Abortion (infectious, toxic, nutritional)

Abortion in farm animals refers to the premature termination of pregnancy with expulsion of a dead or nonviable fetus before the normal end of gestation. This reproductive failure represents one of the most economically significant conditions in livestock production, affecting cattle, sheep, goats, swine, horses, and other species raised for food, fiber, and breeding purposes. Abortion can occur at any stage of pregnancy, though the term is most commonly applied to pregnancy losses occurring after organogenesis is complete, with earlier losses often termed embryonic death or early embryonic loss. Understanding the diverse causes of abortion and implementing appropriate diagnostic, treatment, and prevention strategies is essential for successful livestock management.

Abortion affects all pregnant farm animal species, though the relative importance of specific causes varies between species and production systems. Cattle abortion is a major concern in both dairy and beef operations, with infectious agents, toxic plants, and nutritional factors all playing significant roles. Small ruminants including sheep and goats are particularly susceptible to certain infectious causes such as chlamydiosis and toxoplasmosis that can cause devastating abortion storms in naive flocks. Swine reproductive losses have been transformed by the emergence of porcine reproductive and respiratory syndrome virus. Equine abortion, while less common in terms of overall livestock numbers, has significant economic impact given the high individual value of horses. Each species has its own spectrum of important abortion causes that producers and veterinarians must recognize.

The economic impact of abortion on livestock operations is substantial and multifaceted. The immediate loss includes the value of the aborted fetus, which may represent significant genetic investment in breeding operations or lost marketable offspring in commercial herds. The dam often experiences reduced productivity, whether through decreased milk production, delayed return to breeding, or compromised health requiring treatment. Diagnostic investigation of abortion cases incurs veterinary and laboratory costs. Perhaps most significantly, some abortion causes such as brucellosis are reportable diseases that can result in quarantine, mandatory testing, and depopulation of affected herds. The welfare implications of abortion extend beyond the lost fetus to include potential suffering of dams experiencing complicated abortions or retained placentas.

Treatability and prevention of abortion depend entirely on identifying the underlying cause. Infectious abortions may be prevented through vaccination, biosecurity, and treatment of carrier animals. Toxic abortions require identification and removal of the offending agent from the animals' environment. Nutritional abortions call for dietary correction and supplementation. In many cases, abortion is a sporadic event with an identifiable cause that can be addressed to prevent recurrence. In other situations, abortion storms affecting multiple animals suggest an infectious or toxic cause requiring urgent investigation. Early detection of abortion risk factors and prompt veterinary involvement are essential for minimizing losses and protecting the remaining pregnant animals in the herd or flock.

Infectious causes of abortion in livestock are numerous and include bacteria, viruses, fungi, and protozoa. Bacterial causes are among the most important and include Brucella species causing brucellosis in cattle, sheep, goats, and swine; Leptospira species affecting all livestock; Campylobacter fetus causing vibriosis in cattle and sheep; Listeria monocytogenes; Chlamydophila abortus causing enzootic abortion of ewes; and various opportunistic bacteria including Trueperella pyogenes, Escherichia coli, and Salmonella species. Viral causes include bovine viral diarrhea virus, infectious bovine rhinotracheitis virus in cattle, border disease virus in sheep, porcine reproductive and respiratory syndrome virus in swine, and equine herpesvirus in horses. Protozoal agents include Neospora caninum, which is a leading cause of bovine abortion worldwide, and Toxoplasma gondii, which causes abortion storms in sheep and goats. Fungal abortion, most commonly caused by Aspergillus species, occurs sporadically in cattle.

Genetic and chromosomal abnormalities contribute to pregnancy loss, though these more commonly cause early embryonic death rather than mid or late-term abortion. Lethal genetic combinations resulting from inbreeding or carrier matings can cause fetal death at various stages of development. Chromosomal abnormalities including trisomies and translocations are incompatible with continued development. Some breed-specific genetic conditions result in fetal abnormalities that cause abortion. While genetic causes typically affect individual pregnancies rather than causing widespread abortion problems, they should be considered when investigating recurrent pregnancy loss in closely related animals or highly inbred populations.

