A double-blinded randomized placebo-controlled non-inferiority trial protocol for postoperative infections associated with canine pyometra.

BACKGROUND: Pyometra is a common infectious condition, especially in elderly bitches. In addition to an infected uterus, dogs may have concurrent urinary tract infection (UTI). The preferred treatment is surgical removal of the ovaries and uterus, whereupon the general prognosis is excellent. In addition, antimicrobial therapy is frequently prescribed for postoperative treatment. However, no research exists on the benefit of postoperative antimicrobial treatment in uncomplicated canine pyometra. Antimicrobial resistance has become a major challenge in treatment of bacterial infections. Diminishing overuse of antimicrobial agents is essential for controlling the development of antimicrobial resistance in both animals and humans. METHODS: This double-blinded, randomized, placebo-controlled two-arm clinical trial is designed to compare the incidence of postoperative infections associated with surgical treatment of uncomplicated pyometra followed by two different treatment protocols. For the study, 150 dogs presenting with an uncomplicated pyometra and that are to undergo surgical treatment will be recruited. Dogs with body weight < 3 or > 93 kg, complicated pyometra, primary disease increasing the risk of infection, or immunosuppressive medication will be excluded. All dogs will receive one dose of sulfadoxine-trimethoprim intravenously as an antimicrobial prophylaxis. Postoperatively, dogs will be randomized to receive either a five-day course of placebo or an active drug, sulfadiazine-trimethoprim orally. During the surgery microbiological samples will be taken from urine and uterine content. The follow-up includes a control visit in 12 days and an interview of the owner 30 days after surgery. If bacteriuria is detected at the time of surgery, a urinary sample will be cultured for bacterial growth at the control visit. The primary outcome is the incidence of a postoperative surgical site infection (SSI), and the secondary outcome is the occurrence of clinical UTI with bacteriuria. Intention-to-treat and per-protocol analyses will be performed to compare outcome incidences between the treatment groups. DISCUSSION: Research-based evidence is necessary to create treatment guidelines for judicious use of antimicrobials. The goals of this study are to provide evidence for reducing the use of antimicrobials and targeting the treatment to patients proven to benefit from it. Publishing the trial protocol will increase transparency and promote open science practices.

Sonographic features of the uncomplicated postoperative abdomen in dogs treated for pyometra by ovariohysterectomy.

Pyometra is a prevalent disease in intact bitches and the standard treatment is ovariohysterectomy (OHE). Published descriptions of normal sonographic findings after OHE are currently lacking. The aims of this prospective observational study were to describe and compare postoperative abdominal sonographic features for three timepoints following OHE in a group of dogs with pyometra and an uneventful recovery. A total of 22 dogs had sequential focused abdominal ultrasound examinations on days 1, 4-6, and 10-15 postsurgery. Recorded sonographic features for each examination time point and characteristics of the cervical stump and the mesovarium, size, and echogenicity of medial iliac lymph nodes (MILNs), presence of free peritoneal fluid, and pneumoperitoneum. The cervical stump appeared as a heterogenous area with a hypoechoic center surrounded by hyperechogenic tissue in all dogs. The cervical stump transverse-sectional area was larger on day 4-6 compared with day 1 and day 10-15 (P = .0009). Mesovarium ligature reactions were identified as heterogeneous and hyperechoic areas with central and/or edge shadowing in all dogs. The size and echogenicity of MILNs and the mesovarium reactions did not significantly differ among time points. Free peritoneal fluid was detected in 45%, 41%, and 9% and pneumoperitoneum in 95%, 82%, and 14% of dogs at sequential time points. Findings from this sample of dogs with an uneventful recovery following OHE due to pyometra can be used to assist veterinarians in interpreting postoperative abdominal ultrasonographic characteristics in future dogs treated surgically for pyometra.

Management of Pyometra Using a Novel Image-Guided Percutaneous Technique: A Case Report.

Pyometra is a uterine infection that causes pus to accumulate in the uterine cavity. Pyometra primarily affects postmenopausal women. Multiple aetiologies, including cervical stenosis, have been identified. Medical therapy using intravenous antibiotics and surgical evacuation are the conventional treatment options for pyometra. Here, we present a unique case of a novel therapy for pyometra in a geriatric patient; percutaneous alleviation of the causative cervical stenosis was performed using balloon dilatation, along with endometrial drainage of the infected fluid through her vagina, a natural route. This technique has overcome the need for other invasive therapies. The patient's clinical condition improved significantly after this minimally invasive treatment. Percutaneous balloon dilatation of the cervix for stenosis or occlusion in patients with pyometra facilitates drainage of the infected endometrial fluid. This alternative management technique ensured a satisfactory postoperative course and tolerance in the short-term follow-up. Furthermore, the technique ensured good aesthetic results, with its minimally invasive approach in selected patients, compared to other means of evacuation.

