Canine reproductive disorders

Transcription

1 Vet Times The website for the veterinary profession Canine reproductive disorders Author : Jennifer Cartwright Categories : RVNs Date : November 1, 2011 Jennifer Cartwright RVN A1, discusses the variety of issues that can lead an owner to ask if their pet should be neutered Summary INpractice, while running our nurse clinics, we are often asked about the benefits of neutering. This is something a nurse should feel confident speaking about, as this will give clients faith in your knowledge and confidence in your practice. It is very stressful for clients to leave their pet with the practice, but if they trust you it makes the experience a little easier for them. This article aims to recap and revise common reproductive disorders in the dog and provide the reader with a better understanding when answering the should I neuter my dog? question. For ease of reading, the article is separated into female and male conditions. Key words neutering, reproduction, prevention, hormonal, congenital Conditions affecting female dogs Follicular cysts This condition is most common in older bitches that have previously had normal seasons. Symptoms. The bitch will tend to have a longer pro-oestrus and a thickened vulval discharge for 1 / 7

2 approximately four weeks afterwards. The season tends to cease due to the lack of luteinising hormone. Diagnosis. Ultrasound is useful, as it will show larger follicles, such as cystic follicles. Cytology of the vagina may be useful, as it will show cornified cells that will not alter at late pro-oestrus. Usually, these cells would not be visible at this stage in the cycle. Blood sampling may show that progesterone levels stay basal, rather than the normal increase. Treatment. Spaying is the treatment of choice, but medical treatment may be necessary first to increase the cyst size, and also to put the bitch in anoestrus. Progesterone drugs can be used to shrink the cysts, but should be used with caution as a pyometra (see later) can be induced. Pseudopregnancy Pseudopregnancy is a very common condition of the entire female that can prove stressful for both dog and owner. The symptoms are usually seen around 10 to 12 weeks after oestrus, and can be caused by the raised plasma prolactin levels or the dog s response to the prolactin. Symptoms. Symptoms include milk production, mammary enlargement, lethargy, aggression, nesting, milky vaginal discharge, anorexia and carrying toys. Occasionally, a pseudopregnancy can be seen in a spayed bitch if she has an ovarian remnant (discussed later in this article) or if she was spayed when her prolactin levels were increased. A dog should not be spayed during a pseudopregnancy, as the bitch may continue to have false pregnancies or it may become a permanent condition. Treatment. Sometimes no treatment is necessary and the pseudopregnancy will resolve spontaneously. A change in the dog s routine can help to break the nesting cycle (such as an increase in exercise). If nesting behaviour is becoming obsessive and causing a problem, antiprolactin agents or reproductive steroids can be used. Antiprolactin drugs may be particularly useful in bitches showing aggression. Spaying bitches when in anoestrus should prevent this problem. Generally, once a bitch starts to have false pregnancies, she will continue to do so at each heat. Ovarian remnant This condition is exactly what it describes. Some ovarian tissue has been left within the animal when spaying, or, in rarer circumstances, some extra ovarian tissue can be found in the ovarian ligament. Symptoms. Animals will show normal signs of being in season, but they tend not to have a vulval discharge. 2 / 7

3 Diagnosis. Blood tests can be performed to show oestrogen levels, but it is cheaper and easier to perform cytology on a vaginal swab while the bitch is in pro-oestrus or oestrus. Plasma progesterone levels can be assessed if signs are seen in the preceding two months. Plasma concentrations of more than 6mmol/L to 9mmol/L indicates luteal tissue is present, and confirms the presence of ovarian tissue. Treatment. An ovariectomy should be performed. While the bitch is receptive to a male, the ovarian tissue will be more visible. However, the risk of haemorrhage is much higher. As previously discussed, if spaying is performed when prolactin levels are high (more than 30 days after ovulation), then a permanent pseudopregnancy can be induced. Spaying two weeks after the male shows an interest is a good compromise. Vaginitis Vaginitis can be a completely normal finding in young bitches more than six months old. Symptoms will usually be seen as a purulent vaginal discharge, but the animal tends to be clinically well. This condition seems to upset owners more than worry the dog, and it tends to spontaneously regress at the first season due to the increase in oestrogen levels. Antibiotics are rarely successful, as the condition tends to be caused by over-secretion from the vaginal glands, rather than infection. Swabs can be taken from adult dogs to assess any infection present. This condition should not be mistaken for a pyometra or pregnancy, and these causes should be ruled out before assuming vaginitis. Vaginitis can be related to various congenital or acquired defects. Vaginal and vulval strictures and constrictions These conditions may never cause a problem, and may go unnoticed unless the bitch is used for breeding. Both can usually be diagnosed with digital palpation. During oestrus, strictures and constrictions may distend to allow mating and, therefore, digital palpation should also be done at this time. Usually these bitches will be unsuitable for breeding as, if mating has been possible at all, whelping problems are common. Therefore, spaying these animals should be performed to prevent other reproductive problems. It is considered unethical to surgically correct these problems. Vaginal tumours Vaginal tumours tend to be benign and are commonly hormone induced. A vulval discharge is usually seen, which may or may not contain blood. Diagnosis can be confirmed with contrast radiographs, or some tumours may be seen with a vaginoscope. Removal with an episiotomy and spaying will usually be curative. Vaginal prolapse/hyperplasia 3 / 7