Environmental and toxic factors cause abortion through direct fetal toxicity, disruption of placental function, or compromise of maternal health. Toxic plants are important causes of abortion in grazing livestock, with specific plants varying by geographic region. In North America, pine needle abortion in cattle is caused by isocupressic acid from ponderosa pine needles. Locoweed and related plants containing swainsonine cause abortion in multiple species. Lupine, poison hemlock, and broom snakeweed are additional plant concerns. Mycotoxins in moldy feed, particularly zearalenone, can cause reproductive problems including abortion. Chemical toxins including nitrates, which can accumulate in drought-stressed forages, cause abortion through fetal hypoxia. Certain medications and chemicals are abortifacient and must be avoided in pregnant animals.

Risk factors for abortion span infectious, nutritional, and management domains. Naive animals introduced to areas where infectious agents are endemic are at elevated risk. Stress from transportation, handling, extreme weather, or concurrent disease can trigger abortion or reactivation of latent infections. Poor body condition and inadequate nutrition compromise the dam's ability to maintain pregnancy. Housing conditions that promote pathogen accumulation or exposure to vectors increase risk. Multi-species farms may face increased risk when definitive hosts for parasitic agents such as cats for Toxoplasma or dogs for Neospora are present. Young animals in their first pregnancy may be at higher risk for some conditions. Timing of exposure during pregnancy influences whether abortion occurs and at what stage.

The pathophysiology of abortion varies by cause but generally involves either direct damage to the fetus or placenta, compromise of maternal support for the pregnancy, or disruption of the hormonal signals required to maintain pregnancy. Infectious agents may cross the placenta and infect the fetus, causing fetal death through direct tissue damage or inflammation. Some pathogens primarily damage the placenta, disrupting oxygen and nutrient exchange and leading to fetal compromise. Toxic agents may directly poison the fetus or damage the placenta. Nutritional deficiencies of specific nutrients including iodine, selenium, and vitamin A can cause abortion through effects on fetal development or placental function. Severe maternal illness or stress can trigger abortion through hormonal mechanisms even without direct fetal infection or damage.

Early warning signs of impending abortion may be subtle or absent, making detection challenging. Behavioral changes such as separation from the group, restlessness, or decreased feed intake may precede abortion by hours to days. Vaginal discharge, which may be clear, mucoid, bloody, or purulent depending on the cause, is an important early sign. Premature udder development in cattle or engorgement in small ruminants may indicate impending parturition or abortion. Changes in the appearance of the vulva, including swelling or relaxation, suggest impending delivery. Some infectious causes produce systemic illness in the dam, including fever, depression, or diarrhea, before abortion occurs. Close observation of pregnant animals during high-risk periods is essential for early detection.

The act of abortion itself may or may not be observed, as many abortions occur without obvious signs of labor. When observed, signs of abortion resemble those of normal parturition and include restlessness, separation from the group, straining, and eventually expulsion of the fetus and placenta. The process may be more prolonged than normal birth, particularly if the cervix is not fully dilated or the fetus is malpositioned. Hemorrhage is variable and may be minimal or significant depending on the cause and any complications. Following abortion, the dam may show signs of straining as she attempts to expel any remaining placental tissue. Observation of the aborted fetus and placenta, when possible, provides valuable diagnostic information.

Behavioral changes following abortion vary by species and individual. Some dams show maternal behavior toward the aborted fetus, licking and protecting it. Others appear disinterested or quickly return to normal herd behavior. Depression is common in dams experiencing complicated abortions or secondary illness. Appetite may be reduced for several days following abortion. In cattle, decreased milk production is expected. Behavioral signs of pain or discomfort may indicate retained placenta, metritis, or other complications. Monitoring the dam's behavior in the days following abortion helps identify animals requiring further intervention.

Physical signs in the dam following abortion include vaginal discharge that persists for days to weeks depending on whether complications develop. The vulva may remain swollen for several days. The abdomen appears smaller as uterine involution progresses. In dairy cattle, milk production drops and milk composition may be altered. Body condition may decline if the dam is not eating well or if she was already in poor condition. Physical examination may reveal fever, dehydration, or other signs of systemic illness depending on the cause of abortion. The mammary gland may show abnormalities including mastitis.

Symptom progression following abortion depends on whether complications develop. In uncomplicated cases, vaginal discharge decreases over one to two weeks, the uterus involutes normally, and the dam returns to cyclicity and eventual breeding soundness. Retained placenta, which is common following abortion, prolongs discharge and increases risk of metritis. Metritis causes fever, foul-smelling discharge, depression, and decreased appetite, and can progress to septicemia if untreated. Some infectious causes of abortion leave the dam as a carrier, shedding organisms that pose ongoing risk to other pregnant animals. Tracking recovery and identifying complications early improves outcomes for individual animals and herd health.

