Normal and impaired postpartum uterine function in the cow Flashcards
Define puerperium.
Time from parturition until the complete uterine involution and resumption of regular oestrus cycles, with normal oestrous behaviour
also known as immediate postpartum period
Average duration of the postpartum period (PP) is 45 days.
Most critical time in uterus point of view.
The puerperium.
Describe normal uterine involution.
Significantly longer in pluriparous (40.6 days) than primiparous (34.0 days).
Average duration of the postpartum period (PP) is 45 days.
Diameter of the previously gravid horn usually halved by 5 days and its length halved by 15 days.
Whole uterus is usually palpable per rectum by 8 - 10 days.
Restoration of the endometrium: during the first 7 - 10 days PP there is noticeable loss of fluid and tissue debris (lochia). Should be gone by 18 days PP at the latest.
The source of infection of the uterus is from
the environment.
Microorganisms ascend the genital tract at parturition and during the puerperium through the relaxed perineum, vulva and dilated cervix.
NB there are always exceptions
Main driver of uterine involution?
PGF2 alpha
Massive release of PGF2alpha occurs during 2 - 3 weeks postpartum.
How does uterine contamination with bacteria after parturition affect uterine involution?
The inflammatory process activates the arachidonic acid cascade and large amounts of PGF2alpha are formed which is an indicator of infectious process and cellular destruction of tissue.
When does FSH secretion resume after parturition?
within 5-20 days
Prior to calving the high steroid production by the placenta suppress LH and FSH synthesis and content in the anterior
pituitary gland.
The critical factor determing when the first ovulation takes place postpartum is
attainment of an LH pulse frequency similar to the follicular phase of the
cycle.
LH pulse frequency in the postpartum cow is regulated by nutrition, body condition score and suckling.
Low LH pulse frequency postpartum causes
the first follicle to become atretic and a second dominant follicle develops.
Without conception - the luteal phase lasts about
6 days.
Metritis can affect the following tissues: (3)
endometrium
myometrium
perimetrium
Pyometra is a purulent inflammation of the endometrium.
Acute metritis usually occurs within what timeframe after calving?
usually during the first 20 days postpartum, is of course clinical (as opposed to subclinical).
Detectable by rectal palpation, a vaginal discharge may be present.
after d20 pp its chronic
Chronic metritis usually occurs within what timeframe after calving?
after day 20 postpartum, can be either clinical or subclinical presentation.
When clinical, is detectable by rectal palpation, a vaginal discharge may be present. When subclinical, is not detectable by rectal palp.
before d20 pp its acute
Describe metritis in cattle.
Is a severe inflammatory reaction of all the layers of the uterus.
Animals are usually septicemic with overt signs of illness such as feve, depression, weakness, inappetence.
Usually occurs soon after calving.
Severe toxic metritis is often caused by what bacterium?
Clostridium spp.
Describe pyometra in cattle.
Purulent infection of the uterus with a closed cervix.
There are few if any overt signs of illness.
Corpus luteum producing P4 contribute to pyo development.
The presence of what predisposes to pyometra in cattle?
The presence of a corpus luteum which puts the uterus under the influence of progesterone and can lead to pyometra (the uterus lacks PGF2alfa which would aid in not developing pyo).
P4 also depresses phagocytic activity.
Describe endometritis in cattle.
Most commonly when bacteria contaminate the uterus during calving or during the early postpartum period.
Contamination of the postpartum uterus is rather common.
Describe synergism between bacterial species that contaminate the postpartum uterus.
Together, some induce abcessation.
Some cause tissue destruction.
Some circumvent host immune defence mechanisms.
Some produce collagenase.
Some produce growth factor for another bact.
Some produce exotoxins that kill leukocytes.
How to identify a uterine infection in cattle. (5)
rectal palpation - most common, least sensitive & non-specific
vaginoscope
uterine fluid culture - most costly, takes time
endometrial biopsy - expensive and complex
endometrial cytology - good option, used in the mare more than in cattle
Endometrial biopsies can be used for (2)
for detection of bacteria in the uterus
for assessment of clinical and subclinical status of the endometrium (histology)
Main indicator for endometritis is a diffuse cellular reaction involving the mononuclear cells (immune cells). Count the immune cells in 6 fields, calc. the average.
