Extreme cystic endometrial hyperplasia

Keywords: feline, uterus, CEH, hyperplasia

The uterus of an adult domestic long haired cat. 

Image size: 1000 x 1333px. Author and owner of copyright: Dr Stephanie N. Simpson (stephanienicolesimpson@gmail.com)

The cat was presented in good health with a mildly distended abdomen. When its uterus was exteriorized, this appeared to be a case of pyometra. However after hysterectomy and upon opening the uterus, no pus was present. Instead, the enlargement of the uterus had been caused by the remarkably distended cystic structures shown here. Because of financial constraints, the histology of the uterus was not examined. In the absence of histopathology, this was presumed to be an extreme expression of cystic endometrial hyperplasia (CEH). 

The case is remarkable because of the dramatic nature of the CEH.

CEH in cats has been eloquently examined, summarized and referenced by Dr Robert Foster (rfoster@uoguelph.ca) and readers are encouraged to visit his site for more information. 

Essentially, CEH is associated with age and occurs in approximately 20 to 40% of cats where no clinical signs are present. The endocrinology of CEH has been investigated and is thought to be linked to a higher-than-normal expression of estrogen receptors in the endometrium. It frequently occurs in a luteal phase but as for pyometra in this species, not all cases occur after ovulation. In dogs by contrast, elevated progesterone, CEH and pyometra are virtually inseparable.

Prolapsed uterus 

Keywords: uterus, prolapse, feline

A barn cat was captured two weeks after a mass was first seen to be protruding from its hind quarters. The cat had given birth to an unknown number of kittens at a time that could not be exactly determined.

Image size: 533 x 800px Copyright: Dr S. H. Cheong (cheong@cornell.edu)

Due to lack of funding, the prolapse uterus was removed under general anesthetic as a salvage procedure. The stump was then compressed and returned to the peritoneal cavity by external pressure. However, due to concerns for humane treatment of the cat and financial constraints, the animal was later euthanized.

Postmortem examination showed no peritonitis or signs of infection of the surgical stump.

Uterine prolapse in cats is well described in standard texts but it is rare. It can be either bilateral or unilateral. Although there is a single publication of uterine prolapse in a cheetah it is likely that the condition occurs in all felids. Interestingly, the condition is even more unusual in bitches, the literature being practically devoid of well documented cases.

Prolapsed uterus in all animals is almost exclusively a postpartum (or post abortion) condition. Extrapolating from the condition in ruminants where uterine prolapse is common, there is general speculation that its causes are similar in cats i.e. uterine flaccidity due to marginal hypocalcemia, secondary uterine atony and tenesmus. It is remarkable however that cats, due to their reclusive nature in the peripartum period, may survive for long periods after the prolapse has occurred. It would be extremely unlikely for a ruminants to survive under those conditions and the same would be true of sows (uterine prolapse is an occasional condition in sows).

The uterus was amputated externally in this case; amputation being more common as a salvage procedure used in ruminants with severe uterine trauma. In cats it is more common to clean the uterus, suture lacerations and return it to the peritoneal cavity after via laparotomy and internal traction. Before compression is applied to the uterus or attempts are made to replace it, the bladder should be emptied via cystotomy because compression from the swollen prolapse can prevent urination. Perhaps obviously, appropriate supportive treatment is also applied. 

The author wish to acknowledge Dr S. H. Cheong for submitting this unusual case to LORI. 

References:

Nothling, J.O. 2002. Uterine prolapse with an interesting vascular anomaly in a cheetah: a case report. Theriogenology. 58:1705-1712

Ozyurtlu, N. 2005. Unilateral Uterine Prolapse in a Cat. Turk J Vet Anim Sci. 29:941-943

Feline pyometra

Keywords: feline, pyometra, uterus

Case #1. This shelter cat was bright, alert, and responsive upon presentation. Apart from an enlarged abdomen, she appeared normal. No history was available. Financial constraints prevented radiology, ultrasonography, UA, serum chemistry and hematology i.e. common diagnostic tools used to diagnose this syndrome. 

