Are Nylon Sutures Absorbable in Veterinary Surgery? A Practical Guide

One of the most commonly asked questions among veterinary professionals and pet owners alike is whether nylon sutures are absorbable. Nylon sutures are actually  non-absorbable and do not degrade inside the body over a clinically relevant timeframe. They must be manually removed once the wound has healed adequately, or in specific internal applications, left permanently in place. Understanding exactly why nylon behaves this way, how it compares to absorbable alternatives, and when it is the appropriate choice for animal surgery, is essential clinical knowledge for anyone involved in veterinary wound closure decisions.

 

What Does Absorbable Mean in the Context of Veterinary Sutures?

 

Before addressing nylon specifically, it helps to establish what absorbable means in a clinical context. Absorbable sutures are materials designed to degrade naturally inside biological tissue after a defined period. Their breakdown occurs through one of two processes: hydrolysis, where water molecules gradually break apart the polymer chains of synthetic materials such as PGA, PGCL, and PDS, or enzymatic degradation, where the body's own proteolytic enzymes break down natural materials such as Chromic Catgut.

 

The practical consequence of absorbability is that no manual removal is required. The suture provides mechanical support during the wound healing process and then disappears as the tissue develops its own collagen-based tensile strength. This makes absorbable sutures the standard choice for internal tissue layers where accessing the suture for removal would require reopening the patient.

 

Non-absorbable sutures, by contrast, do not degrade through either of these mechanisms within a clinically meaningful timeframe. They retain their structural integrity inside or on the body indefinitely unless removed. For a detailed overview of how absorbable and non-absorbable materials each contribute to surgical outcomes, see Understanding the Difference in Absorbable vs Non-Absorbable Veterinary Sutures.

 

Are Nylon Sutures Absorbable?

 

Nylon sutures are classified as non-absorbable. Nylon is a synthetic polyamide polymer with a highly stable chemical structure that resists both hydrolytic and enzymatic breakdown under normal physiological conditions. When implanted in animal tissue, nylon retains its tensile strength and physical form far beyond the timeframe associated with wound healing. It does not dissolve, degrade, or disappear on its own during the healing period.

 

There is an important nuance worth noting. Over a very long period, measured in years rather than weeks or months, nylon can undergo very slow hydrolysis and gradual loss of tensile strength. Some literature notes that nylon may lose approximately 15 to 20 percent of its original tensile strength per year under physiological conditions. However, this slow process is not clinically equivalent to absorption. Nylon is not designed to degrade within the healing timeline, it does not disappear from tissue, and it cannot be relied upon to dissolve in the way that true absorbable sutures do. In all practical and regulatory classifications, nylon remains a non-absorbable suture material.

 

This distinction matters in clinical decision-making. If a veterinary surgeon selects nylon for an internal tissue layer expecting it to degrade before the animal returns for a follow-up, the expectation will not be met. Nylon placed in inaccessible internal sites will remain there. This makes correct material classification an important foundation of proper suture selection.

 

What Nylon Sutures Are Made From

 

Nylon sutures used in veterinary surgery are made from Polyamide 6 or Polyamide 6,6, two closely related synthetic polymers with slightly different molecular structures but very similar mechanical properties. ASSUNYL®, the nylon suture supplied by Gexfix International Corp. in partnership with Assut Europe S.P.A., is manufactured as a monofilament from Polyamide 6 or 6,6.

 

The monofilament structure means ASSUNYL® consists of a single continuous strand rather than multiple filaments braided together. This gives the suture a smooth, non-porous surface that passes easily through tissue with minimal drag and resists bacterial colonization, since there are no interstices between braided strands for bacteria to inhabit. These properties make it particularly well suited to skin closure where the suture is exposed to the external environment for the full duration of its time in the wound.

 

Properties That Make Nylon Suitable for Veterinary Animal Surgery

 

Nylon's non-absorbable classification, combined with its specific mechanical and biological properties, defines where and why it is used in animal surgery.

 

High tensile strength: ASSUNYL® nylon provides consistent and reliable tensile strength throughout the healing period. Because it does not degrade, the mechanical support it offers does not diminish over time the way absorbable suture strength does. For skin closures where the suture must hold for 10 to 14 days until adequate epithelialization occurs, this consistent strength is a reliable clinical attribute.

