Flashcards in Bovine Deck (459)
How is a diagnosis of mummification made?
Usually made beyond term, time of calving approaches and no imminent signs are seen, general health of dam is unaffected, small hard uterus via rectal exam, no placentomes, no foetal fluids, no fremitus. Blood sample for oestrone sulphate or pregnancy specific protein B will confirm absence of viable foetus.
When does maceration occur?
If luteal regression occurs and cervix dilates but mummy remains in utero maceration follows. Corpus luteum regresses, parturient process begins but fails to run complete course, bacteria enter the partially dilated cervix and by putrifaction and autolysis the soft tissues regress until a compact mass of bones remain.
How is mummification treated?
Injection with PFG2a can be tried to lyse CL and cause expulsion of mummy. not always effective. in most cases mummified calf may be pushed into cervix/ vagina but require manual assistance to remove. Corticosteroids are ineffective when a dead foetus is present.
How is maceration treated?
Rarely attempted because it is rarely effective. Uterus may be manually emptied of bones but smaller ones usually remain and are invariably attached to or embedded within the endometrium where they cause residual chronic inflammation and stop contraception.
How does pre partum metritis and emphysema occur?
Most commonly encountered in the peri partum period, most notably in cases of neglected dystocia. Uterine infection by gas producing bacteria which usually gain access via the cervix. the uterine contents provide an ideal medium for bacterial growth. Bacteraemia renders the dam acutely ill and the conition may be rapidly fatal.
What is hydramnios?
Gradual accumulation of excess volume of amniotic fluid around mid- late trimester, caused by foetal abnormality impairing ability to swallow fluids. Most cases go to term. induction of calving/abortion rarely required.
What is hydrallantois?
The most common cause of dropsy in the foetal membranes, seen in in last trimester, caused by abnormal placental function and normally the foetus is normal. Sudden onset severe abdominal distension in last trimester associated with massive voluume of allantoic fluid up to 250 litres, cow has distended pear shaped abdomen. Fluid accumulation can lead to rupture of pre pubic tendon and compression of abdominal organs. twin pregnancy is main ddx.
What is foetal anasarca and how does it occur?
A grossly oversized foetus may be aborted - up to 3x normal birth weight, it has excessive subcutaneous fluid grossly distorting whole body and will cause dystocia problems. Quite rare. caused by an autosomal recessive gene. Mild hydrallantois and oedema of the foetal membranes may accompany foetal anasarca.
How does a schistosoma reflexus calf present?
Foetus is presented with 4 feet or intestines at vagina of dam and may require partial embryotomy or caesarean section to deliver.
What are the predisposing factors to a prolapse of the vagina/+- the cervix?
Multifactorial but probably a combination of overcondition, abnormal relaxation of pelvic ligaments associated with increased oestrogen levels and other unknown factors.
describe how to replace a prolapse?
Give caudal epidural analgesia 5-8ml lignocaine, clean perineum and prolapsed tissue, lubricate and replace prolapse by steady manual pressure, drainage of urine via a needle catheter by puncturing the vaginal wall may help in some cases, check replacement correct and no damage done during replacement, give antibiotic and NSAID cover if vaginitis present, select method for retaining prolapse.
What methods are there for retaining prolapses?
trusses and harnesses - not really used in cows
Sutures - most common method. Buhners suture is the best suture technique, least traumatic and doesnt induce straining. Sutures MUST BE REMOVED AT START OF PARTURITION.
When do cows usually resume cyclicity after calving?
90% of dairy cows resume cyclicity by 50 days, 70% of beef cows by 50 days.
How is ovulation inhibited during pregnancy?
Waves of follicles develop and become atretic in the ovaries - ovulation is inhibited by high progesterone levels during pregnancy giving negative feedback on the hypothalamus. Following parturition FSH induced waves of follicular growth are soon accompanied by ovulation and return of regular cyclicity.
When can the first dominant follicle be detected after calving?
7-20 days pp in dairy and beef cows.
What controls the time of the first pp ovulation?
FSH present in sufficient amounts to stimulate waves of follicular growth by 10-20 days but ovulation of dominant follicle requires sufficient LH pulse frequency. LH pulse frequency controlled via gnRH pulse generator in hypothalamus. Delay in pp ovulation in beef cows c/f dairy cows due to delay in sufficient lH pulse frequency rather than FSH problem.
How do nutritional effects cause extended anoestrus?
Inadequate energy in late pregnancy early post partum period can cause extended anoestrus due to suppression of LH pulse frequency. NEB in early pp period affects levels of circulating insulin and growth hormone and oocyte quality.
How can suckling extend anoestrus?
Greater impact from natural suckling than milking therefore more effect in beef cows. Frequency and duration of suckling affects LH via opiod release interfering with gnRH output in hypothalamus.
How does the season affect pp anoestrus?
first dominant follicle appears - 20 days pp in spring, 7 days pp in autumn.
What factors cause delayed uterine involution which can influence anoestrus?
Assisted calvings, RFM, metritis etc can cause delayed involution which may delay resumption of cyclicity.
What other conditions may lead to extended anoestrus?
Cystic ovarian disease - cysts form due to failure of ovulation of early dominant follicles and this can delay the next wave of follicular development. persistent corpus luteum - usually found along with uterine infection/pyometra as this can lead to failure of endometrial PGF2a release. Treat with PG injection.
How can nutritional anoestrus be diagnosed?
Palpate two small hard ovaries with no CL or large follicles with similar rectal findings in 10-14 days. or have two low progesterone values in milk or blood recoded 10 days apart.
How can nutritional anoestrus be treated?
sort out management and nutrition.
Progesterone releasing devices for 9-12 days to mimic luteal phase then ovulation within 2-3 days of implant removal.
GNRH injection - single dose of 5ml receptal given >55days pp will give oestrus in most acylic cows within 23 days.
What is the minimum period after pp that cows should be bred?
42 days - before this the pregnancy rates will be poor. (40-60 days).
Which hormone treatments can be given to improve fertilisation rates?
GNRH on day of service. GnRH injection induces an LH surge ensuring ovulation occurs synchronous with the insemination.
GNRH at day 11-12 post service. GnRH causes LH release > luteinisation of large 2nd wave follicles _ ovulation and formation of accessory CLs. This reduces oestradiol secretion from 2nd wave follicles and reduces chance of early luteolysis if embryo is late to produce BTP1..
Describe the OVSYNCH/intercept regime?
A combination of GnRH and prostaglandin can be used to synchronise dairy cows for fixed time AI.
Day 0 - GNRH
Day 7 - prostaglandin
Day 9 - GnRH
Day 10 - AI 72 hours post PG
What is the cause of repeat breeders?
Undiagnosed pathology and failure of fertilisation - hostile uterine environment for sperm, blocked oviduct/salpingitis, delayed ovulation, bursal adhesions, cervical non patency, hostile uterine environment for embryo which dies on entry to uterus.
Failure of sufficient btp-1 production from embryo leading to failure of maternal recognition of pregnancy.
What may cause uterine tears?
Normally associated with dystocia and excessive traction, large calves.
What are the causes of a uterine prolapse?
Normally associated with the delivery of a large calf, prolonged parturition and straining. Hypocalcaemia is often present. Usually occurs within hours of a calf being delivered. most common in multiparous cows.