Pyometra: Atypical cause of pediatric abdominal pain following complicated appendicitis.

This case is significant to the practice of emergency medicine and describes a unique post-operative infection that to my knowledge has not been described in this age group or under this set of circumstances before. Pyometra is a rare disease that is classically seen in an older cohort, and not commonly on the differential for pediatric patients presenting to the ED with vaginal discharge and fever. While post operative complications such as abscesses may be common following a surgery, intrauterine infections in this context are rare and the treatment is unique. It is important for emergency physicians to have knowledge of pyometra to keep on their differential for abdominal pain and fever after surgery, as well as be familiar with its management and which consultants may need to get involved.

Laparoscopic-assisted ovariohysterectomy for the treatment of pyometra in a Bengal tiger (Panthera tigris tigris).

A laparoscopic-assisted ovariohysterectomy was performed in a 19-year-old intact, female Bengal tiger (Panthera tigris tigris) presented for surgical treatment of pyometra. A multi-port technique was used with intra-corporeal sealing of the ovarian pedicles and extra-corporeal ligation of the uterine vessels and body. The tiger recovered from surgery and anesthesia without complication, was released into its enclosure the same day, and has remained clinically normal. Laparoscopic-assisted ovariohysterectomy may have advantages over open ovariohysterectomy for treatment of pyometra in the tiger.

Ovario-hystérectomie assistée par laparascopie pour le traitement de pyométrite chez un tigre du Bengale(Panthera tigris tigris). Une ovario-hystérectomie assistée par laparascopie a été réalisée sur un tigre du Bengale femelle intacte âgée de 19 ans (Panthera tigris tigris) présentée pour le traitement chirurgical d'un pyomètre. Une technique multi-ports a été utilisée avec le scellement intracorporel des pédicules ovariens et la ligature extracorporelle des vaisseaux et du corps utérins. Le tigre s'est rétabli de la chirurgie et de l'anesthésie sans complication, a été remis en liberté dans son enclos le même jour et est demeuré cliniquement normal. L'ovario-hystérectomie assistée par laparoscopie peut avoir des avantages par rapport à l'ovario-hystérectomie ouverte pour le traitement du pyomètre chez le tigre.(Traduit par Isabelle Vallières).

Closed cervix is associated with more severe illness in dogs with pyometra.

BACKGROUND: Pyometra, a life-threatening bacterial infection of the uterus, is classified as open or closed depending on the functional patency of the cervix i.e. presence or absence of vaginal discharge. In closed cervix pyometra, pus and bacterial products accumulate in the uterus, which is thought to induce a more severe illness. The aim of this study was to investigate whether disease severity or outcome differed in dogs with open or closed cervix pyometra. RESULTS: Prospectively collected data from 111 female dogs diagnosed with pyometra at the University Animal Hospital, Swedish University of Agricultural Sciences, Uppsala, intermittently during 2005-2012 was analyzed. Seventy-two dogs (65%) had open cervix, whereas 39 dogs (35%) had closed cervix. Differences between the two groups were explored by Wilcoxon Two Sample Test for continuous variables and Chi-square or Fisher's exact test for categorical variables. P < 0.05 was considered significant. In dogs with open cervix the median age was 9.0 years and the median weight 26.0 kg. In dogs with closed cervix the median age was 9.6 years and the median weight 25.0 kg, with no significant differences between the groups (p = 0.69 and 0.24, respectively). Five dogs (4.5%) died, all with open cervix, and 16 dogs (14%) had complications. The general physical condition was moderately or severely depressed in 30% (21/71) of dogs with open cervix (severely depressed in 4 dogs, moderately depressed in 17 dogs) and in 56% (22/39) of dogs with closed cervix (severely depressed in 3 dogs, moderately depressed in 19 dogs). The general physical condition was mildly depressed in 41 dogs with open cervix and 16 dogs with closed cervix, whereas it was normal in nine dogs with open cervix and one dog with closed cervix. None of the included dogs had very severely depressed general physical condition or were non-responsive. Leukocytosis, neutrophilia, monocytosis and moderately to severely depressed general condition was more commonly found in dogs with closed cervix (p = 0.003, p = 0.008, p = 0.003 and p = 0.006, respectively). Sepsis was more commonly present in closed cervix pyometra (77%, 30/39 dogs) compared to open cervix pyometra (51%, 36/71 dogs) (p = 0.007). Presence of prolonged postoperative hospitalization did not differ significantly between the two groups. CONCLUSIONS: In dogs with closed cervix, sepsis was more common, the general physical condition more often moderately to severely depressed and leukocytosis, neutrophilia and monocytosis more frequently found. The results showed that closed cervix was associated with a more severe illness than open cervix at admission but not with poorer outcome as measured by postoperative hospitalization. These findings may be clinically valuable for optimizing monitoring and treatments in dogs with the disease.

