How do calcium phosphate urinary stones form?

Calcium phosphate stones are related to urine composition, low water intake, diet, and individual factors. Your vet will assess the underlying cause through urinalysis and imaging and provide appropriate management advice.

Can calcium phosphate stones be dissolved with a special diet?

Whether dissolution is possible depends on stone composition and size. Some non-obstructing stones may be gradually dissolved with a prescription diet, but this must be assessed and monitored by your vet using urinalysis and imaging.

How soon should follow-up be scheduled after treatment?

A first follow-up urinalysis and imaging is generally recommended within 1–3 months after treatment, with frequency adjusted according to progress. Please follow your vet's schedule for rechecks.

How can the risk of urinary stone recurrence be reduced?

Common strategies include increasing water intake, adjusting diet formulation, and regular urinalysis. If stones recur repeatedly, referral to a urinary specialist for further evaluation is recommended.

How much do the tests and treatment usually cost?

Costs vary by clinic and region — ask your vet for an estimate before proceeding.

Disease Guide

Calcium Phosphate Urinary Stones in Dogs & Cats: Symptoms, Diagnosis & Prevention [2025]

Calcium phosphate stones are often linked to metabolic disorders and typically require surgical removal along with investigation of the underlying cause.

Take 1 minute to check the symptoms first

Last updated: 2026/01/06

Pethealthmap Editorial Team

Sources: ISFM, WSAVA, National Taiwan University Veterinary Teaching Hospital

When to See a Vet

Seek Emergency Care Immediately

•Complete inability to urinate with continuous straining or signs of obvious distress
•Persistent heavy blood in urine or passing blood clots accompanied by weakness
•Marked weakness, inability to stand, or persistent lethargy

Schedule a Clinic Visit Soon (within 24–72 hours)

•Frequent straining but producing only small amounts of urine with signs of discomfort
•Darkened urine color or occasional blood in urine requiring ongoing monitoring
•Decreased appetite and noticeably reduced activity level

01What symptoms indicate something is wrong?

Common clinical signs and warning signals of urinary stones that suggest possible bladder or urethral irritation or obstruction.

Visible blood in urine — pink, red, or containing clots
Frequent straining with little or no urine output, or difficulty urinating
Signs of pain during urination such as crying out, wincing, or urine dribbling
Changes in urination frequency, including sudden increase or nighttime urination
Decreased appetite, reduced activity, or low energy
If abnormal urination is noticed, arrange a clinic visit promptly

Seek emergency care immediately if you notice the following symptoms:

⚠️ Complete inability to urinate with continuous straining or obvious distress
⚠️ Heavy continuous blood in urine or blood clots passed, accompanied by weakness
⚠️ Marked weakness, inability to stand, or persistent lethargy

02How do you assess the situation at home? Key home monitoring points and when to seek emergency care

Key things to observe and record at home to help the vet quickly understand the course and changes of the condition.

Note when blood in urine was first seen, how often it occurs, and any changes in colour
Measure and record daily water intake and urine output or frequency
Use your phone to take video of urination or photos of blood in urine for reference
Observe any changes in alertness, activity level, and appetite
Weigh your pet regularly and record short-term weight changes to aid assessment
If symptoms persist or worsen, arrange a clinic visit as soon as possible

03How will the vet diagnose this? Common diagnostic tests

Tests performed at the clinic, focusing on locating stones, assessing their size, and checking for secondary obstruction or infection.

Physical examination

abdominal palpation and assessment of urinary discomfort

Urinalysis

urine sediment, pH, protein, and bacterial testing

Blood and biochemistry panel

to evaluate kidney function and overall health

Abdominal X-ray

to confirm stone location, size, and number

Ultrasound or CT if needed

to assess the bladder, kidneys, and urethra

Specialist referral or further management may be recommended based on findings

04How is this treated and managed after diagnosis? Medication, dietary changes, and home care guide

Treatment depends on stone composition and whether obstruction is present, with the focus on relieving symptoms and preventing recurrence.

Conservative management: prescription diet, increased water intake, and supportive care
Emergency urinary catheterisation or surgery may be required if obstruction is present
Regular follow-up urinalysis and imaging are recommended after treatment
Long-term monitoring to detect recurrence and adjust diet or lifestyle accordingly
Home care focus: encourage water intake and monitor urination habits
Follow-up at a clinic with urology expertise is recommended

05What should you prepare before seeing the vet? Key information to help the vet quickly identify the cause

Note when symptoms first appeared and how often they have occurred

Prepare a record of water intake and urination over the past 2–3 days

Bring a small fresh urine sample if possible

List all current medications and supplements being used

Bring copies of past X-rays or test reports if available

Call ahead to book an appointment and describe current symptoms and urgency

This content is for reference only and cannot replace a professional veterinary diagnosis. If your pet shows signs of illness, please seek veterinary care promptly.