Prolonged interestrous intervals

  • If the interestrus interval is prolonged, it implies that the pregnancy recognition signal was received, but the pregnancy was subsequently lost. This results in a heat cycle that is greater than 21 days long.
  • If we make a diagnosis of pregnant followed by a later diagnosis of non pregnant, this also indicates embryonic death (assuming our pregnancy diagnosis method is accurate).
  • The terms early embryonic death (EED) has been used for years to indicate that the pregnancy was lost after the pregnancy recognition signal. As earlier pregnancy diagnostic methods become available, this will be termed late embryonic death and EED will be used for embryonic loss before the pregnancy recognition signal, which would result in a normal 21 day interestrus interval.
Iatrogenic cause of Early Embryonic Death
  • This loss is commonly around 1-7%.
  • One study says that palpation of the fetal membrane slip resulted in more lost pregnancies, however there was a significant difference among the palpators in the study. This indicates that the skill of the examiner makes a difference.
  • We found no evidence at the University of Minnesota in the teaching herds investigated there.
  • Another study showed that pregnancy rates decreased, but only minimally, and the cows were checked twice between 42-46 and 46 days of gestation.
  • When the cows are checked makes a difference. If you examine cows at 30 - 45 days, then you will probably see a higher embryonic loss. This is because you are getting more of the ones that would have been lost anyway. If you check at 60 days, all those that are lost through 60 days are never diagnosed pregnant. Are you causing the loss????....probably not.
  • If palpation is compared to noninvasive methods of pregnancy diagnoses, the embryonic loss rate is not different. (Theriogenology 66 (2006) 667.)
    • 258 cows pregnant by ultrasound 29-32 days- one FMS - Embryonic loss 14.7%
    • 262 cows pregnant by ultrasound only 29-32 days- Embryonic loss 13.47%
    • Cows - 16.4% > heifers 8.8%
  • We can generally conclude that gentle palpation does not cause embryonic death.

Venereal Diseases
  • There are two common venereal diseases in cattle, Trichomonas fetus (Tritrichomonas fetus) and Campylobacter fetus. They cause similar diseases and may be in a herd together.
Trichomonas fetus (Tritrichomonas fetus)
  • This is protozoan.
Clinical signs
  • You see a herd infertility, and a prolonged calving season with a reduced calving rate.
  • Post service pyometra or abortion are rare, postservice pyometra is almost pathognomonic for the disease.
  • Trich. was isolated in 50% of all cases in California when Trich. was in the list of rule outs.
  • When an infected bull contaminates a susceptible female, Trich. localizes in the vagina, uterus, and oviduct causing vaginitis and endometritis. You may see some discharge. At this point there is no conception failure or interference with the conceptus.
  • However, about 50 days post-service the cow has inflammation of uterus which causes the embryo to die.
  • The cow remains infected 2-6 months (some cows remain infected the duration of pregnancy)
  • Eventually the cow gains immunity that lasts 2-6 months (this means that they may be susceptible again next year).
  • The carrier state decreases with time and is usually eliminated after 2 estrous cycles (is it cycles or time???)
  • An infected cow may carry a calf to term and remain a carrier into next breeding season. This allows herds to remain infected.
  • Males are usually asymptomatic
  • The organism localizes in the penile crypts, prepuce, and anterior urethra. Since the crypts get deeper as the bull gets older, bulls greater than 4 years old become chronic carriers, whereas bulls less than 4 years old may have spontaneous recovery or immunity.
  • Diagnosis is by isolation of organisms from the animal.
  • It is commonly found in the pyometra fluid of postbreeding pyometras. The organism is in the abortion fluids (amnion, fetal stomach).
  • Culturing the cervical vaginal mucus culture gives poor results. (5/280 in CA study)
  • In males the preputial smegma can be cultured. The sample can be obtained by inserting a dry A.I. pipette into the preputial fornix and scraping the prepuce while aspirating the smegma. The sample is transported in special "pouch" or Lactated Ringers and cultured in Diamond's Media. The media is examined at 400 power in 24 and 48 hours (examine bottom layer in tube) to look for organisms. The test is not diagnostic if the culture is negative, but any positive culture is diagnostic. You need 3 negative cultures at 1 week intervals to be 90% sure the bull is free of the organism.
  • A PCR test is available - Transport in the InPouch TF kit
    • The "In Pouch" system for transport and culture gives improved recovery. (

Click for information


  • Louisiana Animal Disease Diagnostic Lab Guidelines for Tritrichomonas Testing - click to link to lab site


