Pyometra
Encyclopedia
Pyometra is a disease of the uterus
most commonly seen in female dogs, but also seen in female cat
s (queens), rabbit
s, ferret
s, rat
s and guinea pig
s. Pyometra is an important disease to be aware of for any dog owner because of the sudden nature of the disease and the deadly consequences if left untreated. It has been compared to acute appendicitis
in humans, because both are essentially empyema
s within an abdominal
organ.
, which was open during her heat, begins to close, and the inner lining begins to adapt back to normal. However, cystic hyperplasia
of the endometrium
(inner lining of the uterus) – known as cystic endometrial hyperplasia (CEH) – may occur at this time for some animals, as an inappropriate response to progesterone
.
Under these circumstances, bacteria
(especially E. coli) that have migrated from the vagina
into the uterus find the environment favorable to growth, especially since progesterone also causes mucus
secretion, closes the cervix (preventing uterine drainage), and decreases uterine contractility. The condition of the cervix is a major factor in the severity of the condition.
as a mismating shot (abortifacient
) in diestrus are at risk for more severe disease because estrogen
increases the number of progesterone receptors in the endometrium. 25 percent of females receiving estradiol in diestrus develop pyometra. Pyometra is less common in female cats because progesterone is only released by the ovaries after mating.
, increased white blood cell
count, and increased alkaline phosphatase
. X-ray
s will show an enlarged uterus, and ultrasound
will confirm the presence of a fluid filled uterus.
and in shock (see septic shock
). Intravenous fluids and antibiotic
s should be given immediately. The treatment of choice is an emergency spay, to remove the infected organ, but as this prevents a female dog from breeding
it is worth noting that some advances have been made in treating pyometra with long-term antibiotics and an agent to cause contraction of the uterus and expulsion of the pus.
). In this condition, the remaining stump of the resected Uterus
becomes infected and filled with a purulent fluid. The symptoms are similar to those of true pyometra. The risk of this condition is significantly reduced if no uterine or ovarian tissue remains from the original ovariohysterectomy. Diagnosis of a stump pyometra may be challenging as pyometra is often discounted as a possibility if the dog has been previously spayed.
Uterus
The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...
most commonly seen in female dogs, but also seen in female cat
Cat
The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...
s (queens), rabbit
Rabbit
Rabbits are small mammals in the family Leporidae of the order Lagomorpha, found in several parts of the world...
s, ferret
Ferret
The ferret is a domesticated mammal of the type Mustela putorius furo. Ferrets are sexually dimorphic predators with males being substantially larger than females. They typically have brown, black, white, or mixed fur...
s, rat
Rat
Rats are various medium-sized, long-tailed rodents of the superfamily Muroidea. "True rats" are members of the genus Rattus, the most important of which to humans are the black rat, Rattus rattus, and the brown rat, Rattus norvegicus...
s and guinea pig
Guinea pig
The guinea pig , also called the cavy, is a species of rodent belonging to the family Caviidae and the genus Cavia. Despite their common name, these animals are not in the pig family, nor are they from Guinea...
s. Pyometra is an important disease to be aware of for any dog owner because of the sudden nature of the disease and the deadly consequences if left untreated. It has been compared to acute appendicitis
Appendicitis
Appendicitis is a condition characterized by inflammation of the appendix. It is classified as a medical emergency and many cases require removal of the inflamed appendix, either by laparotomy or laparoscopy. Untreated, mortality is high, mainly because of the risk of rupture leading to...
in humans, because both are essentially empyema
Empyema
Pleural empyema is an accumulation of pus in the pleural cavity. Most pleural empyemas arise from an infection within the lung , often associated with parapneumonic effusions. There are three stages: exudative, fibrinopurulent and organizing. In the exudative stage, the pus accumulates...
s within an abdominal
Abdomen
In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...
organ.
Cause of pyometra
Pyometra is a result of hormonal and structural changes in the uterus lining. This can happen at any age, whether she has bred or not, and whether it is her 1st or 10th heat (although it becomes more common as the dog gets older). The main risk period for a female is for eight weeks after her peak standing heat (or estrus cycle) has ended. Normally during this period, the cervixCervix
The cervix is the lower, narrow portion of the uterus where it joins with the top end of the vagina. It is cylindrical or conical in shape and protrudes through the upper anterior vaginal wall...
, which was open during her heat, begins to close, and the inner lining begins to adapt back to normal. However, cystic hyperplasia
Hyperplasia
Hyperplasia means increase in number of cells/proliferation of cells. It may result in the gross enlargement of an organ and the term is sometimes mixed with benign neoplasia/ benign tumor....
of the endometrium
Endometrium
-Function:The endometrium is the innermost glandular layer and functions as a lining for the uterus, preventing adhesions between the opposed walls of the myometrium, thereby maintaining the patency of the uterine cavity. During the menstrual cycle or estrous cycle, the endometrium grows to a...
(inner lining of the uterus) – known as cystic endometrial hyperplasia (CEH) – may occur at this time for some animals, as an inappropriate response to progesterone
Progesterone
Progesterone also known as P4 is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy and embryogenesis of humans and other species...
.
Under these circumstances, bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
(especially E. coli) that have migrated from the vagina
Vagina
The vagina is a fibromuscular tubular tract leading from the uterus to the exterior of the body in female placental mammals and marsupials, or to the cloaca in female birds, monotremes, and some reptiles. Female insects and other invertebrates also have a vagina, which is the terminal part of the...
into the uterus find the environment favorable to growth, especially since progesterone also causes mucus
Mucus
In vertebrates, mucus is a slippery secretion produced by, and covering, mucous membranes. Mucous fluid is typically produced from mucous cells found in mucous glands. Mucous cells secrete products that are rich in glycoproteins and water. Mucous fluid may also originate from mixed glands, which...
secretion, closes the cervix (preventing uterine drainage), and decreases uterine contractility. The condition of the cervix is a major factor in the severity of the condition.
