Bovine Viral Diarrhea Virus and Cattle Health

Infectious Infertility & Abortion in Cattle

• Infectious infertility and abortion in cattle are significant issues affecting animal reproductive efficiency.
• Reproductive issues can range from mild decreases in fertility to complete abortion storms.
• Specific infections can cause fertilization failure, embryonic death, or fetal death (after day 42 of gestation).
• These infections may impact the embryo/fetus, uterine environment/placenta, or corpus luteum (CL).

Pregnancy Loss

• Embryonic death occurs before day 42 of gestation.
• Fetal death occurs after day 42 of gestation.
• Abortion (most common) is the expulsion of a dead fetus.
• Stillbirth refers to a full-term fetus born dead.
• Mummification is the preservation of the fetus as a dry, contorted mass due to placental fluid resorption.
• Maceration is the progressive bacterial digestion of a dead fetus.

Risk Factors for Embryonic Death

• Heat stress
• Dietary protein deficiency
• Genetic merit of cows
• Milk yield
• Subnutrition (negative energy balance)
• Low progesterone concentrations
• Infections (Trichomoniasis, Campylobacteriosis, IBR, BVD, Leptospirosis)
• Subclinical endometritis
• Salpingitis
• Mastitis
• Genetic gamete defects

Abortion

• Abortion is the termination of a pregnancy with fetal death and expulsion.
• It is often a result of infection.

Stillbirth

• A stillbirth is the birth of a full-term dead fetus.
• The lungs of the fetus will not float in water. (indicating lack of respiration).

Fetal Maceration

• Fetal death occurs without abortion, with bacterial digestion.
• No placentomes and less fetal fluid in the uterus.
• The cow may display fetid vaginal discharge and septicemia.
• CL persistence and chronic endometrial damage are often associated.
• Treatment options include slaughter (for valuable animals) or PGF2a or colpotomy.

Fetal Mummification

• Fetal death occurs, with CL persistence.
• No clinical signs are present.
• Fetal membranes are dry and wrinkled (placental fluid resorption).
• The uterus adheres to the fetal shape, forming a dry and contorted mass.
• The cervix stays closed during prolonged gestation.

Fetal Mummification (Additional Detail)

• Mummification becomes noticeable between 3-8 months of gestation.
• Autolysis and fluid reabsorption occur in a sterile environment.
• Umbilical vessels constrict, and the placenta becomes congested.
• There are no placentomes.
• Treatment options involve PGF2a or Colpotomy.

Infectious Infertility Associated Viruses

• Leptospirosis
• Bovine Viral Diarrhea Virus (BVD)
• Infectious Bovine Rhinotracheitis Virus (IBR)

Impact of Infectious Infertility on Reproductive Efficiency

• Decreased conception, pregnancy and calving rates
• Extended postpartum intervals
• Delayed first calving in heifers
• Delayed return to estrus and service
• Increased abortions
• Reduced weaned calf numbers and weights
• Increased culling and replacement rates

Bovine Viral Diarrhea Virus (BVD)

• BVD can cause embryonic death and abortion.
• The outcomes (embryonic death, abortion, congenital defects, and stillbirths) depend on multiple factors, including biotype, genotype, virulence, immunity, stage of pregnancy, and co-infections.
• BVD affects cow's fertility by affecting fertilization failures/embryonic death.
• Issues like oophoritis, granulosa cell necrosis, and delayed follicular development are observed.

Bovine Viral Diarrhea Virus (BVD) (Continued)

• Infection with BVDV NCP (non-cytopathic) occurring within 125 days of gestation can lead to persistently infected calves.
• BVD can cause immunosuppression, affecting innate and cell-mediated immunity, as well as humoral immunity.

Bovine Herpes Virus 1 (IBR)

• IBR is endemic in livestock farming in America, causing clinical diseases after acute infection or viral reactivation.
• IBR can create respiratory and reproductive diseases in animals, including Infectious bovine rhinotracheitis, pneumonia (young animals), effect on embryo, oophoritis, necrosis of CL, abortion.
• Abortion is most common during the 4-month gestational period.
• Conjunctivitis and encephalitis, along with pustular vulvo-vaginitis, can occur as additional problems.

