Lateral Flank Approach for Ovariohysterectomy in Cats

Vladimir Stojanoski, DVM, Spec. surg. vet.

Irena Mandevska, DVM.

Animal Care Clinic, Clinic for surgery, oftalmology andstomatology, Bitola, Macedonia


The ovariohysterectomy is a routine procedure which is recommended primary for control of the population of cats. Until now there are various access techniques that are described in the literature for the ovariohysterectomy(OVH) at cats. In this study of ovariohysterectomy, 500 adult female cats at the age of 6 months to 9 years with bodyweight  of 2,5-5 kg, were covered. In OVH a small lateral accessed cut is made which minimizes the presence of bleeding during incision, easy access and extraction of the ovaries and the horns of the uterus is obtained during the procedure, also minimization of postoperative complication, shorten the time of the surgical procedure (give or take 20 minutes per intervention), also the healing of the wound and the pain threshold postoperative, all this examined by Feline grimace scale fact sheet(Evanelista at all 2019) are significantly smaller. 96% of the clinics in the USA apply the “Flank” lateral access for OVH at cats, but in our region this technique is still not well known though the benefits of it are greater, in contrast to other techniques of OVH at cats.



The managing of the population of domestic cats is a global issue which raises the question of the individual wellbeing of the cats (Roberts et all, 2015). OVH is a routine procedure that is recommended as the best method in controlling the population of cats (Levy et all, 2003). Traditionally, OVH is made by medial ventral or lateral “Flank” access which in the world and also our region is still not accepted as a routine everyday technique. Because of the positive feedback, the lateral “Flank” access for OVH at cats is more and more applied in the world.

The left side of incision was preferred in the start of applying the lateral “Flank” access (McGarthet all, 2004) and also many incisions were applied in horizontal and vertical direction of the abdominal oblique muscles in OVH at cats (Hogue, 1991). Generally, at the start of the application of this technique, the length of the incision was 2-3cm м (McGrath et all, 2004; Coe et all, 2006; Rana, 2007; Kiani et all, 2014). In comparative studies Ghanawat and Mantri (1996), Shuttleworth and Smythe (2000), Coe et all, (2006) and Rana (2007) reported significantly smaller incision with the lateral “Flank” access 1-1,5 cm compared to the medial ventral access. Examining the technique and comparing the suturing of the skin with skin and intradermal sutures a conclusion was gained that the healing of the wound with intradermal suture is way quicker and the discomfort of the patient is greatly reduced. Also by applying this technique the time needed for wound healing is shortened, the trauma of the abdominal muscles is way smaller because the incision is lateral, the pressure over the wound and the incision is greatly reduced.



In this study were covered 500 female adult cats, the youngest older than 6 months and the oldest younger than 9 months. All patients undergone: general clinical examination, blood test and ultrasonography for confirmation of pregnancy. Every cat that did not showed deviations in the clinical examination, blood test also were not pregnant was included in this study. Every cat was preoperatively deprived of food 12-24h and water 6h. At all patients a venous path was established, a venous anesthesia was applied, also intubated and a breathing monitoring was used thanks to a Breathe Safe Respiratory Monitor. During the procedure a NaCl0.9% infusion was applied in dose of 20ml/kg/h. The surgical field was shaved by a shaving machine with No. 40F knife, and also disinfected by 4% chlorhexidine. Also the surgical field was covered by surgical covers (sheets) with dimensions of 45-45cm, a surgical knife 10 was used and as a surgical thread we used monofilament Monosyn 3-0. We used the general surgical set for sterilization (with spay hook), sterilized by the method of dry sterilization. Postoperatively as an analgesic a single dose of NSAID – meloxicam 0.2mk/kg i/v was applied.



One of the most common indication for implementing this access is sterilizing of breastfeeding cats and also sterilizing cats with hyperplasia of the mammary glands. When the OVH is made during lactation it’s a better choice to use the lateral “Flank” access rather than the medial ventral access because the occurrence of dermal and subdermal heamorrhagia is very rare almost unnoticeable, also swelling, infection and discharge of the mammary gland are absent. Besides that, by using the lateral “Flank” access in cats during lactation, there is no disorder in the function of the mammary gland, so these patients can continue the breastfeeding postoperative the next day.