 

Minimal tissue reactivity: Nylon is biocompatible and provokes minimal inflammatory response in most animal patients. The synthetic polymer structure does not trigger the enzymatic or immune reactions that natural materials such as silk or Chromic Catgut can produce. This low reactivity supports cleaner wound healing and reduces the risk of suture-related inflammation at the closure site.

 

Smooth monofilament surface: The single-strand construction of ASSUNYL® minimizes tissue drag during placement, reduces bacterial adherence compared to braided materials, and produces less scarring at the suture entry points. For skin closures in visible areas of short-haired animals, this translates to better cosmetic outcomes after suture removal.

 

Controlled removal: Because nylon does not dissolve, it can be removed at the clinically appropriate time once wound healing is confirmed. This gives the veterinarian full control over how long the closure is supported and allows direct inspection of the healed wound at the time of removal.

 

For a deeper look at how these properties support skin closure outcomes in veterinary patients, see Veterinary Guide to the Best Sutures for Skin Closure After Surgery.

 

How Nylon Sutures Support Wound Healing in Animals

 

While nylon sutures themselves do not participate in the biological process of wound healing, they support it by maintaining mechanical closure of the wound during the period when the tissue is rebuilding its own structural integrity.

 

After skin closure with nylon, wound healing progresses through the standard three phases. During the inflammatory phase in the first five days, the suture bears the full mechanical load of the closure while the body initiates its immune and clotting response. During the proliferative phase from approximately day five to fourteen, fibroblasts lay down collagen and the wound begins to develop its own tensile strength. The nylon suture continues to support closure during this period. During the remodeling phase from week two onward, collagen matures and the wound approaches its final tensile strength, at which point the nylon can be removed as it is no longer needed.

 

This alignment between the nylon retention period and the wound healing timeline is deliberate. For most skin closures in dogs and cats, sutures are removed between 10 and 14 days post-operatively, which corresponds to adequate epithelialization and early remodeling. In large animals or high-tension closures, removal may be extended to 14 to 21 days.

 

For a full explanation of how wound healing phases interact with suture performance, see How Veterinary Suture Material Impacts Surgical Outcomes in Animals.

 

When Nylon Is the Appropriate Choice in Animal Surgery

 

Nylon's non-absorbable classification makes it appropriate for specific clinical contexts and inappropriate for others. Understanding both is as important as understanding the material's properties.

 

Primary skin closure is the most common application for nylon in veterinary animal surgery. Whether following a routine spay, an orthopedic procedure, a tumor excision, or a traumatic laceration repair, nylon sutures placed using a simple interrupted or continuous pattern provide reliable, tension-appropriate external closure with predictable removal timing. ASSUNYL® is available in a range of sizes and needle configurations to accommodate the full range of veterinary skin closure applications.

 

Orthopedic and tendon-adjacent repairs sometimes use nylon for permanent structural fixation where the suture is intended to remain in place long-term. In these applications, the non-absorbable nature of nylon is an advantage rather than a consideration to manage. The suture provides indefinite mechanical support in a high-tension anatomical location.

 

Cardiovascular and ophthalmic procedures may also use fine-gauge nylon sutures in specialized applications where long-term structural integrity is required and the material's smooth, inert properties are advantageous.

 

Nylon is not appropriate for internal tissue layers where suture removal is not planned and where the permanent presence of a non-absorbable material would create a long-term foreign body burden. For these layers, absorbable sutures such as ASSUFIL® PGA, PGCL, or ASSUFIL® PDS monofilament are the correct choice.

 

How Nylon Compares to Absorbable Sutures Used in Veterinary Practice

 

Understanding the differences between nylon and the absorbable materials it is often used alongside helps veterinary professionals make clear and confident suture selection decisions.

 

Nylon vs PGA (ASSUFIL®): PGA is a braided and coated absorbable suture that degrades through hydrolysis over 60 to 90 days. It is used for internal layers, gastrointestinal closures, subcutaneous tissue, and reproductive procedures. Nylon is used for the skin surface above these layers. The two materials are complementary, not interchangeable.

 

Nylon vs PDS monofilament: PDS is a long-duration absorbable monofilament that retains tensile strength for up to 180 days before complete absorption. Like nylon it is a monofilament with smooth tissue passage, but unlike nylon it is designed for internal applications and will eventually disappear. PDS is used in body wall closure, fascia, and high-tension deep tissue layers.

