Short answer: If a dog drinks more than 100 mL/kg/day (50 mL/lb), that’s polydipsia. The top causes are kidney disease, diabetes mellitus, Cushing’s disease, pyometra (intact females), hypercalcemia, and some medications (steroids, furosemide, phenobarbital). A sudden increase needs a vet visit with bloodwork + urinalysis.
🚨 Red flag — call your vet now if: intact female with off food + lethargy + increased thirst (pyometra is fatal without surgery); or polydipsia + vomiting + lethargy + weakness (could be Addison’s crisis or DKA).
What you should actually do
- Normal water intake: 50-100 mL/kg/day (25-50 mL/lb). Polydipsia threshold: >100 mL/kg/day.
- Measure for 48 hours by leaving one bowl and refilling with a measuring cup – more accurate than guessing.
- Diabetes mellitus: polyuria + polydipsia + weight loss despite ravenous appetite. Diagnosed with fasting blood glucose + urinalysis.
- Cushing’s (HAC): pot belly, thin skin, increased panting, hair loss, polydipsia. Diagnosed with LDDS or ACTH stim test.
- Pyometra: intact unspayed female + lethargy + off food + vaginal discharge + polydipsia = surgical emergency.
PU/PD (polyuria/polydipsia) is one of the most common presenting complaints in dog clinics and triggers a well-defined diagnostic workup: CBC, chemistry, T4, urinalysis with specific gravity, and ideally a urine culture. Specific gravity below 1.030 in a dog with increased thirst is the key finding – it means the kidneys are not concentrating urine.
Less commonly: psychogenic polydipsia (behavioral), liver disease, hypoadrenocorticism (Addison’s), hyperthyroidism (rare in dogs), and central or nephrogenic diabetes insipidus. Almost all of these have specific treatments, but the diagnosis hinges on early bloodwork.
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⚕️ Medical Disclaimer
The information on this page is intended for educational purposes only and does not replace a hands-on veterinary examination. Drug doses depend on your dog’s complete clinical picture, concurrent medications, and the exact product formulation. Always confirm dosing with your veterinarian before administering any medication, and contact a 24-hour veterinary emergency service or animal poison control immediately if you suspect a medication overdose or adverse reaction. Editorial standards: every drug dose published on PuppaDogs is cross-checked against multiple authoritative veterinary references and reviewed by PuppaDogs Veterinary Editorial Team before publication.
