Clinical History
The dog was presented with a purulent vaginal discharge which the owner reported had been present for 1 week, following the bitch's first oestrus. The dog was inappetant, not polydipsic, had no vomiting, recorded a temperature of 38.6 C, had pink mucous membranes and a capillary refill time of 1 second. Generally the dog was fairly bright. Nothing abnormal could be palpated in the abdomen and a white blood cell count showed a high count of 38.2 10 9/L. The dog was admitted and put on a slow infusion of 1 litre of compound sodium lactate (Hartmann's, Ivex) overnight, and given an antibiotic injection of 225 mg of ampicillin (Norobritten, Norbrook) by subcutaneous route. The owners signed a consent form for any necessary surgery and general anaesthesia. A pre-anaesthetic clinical check revealed no respiratory or cardiovascular abnormalities.

Radiography
The following morning the dog was sedated with 0.6 mg acepromazine (ACP, C VET) and 0.3 mg buphrenorphine (Temgesic, Schering Plough) by intramuscular route and a right lateral radiograph of the abdomen was taken under sedation. The radiograph confirmed the diagnosis of a pyometra. See radiograph 1 right.

The dog which had been starved overnight was started on a further infusion of Hartmann's, and one hour later was given a general anaesthetic in order to perform an ovario- hysterectomy.

Surgical preparation
General anaesthesia was induced with 180 mg propofol (Rapinovet, Schering Plough) by slow intravenous injection, given to effect. Endotracheal intubation was achieved using an 11 mm cuffed tube. The dog was connected to a semi-closed parallel Lack circuit with a 4L resevoir bag. Flow rates of 4L nitrous oxide and 2L oxygen were used, together with halothane as the inhalation agent, in order to maintain anaesthesia. Further analgesia was given with 13 mg of carprofen (Rimadyl, Pfizer) by subcutaneous route. The antibiotics were also repeated. The dog was placed in sternal recumbency and an area was prepared (as in the first paragraph of Appendix 1) extending from the vulva to the ziphisternum, and 4 cms lateral to the mammary glands on either side. The bladder was expressed manually and the dog was moved into theatre, where it was placed in dorsal recumbency with the thorax supported in a cradle. The hind legs were extended and tied caudally and the surgical site was prepared as in the second paragraph of Appendix 1. See Figure 1 above.

A standard kit (as listed in Appendix 2) was laid out, with 6 additional spey forceps and 8 additional swabs.

Surgery
The surgeon draped the surgical site using 4 drapes arranged to leave a rectangular area exposed, over the midline. A swab count was taken before surgery commenced and a written tally was recorded as 10 swabs. An incision through the skin and subcutaneous tissue was made along the midline just caudal to the umbilicus, extending cranially for approximately 9 cms. This exposed the linear alba, which was grasped and elevated whilst a stab incision was made through it into the abdomen. Blunt Mayo scissors were used to extend the incision to the length of the skin incision, exposing the abdominal contents. The bladder was lifted out of the abdomen and reflected caudally. Both horns and body of the uterus were then lifted out of the abdomen and the body reflected caudally. See Figure 2 above.