Emergency symptoms requiring immediate veterinary attention include heavy hemorrhage during or after abortion, indicating possible uterine tear or abnormal placentation. Prolapse of the uterus or vagina is a medical emergency requiring immediate intervention. Signs of severe systemic illness including high fever, profound depression, recumbency, or shock indicate septicemia and require aggressive treatment. Difficulty delivering the fetus with prolonged unproductive straining suggests dystocia requiring assistance. Any abortion in a species or situation where reportable diseases are possible mandates immediate veterinary involvement for proper sampling and reporting. Multiple abortions occurring within a short period suggest an abortion storm requiring urgent investigation to protect remaining pregnant animals.

Clinical examination of the aborting or post-abortion dam provides initial assessment and guides sample collection. The veterinarian will evaluate the dam's overall condition, check for signs of systemic illness, and examine the reproductive tract for evidence of retained tissue, infection, or trauma. History taking is critically important and should include the stage of pregnancy at abortion, any observed clinical signs preceding abortion, recent introductions or exposures, vaccination history, nutritional management, and any known environmental changes or stressors. Information about other pregnant animals in the herd and any concurrent health issues provides important context. Physical examination of the aborted fetus and placenta, when available, often provides diagnostic clues.

Diagnostic testing of aborted fetuses and placentas is essential for determining the cause of abortion. Comprehensive abortion workups typically include bacterial culture of fetal stomach contents, lung, and liver; viral isolation or PCR testing for relevant agents; histopathologic examination of fetal and placental tissues; and in some cases, fluorescent antibody testing or immunohistochemistry for specific pathogens. Proper sample collection and submission are critical for diagnostic success. Samples should be collected as soon as possible after abortion, kept cool but not frozen for most tests, and submitted to diagnostic laboratories with appropriate history. The placenta is particularly valuable for diagnosis and should always be submitted when available. In cases of suspected toxic abortion, samples of feed, water, and plants from the animals' environment may be submitted.

Differential diagnosis of abortion is extensive and varies by species, geographic region, and production system. In cattle, the primary differentials include Neospora caninum, bovine viral diarrhea virus, infectious bovine rhinotracheitis virus, Leptospira species, Campylobacter fetus, brucellosis, and fungal abortion, along with toxic and nutritional causes. In sheep and goats, Chlamydophila abortus, Toxoplasma gondii, Campylobacter species, border disease virus, and Listeria monocytogenes are important considerations. Swine abortion differentials prominently feature porcine reproductive and respiratory syndrome virus along with porcine parvovirus and Leptospira species. The diagnostic laboratory provides guidance on which tests are most appropriate based on the clinical picture and epidemiological situation.

Herd-level diagnostics extend beyond the individual abortion case to assess the broader situation and identify systemic problems. Serological surveillance of pregnant and open females can identify exposure to infectious agents. Testing of bulls or boars for venereal pathogens may be indicated. Feed and forage analysis helps identify nutritional deficiencies or toxins. Environmental assessment identifies potential exposure to toxic plants, contaminated water, or other hazards. Review of production records, including conception rates, previous abortion history, and other reproductive parameters, places the current problem in context. When abortion storms occur, investigation should be thorough and rapid to identify the cause and implement control measures before additional losses occur.

Emergency treatment of abortion focuses on managing complications in the dam and initiating diagnostic investigation. Dams experiencing dystocia during abortion require obstetrical assistance to extract the fetus, with appropriate attention to hygiene and minimizing trauma. Significant hemorrhage may require supportive care including intravenous fluids and, rarely, blood transfusion. Uterine or vaginal prolapse requires immediate correction and retention, typically under epidural anesthesia. Anti-inflammatory medication helps manage pain and inflammation. Antibiotics may be administered prophylactically or therapeutically depending on the clinical situation. The aborted fetus and placenta should be collected and preserved for diagnostic submission.

Medical management following abortion depends on the cause and any complications present. Retained placenta is a common sequela of abortion and is managed differently by species. In cattle, manual removal is generally contraindicated due to risk of uterine damage, and treatment relies on systemic antibiotics and uterine involution, sometimes aided by uterine lavage. In small ruminants and swine, placentas are often smaller and may be manually removed more safely. Metritis requires systemic antibiotic therapy, with drug selection based on likely pathogens and withdrawal time considerations for food animals. Supportive care including fluids, anti-inflammatories, and nutritional support aids recovery. Treatment of the underlying cause, when a treatable infectious agent is identified, reduces risk to other pregnant animals and the dam's future fertility.

