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Fluid therapy: dog and cat
A professional reference for veterinary specialists. It does not replace clinical judgement.
Calculator
Guideline or consensus statementRecommendations agreed by a panel of veterinary specialists after reviewing the evidence. They guide practice and do not authorise a product.
The result is arithmetic on the figures below. The plan, the fluid and its rate are the veterinarian's decision; reassess the animal regularly and adjust.
Maintenance
Guideline or consensus statementRecommendations agreed by a panel of veterinary specialists after reviewing the evidence. They guide practice and do not authorise a product.
| Formula | Dog | Cat |
|---|---|---|
| Per kg | 60 ml/kg/day | 40 ml/kg/day |
| Allometric | 132 × kg0.75 ml/day | 80 × kg0.75 ml/day |
| Linear with a constant | 30 × kg + 70 ml/day | 30 × kg + 70 ml/day |
| Puppies and kittens | 3 × the adult figure | 2.5 × the adult figure |
- No formula has been shown to be better than another. The daily volume is given over 24 hours.
- Water and liquid food by mouth or tube, and fluid given with injections, infusions and flushes, count towards the total.
- A blanket „twice maintenance" rate is not recommended: at that rate a 5% deficit takes about 33 hours to replace, longer than the recommended 12-24 hours.
Dehydration deficit
Guideline or consensus statementRecommendations agreed by a panel of veterinary specialists after reviewing the evidence. They guide practice and do not authorise a product.
Deficit (ml) = body weight (kg) × dehydration (%) × 10
- Replace the deficit over 12-24 hours together with maintenance and ongoing losses, then reassess; if it is not corrected, recalculate for the next 12-24 hours.
- Before a planned anaesthetic, about 80% of the deficit is corrected in the preceding 24 hours.
Estimating dehydration from the examination
| Dehydration | Findings |
|---|---|
| < 5% | Not detectable on examination |
| 5-6% | Slight change in skin turgor |
| 6-8% | Skin turgor mildly reduced, mucous membranes dry |
| 8-10% | Skin turgor clearly reduced, eyes sunken in the orbits |
| 10-12% | Skin tent does not return, corneas dull, signs of hypovolaemia |
| > 12% | Hypovolaemic shock, risk of death |
An estimate only. Dry mucous membranes can occur without dehydration, for example in kidney disease. Weigh the animal: a change in body weight is the most useful follow-up.
Hypovolaemia: bolus
Guideline or consensus statementRecommendations agreed by a panel of veterinary specialists after reviewing the evidence. They guide practice and do not authorise a product.
Guideline or consensus statementRecommendations agreed by a panel of veterinary specialists after reviewing the evidence. They guide practice and do not authorise a product.
| Dog | Cat | |
|---|---|---|
| Isotonic buffered crystalloid, one bolus | 15-20 ml/kg | 5-10 ml/kg |
| Given over | 15-30 minutes | 15-30 minutes |
- After each bolus reassess perfusion: heart rate, capillary refill, pulse quality, blood pressure, mentation. If it improved but is not normal, repeat the same or a smaller bolus.
- Cats in shock are often bradycardic, hypothermic and hypotensive and are easily overloaded: small boluses of 5 ml/kg and active rewarming.
- The older „shock dose" totals (dog 80-90 ml/kg, cat 50-55 ml/kg, 2013) are no longer given; the volume is titrated bolus by bolus.
Fluids under general anaesthesia
Guideline or consensus statementRecommendations agreed by a panel of veterinary specialists after reviewing the evidence. They guide practice and do not authorise a product.
Guideline or consensus statementRecommendations agreed by a panel of veterinary specialists after reviewing the evidence. They guide practice and do not authorise a product.
| Dog | Cat | |
|---|---|---|
| Starting rate | 5 ml/kg/h | 3-5 ml/kg/h |
- For an animal with normal heart and kidney function. A healthy animal under short injectable anaesthesia often needs no intravenous fluid.
- Once one anaesthetic has given 20 ml/kg, reassess the plan.
- The former routine 10 ml/kg/h had no evidence behind it and is no longer recommended.