A purulent vaginal discharge was observed and an abdominocentesis produced pus. Laparotomy revealed a markedly enlarged, pus filled uterus.

Image size: 1306 x 1338px Copyright: Dr S. N. Simpson. stephanienicolesimpson@gmail.com

Although this cat appeared to be healthy, it is likely that its condition would have degenerated rapidly over the next few days. Cats with advanced pyometra are often severely dehydrated and debilitated. Vomiting may occur. This cat was dropped off anonymously at the shelter, possible because her enlarged abdomen suggested that she was pregnant. That error that may have saved this animal's life. 

Case # 2: A mature cat of unknown age was presented with a history of anorexia of 2 days duration. This was an indoor-outdoor cat, with no history of estrous activity.  She was febrile (39.8 deg C) and mildly dehydrated. Palpation suggested that a distended uterus was causing abdominal enlargement. Financial constraints prevented additional diagnostic tests.  As shown below, ovariohysterectomy revealed pyometra.

Image size: 426 x 588px. Copyright: Dr Jonathan Spears. jspears@upei.ca

Case # 3: A nine year old Bengal cat that had been nursing kittens for seven weeks was presented with a purulent vaginal discharge. The cat had a normal appetite and was bright, alert and responsive. Yet remarkably, her CBC showed an extremely high neutrophil count (134 x 109/L) with toxic changes, 52 % bands and occasional myelocytes. Her hematocrit and hemoglobin were normal. There was no history of PU/PD.

Because this cat was still suckling kittens and there was no record of postpartum breeding, luteal support for a suspected case of pyometra would have been remarkable. Interestingly, her serum progesterone concentration was 13.3ng/ml indicating that she did indeed have corpora lutea in her ovaries. Although ovulation in the absence of copulation is common in cats, it is statistically more likely that she had been bred than ovulated spontaneously. Cats can show (fertile) estrus within 10 days postpartum. Therefore it is is likely that she had left her kittens, returning to them after being bred by the resident tom cat in this house. Alternatively ovulation in could also have been stimulated by the mere presence of this male (see below).

The uterine contents of the Bengal cat consisted of cell debris and many degenerate neutrophils with a moderate number of intracellular and extracellular rod-shaped bacteria (E.coli?). Neither Gram staining nor culture were performed.

Image size: 648 x 868px  Copyright: Dr Jane Eye. janeeye@fundyvets.com

Cases 3 and 4.

Both tracts (animals and tracts A & B) were from feral cats presented for routine ovariohysterectomy. Neither cat was symptomatic. Because of cost constraints, blood chemistry and hematology were not requested for either cat. Animal A was estimated to be less than one year of age; certainly a young cat, based on the appearance of her teeth. No record was made as to the presence or absence of luteal tissue in this animal. Certainly, pyometra was supported by progesterone in cat B. Her left ovary was transected to reveal three corpora lutea.

Photographic white balance was matched for both images, therefore the tract from cat A is indeed purple and congested in comparison to that of cat B, the older animal. Also interesting is the difference in color of the pus that had accumulated in each animal. The reason for these differences is unknown.

Image size: 1555 x 892px

Interestingly, vaginal cytology from cat A and uterine cytology from cat B showed no bacteria. Presumably most of the bacteria had been phagocytosed by the influx of neutrophils, most of which had undergone karyorrhexis and karyolysis. Only a few partially intact neutrophils were evident in the uterine cytology of cat B (black arrows).  Indeed, data show that vaginal cytology in cats with pyometra will often be devoid of bacteria.

Image size: 1632 x 1238px

Copyright for the images from Cat A belongs to: Dr Deirdre Carver deecraffa@gmail.com

Case # 5

The following image shows the radiographic appearance of pyometra in a cat of unknown breed and age; its enlarged uterus is indicated by arrows.