  • Dimetridizole works, but is illegal in food animals in the US. It is given orally for 5 days. The cost is about $125/bull. It has a bad taste and there may be resistant strains.
  • Ipronidazole
    • This drug is also illegal for food animals in the US. To use, give a pretreat of 15,000 I.U./lb. penicillin for 2 days to decrease the Micrococcus organisms that destroy the imidazole ring.
    • It was found to be 100% effective in 30 bulls cultured weekly in California.
    • The cost is about $24/bull.
  • Acriflavine (Bovoflavin) is not available in U.S.. It is applied locally. The treatment is time consuming and no efficacious. It may however be tried for resistant strains. You can use the bull after a negative culture 45-60 days post treatment.
  • Sexual rest for 2-3 heat cycles will usually clear the establish resistance.
  • Control measures include:
    • depopulation,
    • using A.I.,
    • maintaining an exposed and an unexposed herd (difficult),
    • sexual rest 90 days postpartum with isolation of the unexposed group,
    • selective culling and use young bulls,
    • cull open cows,
    • test bulls as a herd survey method, and
    • vaccination .

  • The vaccine is a whole cell vaccine made by Fort Dodge. 


    • Two doses recommended. One month and 5 to 7 days before exposure
      • Compliance is probably low, leading to ineffectiveness
    • It helps clear the infection in weeks (vs months for natural) and decreases infection rate and increases pregnancy rate. It appears not to help eliminate the disease in bulls. Vaccinated cows clear infections sooner. The vaccine is given twice initially, then an annual booster.
    • Comments by veterinarians say it is better than nothing, but not by much.

  • Keep a closed herd, so infection cannot be introduced.
  • Test bulls 3 times before entry into the herd.
  • Use virgin bulls if possible on clean cows.
  • Isolate new females for 90 days (2 heat cycles) to clear any infection.

Campylobacter fetus ss. fetus (Vibriosis)

Clinical signs

  • Infertility is seen in 50% of cases. You also see a delayed return to estrus indicating embryonic death in 50% of cases.
  • The semen and the vibrio enter the cervix at coitus. On the first exposure the organism kills the ova. On the second exposure the ova survives. About 50% of the ova are destroyed by 14 days, so the heat cycle is normal.
  • The Vibrio is in the cervical mucus 3 weeks to 3 months. Eventually immunity is established after several breedings. The immunity lasts about 1 year (cows can be reinfected 2-3 years later).
  • Bulls are infected by a carrier cow and the Vibrio grows in the penile crypts. The is no immunity, but the infection is eliminated during the non-breeding season. There is no direct effect on bull fertility, but a bull may become exhausted from over-breeding, since the cows keep coming back into heat.
  • A tentative diagnosis can be made when you see repeat breeding cow and a long calving season. Pregnancy rates will be 20-30% after 60 days of breeding. You may see high pregnancy rates in heifers bred to virgin bulls and low pregnancy rates in first calf heifers. This is because the virgin heifers and bulls have no exposure and the first calf heifers have no immunity when exposed to the herd breeding situation.
  • To confirm a diagnosis a cervical vaginal mucus culture 3 weeks to 3 months post infection can be taken. Keep the culture no dry ice if it is longer than 6 hours to get it to a lab. Culture in Clark's medium. The first positive culture is diagnostic of herd infection.
  • The cervical vaginal mucus agglutinins are of no value, because false positives are common if the samples are taken during metestrus.
  • In the bull a preputial wash and culture can be performed. Again, you need several attempts as false negatives may occur.
  • The virgin heifer test uses a breeding by a suspect bull to a virgin heifer. You culture the cervical vaginal mucus 3 weeks post breeding.
  • Control measures include A.I. and vaccination. You should vaccinate cows 30-90 days before breeding, and then booster annually. Using the vaccine in bulls is experimental only and may decrease fertility.
  • Vibrio-Lepto-5
  • Streptomycin is currently unavailable. The dose was 10 mg/lb subcutaneous for 10 days and ; 5 mg of a 50% solution locally for 5 days. The animals are susceptible to re-infection.
  • Vaccination may hasten recovery.
A summary of Trichomoniasis and Vibriosis

Hemophilus somnus 367-368
  • Hemophilus is a gm negative nonmotile, nonsporulating coccobacillus.
  • Normal vaginal flora
Clinical signs
  • Prolonged interestrous intervals were seen in a group if cows that cultured positive in the cervical mucus.
  • Infertility was seen in a poorly managed dairy herd. Cervical mucus cultured positive and the bull cultured positive.
  • Need pure culture and inflammation present to diaganose
Treatment of cows and bull and better management corrected problem.
  • Seven months later there were no positive cultures and fewer problems in the herd. Was it management primarily??
  • Vaccine??? 


contributed by Bruce E Eilts and modified  on 9 October 2007

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contributed by Bruce E Eilts on 25 September 2012


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