For most bitches kept as companions, spaying at a young age is a smart choice. But spaying a young bitch may not be an option when she is going to be used for breeding, and some owners elect not to spay their bitches even though they don’t plan to breed them.
Older intact bitches are subject to several health problems that spayed bitches, especially those spayed young, are not.
Pyometra, a potentially fatal infection of the uterus, is probably the most serious health problem that can affect unspayed bitches. Its incidence increases with age beginning at around 4 years. One study in a Beagle colony found the mean age of infection was 9.4 years (1). Another study, based on insurance data in Sweden, showed that 23 percent of all bitches developed pyometra before the age of 10 years (2). Spaying is the treatment of choice, but some dogs still die from overwhelming infection.
Hydrometra, mucometra and hemametra are conditions in which sterile fluid, mucus or blood accumulates in the uterus. Although uncommon, they are more likely to occur in older, intact bitches. Spaying is the treatment of choice. The prognosis is usually excellent, except for hemametra (blood accumulation) in which blood loss and anemia may be life threatening.
Uterine cancer is uncommon in dogs, but is more likely in intact bitches 10 years of age and older. Most tumors are benign. Spaying is the treatment of choice.
Ovarian cancer is also uncommon in dogs. With the exception of one type, teratomas, it is more common in older bitches. About a third of ovarian tumors will spread locally; fortunately, the prognosis is good, with spaying usually fixing the problem.
Mammary cancer is not uncommon in bitches. The average age at diagnosis is 10 years. Some mammary tumors are benign, others malignant. Surgical removal is the treatment of choice, with radiation or chemotherapy for malignant cases. Bitches that were overweight when young, and that have eaten homemade diets high in beef and pork, appear to be at greater risk (3). Spaying a bitch before her first heat is the single best prevention; spaying before her second heat also has a significant effect. It was long thought that the protective effect of spaying was lost after four heat cycles or by 21/2 years of age, but a recent study suggests that some slight protection is afforded at any age, even when spayed at 9 years (4).
Because any surgery is more difficult in older dogs, the message is simple: If you no longer plan to breed your bitch, spay her now.
1. Fakuda S: Incidence of pyometra in colony raised beagle dogs. Exp Anim 2001; 50: 325-328.
2. Hagman R: New aspects of canine pyometra. Doctoral thesis, Swedish University of
Agricultural Sciences, Uppsala, 2004.
3. Pérez A, Rutteman GR, Peña L, Beynen AC, Cuesta P. Relation between habitual diet and canine mammary tumors in a case-control study. J Vet Intern Med. 1998 May-Jun;12(3):132-9.
4. Sorenmo, K; Shofer, F; Goldschmidt, M: Effect of Spaying and Timing of Spaying on Survival of Dogs with Mammary Carcinoma. Journal of Veterinary Internal Medicine. Volume 14 Issue 3, Pages 266 – 270.
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