Surgical intervention is occasionally required for abortion complications. Caesarean section may be necessary if a fetus cannot be delivered vaginally due to size, position, or cervical problems. Uterine tears sustained during abortion or obstetrical manipulation may require surgical repair. Uterine prolapse that cannot be replaced and retained may rarely require amputation. Ovariohysterectomy is occasionally performed in valuable individual animals with severe uterine damage. These surgical interventions require appropriate facilities, anesthesia, and postoperative care. In food-producing animals, surgical treatments must be weighed against the animal's value and food safety considerations.

Supportive care optimizes recovery and future fertility. Rest and reduced stress allow the dam to recover. Appropriate nutrition supports healing and return to body condition. Monitoring for complications including metritis, mastitis, and systemic illness allows early intervention. In dairy cattle, regular milk-out of the affected quarter prevents mastitis and removes potential residues from any administered medications. Documentation of treatment, including all medications administered with their withdrawal times, ensures food safety compliance. Animals recovering from abortion should be monitored during subsequent breeding and pregnancy for any residual fertility problems.

Herd-level management responses depend on the diagnosed or suspected cause of abortion. For infectious causes, isolation of aborters, removal and disposal of aborted material, and disinfection of contaminated areas reduce transmission. Vaccination of susceptible animals may be indicated, though some vaccines cannot be given to pregnant animals. For toxic causes, identification and removal of the toxic agent from the environment is essential. Nutritional causes require diet reformulation and supplementation. In all cases, enhanced monitoring of remaining pregnant animals allows early detection of additional cases. Communication with veterinary authorities is required when reportable diseases are suspected or confirmed.

Treatment decisions must balance individual animal needs with herd health and economic considerations. The cost of treating an individual dam must be weighed against her value and future productivity. Chronically infected animals that pose ongoing risk to herd health may need to be culled. Food safety considerations, including withdrawal times for any treatments, influence decisions about marketing recovered animals. Regulatory requirements for reportable diseases may mandate specific actions. Working with a veterinarian helps navigate these complex decisions while protecting animal welfare, herd health, and the producer's economic interests.

Recovery timeline following abortion varies based on the cause, any complications, and individual animal factors. Uncomplicated abortion without retained placenta or metritis typically allows return to estrus within three to six weeks in cattle and sheep. Complete uterine involution takes approximately four to six weeks in cattle. Animals with complications such as retained placenta or metritis have prolonged recovery, with return to normal reproductive function taking two to three months or longer. Some infectious causes leave permanent damage to the reproductive tract, resulting in infertility. Nutritional recovery, particularly regaining body condition, may take several months depending on the dam's condition at abortion.

Post-treatment care and monitoring focus on identifying complications and supporting return to reproductive soundness. Daily observation of the dam for several days following abortion detects early signs of metritis, mastitis, or systemic illness. Temperature monitoring helps identify developing infection. Vaginal discharge should be monitored, with persistent purulent or foul-smelling discharge indicating ongoing uterine infection. Feed intake and body condition should be tracked. In dairy cattle, milk production and quality are monitored. A reproductive examination several weeks after abortion assesses uterine involution and identifies any abnormalities that might affect future fertility.

Prognosis for future fertility depends on the cause of abortion and any resulting damage. Most dams recovering from uncomplicated abortion have good prognosis for future pregnancy, particularly when the cause is identified and addressed. Infectious abortions that cause minimal uterine damage have good prognosis with appropriate treatment and prevention of reinfection. Abortions complicated by metritis have more guarded prognosis, as severe uterine infection can cause scarring or adhesions that impair fertility. Certain infections, including some strains of Campylobacter, can cause permanent tubal damage and infertility. Physical damage to the reproductive tract from dystocia or obstetrical manipulation carries variable prognosis depending on severity.

Return to breeding and production requires adequate recovery time and confirmation of reproductive soundness. Most veterinarians recommend waiting at least two normal estrous cycles before rebreeding following abortion, allowing time for uterine involution and clearance of any infection. Breeding soundness examination, including uterine palpation or ultrasound, confirms readiness for breeding. For valuable animals, uterine culture or cytology may be performed to ensure clearance of infection. In dairy cattle, return to milk production following abortion is typically complete within a few weeks, though production may be somewhat reduced compared to a normal lactation. Any food safety withdrawal periods from treatments must be completed before milk or meat enters the food supply.

