Diseases of the Reproductive System

Chapter 10 Diseases of the Reproductive System

The female reproductive system consists of two ovaries and the female duct system, including the oviducts, uterus, cervix, vagina, and vulva (Fig. 10-1). The primary functions of this system are to provide eggs for fertilization and to protect the developing embryo during pregnancy. All of these structures are composed of tissue that is sensitive to hormones produced by the female.

Figure 10-1 Female urinary and reproductive organs of bitch (lateral view).

(From Colville T, Bassert JM: Clinical anatomy and physiology for veterinary technicians, St Louis, 2002, Mosby, by permission.)

Hormones such as estrogen and progesterone act on the reproductive system to prepare it for pregnancy and to maintain that pregnancy. When the response to these hormones is abnormal, disease can result. Although not technically a part of the female reproductive system, the mammary glands are also reactive to hormonal abnormalities, and diseases involving them are frequently seen in small-animal practice.

The male reproductive system consists of two testicles and the male duct system, including the urethra, prostate gland, and penis (Fig. 10-2). Other structures often involved with disease processes are the scrotum and the prepuce. The main hormonal influence in the male system is testosterone, although abnormal estrogen levels can also affect the male reproductive system.

Figure 10-2 Male urinary and reproductive organs of dog (lateral view).

(From Colville T, Bassert JM: Clinical anatomy and physiology for veterinary technicians, St Louis, 2002, Mosby, by permission.)

Diseases that involve the reproductive system are frequently seen in veterinary practice. These include vaginal disorders, uterine disorders, pregnancy disorders, lactation disorders, disease of the prostate, and neoplasia of the genital system and mammary glands.

FEMALE REPRODUCTIVE DISEASE

Vaginal Disorders

Vaginitis

Vaginitis is a fairly common occurrence in prepuberal bitches. The most common sign of juvenile (puppy) vaginitis is vulvar discharge. This condition responds well to systemic antibiotic therapy and usually resolves after the first estrous cycle. Adult vaginitis can be the result of a variety of factors. Anatomic abnormalities, bacterial infection, traumatic injuries, or chemical irritation can all result in vaginal inflammation. Viral vaginitis also occurs in conjunction with canine herpesvirus infections.

Pseudopregnancy

Pseudopregnancy is an exaggeration of the normal hormonal changes that occur during the estrous cycle in the nonpregnant bitch. Clinical signs can be related to decreasing levels of progesterone and increasing levels of prolactin. Dogs undergoing pseudopregnancy may exhibit weight gain, mammary gland enlargement, lactation, and a mucoid vaginal discharge. These dogs may carry around stuffed toys and demonstrate increased mothering behavior.

Signs of the pseudopregnancy usually develop 6 to 12 weeks after estrus and may last 1 to 3 weeks. Signs are usually self-limiting. Therapy, when necessary, is usually aimed at decreasing milk production. Therapeutic methods including mild water restriction, diuretics, and preventing oral stimulation by the bitch can be used. Ovariohysterectomy is the only permanent cure for those dogs that exhibit this problem.

Avoid the use of phenothiazine tranquilizers in these animals because they may increase prolactin secretion.

Pyometra

Pyometra is also frequently seen in small-animal medicine. Increasing levels of progesterone after ovulation result in hyperplasia and hypertrophy of the endometrial glands of the uterus. Inappropriate response results in cystic endometrial hyperplasia with accumulation of fluid within the uterine lumen. Progesterone also produces a decrease in myometrial contractions and predisposes the uterus to secondary bacterial infection (pyometra). The most common microorganism isolated in pyometra is Escherichia coli, although Staphylococcus spp., Streptococcus spp., Klebsiella, Pasteurella, Proteus, and Moraxella have also been implicated.

The development of pyometra appears to be the final stage of a continuum beginning with endometrial hyperplasia and progressing through cystic endometrial hyperplasia and endometritis. Animals presented for treatment tend to be middle-aged or older, within 60 days of their last estrous cycle.

CLINICAL SIGNS

• Vulvar discharge

• Abdominal enlargement

• Polyuria/polydipsia

• Dehydration

Pregnancy Disorders

Disorders of pregnancy include fetal death and abortion/reabsorption, dystocia, inappropriate maternal behavior, mastitis, and puerperal tetany. Although other problems are associated with pregnancy and parturition, these are the most commonly seen problems in small-animal medicine. The normal gestation period for the dog and cat is between 62 and 65 days. Fetuses can be palpated about 25 to 36 days after breeding in the dog, and 21 to 28 days in the cat. Fetal skeletal mineralization can be detected radiographically at 45 days gestation. Ultrasonography can provide information on the status of the fetuses after about 20 days. It is difficult to determine the number of fetuses, especially in large litters.

Fetal deaths early in gestation result in reabsorption with no expulsion of uterine contents. Owners may report that the animal has “failed to conceive” after what they consider a successful breeding. Organisms such as Brucella canis, canine herpesvirus, feline infectious peritonitis, feline leukemia virus, and panleukopenia can produce fetal death or abortion.

Dystocia can be defined as difficulty in delivery of fetuses through the birth canal. The causes of dystocia can be divided into fetal factors, maternal factors, and combinations of both. Fetal factors include large fetuses (large puppy or kitten, fetal anasarca, or hydrocephalus) and abnormal positioning (transverse presentation). Breech presentation is not an abnormality in the bitch or queen. Maternal factors include a narrowed birth canal (developmental or trauma related) and uterine inertia (lack of coordinated contractions or exhaustion of the uterine musculature from prolonged contractions).

Dystocia

DIAGNOSIS

• Physical examination with digital palpation of vagina

• Radiography to evaluate the fetal position, size, and number

• Ultrasonography to evaluate fetal viability and distress

INFORMATION FOR CLIENTS

• Owners should prepare a whelping box for the animal, and make sure the animal is comfortable sleeping in that box before whelping.

• Nutrition of the pregnant animal is important, with increased demands being placed on the mother as the litter develops.

• During the birthing process, owners should be advised to closely supervise the animal but not hover around, creating stress for the mother. Children and other pets should be kept out of the area.

• If labor and delivery are not progressing steadily, veterinary help should be obtained.

• Owners can predict parturition by monitoring the rectal temperature of the animal. Rectal temperature usually declines below 100° F 24 hours before the beginning of labor.

• After a cesarean section, owners may have to support the neonates until the mother is fully recovered.

• Ovariohysterectomy can be performed at the same time as the cesarean section in animals not used for breeding.

Inappropriate Maternal Behavior

Appropriate maternal behavior is important to the survival and development of neonates. Nursing, retrieving, grooming, and protecting are all considered normal behavior. The dam should demonstrate caution when moving about the whelping box; she should lie quietly while the neonates nurse. Because puppies and kittens do not have the ability to thermoregulate their body temperature during the first few weeks of life, the mother is responsible for keeping them warm. Grooming is important to stimulate cardiovascular and respiratory function, to stimulate elimination, and to remove waste material from the coat. Some dams, however, display increased protective behavior or fear-induced behaviors. Some cannibalize their litters. When these inappropriate behaviors occur, it is the responsibility of the owner to intervene and protect the health and well-being of the neonates.

Tags: Common Diseases of Companion Animals

Aug 31, 2016 | Posted by admin in GENERAL | Comments Off

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