Quote 4the day: Life throws curve balls at us all either catch it or duck. Horses throw clods of mud at us we can dodge them!!!
Fact 4the day:
OSTEOCHONDRITIS DISSECANS (OCD)
Osteochondritis dissecans (OCD) is a relatively common developmental disease that affects horses of all types. Although the exact cause of OCD and the steps leading up to it are not definitively known, there is a reasonable consensus about the general cause. In order to understand how OCD occurs, one must first understand how joints form. Differentiation of bones and joints occurs through a process known as endochondral ossification. Endochondral ossification is responsible for the formation of normal bones as well as normal articular cartilage, the smooth covering at the ends of bones which allows joints to glide smoothly. Normal pain-free joint function depends on a smooth cartilage surface of consistent thickness with a strong supporting plate of bone underneath, known as the subchondral bone plate. Failure of the developmental process leads to a disturbance in the formation of joint cartilage and the bone supporting it. The resultant cartilage and subchondral bone is irregular in thickness and weaker than in normally developing areas. There may be a loss of blood supply and necrosis of the abnormal tissue. Forces placed on these abnormal areas when the horse ambulates may cause further damage to the abnormal tissue. This can lead to several problems which are recognized as OCD, including local detachment and fracture of cartilage and bone. These detached areas may remain partially attached to the surrounding tissue, which then exist as loose flaps of tissue, or may become completely detached, resulting in free-floating islands which can travel throughout the joint. These loose flaps and islands of abnormal cartilage and bone can cause inflammation in the joint, and over time may cause damage to the normal cartilage.
Causes and Risk Factors
Several causes of OCD are known, although the disease is generally considered to be multifactorial. As a result, the disease is not usually caused by any one factor, but rather a combination of several factors acting together. These known factors include:
*Rapid growth and large body size: An unusually rapid phase of growth and/or growth to a large size can be associated with OCD formation.
*Nutrition: Diets that are very high in energy or have an imbalance in trace minerals, low-copper diets in particular, can lead to OCD formation.
*Genetics: Risk of OCD may also be partially inherited, although the mode of inheritance is not well defined and other factors are often required before an OCD fragment forms. Genetics can also be responsible for the horse’s response to the other factors presented here, as well as rate of body growth.
*Hormonal imbalances: Imbalance in certain hormones during development, including insulin and thyroid hormones, can encourage OCD formation.
*Trauma and exercise: Trauma to a joint, including routine exercise, is often involved in formation and loosening of the OCD flap or fragment.
Incidence and Prevalence
Since all these factors are involved in a complex series of interactions it is not possible to predict which horses will develop OCD, and is therefore difficult to prevent the formation of OCD in individual animals. Clinical prevalence of OCD is usually between 5 and 25% in a given horse population, but radiographic signs of abnormal development can be as high as 60% in certain groups (Wittwer et al. J Vet Med A Physiol Pathol Clin Med 2006).
Signs and Symptoms
OCD may be detected as early as 5 months of age, or as late as skeletal maturity (approximately 3 years of age). However, in young horses, it is recommended that the final diagnosis should be made when the horse is about 1 year of age. The most common sign of OCD is effusion (swelling) in the joint of a young horse. Often, the joint swelling is first noticed shortly after the horse begins a formal training and exercise program. Depending on the location and severity of the OCD, the horse may be noticeably lame on the leg, may only be lame during high-speed work, or may not have detectable lameness at all. OCD can occur in virtually all joints, however there are several joints which are affected much more commonly. The most commonly involved joints are the hock, the stifle, and the fetlock. The shoulder can also be involved, although this is seen with less frequency in horses.
Prevention of OCD can be difficult due to the multifactorial nature of the disease. Owners should try to develop a balanced feeding program with a goal of providing proper trace mineral amounts and preventing excessive growth rates. Consultation with a veterinarian and laboratory feed evaluation may be necessary. Although understanding of the role of genetics in the development of OCD is still incomplete, more information concerning this factor will likely be forthcoming in the coming years.
OCD is best treated by surgical removal of the abnormal bone and cartilage in most cases. A veterinary surgeon can make specific recommendations about treatment. The most common technique used for surgical removal of OCD fragments is arthroscopy. Arthroscopic removal is usually preferable to arthrotomy (an open joint approach), since skin incisions are small, less surgical trauma is caused, post-surgical recovery time may be reduced, and a more thorough exploration of the joint can be performed at the time of surgery. Arthroscopic OCD fragment removal usually requires general anesthesia. The surgeon makes two or more small incisions into the joint through which an arthroscope is placed to visualize the joint and instruments are introduced to remove the OCD fragments.
Surgical aftercare recommendations depend on the location and severity of the OCD but typically involve a period of rest followed by progressive exercise. Full return to training may require several months. Postoperative bandaging will be required for some OCD locations. Medication may be prescribed, including anti-inflammatory medications. A recheck examination and suture removal may also be required. It is important to understand the aftercare requirements before committing to surgery. Specific recommendations are made by the surgeon for each case.
Following proper treatment, prognosis for athletic function is good to excellent for many types of OCD. Some OCD locations, such as the shoulder, may have a reduced prognosis. It is important to discuss the expected outcome, including appearance of the operated joint, with the surgeon during treatment selection.
Thought 4the day: Not so long ago one of our horses was taken back from the home they were at in a poor state. (We won't mention names etc). Things took a turn for the worst when an abnormal bone growth started to form on her head and the only way to describe how they would end up was like the elephant man. A knock/trauma would of started this and it didn't seem to want to stop growing. With help ...from the vet, medications and a great friend the horse in question was allowed out for the first time yesterday in a long time and my god they exploded and cavorted around in a true baby like style!!! The swelling is subsiding in some places but not in one but in time if it carries on the way things are going things should improve some more. We thought at one point we might have to put this horse to sleep as there vision etc was becoming impaired and they did stop eating but now weight is near perfect!! The thought is never give up. Even if things don't go the way they should as they don't always do this (we learnt this lesson with a home but we do checks for this reason even if you think we haven't been in months we have!) carry on as you will get there!!!