Vaccination protocols form a cornerstone of infectious abortion prevention and should be tailored to the specific disease risks in each region and operation. In cattle, vaccines are available for bovine viral diarrhea, infectious bovine rhinotracheitis, leptospirosis, campylobacteriosis, and in some areas brucellosis. Sheep and goat vaccines include those for chlamydiosis, campylobacteriosis, and toxoplasmosis, depending on regional availability. Swine vaccines target porcine reproductive and respiratory syndrome virus and porcine parvovirus. Equine herpesvirus vaccines help prevent viral abortion in horses. Vaccination timing is critical, with most vaccines requiring administration before breeding or early in pregnancy to provide protection during the vulnerable gestational period. Consultation with a veterinarian ensures appropriate vaccine selection and timing.

Biosecurity measures prevent introduction of abortion-causing agents to naive herds. Purchasing replacement animals only from known disease-free sources reduces risk of introducing infected carriers. Quarantine and testing of new arrivals before integration provides an additional safety margin. Closed herd management, when practical, eliminates the risk associated with bringing in outside animals. Preventing contact with wildlife reservoirs, including controlling dog and cat access for Neospora and Toxoplasma prevention, reduces exposure risk. Proper disposal of aborted material and placentas prevents environmental contamination and exposure of susceptible animals. Movement restrictions during abortion outbreaks contain spread.

Nutritional prevention ensures that pregnant animals receive all nutrients required for successful pregnancy. Adequate energy intake maintains body condition, with target condition scores varying by species and stage of pregnancy. Protein requirements increase during late gestation and must be met through appropriate feeding. Specific mineral and vitamin requirements include iodine, selenium, copper, manganese, and vitamins A, D, and E, with deficiencies of any potentially causing abortion or fetal abnormalities. Feed testing and ration balancing ensure nutritional adequacy. Avoiding mycotoxin-contaminated feeds protects reproductive function. Clean, fresh water should always be available. Consultation with a nutritionist helps optimize feeding programs.

Management practices that reduce stress and optimize health support pregnancy maintenance. Minimizing transportation, handling, and other stressors during critical periods of pregnancy reduces stress-induced abortion risk. Appropriate stocking density prevents crowding stress. Providing adequate shelter protects against temperature extremes. Parasite control maintains general health and prevents anemia and debilitation. Concurrent disease prevention and prompt treatment of illness support overall health. Monitoring body condition and adjusting nutrition maintains optimal status. Training personnel in proper handling techniques reduces animal stress.

Quarantine and testing protocols provide additional protection for valuable breeding herds. New animals should be quarantined for at least thirty days before introduction to the breeding herd. During quarantine, testing for relevant abortion-causing pathogens should be performed, with specific tests depending on species and regional disease risks. Animals from herds with unknown or suspect disease status warrant extended quarantine and more comprehensive testing. Breeding soundness examinations before introduction ensure reproductive normalcy. For particularly valuable or disease-sensitive operations, only animals from certified disease-free herds should be considered for purchase.

Daily management and monitoring of pregnant animals support early detection of problems and optimal pregnancy outcomes. Pregnant animals should be observed daily for signs of illness, abnormal behavior, or impending abortion. Recording systems should track breeding dates and expected due dates, allowing appropriate timing of management interventions. Pregnant animals should be grouped appropriately, with high-risk individuals receiving closer observation. Nutritional management should be adjusted throughout pregnancy to meet changing requirements. Environmental hazards including toxic plants should be identified and access prevented. A working relationship with a veterinarian ensures professional support is available when needed.

Housing and environmental management create conditions supporting healthy pregnancy. Pregnant animals require adequate space, clean and dry bedding, protection from temperature extremes, and access to clean feed and water. Housing should minimize exposure to potential abortion-causing agents, including wildlife that may serve as disease reservoirs. Ventilation should maintain air quality without creating drafts. Isolation facilities should be available for animals showing signs of impending abortion or illness. Calving or lambing areas should be clean and well-designed for observation and intervention when needed. Handling facilities should allow safe and low-stress management of pregnant animals.

Herd health programs integrate abortion prevention into comprehensive reproductive management. Vaccination schedules should be established and consistently implemented. Parasite control programs should be appropriate for pregnant animals, avoiding products that are contraindicated during pregnancy. Nutritional programs should be reviewed and adjusted seasonally and based on forage testing. Biosecurity protocols should be documented and enforced. Disease surveillance, including monitoring for abortion and other reproductive problems, provides early warning of emerging issues. Regular veterinary reviews of reproductive performance help identify areas for improvement.

