Uterus - Inflammatory Pathology
INFLAMMATION
Inflammation of the uterus may be infective or non-infective and in either case is influenced by hormonal factors.
- Endometritis = Inflammation of the endometrium
- Metritis = Inflammation of the whole uterine wall
- Placentitis = Inflammation of the foetal attachment point of the uterine wall
- Endometrosis = Chronic endometritis (mare)
- Pyometra = Accumulation of pus in the uterine lumen
INFECTIVE INFLAMMATION OF THE UTERUS
Main routes of infection
- Via the cervix at oestrus or parturition.
- Haematogenous, mainly in the pregnant uterus.
Defence mechanisms
- Closed cervix except at oestrus and post-partum.
- Mucous secretions.
- Leucocytosis of oestrus.
- Oestrogen levels at oestrus render the uterus unsuitable for the growth of certain organisms.
Infection at mating
- First mating may lead to mild non-specific endometritis and infection is usually rapidly cleared by neutrophils.
- Infected semen via AI or natural infection can lead to apparent decreased fertility or abortion/stillbirth.
Post-partum
- Infection of the non-pregnant uterus is usually via the vagina after parturition or abortion, there is increased risk if retained placenta, dystocia or failure of involution (in the bitch).
Cow: A. pyogenes, Fusiformis, S. aureus, E. coli
Sheep: Clostridia.
Bitch/queen: E. coli, Staphylococcus, Streptococcus.
Mare: Strep. zooepidemicus, E. coli, Pseudomonas, Klebsiella (may also occur as a result of chronic endometritis unrelated to parturition).
Gross lesions
Foul smelling dark red/yellow uterine contents with placental debris and ulcerated and congested haemorrhagic mucosa. Fibrin tags present on serosal surface.
Sequelae
- Septicaemia - fever, depression
- Embolic spread - endocarditis, renal infarcts
- Ascending infection - salpingitis
- Descending infection - cystitis and pyelonephritis
- Chronic endometritis
- Pyometra - cow may be associated with persistent CL, i.e. uterus is susceptible to infection but the cervix is closed.
(Pyometra may also occur as a result of mechanical obstruction of the cervix, e.g. by scar tissue as a result of prolonged endometritis or dystocia. In dog and cat pyometra is usually associated with cystic hyperplasia of the endometrium ).
Information by permission of Professor RW Else