An ovariohysterectomy, or spay, is the surgical process by which the entire female reproductive tract is removed; this includes the uterus, uterine horns, ovaries and oviducts. Although there are some health benefits that have been reported by having this process done, there are also negative side effects associated with spaying a dog.
Bone Cancer (Osteosarcoma)
Osteosarcoma, or bone cancer, is a common cancer in dogs of larger breeds with a poor prognosis. The National Animal Interest Alliance (NAIA) states that if spaying is completed before the dog is one year of age, this significantly increases the risk of developing bone cancer. According to Cancer Epideiology, Biomarkers & Prevention, the incidence rate of osteosarcoma in female dogs that were spayed before the age of one was three times greater than the rate of female dogs that were sexually intact. Treatment options for dogs suffering from osteosarcoma include amputation, neurostimulation, acupuncture and chiropractic medication and palliative radiation.
Dogs are more likely to be overweight if they have been spayed or neutered; the NAIA also states that female dogs that have been spayed are twice as likely to become obese in comparison to female dogs that are sexually intact. Obesity then brings additional health problem in dogs including oral disease, hypothyroidism, lower urinary tract disease and even diabetes mellitus.
Adverse Vaccine Reactions
When a dog has an adverse reaction to a vaccine, this includes allergic reactions, cardiac arrest, hives, cardiovascular shock and sudden death. When a female dog is spayed, this removes the organs that produce the hormones that are necessary in producing an immune response to the actual vaccination. The NAIA reports that female dogs who have been spayed are 30 percent more likely to have an adverse reaction to a vaccine.