Prostatic disease in dogs is an important differential diagnosis for male canine patients presenting with lower urinary tract signs, recurrent infections, or abnormal prostate size on rectal examination. Prostatic washing (also called prostatic lavage or prostatic flush) is a minimally invasive diagnostic procedure that allows veterinarians to obtain samples for cytology, culture, and sensitivity testing. This blog post reviews the indications, required supplies, and technique to perform a successful prostatic wash in dogs.
Indications for Prostatic Washing in Dogs
Veterinarians should consider a prostatic wash when clinical signs and diagnostics raise concern for prostatic disease, such as:
- Hematuria or hemospermia in intact male dogs
- Recurrent urinary tract infections despite appropriate antimicrobial therapy
- Abnormal prostate palpation (asymmetry, enlargement, pain, or nodularity)
- Radiographic or ultrasonographic changes consistent with prostatitis, cysts, abscesses, or neoplasia
- Fertility evaluations when prostatic contribution to ejaculate is questioned
Obtaining samples via prostatic wash can help distinguish between benign prostatic hyperplasia (BPH), bacterial prostatitis, prostatic cysts, or neoplasia, guiding treatment recommendations and improving patient outcomes.
Supplies Needed for Prostatic Wash
Before performing the procedure, assemble the following supplies:
- Sterile urinary catheter (usually 5–8 Fr red rubber or polypropylene catheter for small dogs; 8–12 Fr for medium/large breeds)
- Sterile saline (0.9% NaCl)
- Sterile lubricant
- Syringes (10–60 mL) for instillation and aspiration
- Sterile collection containers (plain tubes for culture, EDTA tubes for cytology)
- Sterile gloves
- Appropriate restraint equipment
- Optional: Sedation supplies (acepromazine, dexmedetomidine, butorphanol, etc. depending on patient temperament and health status)
Technique: How to Perform a Prostatic Wash in Dogs
Follow these steps to maximize diagnostic yield while minimizing patient stress:
1. Patient Preparation
- Place the dog in lateral recumbency or standing, depending on temperament and clinician preference.
- Clean the preputial area with antiseptic solution to reduce contamination.
- Sedation may be helpful, especially in anxious or fractious dogs.
2. Catheter Placement
- Lubricate and aseptically insert the urinary catheter into the urethra.
- Completely empty the urinary bladder before beginning the prostatic wash to prevent dilution and contamination of samples.
- Withdraw the catheter to the level of the prostatic urethra located caudal to the urinary bladder neck.
- Confirm correct positioning by palpation per rectum.
3. Digital Prostate Massage
- Digitally massage the prostate per rectum for ~1 minute to dislodge cells and bacteria into the fluid.
4. Saline Infusion
- Instill 5–10 mL of sterile saline per 10 kg body weight into the urinary catheter
- Avoid excessive volume, which may cause reflux into the bladder.
5. Aspiration
- Gently aspirate the infused fluid back into the syringe.
- Repeat infusion, massage, and aspiration 2–3 times to maximize cellular and bacterial yield.
6. Sample Handling
- Place aspirated material into sterile containers for culture (aerobic & anaerobic) and EDTA tubes for cytology.
- Label appropriately and submit to the diagnostic laboratory without delay.
Clinical Tips and Considerations
- Avoid urinary bladder contamination by ensuring the catheter tip remains within the prostatic urethra rather than the urinary bladder.
- If no fluid is retrieved, gently reposition the catheter and attempt again.
- Ultrasound guidance may improve catheter placement in challenging cases.
- Consider adjunctive diagnostics such as fine-needle aspiration (FNA), ultrasonography, or ejaculate fraction collection to complement results.
Conclusion
Prostatic washing in dogs is a valuable, minimally invasive diagnostic tool for evaluating prostatic disease. With proper technique, clinicians can obtain high-quality samples for cytologic evaluation and culture, ultimately improving diagnostic accuracy and patient care. Incorporating this procedure into practice empowers veterinary professionals to better manage common canine prostatic disorders.
