Endometritis

Endometritis is an inflammation of the endometrium, the inner lining of the uterus, that occurs in intact female dogs. This condition typically results from bacterial infection ascending into the uterus, though it can also develop from other inflammatory processes. Endometritis exists on a spectrum of uterine disease, ranging from mild inflammation that may resolve with treatment to severe infection that can progress to pyometra if not addressed. Understanding endometritis is important for owners of intact female dogs, as early recognition and treatment can preserve fertility and prevent life-threatening complications.

The uterus normally maintains a relatively sterile environment protected by the closed cervix and local immune defenses. However, certain conditions allow bacteria from the vagina to enter and establish infection in the uterine lining. The hormonal changes associated with the estrous cycle, particularly the progesterone-dominant phase following estrus, create conditions that favor bacterial colonization. The cervix opens during estrus, allowing bacterial entry, and progesterone subsequently suppresses local immune responses that would normally clear these organisms. Additionally, the structural changes of cystic endometrial hyperplasia provide an ideal environment for bacterial growth.

Endometritis can occur in several clinical contexts, with the postpartum period representing one of the most common settings. Following whelping, the cervix remains dilated for a time, and the uterus must heal from placental attachment sites. Retained placental tissue, stillborn puppies, or trauma during delivery can predispose to bacterial infection. The term metritis is sometimes used specifically for postpartum uterine infection, though endometritis and metritis are often used interchangeably in veterinary medicine. Regardless of the specific cause, uterine infection requires prompt veterinary attention.

Treatment of endometritis depends on the severity of infection and the dog's breeding status. Mild cases may respond to antibiotic therapy, particularly if diagnosed early and if the cervix is open allowing drainage of infected material. More severe infections, or those not responding to medical management, may require surgical removal of the uterus and ovaries (ovariohysterectomy). For valuable breeding dogs, attempts at medical management may be pursued more aggressively, though this approach carries risks of treatment failure and complications. Prevention through appropriate reproductive management and prompt attention to postpartum abnormalities offers the best approach to this condition.

Endometritis develops when bacteria colonize the normally sterile uterine environment and establish infection in the endometrial lining. This process requires both an opportunity for bacterial entry into the uterus and conditions that favor bacterial survival and multiplication over the body's defense mechanisms. Understanding the causes and risk factors for endometritis helps owners and veterinarians recognize vulnerable periods and implement preventive measures.

Bacterial entry into the uterus most commonly occurs during estrus when the cervix opens to allow mating and potential conception. Vaginal flora, including Escherichia coli, Staphylococcus, Streptococcus, and other bacteria, can ascend through the open cervix into the uterine lumen. Under normal circumstances, the uterus clears these bacteria through local immune mechanisms. However, when conditions favor bacterial survival, colonization occurs. Natural breeding can introduce bacteria directly into the uterus, and artificial insemination, particularly if performed with suboptimal technique, may also introduce contamination.

Hormonal influences play a critical role in creating conditions that allow endometritis to develop. Following ovulation, progesterone becomes the dominant hormone during the luteal phase, typically lasting about two months in dogs regardless of pregnancy status. Progesterone stimulates endometrial gland development and secretion in preparation for potential pregnancy but also suppresses uterine immune responses. This hormonally induced immunosuppression allows bacteria that entered during estrus to establish infection rather than being cleared. The longer a dog has experienced repeated estrous cycles, the more cumulative changes develop in the endometrium.

Cystic endometrial hyperplasia (CEH) creates an endometrial environment highly susceptible to infection. This condition, discussed separately in detail, involves progressive thickening and cyst formation in the uterine lining that develops over successive estrous cycles. The abnormal endometrium provides nutrients and protected spaces for bacterial growth while also being associated with impaired local immunity. The combination of CEH and bacterial infection represents the CEH-pyometra complex, with endometritis representing an early stage that can progress to more severe pyometra.

Postpartum uterine infection, sometimes specifically termed metritis, develops through several mechanisms related to the whelping process. The cervix remains open following delivery, allowing ascending bacterial contamination. Retained placental tissue provides a growth medium for bacteria. Prolonged or difficult labor may damage uterine tissues. Retained dead fetuses cause severe contamination. Manual assistance during delivery can introduce bacteria. Poor hygiene during the whelping process increases contamination risk. The stress of parturition may temporarily suppress immune function. All these factors combine to make the postpartum period a high-risk time for uterine infection.

