Intervertebral disc disease (IVDD) in the dog is a common clinical disorder manifested by pain, a partial loss of limb function, paralysis, and sometimes a loss of feeling in the hind limbs. IVDD can occur in the neck (cervical) area, the middle of the back (thoraco–lumbar region) or in the lower (lumbosacral) region of the back. It occurs most frequently in the dwarf (chondrodystrophic) breeds such as the Dachshund, Pekingese, Shih Tzu, Corgi, Basset Hound or American Cocker Spaniel. IVDD can also occur in other breeds such as the German Shepherd, Labrador Retriever and many others.
In an all breed analysis, neutered male dogs had elevated risk for intervertebral disc disease (IVDD).183 A recently published retrospective analysis demonstrated a correlation between early neutering/spaying (<12 months of age) and risk of intervertebral disc herniation (IVDH) in dachshunds of both sexes.185
Drawing from the “Canine-human connection“, studies show us that bone loss accelerates when women lack adequate estrogen and men lack adequate testosterone. Estrogen deficiency has been well studied in women and is known to be a risk factor for degenerative disc disease and osteopenia/osteoporosis. In 1995, a women’s study found the incidence of degenerative lumbar spondylolisthesis was about three times higher in women with a history of ovariectomy (ovary removal), compared with age-matched control subjects who did not undergo ovariectomy.186 In men, the best comparison for neutered male dogs is the unusual circumstance where a human male has had his testes removed for medical concerns. Male patients with testes removed had higher rates of osteoporosis and osteopenia compared to population controls. Low testosterone levels in these patients were significantly associated with lower bone mineral density, a risk factor for bony fractures.189
In more recent research, studies have focused on understanding the mechanism/s by which this degeneration occurs. In a recent study of ovariectomized rats, estrogen and parathyroid hormone supplementation improved osteoporosis and retarded the progression of lumbar intervertebral disc degeneration. The underlying mechanisms involve nutrient supply disorders, cell type changes (a decrease in notochord cells and an increase in chondrocyte-like cells), matrix degradation and reduced Wnt/β-catenin pathway activity, the specifics of which remain unclear.187
Dachshunds are particularly noted for IVDD diagnosis and it is important to note spay/neuter is a documented risk factor for the condition. The authors of this study suggest that considering the high prevalence, morbidity and mortality of IVDD progressing to disc herniation (IVDH) in dachshunds, increased IVDH risk associated with spay/neuter is a key factor to consider in deciding whether and when to spay or neuter.185
Realistically, from our perspective, considering the downside of IVDD and IVDH in dachshunds and all other susceptible breeds, the decision to avoid spay/neuter and sterilize your dog in a manner that spares their hormones (tubal ligation or vasectomy) should be preferable.