Feline Urinary System
The feline urinary system is one of the biological systems necessary to maintain the cat’s health. It works to maintain the proper amount of water in the body, as well as the body chemistry. Therefore, it has several important functions: gets rid of waste products created when food is transformed into energy, maintains the correct balance of water and electrolytes within the body’s cells, and processes vitamin D. The urinary system also produces the hormones erythropoietin and renin, which maintain healthy blood pressure, producing blood cells, and absorbing salt.
A cat’s urinary tract is a system made up of the kidneys, ureters (which connect from kidneys to bladder), the bladder, and urethra. These organs work together to produce, transport, store, and excrete urine.
The first major organ is the kidney. Like humans, cats have two kidneys located in the abdominal cavity under the backbone, close to where the last rib meets the spine. The indentation of the “bean” in the been-shaped organ is called the hilus. This is the area where the blood vessels, nerves, and ureters enter and leave the kidney.
When water and nutrients are absorbed into the bloodstream in the small intestine, the bloodstream takes the water to the kidneys for filtration. In the kidney, there are hundreds of nephrons, microscopic filtering units, that have the ability to form urine itself. Each nephron consists of a circular ball-shaped cluster of small blood vessels called a glomerulus and a renal tubule, a small tube. Once the unwanted substances are excreted in the urine, the rest, such as water and certain salts, are returned to the bloodstream.
By regulating fluids, kidneys regulate the acid-base balance of the blood and blood pressure. This keeps the feline’s body chemistry in balance while it removes toxins. The kidneys also monitor and maintain the balance of body water, ensuring that body tissues receive enough water to remain hydrated and function properly.
To move the liquid waste products, the ureters, two small tube-like organs, connect the kidneys to the bladder.
The bladder is a collapsible muscular organ shaped like a balloon. It is also located in the abdomen just in front of the pubic bone of the pelvis, held in place by the ligaments in the region. The bladder functions as a means for temporary urine storage.
A circular muscle called a sphincter controls the outlet opening of the bladder, keeping the urine from leaking out. Once the bladder reaches a certain point of distention, nerves in the bladder wall notify the brain to empty the bladder. When
appropriate, the animal will voluntarily relax the sphincter to release the urine, which will enter the urethra to be carried outside the body.
Diseases and Disorders of the Urinary System
A well balanced diet is important to keep the urinary system healthy. An improper diet can lead to urinary tract problems such as struvite crystals. Struvite crystals are comprised of magnesium, and phosphorous, and may collect in the bladder or within the urethra, where they block the urinary pathway.
- Feline lower urinary tract disease (FLUTD): It is a common disorder seen in both male and female cats. The exact cause is unknown but it may be influenced by bacterial or viral infections as well as certain dietary factors. FLUTD is characterized by painful urination with or without the presence of blood. It is very uncomfortable and can be life-threatening. Also known as feline idiopathic cystitis (FIC) and feline urologic syndrome (FUS).
- Pyelonephritis: This refers to infections of the kidney due to bacteria. It may also be secondary to severe, chronic, or recurrent bladder infections. With time, the bacteria associated with bladder infections may travel up the ureters to infect the kidneys.
- Urinary tract stones: Most commonly found in the bladder, these stones are a buildup of calcium deposits. Symptoms are similar to cats with FLUTD and treatment varies on the type number, and location of the stones.
- Kidney failure: This disease results when the kidneys are not able to remove toxins from the body or can no longer regulate water and electrolyte balance. Cats can lose up to ⅔ of their functional kidney capacity without signs of kidney failure. After ¾ of the capacity is gone, toxins and abnormal levels of minerals and electrolytes begin to build up in the blood stream. Can be acute, caused by obstruction of the lower urinary tract followed by exposure to toxins, or chronic kidney failure, due to degeneration and deterioration.
- Tumors: It is relatively rare for tumors to occur in the urinary tract for cats. The most common urinary tumor is lymphosarcoma of the kidneys, which affects both kidneys at the same time.
- Trauma: Fractures of the pelvis may cause disruption in the urethra and/or the bladder. Fractures of the spine and tail may result in paralysis of the bladder. Hemorrhages or rupture of the kidneys, ureters, or bladder may also occur with trauma to the abdomen.
Feline Reproductive System
Just like humans, cats reproduce sexually between two partners, a male and female. Both genders have their own set of reproductive system, In male cats, the genital tract provides the pathway for semen, which contains the sperm cells. In female cats, the genital tract includes both the ovaries, which contain the egg cells, and the womb, which will carry and nurture the young as they develop.
The penis is the male copulatory organ. It contains vessels and connective tissue specialized to produce an erection, which facilitates penetration of the penis into the vagina of the female. The tip is called the glans and is covered with 120 to 150 penile spines, directed backward. These spines appear at about 12 weeks of age and are fully developed at puberty. They are absent in neutered male cats, disappearing by six weeks after castration.
It is located within the prepuce, which acts as a moist protective covering for the non-erect penis, and not erect, it is only visible on the posterior of the body.
The scrotum is located beneath the anus and only visible when the tail is lifted upwards. It is a pouch divided by a thin wall into two cavities, each of which is occupied by a testicle, an epididymis, and the tail end of the spermatic cord. The layer underneath the skin is called the dartos, a layer of tissue that is made up of muscle and connective tissue.
Because of its location and lack of fact, the scrotum functions as a temperature regulator for the testicle and epididymis. The temperature within the scrotum is generally several degrees lower than the abdomen. This lower temperature is essential for the normal manufacturing and maintenance of sperm.
