Spaying and neutering can lead to long-term health problems in dogs. A recent review article summarizes these problems and illuminates the role of luteinizing hormone (LH).
Ovaries and testes — the gonads — produce hormones such as estrogen and testosterone. Research has shown that removal of the gonads through spaying and neutering is associated with an increased risk of several long-term health problems including obesity, urinary incontinence, bladder stones, hypothyroidism, diabetes mellitus, hip dysplasia, cruciate ligament rupture, behavioral changes (including owner-directed aggression and fear), cognition problems, as well as several forms of cancer (including leukemia, prostate cancer, bone cancer, skin cancer, splenic cancer, and bladder cancer).
In this review article, renowned veterinary theriogenologist Dr. Michelle Kutzler of Oregon State University explains that removal of the gonads prevents the feedback of estrogen and testosterone on the pituitary and hypothalamus. As a result, LH is continuously elevated. There are LH receptors in many parts of the body, and their over-exposure to LH may be related to the significant negative health effects that can result from traditional spay and neuter surgery.
All dog owners should understand the impact of hormone loss due to spaying and neutering, which can vary depending on the age, breed, sex, and size of the dog. Hormone-sparing sterilization is an option to maintain normal hormone levels while preventing pregnancy. See our pages on ovary-sparing spay and hormone-sparing male sterilization.