The mammary hyperplasia, also known as fibro adenomatous hyperplasia or mammary hypertrophy -fibroadenomal complex (Dolly Parton Syndrome) – image 1, represents a benign formation during estrous cycle or breastfeeding at cats that characterizes with fast abnormal growth of one or more mammary complexes (Hayden at all, 1981). As a choice of treatment its recommended to use ovariectomy or ovariohysterectomy, that results with regression of the mammary hyperplasia within a time period of 3-4 weeks (Wehrend and all, 2001). The use of this technique during lactation eliminates the occurrence of rupture of the mammary complexes triggered by a wound infection that appears as a complication by using the medial access of OVH.274135312_291687186401383_2989444432093713041_n


The advantages of the lateral “Flank” access to OVH at cats includes the possibility to over watch the surgical wound from distance and reducing the potential to eviscerate due to dehiscence of the wound sutures (Dorn & AS, 1975; Krzaczynski, 1974; Miller &Zawistowski, 2012). These advantages are very important while working with wild, feral and homeless, scared animals or animals whose owner is not always capable to transport the patient back to the clinic/ambulance. The capability for these animals to be brought back for routine control postoperative is very limited, thus very often, observing from distance is necessary.

The lateral “Flank” access allows visual assessment of the wound without manipulating with the patient, which is not the case by using the ventral-medial access.

Evisceration of the abdominal organs or dehiscence of the sutures are very uncommon because the forces of gravity using the lateral “Flank’ access are weaker than using the ventral-medial access (Dorn & AS, 1975; Krzaczynski, 1974; Miller &Zawistowski, 2012; Janssens&Janssens, 1991). In addition, the overlapping of the oblique abdominal muscles helps keeping the integrity of the abdominal wall, which makes the possibility of such complications to occur very small.

With the lateral access, the ipsilateral ovary and the horn of the uterus is spotted right under the incision, which makes them very easy to locate. This shortens the time, normally needed to locate the ovary during the ventral-medial access, thus shortens the time needed for the whole operation.


Contraindications of the lateral “Flank” access includes: distension of the uterus respectively gravity or pyometra, overweight or patient younger than 12 weeks (Dorn & AS, 1975; Krzaczynski, 1974; Janssens&Janssen,s 1991; Dorn &Swist, 1977). Some authors describe the risk of visual scar or imperfections of the color and fur growth of the operation field (Janssens&Janssens, 1991). At patient that are highly gravid or have a uterine distension/pyometra, the lateral “Flank” access is not recommended because we do not have a clear access to manipulate with the uterus. If the gravity or pyometraare identified by accident, the lateral “Flank” access is extended for relieved extraction of the uterus. However, extending the incision can increase the risk of muscle trauma or potential bleeding, undermining the primary advantages of the lateral “Flank” access during OVH (Salmeri at all, 1991).



The primal disadvantage of the lateral “Flank” access is the limited visual exposure in occurrence of possible complications (Dorn & AS 1975; Krzaczynski, 1974; Janssens&Janssens, 1991; Dorn &Swist, 1977).

The second important concern is that when a cat is brought, but it’s unknown if the same cat has undergone a OVH, the surgical scar is small and the point of incision is not always typical to be made at the same location, even if it’s made on the same side of the previous incision, in contrast to the medial ventral access where the incision is typically spotted on exact location respectively under the umbilicus along the linea alba (Miller &Zawistowski, 2012). This could lead to an unnecessary surgical intervention if the surgeon is not aware of the possibility that the lateral “Flank” access might have been used for OVH. Therefore, when the lateral “Flank” access is used, it is necessary to mark the cat that is operated, like tattooing of the umbilicus or linea alba along the abdomen, or by incising the tip of the left ear at the homeless or feral cats (Miller &Zawistowski, 2012).


Anesthesia of the patient

Ovariohysterectomy is a routine surgical procedure by which in this study is used an intravenous anesthesia.

Sedation/anesthesia in combination with midazolam:

  • Dexmeditomidin10 µg/kg i/m
  • Midazolam2mg/kg i/v and
  • Ketamine 2mg/kg i/v – slowly applicate till effect is achieved
    • For maintenance of anesthesia if needed Propofol is administered like a bolus of – 0,4mg/kg
    • Intubation and monitoring of breathing with Breathe Safe Respiratory Monitor (image 2).
      Image 2 - Breathe Safe Respiratory Monitor

      Image 2 – Breathe Safe Respiratory Monitor

      Instruments that are used for the procedure

      Standard set for sterilization: surgical gloves, surgical sterile sheet, surgical tweezers – Adison tissue, scalpel – No. 10, needle holder – Mayo Hager, hook (spay hook) for ovariohysterectomy, four surgical forceps – Mosquito forceps, surgical scissors – mayo scissor curved, four Backhaus towel clamps, surgical knife – No. 10, monofilament (Monosyn 3-0) resorptive threat, sterile gauze (image 3).