Image size: 3373 x 2192px

The author acknowledges the assistance of Dr L. Zwicker ACVR in retrieving this image for the LORI collection.

Case # 6

A striking DV radiograph of pyometra in a fifteen year old cat presented for  sudden inappetence. Interestingly, there was no overt vaginal discharge and the cat was bright, alert and responsive, with a normal CBC and and only a mildly elevated BUN.

The smooth-bordered, bilateral, radio opaque masses are pus-filled uterine horns.

Image size: 705 x 720px. Copyright Dr Megan Yanos. myanos@upei.ca.

There was no history of breeding and because the ovaries were not examined during surgery, it was not known if this case of pyometra was supported by a progesterone dominated environment. The uterine horns were distended with 2.26 liters of pus, a figure derived through pre- and postoperative weighing of the cat. Uterine cytology was characterized by a mixture of neutrophils and lymphocytes. No bacteria were isolated. Recovery was uneventful.

________________________


Notes: Pyometra in cats shares many similarities with pyometra in dogs but remarkably and in contradistinction to the situation in dogs, luteal support is often absent in cats. In a recent review, corpora lutea were only present in 40 to 70% of cats with pyometra. Other cats in that review were either anestrus or in a follicular phase.

It is noteworthy that PU/PD appears to occur less frequently in cats than dogs; in less than 10% of cats in one review. However, trends in blood chemistry and cytology are similar to those seen in bitches However, the cases in this LORI entry demonstrate that cytology and clinical chemistry can be quite variable.

Although pyometra can occur in the absence of corpora lutea in cats, data in other species suggests that pyometra in cats is probably exacerbated in a progesterone-dominated environment. In that regard, it should be noted that spontaneous ovulation is common in cats, especially in some individuals, so luteolysis (using prostaglandin) should always be part of medical treatment, even if there is no history of breeding. As mentioned, the well known pheromone effect of  males on induction of ovulation in other species has its counterpart in cats as well i.e. the presence of males can  increase the incidence of spontaneous ovulations in non-mated queens.

Spontaneous ovulations also occur in wild felids therefore the stimulatory effect of males should be considered when housing is planned for those animals. Not surprisingly, pyometra has been reported in captive lions, tigers, ligers (lion x tiger) and leopards. Symptoms, diagnosis and treatment in wild felids are essentially the same as for domestic cats and presumably just as variable!

The value of vaginal cytology for the diagnosis of feline pyometra must be emphasized, especially because all cats are fastidious, eliminating evidence of vaginal discharges.

The progesterone receptor site antagonist aglepristone, has been used safely for medical treatment of pyometra in domestic cats but the author is not aware of it use in wild felids .

In general, E.coli is the principle pathogen involved in feline pyometra but as is the case in canine pyometra, many other bacteria have been isolated.

Selected references:

1.Agudelo CF. Cystic endometrial hyperplasia-pyometra complex in cats. A review. Vet Q. 2005;27:173–182.)

2. Gudermuth, D.F. et al 1997 Incidence of spontaneous ovulation in young, group-housed cats based on serum and faecal concentrations of progesterone.J. Reprod Fert. Supplement. 51:177-184.

3. Nak, D. et al. 2009. Follow-up examinations after medical treatment of pyometra in cats with the progesterone-antagonist aglepristone Journal of Feline Medicine and Surgery (2009) 11, 499-502.

4. Schramm, R.D. 1994. Spontaneous and induced ovulation in the lion (Panthera leo). Zoo Biology. 13:301-307

5. McCain, S. 2009. Pyometra in captive large felids: a review of eleven cases.J Zoo Wildl Med.40:147-51

6. Munro, R and Munro, H.M. 1974. A case report of pyometra in the leopard (Panthera pardus).Br Vet J. 130:175-179.

Uterine rupture and fetal mummification

Keywords: mummified, rupture, uterus, feline.