The symptoms of endometritis vary depending on the severity of inflammation and infection, whether the cervix is open or closed, and how long the condition has been developing. Early or mild endometritis may produce subtle signs that owners could easily miss, while severe or progressing infection causes obvious systemic illness. Recognition of symptoms at any stage allows for appropriate veterinary intervention and prevents progression to more serious disease.

Vaginal discharge represents the most visible sign of endometritis when the cervix is open, allowing uterine contents to drain. The character of the discharge varies from slightly cloudy or mucoid to frankly purulent (pus-like) depending on the severity and type of infection. Color ranges from yellowish to greenish-brown, and the discharge may have a foul odor. The volume of discharge can range from minimal spotting to copious amounts that soil the dog's bedding and coat. Any vaginal discharge outside of normal estrus or the early postpartum period warrants veterinary evaluation.

Reproductive abnormalities may be the first indication of endometritis in breeding dogs. Failure to conceive despite apparently normal mating may indicate subclinical uterine infection interfering with implantation. Early pregnancy loss can occur when endometritis prevents embryo survival or implantation. Irregular estrous cycles may suggest underlying uterine disease. Breeders who track reproductive performance may notice declining fertility before other symptoms become apparent. These subtle reproductive signs highlight the importance of evaluating breeding dogs for uterine health.

Systemic illness develops as infection severity increases and bacteria or toxins enter the bloodstream. Fever commonly accompanies moderate to severe endometritis, though body temperature may be normal in early or mild cases. Lethargy and decreased activity levels reflect the body's response to infection. Appetite typically decreases, with affected dogs showing reduced interest in food. Increased water consumption and urination may develop as bacterial toxins affect kidney function. Vomiting can occur with more severe systemic involvement. These signs indicate that the infection is affecting overall health, not just the uterus.

Postpartum endometritis (metritis) presents during or soon after the whelping period with characteristic signs. Normal postpartum discharge (lochia) transitions to abnormal discharge that persists longer, becomes more purulent, or develops a foul odor. The mother may show decreased interest in her puppies, poor milk production, or reluctance to nurse. Fever typically develops within the first week after whelping. Abdominal pain may be evident. If stillborn puppies or retained placentas are involved, the onset may be particularly acute. Any illness in a recently whelped dog should prompt immediate veterinary evaluation.

Owners should be alert to the timing of symptoms relative to the reproductive cycle. Endometritis most commonly develops in the weeks following estrus, during the progesterone-dominant phase when the uterus is most vulnerable. Symptoms appearing one to three months after heat suggest uterine infection. Any vaginal discharge outside of estrus requires evaluation. Postpartum symptoms developing within the first one to two weeks after whelping suggest uterine infection. Prompt veterinary attention when symptoms are first noticed provides the best opportunity for successful treatment.

Diagnosis of endometritis combines clinical history, physical examination findings, and diagnostic testing to confirm uterine infection and assess its severity. The diagnostic approach helps distinguish endometritis from other conditions that might cause similar symptoms and guides treatment decisions. Because endometritis exists on a spectrum from mild inflammation to severe infection progressing toward pyometra, accurate assessment of disease severity is important for treatment planning.

Clinical history provides important context for evaluating suspected endometritis. The veterinarian will ask about the dog's reproductive history, including when the last estrus occurred, any recent breedings, and previous pregnancies or whelping. Recent whelping history is particularly relevant if postpartum metritis is suspected. Any observed vaginal discharge is characterized regarding color, consistency, odor, and duration. Changes in appetite, activity level, water consumption, or other systemic signs are noted. This information helps establish the likelihood of uterine infection and its probable cause.

Physical examination assesses both reproductive findings and overall health status. Vital signs including temperature, heart rate, and respiratory rate are recorded. Fever suggests active infection with systemic involvement. The vulva is examined for discharge, and the character of any discharge is documented. Abdominal palpation may detect an enlarged or painful uterus in some cases, though early or mild endometritis may not produce palpable changes. Dehydration, depression, or other signs of systemic illness are noted. Mammary glands may be evaluated if postpartum concerns exist.

Diagnostic imaging, particularly ultrasonography, provides valuable information about uterine condition. Ultrasound can visualize uterine enlargement, thickening of the uterine wall, and fluid accumulation within the uterine lumen. The presence and extent of endometrial cysts may be apparent. Ultrasound helps differentiate endometritis from pregnancy in recently bred dogs. Changes suggestive of progressing pyometra can be identified. Radiographs (X-rays) may be taken to rule out other conditions or assess for retained fetal skeletons in postpartum cases.