Unusual case of pyometra in a bichon frise dog.

An intact female bichon frise dog with anorexia and chronic vaginal discharge, was clinically diagnosed with an open pyometra upon workup and ovariohysterectomy. Two cystic structures were identified protruding from the uterine body and the wall appeared thickened. Histopathology revealed pyometra, cystic endometria hyperplasia, and adenomyosis with squamous metaplasia.

Cas inhabituel de pyométrite chez une chienne Bichon frisé. Une chienne Bichon frisé intacte atteinte d'anorexie et de pertes vaginales chroniques a reçu un diagnostic clinique de pyométrite ouverte après le profil sanguin et l'ovariohystérectomie. On a identifié deux structures cystiques qui faisaient protrusion du corps utérin et la paroi semblait épaissie. L'histopathologie a révélé la pyométrite, l'hyperplasie de l'endométrite cystique et l'adénomyose avec une métaplasie squameuse.(Traduit par Isabelle Vallières).

Spontaneous perforation of pyometra presenting as acute abdomen: a rare condition with considerable mortality.

Pyometra is an uncommon and potentially lethal disease that occurs mainly in postmenopausal women. Spontaneous perforation of pyometra presenting as acute abdomen is an extremely rare complication of pyometra, and the patients are always admitted to the emergency department. An additional case is reported herein. In addition, a literature review was performed between 1949 and 2015. A correct preoperative diagnosis was made in 21.05% of all the cases. Of all cases, 25.71% were associated with malignant disease. The mortality rate of spontaneous perforation of pyometra is 31.88%. Thus, it should be considered in the differential diagnosis of acute abdomen in elderly women. Total hysterectomy along with bilateral salpingo-oophorectomy is the preferred treatment. Administration of broad-spectrum antibiotics and postoperative intensive care support are essential to reduce the high mortality.

Pyometra in elderly post-menopausal women: a sign of malignity.

PURPOSE: To describe the clinical and histopathological characteristics of 12 patients with pyometra and highlight the increased incidence of gynecological malignancy in these patients. MATERIALS AND METHODS: The authors examined the medical records of 12 patients with pyometra, who were treated between 2009 and 2013. RESULTS: All patients were post-menopausal, and their mean age was 70.83 ± 6.978 years (min = 61, max = 82). To remove purulent fluid via dilation and because of the probability of malignancy, three patients (25%) underwent cervical biopsy and endometrial curettage; the other nine patients (75%) underwent curettage alone, with suitable antibiotic therapy. Of the 12 patients, nine (75%) had gynecologic malignancy [(endometrial cancer, n = 5, 41.6%), (cervical cancer, n = 3, 25%), (uterine leiomyosarcoma, n = 1, 8.3%)]. In three (25%) patients, the cause of pyometra was benign pathologies, among which the most common were leiomyomas (n = 2, 66.6%). CONCLUSION: Pyometra diagnosed during the post-menopausal period should be considered a complication caused by gynecological malignancy until proven otherwise.

Single Incision, Laparoscopic-Assisted Ovariohysterectomy for Mucometra and Pyometra in Dogs.