During routine ovariohysterectomy in a cat, the surgeon encountered a pregnant uterus containing five normal embryos estimated to be approximately 28 days old. A sixth enlargement, its location indicated by the orange ring in the inset below, contained an embryo that had died recently.

Image size: 888 x 629px  Copright: Dr Robin Bain: psah7423108@hotmail.com

Three mummified fetuses (A above and below as well as B and C below) were found outside the uterus.

Image size: 1203 x 868px

Also outside the uterus, was a fetal femur and a structure (D) that resembled a ovarian remnant, containing corpora lutea. There were numerous adhesions between fetuses A and B and the omentum in the left side of the peritoneal cavity, adjacent to the spleen,  Fetus C was found in the right side of the abdomen, not attached to omentum. The face of this mummified fetus is indicated by a yellow ring in image C.side 2.

Histology of structure D showed that it contained luteal-like cells, supporting the contention that it was an ovarian remnant. Macrophages in the specimen were laden with hemosiderin,  also suggesting a traumatic origin for the structure. It is likely that a fragment of the ovary was torn away during the incident that traumatized the rest of the tract.

The dead embryo is shown here, just above the scale and between the other embryos. The other embryos were viable at the time of surgery. On the right side, one of those embryos has been exteriorized, showing its large yolk sac, typical of this stage of gestation.

Image size: 1159 x 553px

Close inspection of the uterus did not reveal any site of rupture that may have released the fetuses into the abdomen. This is not surprising because the uterus has a remarkable ability to heal by first intention after rupture; perusal of the literature indicates that it is not uncommon to find no evidence of a rupture site.

This cat had produced a litter of three or four kittens (the number is uncertain) within the six month period prior to surgery. It is possible that the mummified kittens encountered here, were part of that litter. However, as is evident here, the uterus healed uneventfully after rupturing, and five kittens were currently in gestation. Therefore, the mummified kittens could have been part of any litter that had previously developed in this cat.

A brief summary of extra-uterine pregnancy in various species:

There are two basic forms of extra-uterine pregnancy: primary and secondary. Primary extra-uterine pregnancies are thought to arise from fertilization that occurs in an extra-uterine environment. Secondary extra-uterine pregnancies arise from zygotes that form within the reproductive tract then escape into the abdomen. Although extra-uterine pregnancies are well described and fairly common in women, there is still doubt about the possibility of primary genesis of such pregnancies. However, it is known that extra-uterine pregnancies do form after retrograde movement of tubule pregnancies, rupture of the fallopian tubes (uterine tube/oviduct) after tubule pregnancies and rupture of the uterus in uterine pregnancies. Embryos may also escape into the abdomen when there is incomplete healing after cesarean sections; this has been well documented. True extra-uterine pregnancies are most common in humans. These may even go to term, producing live babies. However, extra-uterine pregnancies of a similar nature also occur in sub-human primates. 

Extra-uterine pregnancies in humans are relatively easy to explain in comparative terms because human embryos show aggressive implantation or nidation providing an ability to implant on surfaces other that the endometrium. Importantly too, human embryos are not required in the uterus for pregnancy recognition. In most domestic animals (apart from carnivora) the presence of the embryo in the uterus is essential to block luteolysis and allow the continuation of pregnancy. By contrast, tubule pregnancies can last for many weeks and as mentioned, extra-uterine pregnancies can even go to term, all in the absence of endometrial signalling.

Extra-uterine pregnancies have also been shown in rabbits, mice, rats and hamsters, all of which have placentation that is more intimate than that of domestic animals. That suggests that they may implant in the abdomen when embryos of domestic species cannot. Indeed, this is the case because embryos of these species can, with varying success implant in muscle, sub-capsular organ tissue, the anterior chamber of the eye and even in testicles! It is not surprising then, to see fairly common reports of extra-uterine pregnancies in rabbits. These may develop well into late gestation but none of the rabbit pregnancies have been known to produce viable neonates (via cesarean section). It is somewhat perplexing however to see how frequently these are reported and then to try and reconcile that with abdominal injury and secondary extra-uterine pregnancies. Perhaps some of these pregnancies arise from retrograde movement of embryos after fertilization in the fallopian tubes. 