Laboratory testing helps assess infection severity and overall health status. Complete blood count commonly reveals leukocytosis (elevated white blood cell count) with active infection, though some cases show normal counts. Blood chemistry profiles evaluate kidney and liver function, important because uterine infections can affect these organs through bacterial toxins. Vaginal cytology examines cells and bacteria from vaginal discharge. Bacterial culture and sensitivity testing of uterine contents, if obtainable, guides antibiotic selection. These tests help stage disease severity and guide treatment decisions.

Treatment of endometritis depends on the severity of infection, the dog's reproductive status and breeding value, and the response to initial therapy. Options range from antibiotic therapy for mild cases to emergency surgical removal of the uterus for severe infections. Veterinary expertise guides the selection of appropriate treatment based on individual circumstances. Regardless of the approach taken, prompt treatment is essential to prevent progression to more severe disease.

Antibiotic therapy forms the foundation of medical management for endometritis. Broad-spectrum antibiotics are typically initiated based on likely causative organisms, with Escherichia coli being the most common pathogen. When possible, bacterial culture and sensitivity testing from uterine or vaginal samples guides antibiotic selection for optimal efficacy. Antibiotic courses typically continue for two to three weeks, depending on response. The success of antibiotic therapy depends significantly on whether the cervix is open (allowing drainage of infected material) versus closed (trapping infection within the uterus).

Prostaglandin therapy may be used alongside antibiotics in some cases to promote uterine drainage and contraction. Prostaglandins cause cervical relaxation and uterine contractions that help expel infected material. This approach is primarily used when attempting to preserve fertility in valuable breeding dogs with open-cervix endometritis. Prostaglandin therapy requires careful veterinary monitoring due to potential side effects including vomiting, diarrhea, and abdominal discomfort. The treatment is typically given as a series of injections over several days while monitoring response.

Ovariohysterectomy (surgical removal of the uterus and ovaries) provides definitive treatment for endometritis and eliminates any risk of recurrence. This surgical approach is recommended when infection is severe, when the dog is not intended for breeding, when medical management fails, or when the condition has progressed toward pyometra. For dogs with closed-cervix infection or severe systemic illness, surgery may be the safest option despite the anesthetic and surgical risks. Spaying eliminates not only the current infection but also the risk of future reproductive tract disease.

Postpartum endometritis (metritis) requires particular attention to the nursing puppies as well as treatment of the mother. Antibiotics selected must be safe for nursing, as drugs pass into milk and affect puppies. Severe metritis may necessitate weaning puppies and hand-rearing if the mother is too ill to nurse or if antibiotic choice requires separation. Supportive care including intravenous fluids, nutritional support, and pain management helps the mother recover. Retained placental tissue or fetal remnants may need to be addressed surgically in some cases.

Followup monitoring ensures treatment success and detects any complications. Repeat examination and ultrasonography assess uterine response to treatment. Blood work may be repeated to confirm resolution of systemic effects. For dogs treated medically with fertility preservation goals, reproductive function is evaluated before future breeding attempts. Any recurrence of symptoms requires reevaluation and potentially more aggressive treatment. Communication between owner and veterinary team helps identify any concerning changes during the recovery period.

Recovery from endometritis varies depending on treatment approach and infection severity, ranging from straightforward resolution with antibiotic therapy to more prolonged recuperation following surgery for severe infection. Understanding the expected recovery course helps owners provide appropriate care and recognize any complications requiring veterinary attention. The prognosis for recovery is generally good when treatment is initiated promptly and appropriate therapy is selected.

Recovery from medically managed endometritis typically occurs over two to four weeks as antibiotics eliminate infection and the uterus heals. Vaginal discharge should decrease and eventually resolve as treatment progresses. Appetite and energy levels return to normal as systemic effects resolve. Follow-up veterinary visits confirm resolution and may include repeat imaging to verify return to normal uterine appearance. Dogs treated with fertility preservation in mind should not be bred until confirmed recovered, with at least one normal estrous cycle passing before breeding attempts.

Surgical recovery following ovariohysterectomy for endometritis follows standard spay surgery protocols with some additional considerations due to the prior infection. The incision typically heals over ten to fourteen days, with suture or staple removal at the end of that period. Activity restriction during healing prevents incisional complications. Pain medication keeps the dog comfortable during recovery. Because infection was present, some dogs may continue on antibiotics after surgery to ensure complete resolution. Most dogs return to normal energy and activity within two to three weeks of surgery.

