Urinary Catheter Management in Companion Animals

The earliest documented use of a urinary catheter traces back to the 6th century BC in the Sushruta Samhita, a foundational Sanskrit medical text by the Indian surgeon Sushruta.¹ Modern catheterization evolved significantly in 1929 when Frederic Foley introduced a self-retaining “hemostatic bag catheter,” later refined in 1937 in his publication in Journal of Urology.^2,3

Although global veterinary catheter usage data are not systematically reported, industry estimates suggest tens of millions of units are used annually. This high usage reflects the prevalence of urinary disorders among companion animals. Approximately 50% of cats over age 10 develop chronic lower urinary tract diseases that necessitate catheterization.⁴ Urolithiasis, a common cause of urethral obstruction, accounts for 10% to 23% of lower urinary tract signs and often requires repeated interventions.⁵ Dogs increasingly undergo catheterization for urinary incontinence and postoperative urinary retention management.⁶

Although urinary catheters remain indispensable for bladder drainage, their use carries risks such as catheter-associated urinary tract infections (CAUTIs), urethral trauma, and mineral encrustation.^7,8 Effective mitigation of these complications requires meticulous attention to indications for catheterization, aseptic insertion techniques, appropriate maintenance protocols, and timely removal. Optimal catheter management is critical to minimize adverse outcomes.

This review examines current catheterization practices in veterinary medicine, including evidence-based indications, catheter selection criteria, insertion and removal methodologies, and daily maintenance strategies. Additionally, it explores common complications such as CAUTIs, trauma, and biofilm formation alongside preventive measures to enhance patient safety and clinical outcomes.

Indications for Catheterization of Companion Animals

Urinary catheterization is indicated for relieving urethral obstructions, evacuating the urinary bladder, obtaining sterile urine samples, and facilitating diagnostic or surgical procedures (e.g., neurogenic lower urinary tract dysfunction, urogenital surgery). Critically ill patients with prolonged immobilization also warrant urinary catheterization. Current guidelines emphasize prompt catheter removal once clinical objectives are met as prolonged catheter use increases risks for complications.^9,10 Postoperative catheters should be discontinued unless specific medical needs warrant continuation.¹¹

Catheter Selection

Ideal catheter materials minimize urethral inflammation, resist mechanical deformation (i.e., kinking), and inhibit bacterial colonization. Common options include silicone, Teflon-coated latex, and polymer-coated variants. Silicone catheters, though stiffer, demonstrate superior resistance to kinking and reduced urethral irritation in humans when compared to latex.^12,13 Polypropylene catheters, although easy to insert, are associated with significant urethral and bladder trauma in cats and are generally discouraged.¹⁴ General-use catheters (e.g., red rubber, feeding tubes) are used for intermittent and short-term indwelling catheterization and exhibit higher bacterial adherence. Unlike balloon-retained Foley catheters, general-use catheters require external securement such as a finger-trap pattern to the prepuce, suturing to the vulvar labia, or perineal taping with a tail wrap for females. Antimicrobial- or hydrophilic-coated catheters may reduce infection risks, yet evidence remains limited within veterinary medicine.¹⁰

Urinary catheter size is measured on the French (Fr) scale, where 1 Fr corresponds to an external diameter of 0.33 mm. The smallest diameter that allows for adequate urine flow should be selected. For male cats, nonballoon tomcat catheters (3.5 Fr through 5 Fr) should be sutured for stabilization. Recommended sizes are 3.5 Fr though 5 Fr for cats and small dogs (e.g., Chihuahua, toy poodle), 5 Fr through 8 Fr for medium-sized dogs (e.g., beagle, bulldog), 8 Fr through 10 Fr for large dogs (e.g., Labrador retriever, Rottweiler), and 10 F through 14 Fr for giant-breed dogs (e.g., Mastiff, Great Dane)¹⁰ Balloon sizes typically range from 3 mL through 10 mL for cats and dogs. Sterile saline or water is recommended for inflation to prevent crystallization or rupture of the catheter balloon.¹⁵ Common urinary catheter types selected for intermittent procedures among dogs and cats (e.g., sterile sample collection, bladder drainage) are illustrated in FIGURE 1.