Almost certainly, extra-uterine pregnancies in ruminants, mares, bitches, sows and cats (all of which have been reported) are secondary in nature i.e they are the result of uterine rupture. None of these animals have placentas that has been shown to implant on any surface other than the endometrium. In the case reported here and elsewhere in LORI, extra-uterine pregnancies are almost certainly the result of uterine rupture. 

For additional detail see Corpa, J.M. 2006. Ectopic pregnancy in animals and humans.Reproduction.131: 631–640) and the numerous papers that have reviewed in that excellent article. 

Feline uterine rupture and mummification

Keywords: feline, uterus, rupture, mummy

During routine ovario-hysterectomy of a shelter cat, the usual structure of the ovaries and uterine horns could not be defined. The right uterine horn had undergone torsion of 360 degrees. However, on examination, the torsion had been relieved so the direction of torsion was not obvious. Nevertheless, the extent of torsion was deduced from the finding that the horn was found to be lying in approximately its normal position and orientation despite that torsion. Importantly, the left uterine horn was still attached to the left ovary but the cranial half appeared to have been torn from its caudal portion. Also, the uterus was no longer attached to the cervix, presumably torn away as well.

The left kidney was absent.

A partially mummified fetus lay in the left caudal quadrant of the abdomen and there were numerous adhesions between the omentum and both uterine horns. A dorsal view of the specimen is shown below; laid out in its approximate in-situ location. A keyed image is shown below this one. Two masses of unknown origin were also found in the abdomen. These are shown at upper left and right in the image.

Image size: 1522 x 1390 px

Dissection of the specimen revealed the following:

Image size: 1522 x 1390 px

Histology of structures A & B was unrewarding; they consisted of masses of homogeneous to broken eosinophilic hyaline-like material, interspersed with cell debris. In some areas there were thin, lamella like structures that may have been membranes at one time. In summary, these were probably necrotic remains of placental fragments.

The orange ring shows the area of probable tearing in the left horn. The red ring indicates the area where the uterus would have been attached to the cervix and vagina. The fetuses have been numbered.

There were five fetuses in the uterus when it had been severely damaged by an unknown accident. Remarkably, there were no overt suggestions of serious trauma to the cat and it was bright, alert and apparently normal on presentation. Yet, during this accident, possibly a car strike, most of the uterus appears to have been torn from both the cervix and the left uterine horn. At that time, it probably underwent torsion, resulting in vascular embarrassment and fetal death. In one case, the uterus obviously ruptured, releasing a fetus into the abdomen.

Extra-uterine pregnancies are not rare in cats Most are thought to result from trauma during pregnancy. Despite its intimate (hemo-chorial) placentation, cats are highly unlikely to have true extra-uterine pregnancies such as those that occur in humans. In humans, placentation is aggressive and nidation on the peritoneal surface is possible.

The left kidney was congenitally absent, a relatively common finding in cats.

For a brief review of extra-uterine pregnancy see this LORI entry.

The author wishes to thank Dr K Ling, AVC community practice & Ms G. Marsh, AVC 2104 for bringing this case to his attention.

 Feline tract with corpora lutea

Key words: ovary, CL, corpora, lutea, uterus, feline, cat

Image size: 1200 x 671 px

The uterus and ovaries of a mature, cycling queen (female cat). Because of the absence of an ovarian bursa, one is able to see corpora lutea once the tract has been removed; this is not possible in bitches. On the right-hand side of this image, an ovary has been transected to show four corpora lutea. Queens usually ovulate only 4 or 5 oocytes, a number that closely parallels the average litter size in this species.

The absence of an ovarian bursa also allows small pieces of the ovary to fracture off the main structure during ovariectomy and to implant in the abdomen. This is a cause of the ovarian remnant syndrome in cats.