Neutering Dogs: Effects on Joint Disorders and Cancers in Golden Retrievers

Abstract

In contrast to European countries, the overwhelming majority of dogs in the U.S. are neutered (including spaying), usually done before one year of age. Given the importance of gonadal hormones in growth and development, this cultural contrast invites an analysis of the multiple organ systems that may be adversely affected by neutering. Using a single breed-specific dataset, the objective was to examine the variables of gender and age at the time of neutering versus leaving dogs gonadally intact, on all diseases occurring with sufficient frequency for statistical analyses. Given its popularity and vulnerability to various cancers and joint disorders, the Golden Retriever was chosen for this study. Veterinary hospital records of 759 client-owned, intact and neutered female and male dogs, 1–8 years old, were examined for diagnoses of hip dysplasia (HD), cranial cruciate ligament tear (CCL), lymphosarcoma (LSA), hemangiosarcoma (HSA), and mast cell tumor (MCT). Patients were classified as intact, or neutered early (<12 mo) or late (≥12 mo). Statistical analyses involved survival analyses and incidence rate comparisons. Outcomes at the 5 percent level of significance are reported. Of early-neutered males, 10 percent were diagnosed with HD, double the occurrence in intact males. There were no cases of CCL diagnosed in intact males or females, but in early-neutered males and females the occurrences were 5 percent and 8 percent, respectively. Almost 10 percent of early-neutered males were diagnosed with LSA, 3 times more than intact males. The percentage of HSA cases in late-neutered females (about 8 percent) was 4 times more than intact and early-neutered females. There were no cases of MCT in intact females, but the occurrence was nearly 6 percent in late-neutered females. The results have health implications for Golden Retriever companion and service dogs, and for oncologists using dogs as models of cancers that occur in humans.

The Social Behaviour of Neutered Male Dogs Compared to Intact Dogs (Canis Lupus Familiaris): Video Analyses, Questionnaires and Case Studies

“…1,2 There are always controversial discussions about neutering dogs, since such an intervention implicates both advantages and disadvantages. Beside several health effects such as an increased risk for cancer, many behavioural changes such as excessive barking and increased anxiety can occur, as shown in a study of castrated Vizslas.…”

“…A study on Golden retrievers 2 as well as one reviewing the cause of death for over 40,000 neutered and intact dogs 8 present similar results, stating that neutered dogs have an increased risk for several types of cancer. Apart from cancer, neutering has also been shown to correlate with an increased rate of autoimmune diseases and other diseases such as joint disorders (hip dysplasia and cranial cruciate ligament tear; 2,9 and dermatological conditions such as a change in coat or fur quality). 10 Adult male dogs are often castrated with the aim to remove undesirable behaviour such as mounting, roaming, aggressiveness and urine marking.…”

A literature review on the welfare implications of gonadectomy of dogs

“…Depending on the study, early gonadectomy can be defined in a variety of ways, including surgery prior to 5.5 months of age 3,4 or before 1 year of age. [5][6][7] Age at gonadectomy was unavailable for other studies [8][9][10] that differentiated only between sexually intact and neutered dogs.…”

“…11 Contrary to the association between neoplasia and gonadectomy in Golden Retrievers, there is not a significant correlation between neutering male or female Labrador Retrievers or German Shepherd Dogs at any age and the development of several neoplasms (lymphosarcoma, hemangiosarcoma, or mast cell tumor). 5,6,14 Further research focusing on specific breeds and also on broader groups of dogs will be important for making recommendations about individual patients. Currently, it is important to acknowledge the large role that genetics and breed play in disease processes when developing recommendations.…”

“…16,21,25,29,30,34,35 These reports are supported by more recent breed-specific literature. In a retrospective study 5 conducted to evaluate Golden Retrievers and the follow-up study 6 conducted to compare results for Golden Retrievers and Labrador Retrievers, extremely few dogs had mammary gland neoplasia regardless of neuter status. This could have been affected by the age of patients included in the studies because the mean age for development of malignant mammary gland tumors is approximately 9 to 11 years, 11,24,28,35 and the 2 aforementioned studies 5,6 only included patients up to 8 years of age.…”