Record keeping and monitoring provide essential data for managing reproductive health. Breeding records should document service dates, sires used, and reproductive technologies employed. Pregnancy diagnosis results should be recorded with attention to fetal age and viability. Abortion events should be documented in detail, including date, stage of pregnancy, any clinical signs, diagnostic results, and treatments administered. Tracking abortion rates over time helps identify trends and evaluate intervention effectiveness. Production records including calving intervals, conception rates, and overall reproductive efficiency provide context for individual abortion cases.

Economic considerations influence abortion prevention investments and response decisions. The cost of vaccination, biosecurity, and other preventive measures must be weighed against potential losses from abortion outbreaks. The value of individual animals affects decisions about diagnostic workups and treatment. Insurance products may be available to manage risk from reproductive losses. Market implications of abortion-causing diseases, particularly those with regulatory restrictions, influence management decisions. Overall farm planning should include reproductive loss as a risk factor with appropriate prevention investments budgeted. Working with veterinary and financial advisors helps optimize decisions.

No breed of livestock has complete resistance to abortion, as all pregnant animals are susceptible to the numerous infectious, toxic, and nutritional causes. However, breed and type do influence risk through associated management practices and genetic factors. High-producing dairy cattle breeds may face elevated risk due to metabolic stress and intensive management. Meat breeds managed extensively on range may have increased exposure to toxic plants and wildlife disease reservoirs. Breeds or lines with high inbreeding may have increased genetic causes of pregnancy loss. Rare breeds with limited genetic diversity may carry lethal alleles at higher frequency. Heritage breeds managed in small populations may lack exposure-based immunity to endemic pathogens.

Production type considerations significantly influence abortion risk and impact. Dairy operations experience abortion as a loss of replacement heifers plus immediate milk production impacts. Beef operations lose potential market animals and may face reduced calving percentages. Sheep and goat operations, particularly those focused on lamb or kid production, are significantly impacted by abortion losses. Seedstock and purebred operations face losses of valuable genetics in addition to direct calf value. Show and exhibition animals may be at elevated risk due to frequent mixing with animals from diverse sources. Commercial operations may tolerate low-level sporadic abortion while breeding operations investigate more aggressively.

Genetic selection and testing have limited but growing roles in abortion prevention. For abortion causes with genetic components, testing and culling of carriers can reduce incidence. Some infectious diseases have documented genetic variation in susceptibility, offering potential for selection. Overall selection for immune competence and general disease resistance may provide some protection. Avoiding close inbreeding reduces risk of lethal genetic combinations. Genetic evaluation of breeding animals and selection decisions that prioritize health and reproductive efficiency contribute to overall reduction in abortion risk.

Several conditions commonly co-occur with or complicate abortion in livestock. Retained placenta is extremely common following abortion, occurring in a high percentage of cases across species. Metritis frequently develops when retained placenta or contamination from the abortion provides substrate for bacterial growth. Mastitis may develop in dairy cattle whose udders have prepared for lactation. Metabolic conditions including hypocalcemia and ketosis may develop in cattle that were close to term when abortion occurred. Systemic illness from infectious causes may precede, accompany, or follow abortion. Secondary infections may establish during the immunocompromised periparturient period.

Conditions with similar presentations to abortion require differentiation. Early embryonic death before day forty-five in cattle results in return to estrus without observed abortion and must be distinguished from failure to conceive. Stillbirth at term must be distinguished from late-term abortion, though the distinction may have limited practical significance. Mummification occurs when a fetus dies but is retained in utero without expulsion. Maceration is the breakdown of a retained fetus without mummification. Premature parturition with delivery of a viable but weak neonate should be managed differently from abortion of a nonviable fetus. Vaginal discharge from conditions other than pregnancy loss, including vaginitis or cervicitis, may be confused with early abortion signs.

Complications and sequelae of abortion extend beyond the immediate event. Retained placenta and metritis have been discussed as immediate complications. Longer-term sequelae may include reduced fertility, repeat breeding, and increased calving interval. Chronic endometritis may persist following inadequately treated acute metritis. Adhesions from severe uterine inflammation may cause infertility. Some infectious causes leave the dam as a carrier or chronically infected, posing ongoing risk to other animals. Psychological effects in bonded animals, including apparent depression or seeking behavior, may occur. Overall herd reproductive performance may be impacted if abortion causes are not addressed.