OBJECTIVE: To describe a single-incision, laparoscopic-assisted technique for ovariohysterectomy and its application for treatment of mucometra and pyometra in dogs. STUDY DESIGN: Prospective case series. ANIMALS: Seven dogs. METHODS: Dogs were included if they had an open or closed pyometra or mucometra and an approximate uterine body diameter of less than 5 cm based on ultrasound or abdominal radiographs. Each dog underwent a laparoscopic-assisted ovariohysterectomy through a single-incision laparoscopic port. RESULTS: The procedure was performed in 6 dogs with pyometra and 1 dog with mucometra. Conversion to an open procedure was necessary in 1 dog with uterine rupture. A 2nd port was necessary in 1 dog to exteriorize the uterine body. Median uterine body diameter was 2.2 cm (range 2-3.9). The median surgical time was 85 minutes (range 40-110). Six of 7 dogs were released from the hospital at 1 day postoperative. Follow up ranged from 7 to 421 days and no complications were reported. CONCLUSION: A single-incision, laparoscopic-assisted technique for pyometra was feasible in dogs, given restricted case selection and experience with single-incision laparoscopy.

Outcome of pyometra in female dogs and predictors of peritonitis and prolonged postoperative hospitalization in surgically treated cases.

BACKGROUND: One of the most common diseases in intact bitches is pyometra--a potentially life-threatening disease associated with a variety of clinical and laboratory findings. The aims of the present study were to describe complications of the disease and to investigate clinically useful indicators associated with peritonitis and/or prolonged postoperative hospitalization. RESULTS: A retrospective study was performed using records from 356 bitches diagnosed with pyometra during the years 2006-2007 at the University Animal Hospital, Swedish University of Agricultural Sciences, Uppsala, Sweden. Of the 356 bitches, 315 were surgically treated by ovariohysterectomy, 9 were medically treated and 32 were euthanized without treatment. In the surgically treated bitches, univariable associations between clinical and laboratory data, risk for prolonged hospitalization (≥ 3 days) and/or signs of peritonitis, were analyzed by Chi-square and Fisher's exact test. Logistic regression models were used to assess multivariable associations.The most common complication observed in surgically treated bitches was peritonitis (40 bitches), followed by urinary tract infection (19 bitches), wound infection (8 bitches), uveitis (6 bitches), and cardiac arrhythmia (5 bitches). Leucopenia and fever/hypothermia were associated with increased risk for peritonitis (18-fold and three-fold, respectively). Moderate to severe depression of the general condition, pale mucous membranes and leucopenia were associated with increased risk (seven-fold, three-fold, and over three-point-five-fold, respectively) for prolonged postoperative hospitalization. CONCLUSIONS: Several clinically useful indicators were identified. Leucopenia was the most important marker, associated with 18-fold increased risk for peritonitis and an over three-point-five increased risk for prolonged hospitalization. Fever/hypothermia, depression and pale mucous membranes were associated with increased risk for peritonitis and/or prolonged hospitalization. The results of the present study may be valuable for identifying peritonitis and predicting increased morbidity in surgically treated bitches with pyometra.

Promoting access to care in pyometra treatment: pathways to collaboration between high-quality, high-volume spay-neuter clinics and private practices.

OBJECTIVE: To compare results from 2 previously published surveys aimed at determining how pyometra is treated in high-quality, high-volume spay-neuter clinics (HQHVSNCs) and private practices (PPs), with a specific focus on identifying opportunities for partnership between the clinic types to improve access to care in pyometra treatment. SAMPLE: Responses from 123 PPs and 87 HQHVSNCs. METHODS: A previously published survey of PPs conducted from June to July 2021 and a similar previously published survey of HQHVSNCs conducted from June to July 2020 were compared regarding demographics, pyometra treatment availability, estimated outcome, alternative outcome, disruption, cost, and protocol between HQHVSNCs and PPs. A comparison was also run of the surveys' responses regarding referral of a pyometra to an HQHVSNC by a PP. RESULTS: Although PPs estimated that economic euthanasia is the most likely alternative outcome for 13% of patients unable to access care at their practice, 80% would be reluctant to refer to an HQHVSNC. The 3 primary reasons indicated by PPs with a reluctance to refer were a perceived lack of prompt appointment availability (20%), lack of aftercare (18%), and lack of adequate equipment (14%). In contrast, most HQHVSNCs estimated that they generally accept referrals the same day (50%) or the next day (30%) and 95% of HQHVSNCs reported having the resources needed to treat most pyometras. CLINICAL RELEVANCE: There are several opportunities for partnership between PPs and HQHVSNCs in the treatment of pyometra. The most frequent concerns expressed by PPs regarding referral to HQHVSNCs were not shared by HQHVSNCs or could be ameliorated by referral to an HQHVSNC for surgery and transfer back to the PP for aftercare.