The testicles perform two major functions: production of sperm and testosterone. Each contain seminiferous tubules that manufacture sperm. Special cells near the tubules called sertoli cells support and supply nutrition to the sperm cells.
The epididymis is an enlarged tube positioned along the edges of the testicle. It consists of an elongated structure composed of a long convoluted or twisted tube. They are the organs where sperm are stored and are used to slowly transport sperm to the ductus deferens. The length of the epididymis and the slow transport of sperm are important in allowing the sperm time to become mature.
The ductus deferens or vas deferens begins at the tail of the epididymis and runs along the border of the testicle. The sperm is transported through the ductus deferens towards the back of the abdomen, passes through the prostate, and empties into the urethra. The ducts are thin muscular tubes that are made up of three layers of muscle.
The prostate gland is very small in the cat. It is normally located near the front of the rim of the pelvis, surrounding the beginning of the urethra as well as the end of the ductus deferens. This organ has multiple openings into the urethra. It is a relatively unimportant organ in the male cat.
Diseases and Disorders of the Male Feline Reproductive System
- Cryptorchidism: This refers to the failure of one or both testicles to descend into the scrotum by seven to eight months of age. The undescended testicle is often retained within the abdomen. Because of the temperature of an undescended testicle is higher than normal, it usually causes infertility.
- Monorchidism: It is a rare developmental condition in which the affected individual usually develops one testicle. It is caused by genetic abnormality.
- Trauma: It may occur to the scrotum, prepuce, and urethra. Includes injuries from automobile accidents, bite wounds, and sharp objects.
Female Reproductive Organs
The female cat’s reproductive tract consists of the female genital organs including the ovaries, uterus, vagina, vulva, and mammary glands. It is responsible of producing and storing egg cells as well as where the embryo develops. Like the male, the reproductive organs are located in the abdomen.
Mammary glands are located in two rows along the outside of the abdomen, running from the groin to the chest. They are composed of connective tissue to provide support, structure, blood vessels, lymphatic vessels, and glandular tissue. Each gland stores and secretes milk. Usually, a cat has four pairs of mammary glands.
Ovaries are located just behind the kidneys and contain the eggs that are waiting to be fertilized. They are suspended from the top of the abdomen by a broad ligament called the suspensory ligament. Other than storing the eggs, the ovaries also produce the female hormones estrogen and progesterone. To connect the ovaries to the uterus are the oviducts or the fallopian tubes. Where the ovaries and oviduct connect is a funnel-like structure, the infundibulum, which catches the egg when it is released from the ovary.
The uterus of the cat is Y-shaped, with the arms, called horns, of the “Y” being longer than the stem, also known as the body. The uterine horns extend from each ovary to join together to form the body of the uterus. The walls are lined with a vascular and glandular lining (mucosa) and contains smooth muscle. The muscular substance of the uterus is called the myometrium; the inner lining is called the endometrium.
It serves as the site for implantation of fertilized eggs and for the growth and development of the fetus. When the female is pregnant, the fetuses are arranged in a row in both horns.
Where the uterus ends, the cervix begins. It contains connective tissue and muscle that form a firm tube-like sphincter. It is usually closed to prevent infection. Only during fertilization and birth is the sphincter of the cervix relaxed or opened.
The cervix separates the uterus from the vagina, which passes through the pelvis. The vaginal walls are made up of an inner mucosal layer, a middle smooth muscle layer, and an external coat of connective tissue. The vaginal mucosa contains numerous folds, which allows for expansion and stretching. It provides a protected passage for fetuses to move from the uterus to the outside and protects the opening of the urethra, where urine leaves the body.
The opening of the vagina is protected by the vulva. It also provides external markings that identify the feline as a female.
When a cat is spayed, the ovaries, oviducts, and uterus are removed.
Diseases and Disorders of the Female Feline Reproductive System
- Ovarian cysts: Cysts may develop from the accumulation of fluids within the follicles. There may cause no clinical signs but the animal may fail to come into estrus (heat) or show signs of continuous estrus.
- Ovarian remnants: This may sometimes occur when a portion of the ovary is cut and left behind during the spaying surgery. Cats show recurrent signs of coming into heat even after the surgery has been performed.
- Metritis: It is the inflammation of the uterus, usually used when uterine inflammation develops after a pregnancy. This develops because of a bacterial infection that ascends up the vagina and enters the uterus through the open cervix.
- Mucometra: This disease usually occurs in older female cats that have not been spayed. The glands and the endometrium of the uterus become enlarged and will sometimes produce large amounts of mucus. The source is usually bacteria entering the uterus through the cervix. Discharge may drain if the cervix is open. If closed, no discharge is seen.
- Uterine prolapse: It is the protrusion of the uterus through the cervix into the vagina. Portions may be exposed at the vulva, usually during or immediately after giving birth or spontaneous abortion.
- Vaginitis: It is the inflammation of the vagina. It can occur in any age of the cat and in both spayed and intact females. Causes include congenital defects, urinary tract infections, bacterial and viral infections, tumors, and trauma. The primary clinical sign is vaginal discharge.
- Galactorrhea: This disease occurs when milk production occurs outside of pregnancy.
- Agalactia: It is the failure to secrete milk at appropriate times.
- Galactostasis: This is the abnormal collection of milk in the mammary glands.
- Mastitis: This disorder is the inflammation and/or infection of the mammary glands. In most cases, it is believed that the bacteria travel up the mammary ducts into the glands, which then become painful, red, and sometimes, swollen.
- Tumors: Can develop all along the feline reproductive tract. Spaying prevents the development of tumors.
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