3/12/2010 - Anatomy and OCD

Vet tip of the Day: Significance of OCD based on anatomic location
Key Words: Osteochondrosis, lameness, joint, anatomy

This cute foal picture is here to remind you that OCD is a developmental orthopedice disease.  In other words, it develops as a foal grows, although it may not manifest itself clinically until later in life when joints are subjected to the rigors of training and controlled exercise.  When we consider the prognosis of various OCD lesions, then, there is one common sense rule to keep in mind: foals that develop significant lameness early in life due to OCD are likely to have more severe lesions than animals that do not show any clinical signs until they are older and in training. 

Regardless of the anatomic location, the larger and deeper the OCD lesion is in a given animal, the less likely it is that surgical treatment will be successful.  In general, the degree of lameness and age at onset correlate with the severity of the lesion.  Consider our mare Classy, a five year old just completing 60 days of fairly rigorous training and only demonstrating a grade 1 lameness and mild joint swelling.  Even before examining her radiographs, one can be hopeful that her prognosis for full function would be favorable.  And this is in fact the case.  Classy has an excellent prognosis for a full athletic career following surgical debridement of her stifle lesions.  On the other hand, a 6 month old weanling with grade 3 lameness and severe swelling of the stifle joint undoubtedly has a more conservative prognosis for an athletic career, even with appropriate treatment.

OCD can occur in any joint in the body. The most commonly affected joints are the stifle, hock and fetlock, and less commonly the shoulder and cervical spine (neck).  Within each of these joints there are several locations where lesions can occur.  In addition, lesions may occur as mineralized cartilage fragments that have separated from the underlying bone (see Classy's x-ray's for a beautiful example) or they may appear as cyst-like lesions, where the cartilage lining the bone is still intact, but is no longer attached in one region, with fluid and tissue debris filling the area between the detached cartilage and underlying bone. Remember our jump painting analogy?  The detached lesions are like paint chips, leaving the wood of the jump exposed, the cyst-like lesions are like bubbles in the paint, detached from the wood, but with the paint surface still intact. 

The prognosis for full athletic function for OCD of the lateral trochlear ridge in the stifle and most locations in the hock is excellent in the majority of cases, particularly when lameness is not severe, and does not become apparent until the horse enters training.  OCD of the fetlock is often treated successfully, but caries a more conservative prognosis in general than lesions of the hock or stifle.  OCD of the shoulder and cervical spine in general carry a guarded prognosis. There are certain anatomic locations where OCD lesions may be detected radiographically in a sound horse during a pre-purchase examination, for example, and be considered clinically insignificant, depending on their severity, and the horse's level of performance.

While surgical debridement (scraping the lesion just as you would scrape the paint on your jumps before correctly applying fresh paint) remains the gold standard for treatment of OCD, there are many emerging treatments under investigation which may alter our approach to this complex disease.  Intra-articular stem cell therapy is one of the most promising of these.  And still, many foals and weanlings with early diagnosis of less severe forms of OCD respond well to simple rest and careful rehabilatation with intra-articular chondoprotective therapy, allowing mother nature to do her own magic in healing lesions.

I've barely scratched the surface of the subject of OCD in these past few posts, but hopefully you will take away the message that in most horses this diagnosis does not mean the end of an athletic career.

I'm off to dinner after a long, cold day of work in windy, 45 degree rain spitting Reno today.

Enjoy.

2/23/10 - Veterinary Specialists

Vet Tip of the Day: Understanding your Veterinarian's Training
Key Words: Diplomate, Board Certification, Residency, Internship

I've been looking at a horse with a challenging lameness problem for a couple of days.  This weekend I examined another horse with an unusual neck problem.  I obtained radiographs of both horses.  Tonight I will e-mail the x-rays of the lame horse to a board certified large animal surgeon for his opinion.  Yesterday I mailed a disc of the neck films to the radiology department at UC Davis where they will be reviewed by a board certified radiologist.  Last week a colleague of mine called me to ask for a consult on a horse with pleuropneumonia.  He was seeking my opinion on treatment options because I am board certified in Large Animal Internal Medicine.

