What Are the Causes of Heat Symptoms in a Spayed Dog?

Spaying, the removal of a female dog's uterus and ovaries, is recommended to owners who have no wish for their dog to breed and produce a litter. The earlier this is done the more it reduces the risk of her suffering health problems in later life. Spaying also prevents uterine infections like pyometra and metritis. However, it is not unknown for a spayed bitch to exhibit heat symptoms, encouraging males to try to mate with her. Several causes are possible.

  1. Ovarian Remnant Syndrome

    • Although the dog cannot become pregnant after spaying, owing to the removal of the uterus, in irregular situations some of the ovarian tissue may remain in the abdomen when the vet ligates (ties off) the blood vessels that attach the ovaries to the uterus and the rest of the body. It may be that the tissue is too small to see at the time of surgery or that a small piece of the ovary is accidentally dropped back in as it is removed. Once it grows it can interact with the brain to form hormones, which cause the remaining tissue to bleed and swell, leading to the heat cycle. Once the ovarian tissue is more visible (usually during heat) it can be removed by the vet.

    Vaginal Infection

    • A dog may display some of the symptoms of estrus (heat) if she has cystitis, a bladder infection. The signs are likely to be the bleeding and swelling of the vulva-the external opening to the vagina-causing the dog to lick the genital area, and increasing, possibly bloody, urination. It can be prevented and treated by routine cleaning and further swelling can be limited by antibiotics or probiotics.

    Dominance Display

    • Dog owners commonly confuse a bitch asserting her dominance for a signal that she is in heat. Spaying will reduce the dog's humping instincts but won't eradicate them because they are not dictated by the sexual hormones. They are almost as likely to arise from boredom or anxiety. It has in fact been suggested that females become more aggressive once spayed because they have had the progesterone hormone removed, which raises serotonin. Whatever the cause of such behavior, an owner must manifest his superiority over the canine to convey that he is "top dog."