Postpartum endometritis recovery involves managing both the mother and the litter simultaneously. Nursing may need to be adjusted or discontinued depending on the mother's condition and medication requirements. Puppies require monitoring for adequate growth if nursing is affected. The mother's temperature and appetite are tracked as indicators of treatment response. Postpartum dogs have additional metabolic demands that should be supported nutritionally during recovery. Follow-up examination confirms resolution before the family is considered fully recovered.

Long-term prognosis after endometritis depends on the treatment approach and disease severity. Dogs treated surgically with ovariohysterectomy have excellent prognosis with no possibility of recurrence. Dogs treated medically with fertility preservation face some risk of recurrence at future cycles, and fertility may be impaired depending on the extent of endometrial damage. Breeders should discuss reproductive prognosis with their veterinarian before future breeding attempts. Regular reproductive health monitoring is advisable for dogs maintained intact after endometritis treatment.

Prevention of endometritis focuses on minimizing bacterial contamination of the uterus, maintaining reproductive health through appropriate management, and recognizing early warning signs before severe infection develops. While not all cases of endometritis can be prevented, implementing appropriate measures significantly reduces risk. For dogs not intended for breeding, spaying eliminates the possibility of endometritis along with other reproductive tract diseases.

Reproductive hygiene during breeding helps reduce bacterial introduction into the uterus. Using artificial insemination with proper technique minimizes contamination compared to natural breeding in some situations. If natural breeding is used, ensuring the male is healthy and the environment is clean reduces risks. Avoiding breeding during abnormal cycles or when discharge is present prevents breeding into potentially infected uteri. Working with a veterinarian experienced in reproduction optimizes breeding practices.

Postpartum management prevents many cases of post-whelping endometritis. Maintaining cleanliness during whelping reduces bacterial contamination. Monitoring for complete delivery of all puppies and placentas identifies retained material that could cause infection. Observing normal postpartum discharge patterns allows early recognition of abnormal changes. Seeking veterinary attention promptly for prolonged labor, retained tissues, or unusual discharge enables early intervention before severe infection develops. Proper nutrition and care during lactation supports the mother's immune function.

Regular veterinary monitoring of intact breeding females identifies developing reproductive issues. Examination after each cycle in dogs with any history of reproductive abnormalities detects early changes. Ultrasonographic evaluation of the uterus can identify cystic endometrial hyperplasia before infection develops. Prompt treatment of any vaginal or uterine abnormalities prevents progression. Open communication with the veterinary team about any observed changes supports early intervention.

Eliminating reproductive risk through spaying remains the most effective prevention for dogs not intended for breeding. Ovariohysterectomy completely removes the uterus and ovaries, making endometritis impossible. This approach also prevents pyometra, ovarian disease, and unwanted pregnancies. For dogs past their breeding careers, spaying eliminates future reproductive health risks. The decision about spaying should be made in consultation with a veterinarian based on the individual dog's situation.

Living with and managing a dog during and after endometritis treatment involves attention to medication compliance, monitoring for treatment response or complications, and making appropriate decisions about future reproductive management. The day-to-day care requirements vary depending on whether the dog was treated medically or surgically and whether fertility preservation is a goal. Understanding these management aspects helps owners provide optimal care throughout the recovery process.

Medication management during antibiotic therapy requires consistency and attention to the prescribed schedule. Antibiotics should be given at regular intervals for the full prescribed duration, even if the dog appears recovered before the course is complete. Incomplete antibiotic courses can lead to recurrence or antibiotic resistance. Some antibiotics should be given with food while others require an empty stomach; following specific instructions optimizes efficacy. Watching for and reporting any adverse reactions to medications allows adjustment if needed.

Monitoring during recovery helps identify both improvement and any complications. Vaginal discharge should be observed and characterized, with improvements in color, consistency, and volume expected as treatment progresses. Any increase in discharge or development of foul odor should prompt veterinary contact. Appetite, energy level, and water consumption provide indicators of systemic health. Temperature monitoring may be recommended, particularly for postpartum cases. Accurate reporting of observations helps the veterinary team assess treatment response.

Activity management differs between medical and surgical treatment. Dogs being treated medically generally do not require strict activity restriction, though avoiding strenuous exercise during active infection is reasonable. Dogs recovering from surgery need standard post-operative restrictions including limited activity, no running or jumping, and protection of the incision site for ten to fourteen days. Elizabethan collars or recovery suits prevent licking or chewing at surgical sites.

