Several reproductive diseases can affect male dogs. This section discusses the most common of these disorders.
Cryptorchidism
Cryptorchidism is a failure of one or both testicles to descend into the scrotum. It is the most common disorder of sexual development in dogs. The condition has a genetic basis and can be inherited from either parent. If both testicles are affected, the dog is sterile. Because the
Proper ovulation in females and ejaculation of fertile and normal sperm by males are regulated through a sequence of events in the brain, nervous system, and sexual organs. For best results, ovulation and deposition of semen into the female genital tract must be closely synchronized. Failure of any step in either sex leads to infertility or sterility. The ultimate result of infertility is the failure to produce offspring. In females, infertility may be due to improper timing of b
Dogs can be bred naturally or artificially. Artificial reproduction techniques include insemination with fresh, chilled, or frozen-thawed semen. Because male dogs are more likely to breed successfully in their home environment, females are generally taken to the male rather than the reverse.
Female dogs usually have estrous cycles twice a year, but the interval between cycles can range from 4 to 13 months. The average interval between cycles is 7
Both sexes have a pair of sexual organs or gonads (ovaries or testes), the main functions of which are to produce eggs or sperm, respectively, and hormones.
The Ovaries
Ovaries are female gonads that produce eggs and female sex hormones, including estrogen and progesterone. Estrogen is necessary for the development of eggs, and progesterone prepares the uterus for pregnancy. Once puberty is reached and th
The reproductive system is the group of organs that produce offspring. In both males and females, the reproductive system is composed of primary sex organs and primary regulatory centers. The primary sex organs are the testes and genital tract in males and the ovaries, fallopian tubes, and uterus in females. The primary regulatory centers are in the brain (the pituitary gland and hypothalamus). They control the production of hormones that in turn influence the function of the primary se
Malignant hyperthermia is seen mostly in pigs, but it has also been reported in dogs (especially Greyhounds), cats, and horses. This syndrome is characterized by abnormally high body temperature and muscle contraction that can potentially lead to death. A rapid and sudden increase in body temperature can be followed by muscle rigidity, a very rapid and irregular heartbeat, increased breathing rate, bluish tinge to skin and mucous membranes, unstable blood pressure, f
In both animals and people, fever may indicate infection, inflammation, an immune-mediated disease, or cancer. Determining the cause of a fever requires a history, physical examination, and sometimes laboratory or other diagnostic tests. Often, a fever resolves on its own or in response to antibiotic therapy. However, in a small percentage of animals, the fever continues or keeps coming back and the cause cannot be determined. This is called fever of unknown origin.
Owners commonly report muscular fatigue of dogs and horses. Muscular fatigue can be caused by numerous disorders of several body systems, which are discussed in other chapters. Fatigue is an issue for working dogs, racing greyhounds, and dogs that compete in agility and other high-intensity events.
Fatigue is a normal consequence of exercise that is continued at high intensity or for prolonged periods of time. It
Most disorders of magnesium metabolism are due to problems associated with absorption of the mineral from the digestive tract. The anatomical differences in the digestive tract between species are associated with the importance of disorders of magnesium occurring in a particular species. Disorders of magnesium metabolism are less common in dogs than in cattle and sheep. Too much magnesium in the blood (hypermagnesemia) is rare but has been r
Calcium is an essential component of the skeleton, and it has important functions in muscle contraction, blood clotting, enzyme activity, the nervous system, and hormone release, among others. Many different metabolic disorders affect calcium metabolism and can lead to abnormal levels of calcium in the blood. A high level of calcium is known as hypercalcemia, while a low one is called hypocalcemia