What is a flank approach? A detailed guide to the veterinary surgical technique

September 23, 2025 •

4 min read

According to a survey of UK veterinarians, 96% use the flank approach for spaying cats. The flank approach is a surgical method that involves making an incision on the side of an animal's body rather than on the abdomen's midline.

Quick Summary

The flank approach is a veterinary surgical technique where an incision is made on an animal's side, or flank, and is often used as an alternative to the traditional midline approach for procedures like spaying.

Key Points

Incision on the Side: A flank approach involves making a surgical incision on the side of an animal's body, as opposed to the traditional midline approach on the abdomen.
Primarily for Spaying Cats: This technique is most commonly used for ovariohysterectomy (spaying) in cats, particularly feral cats and lactating queens.
Easier Monitoring: The flank incision's location makes it much easier to monitor for healing and complications from a distance, which is ideal for uncooperative or feral animals.
Reduced Evisceration Risk: Due to the protective layers of flank musculature, there is a lower risk of internal organs protruding if the wound should break open.
Avoids Mammary Tissue: It is the preferred method for lactating females and those with mammary hyperplasia, as it avoids trauma and infection of the delicate mammary gland tissue.
Surgical Proficiency Required: While efficient once mastered, the limited exposure of the flank approach can pose challenges for locating organs and managing complications for less experienced surgeons.

Understanding the Flank Approach in Veterinary Surgery

What is a flank approach in surgery?

In veterinary medicine, the flank approach is a specific surgical technique where the incision is made on the side of the animal's body, typically just behind the ribs. This is in contrast to the more common ventral midline approach, where the incision is made along the center of the abdomen. While it is most famously associated with ovariohysterectomy (spaying) in cats, especially feral cats, it can also be used for other abdominal or urogenital procedures in various animals, including dogs and livestock.

The flank approach is not a universal solution but a specialized technique chosen for specific clinical or logistical reasons. The decision to use a flank incision is based on several factors, including the animal's temperament, health status, and the practicalities of postoperative care. Its use is a testament to the versatility and adaptation required in modern veterinary practice.

Key reasons for using a flank incision

Veterinarians may opt for a flank approach over a midline incision for several important reasons:

Postoperative Incision Monitoring: For feral or fractious animals, a flank incision is much easier to observe from a distance, such as while the animal is in a cage during recovery. This minimizes stress on the animal and reduces the risk of injury to veterinary staff by avoiding unnecessary handling. The incision is clearly visible, allowing for quick assessment of healing and signs of complications.
Minimizing Trauma to Mammary Tissue: The flank approach is particularly beneficial for lactating or pregnant animals, or those with significant mammary hyperplasia. It avoids the mammary gland tissue, reducing trauma, bleeding, and potential infection risks that can occur with a midline incision through swollen, vascularized tissue.
Reduced Risk of Evisceration: Should the wound dehisce (break open), the risk of evisceration (internal organs protruding) is lower with a flank incision. The flank musculature provides a natural protective barrier, unlike the linea alba in a midline incision, which is a fibrous, non-muscular tissue.
Accessibility in Specific Cases: In some scenarios, a flank approach offers better access to the target organs. For example, in certain bovine or equine surgeries, it can provide a direct route to the abdominal cavity.
Convenience for Recovery: For lactating queens, a flank spay allows kittens to continue nursing without disturbing the surgical site, as the incision is away from the mammary glands.

Performing a flank approach in cats

The surgical procedure for a flank spay in a cat is a well-established practice, though it may vary slightly between clinics and veterinarians. The process typically involves:

Patient Positioning: The cat is positioned on its side, with the target flank clipped and prepared for surgery.
Incision: A small incision, typically around 2 cm, is made through the skin and subcutaneous tissue on the flank, often between the last rib and the iliac crest.
Muscle Layer Dissection: The surgeon carefully dissects through the different layers of flank musculature (external abdominal oblique, internal abdominal oblique, and transversus abdominis) by splitting the muscle fibers rather than cutting them. This minimizes trauma and speeds up recovery.
Organ Retrieval: A spay hook is used to locate and exteriorize the uterine horn and ovary. This step can sometimes be more challenging than in a midline spay due to the limited exposure.
Ligation and Excision: The ovary and uterine body are ligated and removed using the standard ovariohysterectomy technique.
Closure: The muscle layers, subcutaneous tissue, and skin are closed separately. Many surgeons prefer intradermal sutures for the skin to prevent the animal from chewing or pulling them out, which is especially important for feral cats.

