International Dairy Topics — Volume 13 Number 5 11

by John Dawson, BVMS, MRCVS, CertCHP, Dip. Cattle Footcare, SeniorPartner of Willows Veterinary Groupand Managing Partner of Embryonics.

Uterine infection in the modern dairycow is a common condition affectinga large number of cows and isestimated to cost in excess of £1.4 billionper annum. The detection of infection andeffective treatment is therefore of greatimportance. Early detection and cure allowscows to get back in calf more quickly andproduce higher yields. Results from studiesshow the prevalence rate of clinicalendometritis to be 17% and cows withclinical endometritis took 27% longer tobecome pregnant. There is a significant costincurred by these individual animals, andtherefore identification coupled witheffective treatment has a large cost benefit.

Common around calving

Infection of the uterus occurs mostcommonly around calving when infectiousagents such as bacteria and viruses can enterthe open uterus, although the infection canenter at other times such as during DIY AIand during service by an infected bull. Infection is very common at or around

calving but the uterine environment and thehormonal and immunological influence onthe uterus results in the majority of theseinfections self-curing within a few days. However, higher proportions of persistent

infection occur dependent on the type ofbacteria or virus involved and the health ofthe calving cow. If there is any concurrentproblem such as retained placenta, milkfever, ketosis or the birth of twins at calvingthe stressful influence of these can increasethe persistent nature of the infection andprevent its self-cure.Many uterine infections can be detected by

the herdsman during his daily routine whilstobserving the cows. The white purulentdischarge produced by these infections canbe seen on the tail and rump of the cow orby the presence of purulent discharge onthe cubicle beds. These can be detectedearly and treated. However, many of theinfections cannot be detected from

observation as there is no obvious discharge.Diagnosis of the low grade and non-discharging cases requires an examination todetect the presence of infection. Early detection and timely treatment of the

uterine infection during routine herd fertilitymanagement programs reduces theprevalence in the herd and the impact of thedisease in the individual animal. Cows which are 2-4 weeks calved are

examined during these visits where use ofultrasonography can aid diagnosis. The infected cases can be detected and

treated, effecting an early cure of the uterineinfection before it becomes chronic andrendering the cow permanently infertile orrequiring more extensive treatment. Uterine infection is defined depending on

the time since calving and the state of thecervix.

Metritis

Clinically metritic animals may not besystemically ill but have an abnormallyenlarged uterus, detected by ultrasound(Fig. 1), and a purulent uterine dischargedetectable in the vagina, within 21 dayspost-partum. The cervix is usually open atthis stage and vaginal discharge is usuallyobvious in most cases and detected orsuspected by the herdsman. The metriticcow can often be off colour with signs ofsystemic disease ranging from lower-than-expected milk yield to marked malaise withan elevated body temperature (pyrexia).Animals with this form of disease, termed

puerperal metritis, have an abnormallyenlarged uterus and a fetid watery red-

brown uterine discharge within 21 days ofcalving. Diagnosis by manual examination todetect the vaginal purulent material can bemade in many cases but ultrasoundexamination is required to definitivelydiagnose and to observe the extent ofuterine infection.Metritis commonly affects around 20% of

animals but some herds can have periods ofup to 50% infection rates. Subsequently 15-20% of cases have clinical disease withmalaise beyond three weeks (clinicalendometritis) and up to 30% have chronicinfection without clinical signs (subclinicalendometritis). Therefore treatment ofmetritis at this stage is required to preventescalation of any malaise of the cow andreduce the number of cases developing intoendometritis which prolongs uterineinfection, further reducing fertility.Ultrasonography is of great benefit in

diagnosing metritis in the small percentageof metritic cows that do not show anobvious vaginal discharge. The presence of

Discharge seen on the cubicle bedbehind the cow.

Discharge found during a manual vaginal examination.

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Early detection of uterine infection in the modern dairy cow

White purulent discharge on the tail ofthe cow.