FIGURE 1A. Types of urinary catheters used for obstruction management in cat and dog- Two-way silicon Foley catheter. Courtesy Kruuse.

FIGURE 1B. Types of urinary catheters used for obstruction management in cat and dog- Polypropylene catheter. Courtesy Kruuse.

FIGURE 1C. Types of urinary catheters used for obstruction management in cat and dog- Hydrophilic-coated catheters. Courtesy Joya Medical Supplies.

Catheter Insertion, Maintenance, and Removal

Indwelling catheters are preferred for prolonged use (e.g., postoperative care), and intermittent catheters are preferred for short-term diagnostics. Before catheter insertion, the retention balloon should be inflated with the recommended volume of sterile saline to check for patency, symmetry, and leaks, then completely deflated. For indwelling Foley catheters, the balloon is then reinflated with sterile saline per manufacturer guidelines after correct placement is confirmed.

Aseptic technique is critical. The insertion site is prepped with povidone-iodine or 0.05% chlorhexidine. For males, catheter length is estimated by the distance from the neck of the bladder (cranial to the proximal femur) to the prepuce. After lubricating the catheter with 2% lidocaine gel, the catheter is advanced into the urethra under sterile conditions. For females, the urethral orifice may be visualized with a speculum or palpated digitally for blind insertion.

Proper catheter placement is confirmed by the absence of resistance during insertion and urine flow from the catheter hub. A notable exception is a ruptured bladder, where urine is absent from the bladder lumen; in those cases, correct placement may be inferred by the ease of insertion and subsequent drainage of uroperitoneum fluid. Resistance during insertion warrants gentle manipulation to avoid iatrogenic trauma. If persistent obstruction or significant hemorrhage occurs, the catheter should be removed. Antibiotic therapy is not indicated solely for hemorrhage but should be initiated if there is a confirmed diagnosis of a urinary tract infection by culture and susceptibility testing.

The catheter must then be connected to a sterile closed-collection system to minimize the risk for ascending bacterial infection. To prevent patient interference and accidental removal, the extension line should be securely taped to the tail of cats and female dogs. This is done by applying adhesive tape (porous white tape) in a loose spiral around the tail. The collection bag should be kept below the level of the patient’s bladder at all times.

The catheter and patient’s genitalia should be inspected at least twice daily for signs of inflammation, discomfort, and leakage. The balloon should be fully deflated before extraction. Traumatic removal or unresolved bleeding mandates prompt clinical evaluation.¹⁶

Complications

Risks for catheter-associated complications include CAUTIs, urethral trauma, biofilm formation, and pericatheter leakage leading to skin irritation. Among small animals, CAUTIs increase treatment costs, promote antimicrobial resistance, and contribute to patient morbidity. For severe cases, particularly in critically ill or immunocompromised patients, biofilm-mediated persistence can lead to life-threatening systemic complications.¹⁷ Antimicrobial-resistant biofilms often necessitate catheter replacement during active infections. Encrustation can obstruct flow, although evidence among veterinary species remains sparse. For cats, indwelling catheters carry a high bacteriuria risk (55% in 1 study), and biofilm reformation negates the benefits of routine catheter changes.¹⁸ Clinical signs of discomfort (e.g., perineal irritation, leakage) warrant reassessment of catheter necessity.

Summary

Urinary catheterization of dogs and cats plays a vital role in managing critical conditions such as urethral obstruction as well as diagnostic evaluations and urogenital surgeries. When implemented with meticulous technique—including appropriate catheter selection, aseptic insertion, and timely removal—their use significantly enhances patient outcomes while minimizing risks such as infection, urethral trauma, biofilm formation, and encrustation. The key to success is adherence to evidence-based protocols, sterility during placement, species-specific strategies for maintenance, and avoidance of unnecessary catheterization. Complications such as CAUTIs and pericatheter leakage underscore the importance of vigilant monitoring and prompt intervention when necessary. Ultimately, optimal urinary catheter management not only mitigates adverse effects but also supports faster recovery, which emphasizes its value as both a therapeutic and diagnostic tool in veterinary medicine.