Comparison: Flank vs. Midline Approach


Feature	Flank Approach	Midline Approach
Incision Location	Side (flank) of the body	Along the midline of the abdomen
Surgical Exposure	Limited; may be difficult to reach contralateral ovary or manage bleeding	Excellent; provides wide access to abdominal organs
Risk of Evisceration	Lower due to overlapping musculature	Higher due to single-layer closure over fibrous linea alba
Wound Monitoring	Easier, can be done from a distance (e.g., for feral animals)	Requires closer inspection and handling of the animal
Use in Lactating/Pregnant Animals	Preferred; avoids trauma to mammary glands	Not ideal; can cause trauma and infection in swollen mammary tissue
Organ Retrieval	Can be more challenging with a smaller incision and limited view	Straightforward with direct access
Overall Speed	Can be faster once a surgeon is proficient, but may take longer if complications arise	Often considered the standard for routine procedures; efficient for experienced surgeons

Postoperative considerations and recovery

Regardless of the surgical approach, proper postoperative care is crucial for a smooth recovery. For a flank approach, a few special considerations apply:

Monitoring Incision: The high visibility of the flank incision is a major advantage during recovery, especially for animals that are difficult to handle. Caretakers should regularly check for signs of infection, swelling, or dehiscence.
Pain Management: As with any surgical procedure, appropriate pain medication is essential to ensure the animal's comfort and aid healing. The pain management protocol should be followed closely as prescribed by the veterinarian.
Activity Restriction: Limiting strenuous activity is important for all postoperative animals. The risk of incision breakdown is reduced with a flank approach, but proper rest is still necessary.
Antibiotics: A course of antibiotics may be prescribed, particularly for feral animals being released back into their environment, to prevent opportunistic infections.

Conclusion

The flank approach is an invaluable tool in a veterinarian's surgical arsenal, offering a viable and often superior alternative to the traditional midline incision in specific cases. While it presents some unique challenges, its benefits, particularly in the context of feral animal management and certain reproductive conditions, are significant. The choice of surgical technique always depends on a careful assessment of the individual patient's needs and circumstances. For more in-depth information on this and other surgical techniques, veterinary students and professionals often consult resources like those provided by the World Small Animal Veterinary Association.

Frequently Asked Questions

While less common than in cats, the flank approach can be used for ovariohysterectomy in dogs, especially in situations where a midline incision is not feasible, such as with excessive mammary development or a skin infection on the abdomen.

For feral cats, the main advantages are the ability to monitor the incision from a distance, less risk of the cat licking or chewing at the wound site, and a lower risk of evisceration should the wound fail. This makes for a safer, lower-stress recovery.

The primary difference is the location of the incision. A flank approach uses an incision on the side, providing limited but targeted access. A midline approach uses an incision along the center of the abdomen, offering a wider view of the abdominal cavity.

There is no evidence to suggest that a flank approach is inherently more painful than a midline approach. Pain management protocols are essential for both techniques, and recovery time is generally comparable. The use of modern pain medications ensures the animal's comfort.

Yes, a flank approach can be used for pregnant animals, particularly if the pregnancy is in its early stages. It is especially useful for lactating animals, as it avoids the enlarged and sensitive mammary glands.

After a flank incision, the fur often grows back in a slightly different pattern or color, which can serve as a long-term identification marker that the animal has been sterilized. For feral cat programs, this is a clear sign that the cat has been spayed without having to handle it.

Like any surgery, there are risks, such as difficulty retrieving the ovary or uterus due to the limited exposure, which can prolong the procedure or increase bleeding. An experienced surgeon is required to minimize these risks.