Uterine diseases in dairy cows: understanding the causes and seeking solutions

Uterine diseases such as metritis and endometritis are highly prevalent in high producing dairy cows. These diseases lead to impaired welfare and fertility , and result in economic loss. The objective of this review article is to provide the current understanding of the underlying causes of uterine diseases and to provide some strategies to prevent them. The causes of uterine diseases are complex and multifactorial; therefore a holistic approach must be taken when trying identitythe causes or prevent them. The dairy cow undergoes a state of negative energy, mineral and vitamin balance during the transition into lactation, which leads to immunosuppression and increased susceptibility to disease. The main risk factors for uterine diseases are primiparity (for metritis only), dystocia , male offspring, twins, stillbirth, abortion, prolapsed uterus, retained placenta (RP), ketosis, and hypocalcemia. Prevention strategies should be focused on maximizing cow comfort and dry matter intake (DMI), preventing hypocalcemia and hyperketonemia, preventing dystocia, prolapsed uterus, abortion, stillbirth and RP. Maximization of cow comfort and DMI can be achieved with appropriate housing and cooling. Management strategies to prevent metabolic and calving related problems include the use of anionic diets, the use of feed additives such as monensin and rumen protected choline, implementation of sound vaccination programs, and the use of sexed semen. Trace mineral and vitamin supplementation beyond what is fed in the diet is still controversial; however some trial s have shown a decrease in RP and stillbirths.mProphylactic treatment ofmcows at high risk for metritis with PGF2α and/ormoxytocin is not warrantedmbecause there is no beneficialmeffect. Prophylactic treatment of cows at high risk for metritis with NSAIDs is contraindicated because it has been found to decrease DMI and increase the degree of negative energy balance; therefore, leading to an increase in the risk of RP and metritis. Prophylactic treatment of cows at high risk for metritis with estradiol is contraindicated because there is no beneficial e ffect on the prevention of metritis and there is a negative effect on long term fertility. Prophylactic treatment of cows at high risk for metritis with antibiotics can reduce the incidence of uterine disease but has no positive longterm effects on fertil ity; therefore, decision to implement prophylactic antibiotic treatment should be based on welfare, economic and legal considerations. Given that most treatments are not very efficacious, efforts should be focused on management strategies to decrease metab olic problems such as hypocalcemia and ketosis, and to prevent risk factors such as dystocia, male calves, abortions, stillbirths, and retained placenta.

Uterine diseases in dairy cows: understanding the causes and seeking solutions

Uterine diseases such as metritis and endometritis are highly prevalent in high producing dairy cows. These diseases lead to impaired welfare and fertility , and result in economic loss. The objective of this review article is to provide the current understanding of the underlying causes of uterine diseases and to provide some strategies to prevent them. The causes of uterine diseases are complex and multifactorial; therefore a holistic approach must be taken when trying identitythe causes or prevent them. The dairy cow undergoes a state of negative energy, mineral and vitamin balance during the transition into lactation, which leads to immunosuppression and increased susceptibility to disease. The main risk factors for uterine diseases are primiparity (for metritis only), dystocia , male offspring, twins, stillbirth, abortion, prolapsed uterus, retained placenta (RP), ketosis, and hypocalcemia. Prevention strategies should be focused on maximizing cow comfort and dry matter intake (DMI), preventing hypocalcemia and hyperketonemia, preventing dystocia, prolapsed uterus, abortion, stillbirth and RP. Maximization of cow comfort and DMI can be achieved with appropriate housing and cooling. Management strategies to prevent metabolic and calving related problems include the use of anionic diets, the use of feed additives such as monensin and rumen protected choline, implementation of sound vaccination programs, and the use of sexed semen. Trace mineral and vitamin supplementation beyond what is fed in the diet is still controversial; however some trial s have shown a decrease in RP and stillbirths.mProphylactic treatment ofmcows at high risk for metritis with PGF2α and/ormoxytocin is not warrantedmbecause there is no beneficialmeffect. Prophylactic treatment of cows at high risk for metritis with NSAIDs is contraindicated because it has been found to decrease DMI and increase the degree of negative energy balance; therefore, leading to an increase in the risk of RP and metritis. Prophylactic treatment of cows at high risk for metritis with estradiol is contraindicated because there is no beneficial e ffect on the prevention of metritis and there is a negative effect on long term fertility. Prophylactic treatment of cows at high risk for metritis with antibiotics can reduce the incidence of uterine disease but has no positive longterm effects on fertil ity; therefore, decision to implement prophylactic antibiotic treatment should be based on welfare, economic and legal considerations. Given that most treatments are not very efficacious, efforts should be focused on management strategies to decrease metab olic problems such as hypocalcemia and ketosis, and to prevent risk factors such as dystocia, male calves, abortions, stillbirths, and retained placenta.(AU)

