Diagnosing canine incontinence

Photo: Monkey Business/Adobe Stock

Approximately 20% of all spayed female dogs and up to 30% of large-breed dogs will develop urinary incontinence.¹ Although any dog can develop incontinence, the condition most commonly affects large-breed female dogs who are middle-aged or older.¹

Typically, incontinence presents as an intermittent or continuous dribbling of urine alongside episodes of normal urination, according to Mark J. Acierno, MBA, DVM, DACVIM (SAIM), professor at Midwestern University College of Veterinary Medicine and associate dean for the school’s Clinical Affairs in Glendale, Arizona. At the Fetch dvm360 Conference in Nashville, Tennessee, Acierno led a lecture on the topic.²

Incontinence can be caused by bladder spams, ectopic ureters, an inability of the bladder dilate, damage to the nerves that control micturition, and urethral sphincter incompetence (USMI)—also called spay-related incontinence. Still, 85% of canine incontinence cases are caused by either ectopic ureters or urethral incompetence.²

Patient history

To diagnose incontinence in a dog, it is important to obtain a thorough history. According to Acierno, the discussion should also include questions about timing. “Knowing the timing is really, really important because a middle-aged female dog who's spayed, who's wetting its bed at night is a very, very different situation than the puppy that is dribbling urine constantly, right?” said Acierno during his talk at Fetch.² “So, the history is really, really important.”

“Is it only at night? And is it happening next to the bed? Because if it's happening next to bed, then the dog woke up, [went] next to the bed, peed on the floor, and went back to sleep, right?” Acierno continued, emphasizing questions that should be considered when discussing the patient’s history. He explained that the scenario would indicate something different if patient were urinating directly on the bed. Considering the timing of events surrounding urination can help clinicians differentiate incontinence from other conditions such as nocturia, pollakiuria, or polyuria.

Physical examination and observation

Part of the diagnostic process when evaluating a canine patient for incontinence includes obtaining a detailed examination of the genitalia. Veterinarians should look for anatomic abnormalities. According to Acierno, patients with incontinence will have wet or stained fur. Scalding and dermatitis will also be present.

“If we don’t [see these] the [patient] is probably not incontinent. It's probably something else,” said Acierno.

He also recommends asking clients to prevent their dog from urinating before the appointment and wait until during the appointment, as observing how the patient urinates can offer valuable information. Things to look for include if the strain is normal or not and if the patient postures correctly after urinating.

Diagnostic workup

After observing the patient urinate and measuring the output, a complete and thorough diagnostic workup should be conducted. This should include a complete blood count, serum chemistry, and urine analysis with aerobic culture.² Conducting a blood count, Acierno explained, will help in ruling out systemic illnesses while urine analysis can help determine if cystitis is causing the incontinence. Additional triggers of incontinence include urinary tract infections, which can themselves result from ectopic ureters and anatomic abnormalities.²

When it comes to imaging, although radiographs can be helpful, ultrasounds are preferred—this method has a higher sensitivity rate in detecting uroliths, tumors, and in certain cases, visualizing ureters. According to Acierno, radiographs miss approximately 27% of uroliths. Meanwhile, ultrasounds will yield only approximately 6% false negatives.²

When looking at an ultrasound, Acierno shared he also looks to see if the bladder is mostly empty. “If it doesn't, then we have a different set of problems, right?” he said.

Neurological examination

Although this step is commonly missed, conducting a neurological examination is a crucial part of the incontinence exam, according to Acierno. Spinal cord disorders above the 5th lumbar vertebra, ie., upper motor neuron lesions, can cause the bladder to empty involuntarily and reflexively, accompanied by increased resistance of the external urethral sphincter. Patients with these disorders may exhibit paresis, paralysis, hyperreflexia, decreased proprioception, and decreased pain perception.²

For lower motor neuron lesions, or lesion of the sacral spinal cord, there is inhibition of bladder sensation from traveling up the spinal cord. Moreover, sacral lesions can affect the pudendal nerve, leading to loss of external sphincter resistance.² Dogs with these lesions typically dribble urine and present with an easily expressed and overdistended bladder. Voiding will also be rare in these patients as they have lost bladder sensation.

As part of the neurological exam, patients may be taken for a walk. “You can get a dog take it for a walk and watch it walk, and do we see gait abnormalities?” said Acierno. “Another thing I'll do, [is] look at the top of the nail, and if they're scuffed, it means they’re dragging our feet which could be indicative of [lumbosacral] (LS) disease, right?

According to Acierno, gently squeezing the distal portion of the penis or edge of the vulva and watching for a reflex contraction of the anus can also be used to assess afferent and efferent function of the pudendal nerve.

Takeaway

As incontinence presents ongoing challenges for veterinary professionals and caregivers, performing a thorough incontinence exam on patients is crucial for accurate diagnosis. To begin, the thorough history of the patient must be discussed with the client, with special focus on the timing of events surrounding urination. Veterinarians should also perform a physical examination and observe for any anatomic abnormalities or clear signs of incontinence, followed by laboratory work and in some cases, imaging. Lastly, the neurological examination poses a crucial part of the exam and must not be overlooked.

References

1. Weir M, Hunter T, Ward E. Urinary incontinence (Urethral incontinence) in dogs. VCA Animal Hospitals. Accessed June 5, 2025. https://vcahospitals.com/know-your-pet/urethral-incontinence-in-dogs
2. Acierno M. How do we turn off this spigot? Managing canine incontinence. Presented at: Fetch dvm360 Conference; Nashville, Tennessee. May 31, 2025.