Standing hand-assisted laparoscopic ovariohysterectomy to treat chronic pyometra in a mare.

OBJECTIVE: To describe a standing hand-assisted laparoscopic ovariohysterectomy in a mare. ANIMAL: A 15-year-old maiden Oldenburg mare. CLINICAL PRESENTATION, PROGRESSION, AND PROCEDURES: The mare was presented for evaluation of bucking under saddle and uncharacteristic aggressive behavior. Evaluation of a 24-hour video of the mare in a stall showed behavior consistent with caudal visceral abdominal discomfort. Reproductive evaluation revealed a pyometra secondary to complete transluminal cervical adhesions. The mare was initially managed medically with disruption of the adhesions and uterine lavage, but the adhesions reformed within 6 weeks and could not be manually disrupted. TREATMENT AND OUTCOME: To eliminate the recurrence of pyometra, the mare underwent standing hand-assisted laparoscopic ovariohysterectomy through bilateral flank incisions. The only complication was a seroma at 1 flank incision that resolved after drainage. CLINICAL RELEVANCE: Complete ovariohysterectomy in the mare is a challenging procedure and has previously been performed under general anesthesia. This is the first report of the procedure being performed completely in the standing mare without inversion of the uterus through the cervix.

Advantages of laparoscopic-assisted ovariohysterectomy versus open ovariohysterectomy for dogs with pyometra not detected in randomized clinical trial.

OBJECTIVE: To compare results for surgery time, perioperative pain, need for rescue analgesia, variables, serum C-reactive protein concentration, and postoperative complications for dogs with pyometra treated with laparoscopic-assisted ovariohysterectomy (LaOVH) versus open-surgery (OS) ovariohysterectomy. ANIMALS: 12 client-owned dogs with pyometra between June 1, 2016, and December 31, 2019. METHODS: Dogs enrolled in this prospective single-center randomized clinical trial had pyometra confirmed by history, physical examination, ultrasonography, and blood work and were randomly assigned to treatment group LaOVH or OS. Differences in results for variables of interest were compared between groups using the Mann-Whitney U test, except the number of dogs requiring rescue analgesia was analyzed using the Fisher exact test. Values of P ≤ .05 were considered significant. RESULTS: 6 dogs were recruited in each group; results for 1 dog in the LaOVH group were excluded from further analysis due to free abdominal fluid detected during surgery. Median surgery time was significantly shorter and median total incision length was longer for the OS group (23 minutes; 106 mm), compared to the LaOVH group (37 minutes; 38 mm). No other results differed significantly between groups. CLINICAL RELEVANCE: Although fewer patients in the LaOVH group required rescue analgesia, this was not statistically significant. Therefore, our results could not prove previously suggested advantages of LaOVH (eg, less perioperative pain or faster recovery) in dogs with pyometra. Additionally, for the LaOVH group, the median surgical time was approximately 50% longer, an assistant was needed, and specialized equipment was required.

Antimicrobials administration, treatment outcome and bacterial susceptibility in canine pyometra cases subjected to ovariohysterectomy.

Pyometra is a bacterial uterine infection that frequently affects intact older bitches. The treatment of choice is ovariohysterectomy, often associated with perioperative antimicrobial therapy. The aim of this retrospective investigation was to evaluate the antibiotic choice at different administration times (pre-surgery, at surgery/during hospitalization, and post-surgery) against complications and outcomes, considering the susceptibility profile of bacteria. The medical records of 51 bitches referred to the Veterinary Teaching Hospital of the University of Turin (January 2021-November 2023) and subjected to ovariohysterectomy and bacteriological examination (bacterial culture and susceptibility tests) of the uterine exudate, were analysed. All animals had a positive outcome without surgical site infections, with a longer hospitalization time in case of peritonitis or sepsis; antimicrobials were administered for an average of 7 days. Comparing the susceptibility of the isolated bacteria towards the antimicrobials administered before, during and after surgery, complete efficacy was observed in 42 %, 46 % and 50 % of cases, respectively. In addition, 5/16 peritonitis cases were treated with an in vitro ineffective antimicrobial, and 30 % of the bitches never received a fully effective antibiotic, according to susceptibility tests using the minimum inhibitory concentration method (MIC). Cephazolin resulted the best option for Escherichia coli, the most frequently isolated bacterium. Our study confirms that pyometra has a good prognosis following ovariohysterectomy and antibiotic administration. Monitoring the clinical evolution without changing the antibiotic according to bacterial susceptibility could represent the right choice in uncomplicated cases. Evaluation of outcomes without postoperative antibacterial treatment or with a shorter course would be another topic worth investigating, with the aim to judiciously reduce the use of antibiotics.