Postpartum uterine diseases in dairy cows

Uterine diseases in dairy cows can be classified as puerperal metritis, clinical metritis, clinical endometritis, and subclinical endometritis. These diseases are highly prevalen t (affect between 20 and 30% of dairy cows) in high producing dairy cows and have been associated with decreased pregnancy per artificial insemination (AI), extended interval to pregnancy, increased culling, and economic losses. Puerperal metritis is characterized by the presence of an abnormally enlarged uterus, a fetid watery red-brownish uterine discharge associated with signs of systemic illness, and fever (>39.5 o C) within 21 days in milk (DIM). Animals without systemic signs but with an enlarged uterus and a fetid uterine discharge within 21 DIM may be classified as having clinical metritis. Clinical endometritis is characterized by the presence of purulent (>50%) uterine discharge after 21 DIM or mucopurulent (50% pus, 50% mucus) after 26 DIM. In the absence of clinical endometritis, subclinical endometritis is defined by the presence of >18% neutrophils (PMN) in uterine cytology samples collected between 21 and 33 DIM or >10% PMN between 34 and 47 DIM. The main risk factors are dystocia, twins, retained placenta, stillbirth, abortion, prolapsed uterus, and ketosis. Metritis can be successfully treated either by systemic or intrauterine antibiotic treatment. Ceftiofur hydrochloride (Excenel ® ) intramuscularly or ceftiofur crystalline-free acid (Excede ® ) subcutaneously are effective in treating metritis, and oxytetracycline intrauterine is effective in abrogating the negative effects of metritis on milk yield and fertility. Intrauterine administration of cephapirin benzathine (Metricure ® ) is an effective treatment for clinical and subclinical endometritis, although not approved in the United States. Administration of PGF2 α does not seem effective for th e treatment of clinical or subclinical endometritis.

Association between immune function and development of uterine disease in dairy cows

The transition to lactation (3 weeks before to 3 weeks after calving) is char acterized by a decrease in dry-matter intake (DMI), lead ing to a sharp decrease in glucose and calcium, and an increase in body fat mobilization in the form of non-esterified fatty acids (NEFA). This results in products such as beta- hydroxybutyrate (BHB A) accumulating from incomplete oxidation of NEFA (Vazquez-Añon et al ., 1994). Neutrophils (PMN) are the main leukocyte type involved in clearing bacteria after uterine infection; however, during the period of negative energy balance, dairy cows experience a reduction in PMN function, including reduced phagocytosis and killing capacity. This reduction is more pronounced in cows that develop uterine disease. Glycogen is the main source of energy for PMN phagocytosis and killing; calcium is an important second messenger for PMN activation; NEFA is associated with impaired PMN oxidative burst activity; and BHBA redu ces PMN phagocytosis, extracellular trap formation, and killing of bacteria. If the immune system is not ab le to eliminate bacterial infection, disease is established. Pathogenic bacteria associated with metritis and endometritis are E. coli , A. pyogenes , F. necrophorum , and P. maleninogenicus . E. coli increases the susceptibility of the endometrium to subsequent infection with A. pyogen es, and A . pyogenes acts synergistically with F. necrophorum and P. melaninogenicus to enhance the severity of uterine disease. Among their effects, E. coli releases bacterial-wall LPS; A. pyogenes produces the cholesterol-dependent cytotoxin pyolysin and a growth factor for F. necrophorum ; F. necrophorum produces a leukotoxin; and P. melaninogenicu s produces a substance that inhibits phagocytosis. A specific E. coli , called EnPEC/IUEC, causes uterine disease, and the virulence factor fimH was mostly associated with disease. For A. pyogenes , fimA was the only virulence factor associated with uter ine disease. The combined effect of bacterial infection and activation of inflammation is damage to the endometrium and embryo, delayed ovulation, shortened or extended luteal phase after ovulation, increased time to first insemination, decreased conception rates, increased time to conception, and increased pregnancy loss.

