee that the label claims of a given product are true.  Therefore, when buying an oral joint supplement, you are completely at the mercy of the manufacturer's ethics regarding the actual contents of the product.

Finally, the third problem is, assuming the product you buy is excellent quality and your horse absorbs the ingredients, there is very limited research availabe indicating what an appropriate dosage is for a given combination of chondroprotective ingredients.  In addition to glucosamine and chondroitin, additional additives found in many joint supplements include cetyl myristoleate (an anti-inflammatory) , hyaluronic acid (a major components of joint fluid), as well as various herbal extracts such as devil's claw, boswellia and avocado extract, just to name a few.

Before you throw in the towel, be comforted in knowing that, while limited, there are a few well designed clinical studies indicating that the oral administration of chondroprotective agents can improve lameness in horses with chronic osteoarthritis.  The bottom line is, at this time there is more unknown than known about these products, so if you choose to give one to your horse, buy a recognized brand manufactured by a company with a longstanding reputation.  Be sure the product is clearly labelled with respect to ingredients, amounts of ingredients, and recommended dosage.  It should be easy to calculate the actual amount of each ingredient you will be giving your horse by reading the label.  The product should have a lot number and expiration date easily identifiable, and there should be clearly printed information telling you how to contact the manufacturer.  Finally, if the product claims to cure everything from laminitis to navicular disease to hock pain in 30 days, don't buy it.  Remember, you get what you pay for, and if it sounds too good to be true, it probably is.

Sunday, February 7, 2010

Fri & Sat Feb 4,5. More on the hock

Vet tip of Two Days!
Key words: osteoarthritis, hock,chondoprotective, joint therapy, glucosamine, chondroitin

My apologies for this late vet tip. It's actually Sunday morning, but it is snowing again and I've get an hour before I go out to do a couple of calls this morning. One of them is to inject the carpus of an older rope horse with chronic osteoarthritis. Do you remember how many joints there are in the carpus and which joint on your body is similar anatomically to this equine joint? (for review see last Wednesday's blog).

Osteoarthritis of the lower hock joints (bone spavin) is the most common cause of chronic lameness that I see in my practice, with forelimb heel pain a close second. Bone spavin occurs in every type of athletic horse, and unfortunately it is not uncommon to see horses develop sore hocks at a relatively early age. The 3 or 4 year old cutting horse is the extreme example, but jumpers, dressage horses, foxhunters, endurance horses, and other western sport horses may have degenerative changes in their hocks before 10 years of age.

Why are these joints predisposed to arthritis more than other joints of the body? Probably because of their unique position of high stress and low motion. Watch your horse's hocks closely as he trots on the longe line. Most of the flexion that occurs is due to motion of the large tibiotarsal joint, which has a large joint space and round, ball bearing like sliding surface where the tibia sits on the knuckle shaped talus. This joint is an uncommon site for osteoarthritis secondary to athletic activity.

Now look at the radiograph from Thursday's blog (the normal hock), then look at this radiograph which demonstrates osteoarthritis in the distal intertarsal and tarsometarsal joints. These are the joints at the bottom of the hock that are complex and relatively rigid in construction. The joint space is the thin black line between the rows of tarsal bones. Imagine the force that flows through these joints when your jumper throws his thousand plus pound body into the air to clear an obstacle or your barrel horse digs in to accelerate out of the turn around the last barrel or your dressage horse sucks it up to sit back on his hocks and put that tremendous effort into a canter pirouette. There isn't much room for error in these joints, because there is very little room for movement, so over time, the stress of high force through tightly packed bone results in chronic inflammation.

Joint fluid lubricates and cushions the cartilage that lines bone surfaces. The inflammatory process causes this fluid to becomes thin and less able to absorb repeated impact. The cartilage, in turn, looses its flexibility and ultimately the bone is left to take up too much of the load of activity. It's response is to say "Hey, I'm working too hard, maybe if there is more of me this job will be easier." Unfortunately, the production of extra bone simply destroys the smooth architecture of the carefully constructed joint anatomy with the end result: pain.

That's how the process starts, now how do we treat it?

Many of the key words for this vet tip are related to the huge topic of joint therapies. Tomorrow's vet tip will be devoted to the subject of oral and intra-articular therapies, and trying to separate fact from fiction. To close today's entry, here is the bottom line: there is sound, repeatable scientific evidence that certain oral and injectable chondroprotective agents can help to alleviate the inflammation, and therefore the pain, associated with osteoarthritis of the hock. The efficacy of these products is variable, and the products themselves are variable. We will look at them in more detail tomorrow.

I hope you are enjoying these vet tips - we are in the process of updating the practice website - the blog name is probably going to change (high brow internet search engine stuff that is GREEK TO ME). I promise to keep everyone up to date as the High Desert Veterinarian continues to explore cyberspace in order to share the knowledge and wonderful life of a practicing veterinarian with you all.

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