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.
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
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.
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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.