Association between immune function and development of uterine disease in dairy cows

The transition to lactation (3 weeks before to 3 weeks after calving) is char acterized by a decrease in dry-matter intake (DMI), lead ing to a sharp decrease in glucose and calcium, and an increase in body fat mobilization in the form of non-esterified fatty acids (NEFA). This results in products such as beta- hydroxybutyrate (BHB A) accumulating from incomplete oxidation of NEFA (Vazquez-Añon et al ., 1994). Neutrophils (PMN) are the main leukocyte type involved in clearing bacteria after uterine infection; however, during the period of negative energy balance, dairy cows experience a reduction in PMN function, including reduced phagocytosis and killing capacity. This reduction is more pronounced in cows that develop uterine disease. Glycogen is the main source of energy for PMN phagocytosis and killing; calcium is an important second messenger for PMN activation; NEFA is associated with impaired PMN oxidative burst activity; and BHBA redu ces PMN phagocytosis, extracellular trap formation, and killing of bacteria. If the immune system is not ab le to eliminate bacterial infection, disease is established. Pathogenic bacteria associated with metritis and endometritis are E. coli , A. pyogenes , F. necrophorum , and P. maleninogenicus . E. coli increases the susceptibility of the endometrium to subsequent infection with A. pyogen es, and A . pyogenes acts synergistically with F. necrophorum and P. melaninogenicus to enhance the severity of uterine disease. Among their effects, E. coli releases bacterial-wall LPS; A. pyogenes produces the cholesterol-dependent cytotoxin pyolysin and a growth factor for F. necrophorum ; F. necrophorum produces a leukotoxin; and P. melaninogenicu s produces a substance that inhibits phagocytosis. A specific E. coli , called EnPEC/IUEC, causes uterine disease, and the virulence factor fimH was mostly associated with disease. For A. pyogenes , fimA was the only virulence factor associated with uter ine disease. The combined effect of bacterial infection and activation of inflammation is damage to the endometrium and embryo, delayed ovulation, shortened or extended luteal phase after ovulation, increased time to first insemination, decreased conception rates, increased time to conception, and increased pregnancy loss.(AU)

Postpartum uterine diseases in dairy cows

Uterine diseases in dairy cows can be classified as puerperal metritis, clinical metritis, clinical endometritis, and subclinical endometritis. These diseases are highly prevalen t (affect between 20 and 30% of dairy cows) in high producing dairy cows and have been associated with decreased pregnancy per artificial insemination (AI), extended interval to pregnancy, increased culling, and economic losses. Puerperal metritis is characterized by the presence of an abnormally enlarged uterus, a fetid watery red-brownish uterine discharge associated with signs of systemic illness, and fever (>39.5 o C) within 21 days in milk (DIM). Animals without systemic signs but with an enlarged uterus and a fetid uterine discharge within 21 DIM may be classified as having clinical metritis. Clinical endometritis is characterized by the presence of purulent (>50%) uterine discharge after 21 DIM or mucopurulent (50% pus, 50% mucus) after 26 DIM. In the absence of clinical endometritis, subclinical endometritis is defined by the presence of >18% neutrophils (PMN) in uterine cytology samples collected between 21 and 33 DIM or >10% PMN between 34 and 47 DIM. The main risk factors are dystocia, twins, retained placenta, stillbirth, abortion, prolapsed uterus, and ketosis. Metritis can be successfully treated either by systemic or intrauterine antibiotic treatment. Ceftiofur hydrochloride (Excenel ® ) intramuscularly or ceftiofur crystalline-free acid (Excede ® ) subcutaneously are effective in treating metritis, and oxytetracycline intrauterine is effective in abrogating the negative effects of metritis on milk yield and fertility. Intrauterine administration of cephapirin benzathine (Metricure ® ) is an effective treatment for clinical and subclinical endometritis, although not approved in the United States. Administration of PGF2 α does not seem effective for th e treatment of clinical or subclinical endometritis.(AU)