      Image 3 - Ovariohysterectomy kit

      Image 3 – Ovariohysterectomy kit

      Position of the patient

      By using the lateral “flank” access the patient could be positioned in right or left dorsal recumbence depending of the surgeons opinion. The access at the right side is preferred by some surgeons because it provides better access to more cranially anatomically placed ovary and because the omentum covers the viscera when it’s used a left sided access (Dorn &Swist, 1977). From our experience there aren’t any advantages whether a left or right sided access is used, but the left side is better because the dominant hand is used for easy manipulation with the suspensory ligament. The animal is placed in lateral position by fixing the limbs in their extension (Krzaczynski, 1974) – image 4.

      Image 4 - Lateral position with limbs fixed in extension

      Image 4 – Lateral position with limbs fixed in extension

      Surgical preparation

      The surgical field is being shaved by starting cranially from the last rib all the way down to the iliac bone in cranial-caudal direction and the transversal processes of the lumbar vertebrae, all the way down to the mammary complex in dorsal-ventral projection.


      Marking the incision

      The carving of the incision may be placed in dorsal-ventral or cranial-caudal direction, however by our experience we use the technique of cranial-caudal incision by which the incision is placed in one conceived central line, two fingers from the last rib, one finger from the transversal processes and two fingers from the iliac bone in diameter of 1-1,5 cm (image 5) depending on the size of the cat, estrus phase, or the presence of other possible complication factors.

      Image 5 - Ready surgical field and appropriate location of incision for a left lateral access (left dashed line: location of the last rib; right dashed line: location of the iliac crest

      Image 5 – Ready surgical field and appropriate location of incision for a left lateral access (left dashed line: location of the last rib; right dashed line: location of the iliac crest

      Surgical technique

      The incision of the skin for the lateral “Flank” access can made in cranial caudal direction paying attention for avoiding the superficial blood vessels. The subdermal tissue must be cut with separating scissors (image 6). The abdominal muscles should be separated from the subdermal tissue and by using a forceps or scissors an incision must be made separately on every layer of the lateral abdominal muscles. When the abdomen is opened its important to fixate the abdominal muscle with a forceps, or the thumb, to maintain the control over the abdominal wall. The ovary or the uterine horn should be placed right under the incision.

      Image 6 - Subcutaneous separation

      Image 6 – Subcutaneous separation

      The horn is pulled out by using  (image 7 top).

      Image 7 - Spay hook (top) and extraction of the horn of the uterus (bottom)

      Image 7 – Spay hook (top) and extraction of the horn of the uterus (bottom)

      20210528_102125 After the extraction of the horn and sighting the ovary, with the help of a forceps the ovary is fixated with the suspensory ligament (image 7 bottom). At older and obese cats the ovary is surrounded by adipose tissue, which requires prolonging the incision of the abdominal wall to achieve better visibility of the surgical field. After fixating the ovary/ligament the blood vessel is being ligated by placing two ligatures also used at the medial ventral access. The wide ligament (including the surrounding ligament) should be blindly separated parallel to the uterine artery at the level of the bifurcation of the uterus. After that, the uterine horn should be lifted to reveal the bifurcation and the contra lateral  horn of the uterus, after which by using the hook the horn is lifted to a level of visibility of the contra lateral ovary, which is fixated with a forceps to the suspensory ligament. Because this ligament is on the opposite side it is harder to pull it out, and because it is shorter, it should be torn bluntly or be cut by scissors, and the rest of the procedure is the same as the other ovary. Then the both horns are pulled out until the bifurcation is visible. The both horns are being ligated twice near the bifurcation and are cut off 0,5 cm over the second ligature.

      The visualization of the contra lateral ovary and horn of the uterus could be difficult to acquire through the small incision, but because the ipsilateral ovary is spotted right beneath the incision, by pulling out the horn all the way to the bifurcation, the contra lateral horn is pulled out by a hook, so is the contra lateral ovary. For easy visualization of the contra lateral ovary, the duodenum (left lateral “Flank” access) or the descendent colon (right lateral “Flank” access) are used to push dorsally the small intestine with the spay hook, simultaneously we pull the abdominal wall ventrally, and by doing so the visibility of the contra lateral ovary is bigger (image 8).