IBR Latency

• IBR has a latency period in nerve ganglia (trigeminal/sacrum).
• Stress can reactivate the virus,
• Dissemination of IBR takes approximately 10 - 17 days.

Oophoritis by BHV1

• BHV1 induces lesions in the ovary (corpus luteum - CL) within 4-9 days post-infection or vaccination.
• This leads to lower P4 (progesterone) concentrations.

Abortion Caused by Infections

• Infections can cause abortion (placental damage and stillbirth).
• The typical abortion time frame is 4-7 months of gestation, but it can also occur weeks or months after infection.
• Infections can result in stillbirths, weak calves, and mortality in young calves.

Diagnosis of Infectious Issues

• Diagnostic methods include PCR, virus isolation, antigen capture ELISA (ACE), and serology (ELISA, SN).
• Fetus tissues such as the kidney, liver, adrenal glands, and lungs are often analyzed.

Bovine Respiratory Disease Complex

• Multifactorial and polymicrobial diseases cause significant economic losses.
• Low feed conversion and yield, high treatment costs, and mortality.
• Stressed calves (young, weaned, transported) are at higher risk.

Vaccination Effectiveness

• Vaccines can be effective tools to prevent abortion and infertility.
• Factors including stress, extreme climates, nutrition, infectious pressure, vaccination route, age at vaccination, and vaccine management affect vaccine effectiveness.
• Attenuated vaccines offer higher and longer-lasting antibodies and may reverse virulence but pose a risk of contamination and immune suppression. In contrast, inactivated vaccines may be safer with lower risk of contamination.

BVD Vaccination Evidence

• BVD Vaccination studies show a mixed range of results with regard to abortions and infection rates, but generally indicates that modified-live virus vaccines show a greater efficacy compared to inactivated viruses, especially with regard to the long term efficacy of the vaccination.

Leptospirosis

• Leptospira is a zoonotic bacterium that causes septicemia and nephritis in young animals.
• There are over 200 serovars and it persists in kidneys and genital tract.
• Leptospira can cause infertility, repeat breeding, prolonged pregnancy complications and abortions in animals.
• Contaminated standing water is a major source of infection.

Campylobacter & Tritrichomonas

• Campylobacter and Trichomonas are obligate pathogens of the bovine genitalia, commonly spread through venereal transmission.
• These microbes can also lead to infertility and sporadic abortion in cattle.
• Bulls are asymptomatic carriers, and young bulls can clear the infection in weeks, while mature bulls are chronic carriers.
• These bacteria do not directly impact early embryonic development but can cause inflammation that results in fetal death (15-80 days).
• Cervix and vagina sites remain infected, leading to infertility and lower pregnancy rates.

Neosporosis

• Neospora caninum is a protozoan that can cause abortion, weak calves, and stillbirths in cattle.
• It also can result in encephalomyelitis and myositis in dogs.
• Infection can be transmitted either endogenously (through birth) or exogenously (through ingestion).

Biosecurity Measures

• Quarantine and isolate animals with high reproductive performance problems.
• Identify and screen animals for infectious diseases.
• Employ treatments such as antibiotics.
• Avoid crowding animals, especially dairy heifers.
• Isolate sick animals and abortions.
• Prevent access to standing water
• Disinfect boots in animal areas.
• Limit contact with wild animals
• Quarantine new bulls and perform a diagnosis for Campylobacter and Tritrichomonas before introducing them to the herd.

Vaccination Protocols (Heifers & Cows)

• Heifer vaccination protocols involve multiple modified-live virus (MLV) vaccinations.
• Cows require vaccination protocols that involve MLV followed by an inactivated vaccine.

This quiz explores the impact of Bovine Viral Diarrhea Virus (BVD) on cattle fertility and overall health. It covers symptoms, consequences of infection during pregnancy, and related infectious infertility concerns. Test your knowledge about BVD and its implications for cattle management.