clinical and behavioral signs (McEntee 2002). These signs may include a painful abdomen, which may be due to ascites, pressure from the tumor on other organs, and/or discomfort if the tumor is large. The bitch may also be anorectic, appear constipated, urinate frequently, or show signs of discomfort when lying down due to the physical size of the tumor putting pressure on other organs.
4.8.1.8 Ovarian Remnant
Ovarian remnant syndrome occurs when some ovarian tissue is inadvertently left behind during ovariohysterectomy or ovariectomy and is characterized by signs typical of an animal that still has ovarian function (Miller 1995; Ball et al. 2010). Behaviorally, signs of estrus may be seen, as mentioned previously. In addition, signs of pyometritis may be present (Ball et al. 2010).
4.8.2 Male Canine
4.8.2.1 Prostatic Disease
The prostate is an accessory sex gland in the male dog. Its primary purpose is to produce fluids to transport and support sperm. It is located caudal to the bladder and generally can be palpated rectally on the pelvic floor if it is not enlarged. There are many diseases that affect the prostate, and most can result in the behavioral changes mentioned below. The most common of these diseases include benign prostatic hyperplasia (BPH), prostatic cysts, and prostatic tumors.
When the prostate is enlarged, regardless of etiology, its location can result in several behavioral changes. A slight increase in size may put pressure on the colon, resulting in tenesmus. This may be confused with constipation or diarrhea because the consistency of the feces may vary. As the prostate continues to enlarge, it may also put pressure on the urethra, resulting in incomplete bladder emptying. Dogs may strain to urinate, urinate frequently, or have a smaller stream of urine. They may also be uncomfortable lifting their leg to urinate, and thus may assume the typical male puppy stance for urination: standing in a sawhorse position with the hips lowered and the rear legs extended caudally. The urine may have some blood in it as well. In addition, the abdomen may be painful, causing the dog to be very uncomfortable. He may show reluctance to lie down or lie down cautiously, similar to a dog with painful joints. Depending on the etiology, if there is a discharge, the dog may lick his prepuce more often.
4.8.2.2 Cryptorchid Testis
The testicles in dogs typically descend into the scrotal sac before six months of age (Gier and Marion 1970), prior to closure of the inguinal ring (Kustritz 2009). Some males will have one (unilateral or mono cryptorchid) or both testicles (bilateral cryptorchid) that have not descended into the scrotal sac. The retained testicle still produces testosterone, but because it is located internally, the sperm are commonly non‐viable. Some may mistake these males for being neutered (Reif et al. 1979). However, because they are still under the influence of testosterone, their behaviors are similar to those of any other intact male dog. There is a significantly higher risk of testicular tumors in dogs with retained testicles that have not been neutered (Hayes et al. 1985; Hayes and Pendergrass 1976).
4.8.2.3 Testicular Tumors
Testicular tumors may result in scrotal, inguinal, or abdominal enlargement, depending on the location of the testes. The size of the mass and the location will dictate any behavior changes that occur. Signs may include a stilted gait with the rear legs, difficulty sitting or reluctance to sit, and discomfort lying down. If the tumor is large enough where the testicle touches the ground when sitting or lying, it may become abraded, resulting in excessive licking to the area. Likewise, if the increase in size causes discomfort, excessive licking is a likely consequence.
Sertoli cell tumors are common in older dogs (Weaver 1983) and result in several behavioral and medical changes (Lipowitz et al. 1973). These tumors tend to secrete estrogen, so male dogs will undergo feminization. Externally, changes include mammary development, alopecia, and testicular and penile atrophy. Internally, there may be bone marrow suppression (Sherding et al. 1981). Behaviorally, Sertoli cell tumors are characterized by decreased libido and the compromised bone marrow results in an increase in infections, fever, anemia, weakness, and lethargy. These signs in a supposedly castrated male may indicate that he was a cryptorchid that was not bilaterally castrated.
Interstitial cell tumors and seminomas also affect the testes, although their resultant change in behavior is generally related to the size of the tumor, as described earlier. Excessive licking of the perianal area (due to the development of perianal adenomas) or enlargement of the inguinal area may be associated with hormonal imbalance.
4.8.3 Normal Sex‐Related Behaviors
4.8.3.1 Marking
Urine marking is a natural behavior for both male and female dogs. Intact males typically mark more than intact females (Pal 2003). Neutering males has been shown to significantly decrease marking in most males (Neilson et al. 1997). Intact and spayed females appear to mark at about the same frequency (Wirant et al. 2004). The intact male will preferentially mark over the urine of an estrus female more than any other urine (Lisberg and Snowdon 2011).
When female dogs urine mark, they may squat, slightly elevate a rear leg while squatting, or alternate between legs while squatting. Just as leg lifting for urination can be a normal variation for female dogs, the squatting position is a normal variation of urination behavior for some male dogs. All of these are normal postures. When a urinary stance is atypical for a particular sex, it is not necessarily reflective of any disease, dysfunction, or abnormality. However, if the urinary stance is atypical for that individual, further investigation to identify underlying medical problems is indicated.
4.8.3.2 Non‐copulatory Mounting
Non‐copulatory mounting is a normal behavior for both male and female dogs. Young dogs often mount during play. In adults, it is more common in the intact male. The behavior in neutered animals is more likely to be a sign of anxiety or conflict (Luescher and Reisner 2008) than sexual in nature. However, anxiety due to other causes may be involved in some cases. If mounting behavior is increasing in the shelter situation, it is important to identify specific triggers and/or motivation if possible. Assessing the anxiety level of the animal being mounted is critical as well, as some dogs respond aggressively to this behavior. A dog that is frequently mounted by other dogs, regardless of the reason, may suffer poor welfare.
4.8.3.3 Masturbation
Masturbation is a normal behavior of both male and female, neutered, and sexually intact animals. It becomes pathological when the behavior is performed to the exclusion of other normal behaviors, such as eating, drinking, and environmental investigation. Frequent masturbation can also lead to an increased incidence of infection or trauma to the prepuce, penis, or vulva.
4.8.4 Effects of Gonadectomy on the Behavior of Dogs
The behavior of gonadectomized male dogs is similar to that of an anestrus female. Early studies indicated that castration of male dogs results in a reduction of sexually dimorphic behaviors, such as mounting, urine marking, roaming, and aggression directed toward other intact male dogs (Hopkins et al. 1976; Neilson et al. 1997). However, it should be noted that in these two studies the behaviors were only reduced in some dogs; none of the objectionable behaviors were completely eliminated. A more recent survey that included more than 9,000 dogs found that urine marking was the only behavior less likely to occur in the castrated dog (McGreevy et al. 2018). This study also found that behaviors relating to fear and aggression were less likely to occur the longer the dog remained