Rules for biopsy collection for bacteriology: (3)
Hygiene (animal and collection), and instruments which allow the keeping of good hygiene.
Fixation media, which provide good conditions for both anaerobic and aerobic bacteria.
Good skills or qualifications for cultivation of samples and identification of isolates.
Uterine effects on fertility.
Uterine infections are a main cause of infertility, they:
increase days “open” aka not pregnant
decrease conception rates
prolong calving intervals
increase culling rates
increase reproductive disorders like ovarian cysts
decrease milk production
Few topic are more controversial among clinicians than treatment of uterine infections in cattle. Why?
Lack of precise diagnostic criteria and lack of controlled trials in which various therapeutic options have been precisely compared.
Many opinions that type of treatment has little effect on the outcome of the disease.
Basic principle in veterinary medicine = the earlier an abnormality is diagnosed and treatment is provided, …?
the faster is the animal return to a normal state of health.
General principle of therapy of endometritis is to halt and reverse inflammatory changes that impair fertility (reduce the load of pathogens, enhance the process of uterine defence and repair).
Treatment strategies for postpartum metritis and endometritis in cattle. (3)
Intrauterine therapy
Systemic antibiotics and supportive therapy
Hormone therapy
Choosing an appropriate treatment of postpartum metritis or endometritis depends on understanding the classification scheme for the disease.
Describe hormone therapy for uterine infections in cattle. (4)
PGF2alfa and it analogues
Objective is to induce estrous cycles = increase in estrogen levels
Effects:
Stimulates uterine tone to aid in evacuating abnormal contents
Increases production of mucus that contains host defence compounds
Induces estrous, which induces luteolysis, reduces progesterone levels, which we know contribute to infection persisting.
When should you not use PGF2alfa hormone therapy for uterine infections?
And when should you and how often?
Don’t use during the 1st week postpartum cause early postpartum treatment (8 – 15 days PP) seems to have lower efficacy according to studies.
Instead use in cows with chronic endometritis after day 25 PP, and mostly used twice (interval of 14 d between injections or 2 consecutive days).
Describe antibiotics for uterine infections in cattle.
Extensive arguments whether AB are even beneficial in case of metritis and endometritis.
Main concern is residues in milk and/or bacterial resistance!
+ Local Intrauterine versus parenteral treatment
Describe intrauterine AB tx of uterine infections in cattle.
You must consider factors that affect the efficacy of drugs inside of the uterus, e.g.:
Days postpartum
Uterine condition
Uterine tissue absorptive capabilities
Drug distribution
The completely involuted uterus has better absorptive capabilities than immediate PP uterus.
Endometritis also makes uterine uptake of the AB not very good. The AB can also locally irritate the uterus further due to not being absorbed properly.
Describe systemic AB usage for uterine infections.
More advantageous than intrauterine which doesn’t work that well.
Provides better drug distribution to all layers of the female genital tract and ovaries whereas intrauterine is absorbed poorly by inflamed endometrium.
Prevents iatrogenically induced contamination of the uterus and injury to the endometrium.
Avoids interference of leukocyte function.
Use penicillin (option for endometritis, postpuerperal metritis, toxic puerperal metritis) or oxytetracycline (cows suffering from less severe form metritis).
Some might opt for ceftiofur, 3rd gen. cephalosporin because its broad spectrum and reaches all uterine layers leaving no residues in milk.
Cows with metritis that have fever and systemic signs should be treated how, with what?
Should be treated systemically with penicillin, oxytetracycline or ceftiofur (3rd gen. cephalosporin).
Cows with metritis without fever do not require antibiotic treatment and can be managed with prostaglandins (e.g. cloprostenol or dinoprost PGF2alfas).
Prevention is better than treating!
