Lymphoma and Intact Female Large Mixed Breed Dogs

We failed to find a significant difference in the incidences of lymphoma, mast cell tumor, osteosarcoma and hemangiosarcoma in intact versus neutered groups. We also failed to find differences in the occurrences of lymphoma, mast cell tumor, osteosarcoma and hemangiosarcoma for each age group. Introduction In the United States, neutering, both spay and castration, are highly recommended by many organizations. In fact, 83 percent of dogs are neutered (Trevejo, Rosalie, Mingyin, & Elizabeth 900), and this trend is increasing. Moreover, early-age neutering has increased because it is highly recommended to neuter dogs before they experience their first heat, especially to decrease the levels of gonadal hormones (Salmeri, et al. Another cancer of concern is the mast cell tumor (MCT), the most popular cancer in canines.

Although many studies observed no gender predilection,for the same gender, neutered females showed a higher frequency than intact females (Monteiro, Beatriz, Sarah Boston, & Gabrielle; White, et al. Two studies on osteosarcoma (OSA) have suggested neutering to be a risk factor as neutered dogs developed this cancer at a higher rate than intact dogs (Ru, Terracini, & Glickman 1998). Moreover, Rottweilers neutered prior to 1 year were 3 to 4 times more at risk than intact Rottweilers (Cooley et al. Another tumor associated with female neutering is hemangiosarcoma (HSA). Methods and Materials Data was collected from Veterinary Medical Teaching Hospital (VMTH) of University of California, Davis’s patient records in the Veterinary Medical & Administrative Computer System (VMACS). Patient records for large (30 – 39 kilograms) female mixed breed dogs between the ages of 1 year and 12 years that visited the VMTH between January 1, 1995 to July 1, 2014 were analyzed.

These criteria were required for inclusion in this study. Neuter Data Collection We collected data for both intact female dogs and neutered female dogs for this study. We recorded the neuter date or age at neutering for each patient. Even if the dog was neutered, if the onset of the tumor was earlier than the age of neuter, the dog was considered intact for the purpose disease calculations. If the date of onset of the tumor was before 01 January 1995 or before the patient was one year of age (<365 days), the dog was excluded from an individual disease calculation. Statistical Analysis Out of 187 cases, 44 were intact and 143 were neutered. We used this data set to determine, at the onset of disease, how many were intact and how many were neutered.

The intact and neutered total may vary because some cases were excluded from the disease analysis during data clean up. Each row represents intact dogs and different neuter age group from <6 months, 6-11 months, 1 year, and 2 to 8 years. The number of diagnosed cases is shown, divided by the total number in that age sub-group, with percentages given in parentheses. We documented the occurrences of lymphoma as well as mast cell cancers in both intact and neutered groups. In the intact group, osteosarcoma and hemangiosarcoma had zero occurrences. As for lymphoma, although intact group showed the highest occurrence, 9. 1% occurrence, MCT and HAS both had 6. 3% occurrence, and zero occurrence for HSA. At the neuter age of two to eight years, there were no significant results as LSA, MCT and OSA had occurrences of 2.

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