The suspensory ligament of the left ovarian pedicle was identified and carefully broken, to allow better exteriorization of the ovary. An assistant gently applied caudal and medial traction to the uterine horn in order to allow the surgeon to apply a ligature, using 4 m polyglactin 910 (Vicryl, Ethicon), 2 cms proximal to the ovary around the ovarian pedicle. A second ligature was placed 1 cm proximally to the first. Then 2 pairs of large spey forceps were used to clamp the ovarian pedicle, both placed distal to the ligatures but proximal to the ovary. The ovarian pedicle was then transected between the two forceps. The forcep remaining on the stump was left in place, and the uterine horn broken away from the remaining ligament and reflected caudally. The process was repeated with the right ovarian pedicle which lies further cranially resulting in the access to this pedicle being more restricted. Cranial traction was then applied to the body of the uterus and a transfixation ligature was placed cranial to the cervix around the body of the uterus. A second, circumferential, ligature was placed nearer to the cervix both with 4 m Vicryl. Two large forceps were placed cranial to the ligatures and the uterine body transected between the two clamps. All three stumps, in turn, had small artery forceps attached to the edge and the large clamps released so that any haemorrhage could be observed. All three had slight oozing and a third ligature was applied to each one. This proved satisfactory and all stumps were replaced into the abdomen. A swab count at this time only showed 9 swabs accounted for. After a recheck the abdomen was searched and the swab was found in the abdomen. The midline was closed with 3 m polydioxanone (PDS II, Ethicon) using interrupted cruciate sutures. The fascia and linear alba were included in the suture, but not the peritoneum. Subcutaneous tissue was closed with 3 m PDS using a simple continuous pattern. Skin was closed with 3 m polyproplene (Ethilon, Ethicon) using a continuous Ford Interlocking suture pattern. Both ovaries were examined after surgery and found to be enlarged, the left having cyst like structures present. Post-operative recovery was uneventful and the dog went home the same day with 10 Rimadyl 50 mg tablets to be given one twice daily with food and 20 Ampicillin 250 mg capsules to be given two twice daily, both to start the following day. If the owners are allergic to penicillin themselves they must wear gloves to administer the capsules.They were advised to get an Elizabethan collar and only to give lead exercise for 5 days. They were also warned to watch the dog's weight after the post-operative period as neutered dogs have a tendency to put on weight. A post-operative check two days later was satisfactory and the sutures were removed after 10 days.

Discussion
Pyometras usually occur in middle aged bitches, and 10 months is quite unusual for this condition. Pyometras can be either open (discharging from the vulva) or closed with no discharge. Generally the latter are usually more likely to be showing more severe symptoms. Medical treatment rarely works and surgery is the option for relieving this condition, which is fatal if left untreated. Although a very common surgical procedure there are several life threatening complications associated with the surgery, coupled with the fact that the animal is quite often very toxic and often collapsed. Incorrect placing of the ligatures on the uterus can lead to them slipping off post-operatively, leading to fatal haemorrhage. Quite often the tissues are very friable and can rupture when being handled, again either leading to serious haemorrhage or contamination of the abdomen with pus which can lead to peritonitis. The bladder was expressed prior to surgery to reduce it's size as much as possible to allow better access within the abdomen. A male dog would also have the risk of passing urine into the abdominal cavity.

With regard to choice of suture materials, despite correct placing of the ligatures all three stumps were oozing after ligation and had to have a third ligature placed on each. Discussion of this point with the surgeon revealed that this was a problem which sometimes occurred when using Vicryl, but not when using chromic catgut. This would imply that it is more difficult to tighten the ligature using Vicryl and that chromic catgut might be a more suitable ligature material. PDS was used to close the subcutaneous tissue in this case, which is more suitable than chromic catgut, as the catgut can provoke a tissue reaction. With regard to suture patterns, simple interrupted could have been used instead of cruciate sutures for the midline but cruciate sutures were considered quicker and are equally efficient. The skin was closed using a continuous Ford Interlocking pattern for speed, but the disadvantages of this type of suture pattern is that it is more difficult and therefore more stressful to remove them. Secondly, if the animal chews at the wound a break in any part of the suture pattern can result in the whole wound opening whereas if an interrupted suture is removed there will only be a small gap in wound closure. This is especially important in an abdominal wound. The importance of conducting a swab count was well demonstrated in this case. Had the number of swabs not been recorded the missing swab would have gone unnoticed and remained within the abdomen, with serious consequences post-operatively.

Draping was carried out with cloth drapes and ideally should have also had a barrier drape to prevent bacterial strike through occurring when the drapes got wet. Analgesia was adequate for the procedure by combining a partial agonist with a non steroidal, although the non steroidal could have been given at the time of premedication to achieve the maximum analgesia during surgery. Rimadyl was a good choice of post-operative analgesia as it can be continued at home and only needs to be given every 24 hours. It is important to warn owners that penicillin can be absorbed through the skin as they have testified, several times, that they have been quite ill after disregarding this advice. Penicillin would appear to be an adequate antibiotic for this procedure and rarely needs a further course to restore the animal to full health. The first injection was given 15 hours prior to surgery and was therefore active during surgery. The outcome of this surgery was successful and the dog did not need to revisit after suture removal.

References:
Anatomy of the Dog, Miller. Saunders 2nd Ed.
1979 Small Animal Surgery, T Fossum. Mosby. 1997