- If the cervix is open, the infected material can leave the body, and this is far easier and safer to treat. This is known as open pyometra.
- If the cervix is fully closed, there is no discharge from the vulvaVulvaThe vulva consists of the external genital organs of the female mammal. This article deals with the vulva of the human being, although the structures are similar for other mammals....
, and like in appendicitis, the uterus may rupture and pusPusPus is a viscous exudate, typically whitish-yellow, yellow, or yellow-brown, formed at the site of inflammatory during infection. An accumulation of pus in an enclosed tissue space is known as an abscess, whereas a visible collection of pus within or beneath the epidermis is known as a pustule or...
escapes into the abdomen, causing peritonitisPeritonitisPeritonitis is an inflammation of the peritoneum, the serous membrane that lines part of the abdominal cavity and viscera. Peritonitis may be localised or generalised, and may result from infection or from a non-infectious process.-Abdominal pain and tenderness:The main manifestations of...
and possible rapid death. This is known as closed pyometra.
Hormonal influences and mis-mating shots
Females that have received estradiolEstradiol
Estradiol is a sex hormone. Estradiol is abbreviated E2 as it has 2 hydroxyl groups in its molecular structure. Estrone has 1 and estriol has 3 . Estradiol is about 10 times as potent as estrone and about 80 times as potent as estriol in its estrogenic effect...
as a mismating shot (abortifacient
Abortifacient
An abortifacient is a substance that induces abortion. Abortifacients for animals that have mated undesirably are known as mismating shots....
) in diestrus are at risk for more severe disease because estrogen
Estrogen
Estrogens , oestrogens , or œstrogens, are a group of compounds named for their importance in the estrous cycle of humans and other animals. They are the primary female sex hormones. Natural estrogens are steroid hormones, while some synthetic ones are non-steroidal...
increases the number of progesterone receptors in the endometrium. 25 percent of females receiving estradiol in diestrus develop pyometra. Pyometra is less common in female cats because progesterone is only released by the ovaries after mating.
Symptoms
The most obvious symptom of open pyometra is a discharge of pus from the vulva in a Female that has recently been in heat. However, symptoms of closed pyometra are less obvious. Symptoms of both types include vomiting, loss of appetite, depression, and increased drinking and urinating. Fever is seen in less than a third of female dogs with pyometra. Closed pyometra is a more serious condition than open pyometra not only because there is no outlet for the infection but also because a diagnosis of closed pyometra can easily be missed due to its insidious nature. Bloodwork may show dehydrationDehydration
In physiology and medicine, dehydration is defined as the excessive loss of body fluid. It is literally the removal of water from an object; however, in physiological terms, it entails a deficiency of fluid within an organism...
, increased white blood cell
White blood cell
White blood cells, or leukocytes , are cells of the immune system involved in defending the body against both infectious disease and foreign materials. Five different and diverse types of leukocytes exist, but they are all produced and derived from a multipotent cell in the bone marrow known as a...
count, and increased alkaline phosphatase
Alkaline phosphatase
Alkaline phosphatase is a hydrolase enzyme responsible for removing phosphate groups from many types of molecules, including nucleotides, proteins, and alkaloids. The process of removing the phosphate group is called dephosphorylation...
. X-ray
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
s will show an enlarged uterus, and ultrasound
Ultrasound
Ultrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing. Ultrasound is thus not separated from "normal" sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is...
will confirm the presence of a fluid filled uterus.
Treatment
The most important aspect of treatment of pyometra is quick action. Female dogs are often septicSepsis
Sepsis is a potentially deadly medical condition that is characterized by a whole-body inflammatory state and the presence of a known or suspected infection. The body may develop this inflammatory response by the immune system to microbes in the blood, urine, lungs, skin, or other tissues...
and in shock (see septic shock
Septic shock
Septic shock is a medical emergency caused by decreased tissue perfusion and oxygen delivery as a result of severe infection and sepsis, though the microbe may be systemic or localized to a particular site. It can cause multiple organ dysfunction syndrome and death...
). Intravenous fluids and antibiotic
Antibiotic
An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...
s should be given immediately. The treatment of choice is an emergency spay, to remove the infected organ, but as this prevents a female dog from breeding
Dog breeding
Dog breeding is the practice of mating selected specimens with the intent to maintain or produce specific qualities and characteristics.Dogs reproduce without human interference, so their offsprings' characteristics are determined by natural selection. Domestic dogs may be intentionally bred by...
it is worth noting that some advances have been made in treating pyometra with long-term antibiotics and an agent to cause contraction of the uterus and expulsion of the pus.
Surgical treatment
Spaying (ovariohysterectomy) completely and promptly removes the infection, prevents uterine rupture and peritonitis, and of course prevents recurrence, in most cases. Spayed animals do very rarely develop pyometra in the uterine stump. Even so, ovariohysterectomy is currently considered the most effective and safest treatment.Stump Pyometra
Stump pyometra is a serious health condition that may occur in female dogs that underwent Ovariohysterectomy (spayingNeutering
Neutering, from the Latin neuter , is the removal of an animal's reproductive organ, either all of it or a considerably large part. The process is often used in reference to males whereas spaying is often reserved for females. Colloquially, both terms are often referred to as fixing...
). In this condition, the remaining stump of the resected Uterus
Uterus
The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...
becomes infected and filled with a purulent fluid. The symptoms are similar to those of true pyometra. The risk of this condition is significantly reduced if no uterine or ovarian tissue remains from the original ovariohysterectomy. Diagnosis of a stump pyometra may be challenging as pyometra is often discounted as a possibility if the dog has been previously spayed.