Economic aspects of applying reproductive technologies to dairy herds

Reproduction continues to be a critical component to maintain a dairy farm economically viable. For every farm and for every cow, there is an optimum time for pregnancy, which is mostly influenced by level of production, persistency of lactation, and parity. In general, as production decreases, lactation number increases, and persistency of lactation decreases, cows should be bred sooner postpartum and pregnancy obtained early in lactation. The voluntary waiting period is determined based on the desired interval postpartum to pregnancy and the pregnancy rate of the farm. As pregnancy rates increase, the voluntary waiting period can be delayed, particularly when milk production is high. Studies in the literature have compared several breeding strategies to obtain a pregnant cow. In general, pregnancies obtained by artificial insemination are cheaper than those originated by natural service. The major reason is that AI programs result in similar or better reproductive performance and are cheaper to implement than natural service programs because of the high costs of acquiring and feeding bulls. Within the AI program, those that incorporate timed AI for first insemination followed by detection of estrus result in lowest median days open and more profit per cow, and the benefits of improving reproduction are greater when milk prices ar e low. The use of embryo technologies as a breeding program for lactating dairy cows, with the aim to improve reproductive performance, is only attractive when the differential in fertility relative to AI is large. In most cases, AI programs have to result in very poor fertility (<15%) for the typical results from embryo transfer (40-45% pregnancy) to be economically attractive at current costs. For dairy heifers, there is littl e justification to incorporate timed AI programs when detection of estrus is excellent, above 70%; however, for farms with detection of estrus below 60%, either timed AI for first AI followed by detection of estrus or timed AI alone improve reproductive performance and reduce the cost per pregnancy.

Economic aspects of applying reproductive technologies to dairy herds

Reproduction continues to be a critical component to maintain a dairy farm economically viable. For every farm and for every cow, there is an optimum time for pregnancy, which is mostly influenced by level of production, persistency of lactation, and parity. In general, as production decreases, lactation number increases, and persistency of lactation decreases, cows should be bred sooner postpartum and pregnancy obtained early in lactation. The voluntary waiting period is determined based on the desired interval postpartum to pregnancy and the pregnancy rate of the farm. As pregnancy rates increase, the voluntary waiting period can be delayed, particularly when milk production is high. Studies in the literature have compared several breeding strategies to obtain a pregnant cow. In general, pregnancies obtained by artificial insemination are cheaper than those originated by natural service. The major reason is that AI programs result in similar or better reproductive performance and are cheaper to implement than natural service programs because of the high costs of acquiring and feeding bulls. Within the AI program, those that incorporate timed AI for first insemination followed by detection of estrus result in lowest median days open and more profit per cow, and the benefits of improving reproduction are greater when milk prices ar e low. The use of embryo technologies as a breeding program for lactating dairy cows, with the aim to improve reproductive performance, is only attractive when the differential in fertility relative to AI is large. In most cases, AI programs have to result in very poor fertility (<15%) for the typical results from embryo transfer (40-45% pregnancy) to be economically attractive at current costs. For dairy heifers, there is littl e justification to incorporate timed AI programs when detection of estrus is excellent, above 70%; however, for farms with detection of estrus below 60%, either timed AI for first AI followed by detection of estrus or timed AI alone improve reproductive performance and reduce the cost per pregnancy.(AU)