What do you know about your veterinarian's training and post-doctoral experience?  All of us practicing veterinary medicine have completed a 4 year graduate veterinary degree program after our undergraduate college years.  When we graduate from veterinary school we receive a doctoral degree: DVM or VMD (if you graduate from the University of Pennsylvania your veterinary degree is awarded in latin so it ends up VMD instead of DVM).  In order to practice veterinary medicine we also have to pass the day long National Board Exam as well as an exam in any state in which we intend to practice.  With a DVM and passing scores on the National Board and state exams, we are licensed to practice all aspects of veterinary medicine according to the laws of the veterinary practice act in the state in which we work.

Unlike human medicine, veterinary medicine does not require an internship or residency after vet school.  However, many individuals choose to complete such post-doctoral training.  Most Colleges of Veterinary Medicine offer rotating small and large animal internship programs which provide a year of experience in medicine, surgery and reproduction under the supervision of experienced faculty members.  Many private practices also offer internship programs, but many of these programs do not fall under the guidance of any governing body.  While some private practice internships are of excellent quality and value, some are not.

After completing an internship, the final phase of advanced clinical training available to veterinarians is residency programs.  Most of these programs take place in a University setting, but there are private practice residency programs as well.  All residency programs must comply with rules and regulations set down by the Specialty College under which they operate.  The three main specialty colleges are the American College of Veterinary Internal Medicine (ACVIM),  the American College of Veterinary Surgeons (ACVS), and the American College of Theriogenology (ACT, reproduction).  There are many subspecialties in the Medicine college.  These include neurology, cardiology, oncology, and large and small animal internal medicine. There are also specialty colleges of Emergency Medicine, Exotic and Zoo Animal Medicine and Critical Care.

As you can see, there are many opportunities for advanced training after the Doctor of Veterinary Medicine is obtained.  My list above is far from complete.  All ACVIM and ACVS residency programs are at least 3 years long.  Some combine their clinical residency with a Masters or PhD program in a basic science.  My Large Animal Internal Medicine Residency was completed at the University of Georgia and was combined with a PhD degree program.  This combination training took 5 years to complete, and offered a great complementary combination of basic research and clinical training which in my case had a strong emphasis on colic, or equine gastrointestinal diseases.  It is important to remember that while we are completing residency programs, not only are we becoming highly skilled experts in our specialty field, but we also are working as practicing veterinarians in a teaching hospital, and so are interacting on a daily basis with other services, including surgery, lameness, reproduction, etc.

At the end of a residency program, the resident candidate's credentials must be approved by their resident mentor, and then they have the priviledge of taking a monster exam.  To give you an idea of how stringent our veterinary specialty residency programs are, when I took the ACVIM Large Animal Internal Medicine exam, the pass rate was 23%.  That means that only 1 of every 5 people who sat for the exam that year received board certification.    

If your veterinarian is a general practicioner, he or she may choose to consult with a specialist from time to time concerning certain issues with your horse, or in some circumstances may choose to refer you and your horse directly to a specialist.  As veterinarians, we have a strict code of referral ethics.  I encourage you to  follow your primary care veterinarian's advice, consult with the specialist, and return to your primary care veterinarian for follow up care.  It is important that specialist referral centers maintain open lines of communication both with their clients and with the referring veterinarians in order to provide the best care to your horse while maintaining continuity of service.

Now that you know a little bit about specialization within the veterinary profession, take advantage of your knowledge and ask your veterinarian any questions you may have about our profession.  Don't be afraid to ask any professional about their credentials and experience.  And if you do take your horse to see a specialist for any reason, be sure that that person is in fact a Diplomate of the Specialty College of Veterinary Medicine in which they are practicing.

To learn more about our specialty colleges, log on to ACVIM.org or ACVS.org

I am your Vet Tip of the Day Blogger,
Chrysann Collatos VMD (Veterinariae Medicinae Doctoris), PhD (Doctor of Philosophy in Physiology), DACVIM (Diplomate American College of Veterinary Internal Medicine)