 

Nylon vs Chromic Catgut (ASSUCROM®): ASSUCROM® Chromic Catgut is a natural absorbable material that loses tensile strength within 15 to 20 days from implantation and absorbs over 90 to 120 days. It is used for mucosal closures and internal ligations. Nylon is not appropriate for these applications because it will not degrade, and its long-term presence in mucosal or internal tissue would create unnecessary complications.

 

For a comprehensive comparison of how absorbable and non-absorbable suture materials are used across procedure types, see Complete Guide to Choosing Veterinary Surgical Sutures for Your Practice.

 

Handling Nylon Sutures Correctly

 

Because nylon is a monofilament, it has a degree of memory, meaning it retains the coiled shape of its packaging and can spring back if not handled with consistent tension control. This memory effect requires that extra throws are used when tying knots to ensure adequate knot security. Experienced veterinary surgeons account for this characteristic as standard practice.

 

The smooth surface that reduces bacterial adherence also requires the additional throws to be tied correctly, since there is less friction between suture strands than in a braided material. A properly tied nylon knot with the appropriate number of throws provides reliable security throughout the healing period.

 

For a detailed discussion of how monofilament handling properties compare to multifilament sutures in veterinary procedures, see How Monofilament vs Multifilament Suture Performs in Veterinary Procedures.

 

Removal of Nylon Sutures After Healing

 

Because nylon is non-absorbable, removing it at the appropriate time is an essential part of wound management. Leaving skin sutures in place beyond the recommended period increases the risk of suture reaction, epithelial tracking along the suture tract, and localized irritation or inflammation.

 

For most small animal skin closures, nylon sutures are removed 10 to 14 days after surgery. The wound should be assessed at removal, confirming that epithelialization has progressed appropriately and the wound is secure before removing the mechanical support the suture provides.

 

In cases where sutures are removed and the wound appears incompletely healed, additional support through bandaging or supplemental adhesive closure may be appropriate until the tissue has developed adequate integrity.

 

For guidance on how long different suture types and wound locations require mechanical support, see How Long Should Sutures Stay In: Complete Healing Timeline Guide.

 

Conclusion

 

Nylon sutures are not absorbable. They are non-absorbable monofilament sutures manufactured from Polyamide 6 or 6,6 that retain their tensile strength and physical structure throughout and well beyond the wound healing period. Their non-absorbable nature makes them the appropriate choice for skin closure and selected permanent internal applications in animal surgery, while absorbable sutures remain the standard for internal tissue layers where suture removal is not planned.

 

ASSUNYL® Nylon monofilament from Gexfix International Corp., in partnership with Assut Europe S.P.A., provides veterinary professionals with a reliable and consistently performing non-absorbable suture for external skin closure across species and procedure types. Alongside the full range of absorbable sutures including ASSUFIL® PGA, PGCL, PDS monofilament, and ASSUCROM Chromic Catgut, Gexfix supports clinics with the complete suture portfolio needed to close every layer correctly.

 

FAQs

 

Q. Are nylon sutures absorbable or non-absorbable?

 

A. Nylon sutures are non-absorbable. They are made from Polyamide 6 or 6,6 and do not degrade through hydrolysis or enzymatic breakdown within the wound healing timeframe. They must be manually removed after adequate wound healing or left permanently in specific internal applications.

 

Q. How long do nylon sutures stay in a veterinary wound?

 

A. In most small animal skin closures, nylon sutures are removed 10 to 14 days after surgery once adequate epithelialization is confirmed. In large animals or high-tension wound sites, removal may be scheduled between 14 and 21 days depending on the healing progress observed at the wound.

 

Q. Can nylon sutures be used inside the body in animal surgery?

 

A. Nylon sutures can be used internally in specific applications such as orthopedic fixation where permanent mechanical support is intended. However, they are not appropriate for internal layers where the suture is expected to dissolve. Absorbable sutures should be used in those locations instead.

 

Q. What is the difference between nylon sutures and absorbable sutures in stitches for medical use?

 

A. Nylon sutures maintain their structure and require removal after wound healing. Absorbable sutures such as PGA and PDS degrade through hydrolysis within defined timeframes, making them suitable for internal layers where removal is not possible without reopening the wound.

 

Q. Why is nylon preferred for skin closure in veterinary patients?

 

A. Nylon's monofilament structure provides smooth tissue passage, minimal inflammatory response, and resistance to bacterial adherence. Its consistent tensile strength through the healing period and controlled removal timing make it one of the most reliable materials for external skin closure across veterinary species.