Spontaneous perforation of pyometra: a report of seven cases and review of the literature.

BACKGROUND/AIMS: The spontaneous perforation of pyometra is very rare and is associated with a poor prognosis. The present study aimed to evaluate the clinical characteristics and prognostic factors for patient survival. PATIENTS AND METHODS: We reported on 7 patients with spontaneous rupture of pyometra. We also reviewed 47 additional published cases. Thus, all 54 patients were analyzed for mortality. RESULTS: We investigated the prognosis in 44 of 54 patients, excluding 8 patients with undocumented outcome and 2 who died of other diseases. The mortality rate was 25% (11 of 44). In univariate analysis, variables such as age, correct preoperative diagnosis, comorbidities, the presence of malignancy, and hysterectomy were not significant between surviving and deceased patients. In bacterial cultures from the peritoneal cavity, the most common etiological organisms were Escherichia coli and anaerobes such as Bacteroides and Peptococcus species. The rate of isolation of anaerobic bacteria was significantly increased in patients who died (odds ratio, 6.33; 95% confidence interval, 1.28-31.02; p = 0.04). CONCLUSION: Antibiotic therapy for E. coli and anaerobes should be considered in patients with spontaneous perforation of pyometra.

Pyometra in a sugar glider (Petaurus breviceps): surgical treatment and postoperative complications.

A 7-year-old female sugar glider showed a well-defined, homogeneous, hypoechoic mass in the caudal abdominal cavity on ultrasound. Exploratory laparotomy revealed both uteri were severely dilated by viscous, purulent exudate. The patient underwent ovariohysterectomy with removal of bilateral vaginal canals. Antibiotic therapy was initiated postoperatively. Histopathological findings were consistent with suppurative metritis, leading to a clinical diagnosis of pyometra. Despite abscess formation in the uterine stump or central vaginal canal and bilateral renal pelvic/ureter dilations postoperatively, the sugar glider survived more than 270 days. Unfortunately, surgical and medical treatments performed in this case did not prove curative. The outcome of this case highlights the importance of further accumulation of cases to define more appropriate therapies for pyometra in sugar gliders.

Manual vacuum aspiration for postpartum pyometra.

Postpartum pyometra is rare; however, it may lead to sepsis. The main initial symptoms are fever, lower abdominal pain and foul-smelling lochia. The treatment includes antibiotic administration and surgical drainage. This is a report of postpartum pyometra following a caesarean section that was successfully treated with manual vacuum aspiration, a simple and minimally invasive option. Other treatment options include pyometra reduction using placenta forceps and the placement of an intrauterine drainage catheter.

Stump pyometra in a spayed female dog secondary to tamoxifen.

OBJECTIVE: To describe a complication associated with the long-term use of tamoxifen for the treatment of sclerosing encapsulating peritonitis in a dog. CASE SUMMARY: A 2-year-old female spayed poodle cross was evaluated for a stump pyometra. The dog was diagnosed with sclerosing encapsulating peritonitis a year prior and was treated with tamoxifen, an oestrogen receptor antagonist, for treatment of the disease. The dog developed a swollen vulva with vulvar discharge and a stump pyometra was diagnosed on ultrasound. Hormonal testing was submitted to evaluate for an ovarian remnant and the dog underwent an exploratory laparotomy, where the uterine stump was removed. No ovarian remnant tissue was identified intra-operatively, and hormonal testing (anti-Müllerian hormone, progesterone, oestradiol) and histopathology were consistent with the absence of ovarian tissue. The tamoxifen was discontinued. The dog recovered uneventfully after surgery. NEW OR UNIQUE INFORMATION PROVIDED: This report describes a complication of treatment of a rarely described clinical disease. While most cases of stump pyometra involve ovarian remnant syndrome, this case report describes a stump pyometra in a dog without remnant tissue that was undergoing treatment with tamoxifen. Tamoxifen has been reported to cause pyometra in intact female dogs. To the authors' knowledge, this is the first case report to describe a stump pyometra in a spayed female dog, secondary to the use of tamoxifen.