International Dairy Topics — Volume 13 Number 5 13

an observable discharge depends on theshape of the reproductive tract, theopenness of the cervix and the amount ofpurulent material in the uterus.When ultrasound is used the image

displays considerable amount of echogenicmaterial within the uterus. There is a bigvariability of the echogenicity of the materialand amount seen (Figs 1 and 2).

Endometritis

Endometritis is an infection of theendometrium, the inner layer of the uterus.It is diagnosed in cattle that have calvedthree weeks and over. It is very common,with an incidence rate of around 17%delaying return to oestrus or preventingconception. Delay to oestrus is caused bythe interference to the production of theprostaglandin hormone which is producedfrom the endometrium. Prevention of conception occurs by either

the infection killing the sperm or interferingwith its transportation up the uterus or bypreventing implantation of the embryo.The degree and severity of the infection is

extremely variable. In some cases theinfection produces a mucopurulentdischarge which can be seen discharging

from the vulva. In the majority of casesthere is no vulva discharge; diagnosisrequires vaginal and rectal examination todetermine both its occurrence and severity.Many cases have only a small amount ofinfection requiring very careful and detailedultrasound examination to visualise thepockets of infection (Fig. 3). These pockets of infection can be very

small occupying only a very small area of theuterus, all other parts looking normal andempty. The methodical ultrasoundexamination ensuring complete visualisationof the uterus allows these to be detected. Inmany cases, due to the quantity, the uterinemucopurulent content can be identifiedquickly and easily by visualising theechogenic material within its lumen (Fig. 4). In a small number of cases no ultrasound

or gross signs are present. Treatment of this condition is usually by an

intrauterine antibiotic lavage, often requiringmore than one infusion. If a corpus luteum ispresent (Fig. 5) then prostaglandin can beadministered to induce cycling of the cow.Endometritis, by its involvement of theuterine lumen, can prevent oestrus cyclingof the cow. Once prostaglandin has been administered

and oestrus is induced the oestrogenenvironment of the uterus helps the cow’sown immune system to self-clear the

infection and infusion of intra-uterineantibiotic preparations when the cow comesinto oestrus can also help cure the infection.Some cases prove refractory to treatment

requiring modified intrauterine infusions andmultiple infusions.

Pyometra

Infection of the uterus more than 21 dayspost-calving in the presence of a closedcervix. Consequently there is no vaginaldischarge and no clinical evidence on vaginalexamination – the cervix is tightly closed anddoes not allow the mucopurulent uterinecontent to pass. The cow does not cycle asthe infection of the endometrium preventsprostaglandin release. Diagnosis can only bemade by ultrasound examination whichidentifies the mucopurulent uterine infection(Fig. 6). There is a large amount of uterine fluid in

these cases which, if diagnosis is attemptedby palpation alone, can be mistaken for apregnancy. The image reveals theechogenicity of the fluid and the absence ofany foetal membranes or placenta.During pregnancy fluid is present in the

uterus and can feel similar to endometritisand pyometra by palpation. If there is apregnancy complication it cannot be

detected by palpation as the fluid andembryo are present but defective. The ultrasound examination candifferentiate problems by identifying theviability of the embryo with thepresence of a heartbeat, the exact sizeof the embryo and the echogenicity ofboth the embryo and the fluid around it(Fig. 7). Palpation has been thetraditional method of rectal diagnosis ofuterine conditions but misdiagnosis canoccur. Only ultrasound can definitivelydiagnose the condition and its severityallowing the best choice of treatmentsleading to an effective early cure. n

References are available from the author on request

Figs. 1 and 2 show metritic infection with a large amount of material. The echogenic appearance of the material is 1: low and 2:high. Figs. 3 and 4 show pockets of echogenic purulent material within the uterus. Fig. 4 shows a large pocket (Easi-Scanultrasound, BCF Technology).

Figs 5, 6 and 7. Left, Corpus luteum; centre, pyometra; and, right, pregnancy complication(Easi-Scan ultrasound, BCF Technology).

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