Future reproductive decisions require careful consideration for dogs treated medically with fertility preservation. The veterinarian can advise on when breeding can safely be attempted based on confirmation of uterine recovery. The risk of recurrence at future cycles exists, and owners should be prepared for this possibility. Some owners elect to breed once more and then spay, while others continue breeding with careful monitoring. For dogs experiencing repeated reproductive issues, spaying may be recommended to protect overall health.

Quality of life considerations apply throughout management of endometritis. Dogs typically feel improved as treatment takes effect, returning to normal appetite and activity. Ensuring comfort, maintaining familiar routines, and providing appropriate nutrition supports recovery. Dogs that have been spayed return to normal life with no ongoing reproductive health concerns. Those maintained intact require continued attention to reproductive health monitoring. Overall, most dogs recover well from endometritis and return to normal quality of life with appropriate treatment and management.

Endometritis can affect any intact female dog, as the condition results from bacterial infection and hormonal influences rather than breed-specific genetic factors. However, certain population characteristics and individual risk factors influence the likelihood of developing this condition. Understanding which dogs face elevated risk helps target preventive measures and monitoring appropriately while recognizing that no intact female is completely immune to uterine infection.

Intact female dogs that have experienced multiple estrous cycles face cumulative risk for developing the underlying uterine changes that predispose to endometritis. Each hormonal cycle exposes the endometrium to progesterone-induced changes that become progressively more pronounced over time. Middle-aged to older intact females that have never been bred may have higher rates of cystic endometrial hyperplasia, which creates conditions favoring bacterial infection. Dogs six years and older represent the highest-risk age group, though endometritis can occur at any age.

Breeding dogs face specific risk factors related to their reproductive activities. Dogs bred to males with poor hygiene or genital infections may be exposed to higher bacterial loads. Artificial insemination performed without proper technique can introduce contamination. Dogs that experience difficult labor or require assistance during whelping face increased postpartum infection risk. Retained placentas or prolonged labor create conditions for bacterial growth. These factors relate to reproductive management practices rather than breed-specific susceptibility.

Breed associations with endometritis primarily reflect associations with the underlying condition of cystic endometrial hyperplasia. Breeds reported to have higher CEH rates may consequently have higher rates of secondary endometritis, though definitive breed predispositions for endometritis specifically are not well established. Any breeding program should maintain awareness of uterine health across all breeding females regardless of breed, with appropriate monitoring and prompt attention to any reproductive abnormalities.

Endometritis exists within a spectrum of uterine disease and relates to several other reproductive conditions through shared causes, similar presentations, or potential for progression. Understanding these relationships helps veterinarians and owners recognize disease patterns and anticipate potential complications. The most clinically significant relationships involve the progression from endometritis to more severe uterine infection if not adequately treated.

Cystic endometrial hyperplasia (CEH) represents the underlying uterine condition that predisposes to endometritis development. As discussed separately, CEH involves progressive thickening and cyst formation in the uterine lining resulting from repeated hormonal exposure over multiple estrous cycles. This abnormal endometrium provides an ideal environment for bacterial colonization. The CEH-pyometra complex describes the spectrum from hormonal uterine changes through bacterial infection to severe pus accumulation. Endometritis occupies a position on this spectrum between uncomplicated CEH and advanced pyometra.

Pyometra represents the severe end of the uterine infection spectrum and can develop from inadequately treated or progressive endometritis. Pyometra involves accumulation of purulent material within the uterus, often with significant uterine distension and severe systemic illness. The distinction between severe endometritis and early pyometra is not always clear-cut, as these conditions exist on a continuum. Any endometritis that fails to respond to treatment or that progresses despite therapy may be developing into pyometra. Pyometra is a life-threatening emergency typically requiring surgical intervention.

Metritis, the term often used specifically for postpartum uterine infection, shares many features with endometritis occurring in other contexts but has unique aspects related to the whelping process. The recently pregnant uterus contains placental attachment sites that must heal, and retained tissue provides infection substrate. The immune changes of pregnancy and lactation may affect infection dynamics. While treatment approaches are similar, the context of nursing puppies and postpartum maternal needs creates additional management considerations. Additionally, vaginal infections (vaginitis) may coexist with or predispose to endometritis by serving as a source of ascending bacteria, and any vaginal infection in an intact female warrants evaluation for uterine involvement.