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
Metabolism refers to all processes in the body that break down and convert ingested substances to provide the energy and nutrients needed to sustain life. Foods, liquids, and drugs all generally undergo metabolic processes within the body. Many foods are complex materials that need to be broken down into simpler substances, which in turn become “building blocks” for the body to use as needed. For example, protein is broken down into amino acids, which are used
Tracheobronchitis is a sudden or longterm inflammation of the trachea and bronchial airways; it may also extend into the lungs. It often occurs in dogs already affected by respiratory disease or a disorder of the lungs or airways. For example, infectious tracheo-bronchitis (kennel cough; see below) often follows a viral infection of the respiratory system. Other causes of tracheobronchitis in dogs include parasites, diseases of the mouth and pharynx, chronic coughing
Tracheal collapse is most common in toy and miniature breeds of dogs, although it may occasionally occur in large-breed dogs. The cause is unknown. Affected dogs have a dry, honking, chronic cough, and labored breathing. They can have trouble breathing during inspiration or expiration. The condition occurs more frequently in dogs that are obese and in those with heart disease or another lung disease (especially chronic bronchitis). Weight loss for obese or overweight dogs i