4 This condition is exaggerated by the presence of oestrogen and is, therefore, commonly seen at oestrus when the vulva swells. Symptoms. Appearance of vaginal wall protruding through the vulva. Treatment. This condition will usually regress after oestrus. Progesterones can be used to accelerate cessation of the condition. It is likely to return at the next oestrus therefore, spaying is recommended to permanently prevent the condition. Ovarian tumours These are uncommon in bitches, but older animals are more susceptible. Ovarian tumours are usually inactive and symptoms usually include a large distended abdomen, ascites and metastasis, rather than hormonal symptoms. If non-malignant and there is no sign of the tumour spreading, spaying can be curative. Pyometra Pyometra is probably the most common reproductive problem seen in bitches, and is potentially lifethreatening. This condition is usually seen in middle-aged dogs that haven t had a litter. The condition occurs when the uterus becomes infected, fills with pus and releases toxins into the circulation. This condition can, therefore, have a serious effect on the rest of the body. Symptoms/history. The bitch will usually be eight weeks post-season, un-neutered (although it can occur in a bitch with an ovarian remnant) and may have been on oestrogen therapy or progesterone therapy. The dog may present with anorexia, appear dull and lethargic, may be collapsed and pyrexic with a distended abdomen, and a purulent discharge may be present, depending on whether the cervix is open or closed. Diagnosis. Haematological changes will show raised white cell counts, which will be higher still if the cervix is closed. Radiography may show an enlarged uterus and displacement of the intestines. Ultrasound is a useful tool in these cases, as the fluid-filled uterus can be visualised. Treatment. The treatment of choice would always be to neuter, as this is not only curative but preventive. The patient should be as stable as possible, but surgery should be performed as soon as possible. Antibiotic therapy should be started immediately, as well as appropriate fluid therapy, dependent on electrolyte results. Post-spay supportive treatment will need to be continued. If raised urea levels are present, tests should be repeated in five to seven days to ensure no permanent damage has occurred. Although an off-licence use of the drug, various literature refer to the progesterone receptor antagonist aglepristone as a treatment for pyometra. It may be useful in patients that are a poor anaesthetic risk or where the bitch is a good candidate for breeding. Some ethical considerations to doing this apply, and it should be stressed the bitch should be spayed 4 / 7

5 once she has had a litter, as the pyometra will most likely recur. Conditions affecting male dogs Most conditions that affect the male dog are of testicular or prostatic origin, although some abnormalities of the penis, prepuce and scrotum can occur. Hypospadia Hypospadia is a congenital condition affecting placement of the urethral opening. Instead of being at the end of the prepuce in its usual position, it can be located anywhere along the prepuce or perineal area. It has been thought this condition can be induced by administering progesterone or oestrogen drugs to a bitch when pregnant. The only treatment for this condition is surgery, but this can be difficult and urethrostomy may be necessary. Testicular tumours These are the second most common type of tumours in the dog, after skin tumours. Cryptorchid animals are more likely to suffer from testicular tumours and there are some breed dispositions. Surgical intervention is required in all cases. Interstitial/Leydig testicular tumours Boxers are commonly affected with this type of tumour, and it is more likely to be seen in older patients. These types of tumour are rarely diagnosed, except at postmortem. The testicles tend to be similar in size, although there may be hard nodules present. Generally, no clinical signs are noted however, there may occasionally be some behavioural changes. Germ cell tumours (seminomas) German shepherds are predisposed to this type of tumour, as are some middle-aged to elderly dogs. Seminomas do not tend to be malignant, and they are more common in cryptorchid dogs. They tend to be unilateral, with one testicle being larger and softer than the other. No other clinical signs are usually seen and the dog will usually be infertile. Sertoli cell tumour Shetland sheepdogs and Weimaraners have the highest incidence of these tumours, and this type is the most significant. They occur at around 10 years of age and more commonly in cryptorchid patients. The testicle tends to be irregular and large, and other clinical signs are seen due to the production of oestrogen. They do not tend to be malignant, but in 10 to 20 per cent of cases they 5 / 7

