2016 Miniature Horse WORLD Issues Summer- E-Magazine | Page 18

Does Gelding Affect Growth ?

Q : Is there any loss of body size or

development from early gelding ? One of our local veterinarians will not geld before the horse is at least one year old . I have a 7 year old who was gelded prior to weaning and is the same size as his fully grown genetic siblings . I thought that early gelding was proven to be no problem and that waiting for them to mature was an old wives ’ tale .

A : The age at which a stallion is castrated

depends on many factors , but managerial convenience usually is the determining factor . Most stallions are castrated shortly after they reach puberty , when the owner finds their masculine behavior to be intolerable . The effect that castration and its timing have on behavior ; physical appearance , and the incidence of various diseases has been studied extensively in cats and dogs , but the same is not true of horses .
Studies on cattle and goats have shown that early castration prolongs growth because castration delays closure of the long bone growth plates . The same may be true of stallions castrated before puberty or at least before the long bone growth plates have closed . The age at which colts reach puberty varies considerably between and within breeds . One study found that the mean age at which Quarter Horse colts reached puberty ranged between 55 and 101 weeks . The growth plates of the long bones that have the most influence on the horses growth close at various time and these times vary among breeds . In another study , growth from distal ( bottom ) end of the cannon bones and pasterns of Thoroughbred-Quarter horse crosses ceased when the horses were 10 weeks old , but growth from the distal end of radius ( forearm bone ) was continuous , though declining , until the horses were about 60 weeks old . Castrating a horse before growth from the distal aspect of the radius or tibia ( the long bone above the hock ) begins to slow is likely to increase his height , but whether this increase is likely to be substantial is unknown .
James Schumacher , DVM , Dipl . ACVS- Professor , Large Animal Clinical Sciences University of Tennessee
Courtesy of TheHorse . com
16 Miniature Horse World SUMMER 2016