Potassium chloride supplementation
Guideline or consensus statementRecommendations agreed by a panel of veterinary specialists after reviewing the evidence. They guide practice and do not authorise a product.
| Serum K+, mEq/l | KCl, mEq/kg/h |
|---|---|
| <2.0 | 0.5 |
| 2.0-2.5 | 0.3-0.4 |
| 2.6-3.0 | 0.2-0.25 |
| 3.1-3.5 | 0.1-0.15 |
| >3.5 | 0.05 |
- Never faster than 0.5 mEq/kg/h. A fluid containing potassium is never given as a bolus.
- The amount per litre depends on the fluid rate: mEq/l = mEq/kg/h × body weight (kg) ÷ fluid rate (l/h). Recalculate it whenever the rate changes.
- Mix the bag thoroughly after adding and use an infusion pump. If hypokalaemia persists, check magnesium. With a high serum potassium no potassium is added.
Subcutaneous fluids
Guideline or consensus statementRecommendations agreed by a panel of veterinary specialists after reviewing the evidence. They guide practice and do not authorise a product.
- 20-30 ml/kg once or twice a day, spread over several sites; at most 10-20 ml/kg per site.
- A balanced isotonic crystalloid (lactated Ringer's or a similar solution). 0.9% sodium chloride is not recommended under the skin: its low pH can make the injection painful.
- Not for an animal that is not dehydrated: there is no benefit, and it can harm animals with heart disease or low blood protein. A new giving set and bag for each patient.
Drip rate
Guideline or consensus statementRecommendations agreed by a panel of veterinary specialists after reviewing the evidence. They guide practice and do not authorise a product.
Drops per minute = rate (ml/h) × giving set (drops/ml) ÷ 60
- Macro-drip sets give 10, 15 or 20 drops/ml; a micro-drip set gives 60 drops/ml and suits small patients (with it, drops per minute equal ml per hour).
- A gravity set has no alarm, and the rate changes with the animal's position and the height of the bag: mark the bag and check the volume given every 1-2 hours. Use a pump where possible.
Fluid overload and monitoring
Guideline or consensus statementRecommendations agreed by a panel of veterinary specialists after reviewing the evidence. They guide practice and do not authorise a product.
Guideline or consensus statementRecommendations agreed by a panel of veterinary specialists after reviewing the evidence. They guide practice and do not authorise a product.
Cats, small dogs and animals with heart disease or oliguric kidney disease are the most easily overloaded.
- Body weight up by more than 10%.
- Faster or more laboured breathing, crackles, falling SpO2.
- A new murmur or gallop rhythm, especially in cats.
- Chemosis, subcutaneous oedema, swollen limbs; serous nasal discharge.
- Pleural effusion or ascites.
Monitoring: weigh the animal two to three times a day, count the respiratory rate every 1-2 hours, record what goes in and what comes out, and review the plan regularly. With signs of overload the infusion is stopped or slowed to keep the catheter open.
Infusion solutions in the reference
Active substances: Calcium chloride, Glucose, Potassium chloride, Sodium chloride, Sodium lactate
Products: Glucose Decefrag, Glucose Dentafill Plus, Glucose Pharmatech, Glucose Reka-Med, Neofleks, Neofleks Dextrose, Polifleks, Polifleks Dextrose, Ringer lactate SEEM, Sodium Chloride Aculife, Sodium Chloride Braun, Sodium Chloride Dentafill Plus, Sodium Chloride Liqvor, Sodium Chloride Reka-Med, Sodium Chloride-SEEM
Listed for navigation; the page does not recommend a product. Check each solution's composition on its label.
Sources
- Guideline or consensus statement. Pardo M, Spencer E, Odunayo A, et al. 2024 AAHA Fluid Therapy Guidelines for Dogs and Cats. Journal of the American Animal Hospital Association 60(4):131-163 2024
- Guideline or consensus statement. Davis H, Jensen T, Johnson A, et al. 2013 AAHA/AAFP Fluid Therapy Guidelines for Dogs and Cats. Journal of the American Animal Hospital Association 49(3):149-159 2013
- Guideline or consensus statement. Grubb T, Sager J, Gaynor JS, et al. 2020 AAHA Anesthesia and Monitoring Guidelines for Dogs and Cats. Journal of the American Animal Hospital Association 56(2):59-82 2020
Professional reference for veterinary professionals. Not advertising and not a substitute for the product label/SPC.
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This reference is still growing. Missing a product? Let us know. · Report an error or request an addition · Updated: 22 Oct 2026