6 can metastasise to the lumbar spine and iliac lymph nodes. Symptoms. Symptoms include enlarged nipples, penile atrophy, gynecomastia, alopecia and skin hyperpigmentation. Bone marrow suppression may occur due to the increase in oestrogen levels. Balanoposthitis This is inflammation of the penis and/or prepuce that shows as a green/yellow discharge. It is seen in young dogs and, although unsightly and upsetting for the owner, it is not signifi cant. In adult dogs, whether it needs to be treated depends on the cause. Swabs can be taken to determine the type of infection, and flushing with a saline solution can also be helpful. The penis should be assessed for injuries, ulcers, tumours and foreign bodies to ensure these are not the cause. Castration will help to reduce the amount of secretions. Testicular torsion This is a rare condition in dogs but one that should be noted. It can be extremely painful and cause sudden shock, collapse, lethargy, anorexia and scrotal swelling. Castration is indicated, as the condition can recur and it can be fatal. Phimosis This is where the penis cannot extrude from the prepuce. It is usually congenital. Surgery is always necessary, as it can cause dysuria. Paraphimosis Paraphimosis is where the penis cannot retract into the prepuce. It can be caused by a congenital defect, foreign body in the prepuce, fracture of the os penis or trauma. It needs treating quickly, as the prepuce will act as a tourniquet, which can cause severe damage to the penis. Anuria and haematuria can occur and, in rarer circumstances, necrosis and gangrene. Treatment. The penis should be retracted as soon as possible. Alpha-2-adrenergic drugs are useful to relax and lower blood pressure, thus allowing the penis to be manually replaced. Cold water compression can also assist. In some instances, surgical intervention is required to enlarge the prepuce opening. One drawback to this is the opening may result in permanent protrusion of the penis. Prostatic disease Diseases affecting the prostate in the dog are relatively common and can take the form of 6 / 7

7 Powered by TCPDF ( infectious, hormonal, anatomical or embryological issues. Symptoms. These include haematuria, lethargy, pain, pyrexia, inappetence and prostate swelling. In the case of endocrine problems, the prostate may become hard and irregular. Some owners also note locomotor problems, including stiffness and oedema in the legs. Treatment. Castration will be curative in most cases, except for the prostatic tumours discussed below. Prostatic tumours These are rare in dogs and carry a very poor prognosis. The growth is rapid and can occur in animals of any age. Metastasis is common and, at present, there is no satisfactory treatment. Cryptorchidism In general, the dog s testicles will descend into the scrotum soon after birth, but may take as long as four weeks. If both have not descended by the age of 10 weeks, then it can be assumed the dog is cryptorchid. It is extremely rare that a dog will have only one or no testicles. It is very important to castrate a cryptorchid dog, as they are more prone to neoplasia, behavioural problems, fertility problems and an increased risk of spermatic cord torsions. The testicle may be found in one of two positions, either in the inguinum area or in the abdomen. At present, no drug to assist testicular descent is available. Although you may not discuss all of these conditions with clients, this article should provide a general idea of the types of conditions that can occur. Further reading Evans J M and White K (1997). Book of the Bitch, Ringpress. Mullineaux E and Jones M (2007). BSAVA Manual of Practical Veterinary Nursing, BSAVA: Gloucester. Simpson G M, England G C W and Harvey M J (1998). BSAVA Manual of Small Animal Reproduction and Neonatology, BSAVA: Gloucester. Article reviewed by Karen Pearson, BVSc, MRCVS 7 / 7