      Image 8 - Extraction of the ovaries

      Image 8 – Extraction of the ovaries

      Image 8 - Extraction of the ovaries

      To visualize the bifurcation of the uterus, by using the spay hook the small intestine and the bladder should be pulled in cranial and ventral direction simultaneously pulling the abdominal wall caudally, by doing so the uterine body lies dorsally of the bladders neck (image 9).

      The abdominal wall at cats is closed by using a continuous suture, embracing  the three layers of abdominal muscles. The skin is closed with a routine intra dermal suture, and by doing so, the extraction of the suture threads postoperatively is unnecessary (image 10).

      Image 10 - Closing the skin wound by placing an intradermal suture

      Image 10 – Closing the skin wound by placing an intradermal suture


      Postoperative care and analgesia

      The postoperative care by using the lateral “Flank” access is nothing special, nor is necessary stationary observing postoperatively, so the patient could be checked out the very same day. The observation is done from distance and there is no need of bringing the patient back for a control. We used a single dose of NSAIL analgesic – meloxicam 0,2 mg/kg i/v.



      In this study for ovariohysterectomy were involved 500 adult female cats at the age of 6 months to 9 years, with bodyweight of 2,5-5 kg. (Domestic and feral) which were electively brought to the clinic, which covers all the world known high standards of working in veterinary medicine.

      The owners and volunteers in charge were informed of the whole process both verbally and in writing detailed description of the procedures and in this publication, their personal data isn’t mentioned and they remained completely anonymous.

      The choice of anesthetic protocol and the analgesia in the postoperative period, depends on the procedure and the health status of the patient, including both acute and chronic diseases.

      Even though there is no standard surgical access to ovariohysterectomy at cats, generally the ventral medial access dominates, in contrast to the lateral “Flank” access, which technique is less preferred (Bartels, 1998; Slatter, 2003).

      The complexity to identify the subcutaneous adipose tissue and the internal and external oblique muscle and the peritoneum, during this access did not showed as a problem, so did the identification of the anatomical position of the ovaries and the uterus.

      The risk of remaining ovarian tissue is rather often complication during ovariohysterectomy at cats, so is loosening of the ovarian ligatures during operation, which however doesn’t result with significant loss of blood (James at all, 2021). These intra operational complications didn’t showed as a problem with the application of the “Flank” lateral access in this study, considering the high level of competence and experience of the main surgeon, as is the use of modern materials for ligation and the use of modern surgical techniques as for ligating the ovaries and the

      uterus and as for the fascia of mm. rectus abdominis.

      By choosing the lateral “Flank” access to ovariohysterectomy at cats, there is lower degree of licking the wound, swelling and lower incidence of complications: bleeding of wound 0,5%, dehiscence of the wound 2%, infections of the wound 2,5% in the postoperative period (image 11).

      Even though there is no general opinion for which procedure is better and it’s not used as a routine procedure, the lateral “Flank” access to ovariohysterectomy at cats in this study provede positive effect in veterinary surgeons during the intra and postoperative process, lower costs of material, so is the greater satisfaction of the owners and the comfort of the patients in the healing period.

      Also the tress hold of pain during the lateral “Flank” access is very low, examined by Feline grimace scale fact sheet (Evanelista at all, 2019) by which a single dose of NSAID – meloxicam 0,2 mg/kg i/v is enough.


      The lateral access in this study showed as better by the personnel that took place in the operations and the owners/fosters of patients because of the shorter operation time (

      generally the difference is 10-15 minutes quicker), smaller surgical incision (1-1,5 cm), eased anatomical locating of the ovaries and uterus, quicker healing of the wound (2-4 days), smaller degree of wound opening (2%), together with the better response of the patient during awakening from anesthesia and in the postoperative period.

      Saving the amount of time for the procedure (around 20 minutes per procedure), the minimal incision for performing the procedure, the shortened time for wound healing in contrast to the standard medial ovariohysterectomy, the tress hold of pain postoperatively is way lower in contrast to the standard medial technique, the postoperative complications are very rare (infection of the wound, dehiscence of the sutures, postoperative bleeding and pain at the animal itself.