New Osteochondrosis Report from ANCCE

Basic concepts and recommendations about Osteochondrosis, elaborated by the ANCCE radiological consultants under the leadership of Dr Manuel Novales Vasco at the University of Cordoba Veterinarian Hospitalpv1nodum@ucoes

INTRODUCTION

Concept of the disease Osteochondrosis is a disease that produces a failure in the normal ossification of joints in horses, which gives way to the accumulation of synovial fluid causing esthetic defects, pain, and, in some cases, lameness In general, this problem appears in the locomotive system of the horse, but it is especially located in the hocks, fetlocks and stifles The disease may appear during the first months of life in which case, there may be spontaneous recovery and stabilize after the first year The symptoms can be detected either while the horse is young or after it has reached adulthood In Holland, a country that has traditionally studied this disease, it has been calculated that some 3,000 or 25% of all foals born foals are born annually with osteochondrosis This represents an estimated ten million euros a year in economic costs This disease is included within the group of growth diseases found in foals generically called Developmental Orthopedic Diseases Other diseases included in this group are subchonral bone cysts, angular limb and flexing deformities, spyphysitis and the Wobbler syndrome which affects cervical vertebras and causes a lack of coordinated movement in animals The following are among the causes of osteochondrosis: genetic pre-disposition this accounts for up to 25% of the causes behind the disease, bio-mechanical traumas, mechanical stress due to inappropriate exercise, obesity, excessively fast growth and imbalanced or inappropriate nutrition One or several of these factors combined can produce the disease Both environmental factors and the way in which a horse is handled are determining factors for a foal to finally develop the disease

Phases in controlling the disease in Spain

In Spain, controlling the disease among PRE horses is divided into three phases:

1. 2003-2006 A number of radiological studies were performed without having defined where and how the disease was to be detected Even after having studied 1,500 horses, the desired results were not attained
2. 2007 An Interpretation Center was created in order to standardize the quality of the studies undertaken and the diagnostic criteria for the disease In the 2007 season, the following studies were performed utilizing a total of 335 horses, 50 of which had not been approved

The results by country were as follows:

The Interpretation Center declared that 142% of the horses studied had not been approved

• 3 2008 Having analyzed the results of the previous season, and followinginternational recommendations, only those horses with serious signs of the disease evident in X-rays were eliminated With this in mind, degrees of injuries were established, based upon gravity Prior to beginning the season, all the horses eliminated during the 2007 season were reviewed, and breeders were informed whether their horses were considered acceptable in this system

Moreover, instructions were given to the veterinarians who review the horses based on the new classification criteria The horses that were not sent to the Interpretation Center in the 2007 season can now be sent, if the vets consider that these horses could be approved under the new classification criteria The University of Cordoba Veterinary Hospital website wwwucoes/corporacion/hcv/ offers complete information about the diagnostic criteria for this disease and the work undertaken during the 2007 season

Basic norms to control the disease at stud farms

Once the disease has been detected at a stud farm, it is good to keep the following concepts in mind: It is a good idea to check all young horses, stallions, mares and their descendents For this, vets usually perform a clinical inspection seeking lameness or the accumulation of fluid in joints and give advice about basic X-ray studies for the risk groups at each stud farm This type of study can be performed on yearlings when the injury is stable, thus diagnosing the disease in its early stages The study of a foal’s ancestors facilitates discovering the genetic causes of the disease on the affected stud farms Stud farm nutrition must be checked, especially the amount of calories consumed by the colts/fillies, caloric sources and mineral imbalances, among others One of the most common problems in young horses is the excessive amount of substances ingested, which causes accelerated growth or fattens the horses subject to these practices Both situations may contribute to the appearance of Developmental Orthopedic Diseases A four year study published in 1996 in the US by Dr Joe Pagan 1996 evaluating thepresence of OCD in fetlock, hock, stifle and back reached the following conclusions:

1. The horses that developed osteochondrosis in the hock and stifle tended to belarger foals at birth, and grew quickly between three and eight months of age
2. Horses that develop OCD in the fetlocks have normal growth rate the first 110 days, but grow much master than the rest of the population later

From this, it can be deduced that excessive body weight and fast growth were the main factors to be taken into consideration in controlling the disease Not only must the amount of calories be controlled, but also the relationship among the various minerals; care must be given not to give excessive phosphorus Another study indicates that the importance of the relationship between copper and zinc, especially in the case of pregnant mares and while the foal is growing, as imbalances in these two minerals could pre-dispose the horse toward these diseases Harris,2005 Dr Pat Harris 2005, a world-renowned specialist in equine nutrition, provided the following recommendations for reducing the incidence of Developmental Orthopedic Diseases, including osteochondrosis, in stud farms:

1. Try to get foals to increase their size and body weight slowly
2. Avoid foals growing too quickly
3. Avoid sudden growth after a period of apparent lack of growth
4. Avoid foals getting too fat

There are two very basic conclusions about nutrition and its effect on DevelopmentalOrthopedic Diseases given by two major world experts in nutrition:

1. Even though the mare and foal have been provided the appropriate nutrition during pregnancy and lactation, there is no guarantee that adult horses will be healthy and able to compete; there is evidence that, in the medium and long-term, proper nutrition will help reduce the risk of suffering problems and diseases Harris, 2005
2. Once a foal has developed osteochondrosis to such an extent that the clinical signs and symptoms can be identified, diet has a minimal effect on solving existent injuries However, it is recommended to reduce caloric intake and avoid excessive body weight while maintaining an adequate amount of proteins and minerals Pagan, 2003

One last factor to keep in mind is controlling exercise during the first year As a general rule, it could be said that the level of exercise in foals is logically important in maintaining the quality of its cartilage, joints and bones McIlwraith, 2005 To date, there is contradictory data about the level of exercise that can be performed Studies in Holland Van Weeren & Bravenveld, 1999 conclude that while exercise does not influence the number of injuries that appear, there is a tendency for these injuries to be more serious in colts/fillies that rest in stalls The exact amount of exercise that PRE colts and fillies need to protect them against the appearance of osteochondrosis is still unknown, but it is certain that if colts and fillies spend a limited amount of time in stables during their first year, and if they are free to exercise at will, this will contribute to preventing the disease download full pdf BIBLIOGRAPHY

Harris PA Hints on nutrition for optimal growth In: Harris PA, Hill SJ and Abeyasekere LA editors Proceedings of the 1st Waltham International Breeding Symposium Newmarket England June 2005 p 41-50

McIlwraith CW What are the major problems associated with growth and how important are they really In: Harris PA, Hill SJ, Abeyasekere LA, editors Proceedings of the 1st Waltham International Breeding Symposium Newmarket England June 2005 p 25-31

Pagan JD, Jackson SG The incidence of developmental orthopedic disease on a Kentucky Thoroughbred farm World Equine Vet Rev 1996; 1: p 20-26

Van Weeren PR, Barneveld A The effect of exercise on the distribution andmanifestation of osteochondrotic lesion in the Warmblood foal Equine Vet J Suppl 1999; p 19