Dosage Guide • FL · NY · VA • Reviewed by Dr. Tiffany Delacruz, DVM
Prednisolone Dosage for a 18 lb Cat
prednisolone · Corticosteroid · Large adult breed (18 lb / 8.2 kg)
What pet owners in Florida, New York, and Virginia need to know about Prednisolone dosing for a 18 lb (large Maine Coons-sized) cat — written by a licensed vet, no specific dose given without an exam.
The dosing principle for Prednisolone
Prednisolone is preferred over prednisone in cats because cats convert prednisone to prednisolone less efficiently. Dosing varies widely by indication: anti-inflammatory dosing typically 0.5-1 mg/kg/day; immunosuppressive dosing can range 2-4 mg/kg/day. Dose is tapered over weeks, never stopped abruptly.
Cats are MORE resistant to corticosteroid side effects than dogs — they can tolerate higher per-kg doses with less weight gain and panting. BUT they're also at higher risk for steroid-induced diabetes mellitus, particularly overweight cats. Long-term doses must be individualized, weight-monitored, and frequently rechecked.
Why 18 lb matters
A 18 lb (8.2 kg) cat falls into the large adult category — typical examples include large Maine Coons, large Norwegian Forest Cats, and overweight Domestic Shorthairs.
Cats over 15-18 lb are often a mix of genuinely large breed (Maine Coon, Norwegian Forest) and excess body fat. Drug dosing for these cats is calculated based on LEAN body weight — not total weight. Many medications are over-dosed in overweight cats when total weight is used. A vet calculates the lean-mass-adjusted dose during the exam.
What Prednisolone is approved for
- Asthma (Siamese cats are over-represented)
- Inflammatory bowel disease
- Allergic dermatitis
- Autoimmune disease
- Some cancers (palliative or adjunctive)
What to watch for in your 18 lb cat
- Increased thirst, urination, and appetite (expected with steroid use)
- Weight gain — closely monitor; obese cats are at higher diabetes risk
- New or worsening infections (steroids suppress immunity)
- Behavioral changes — some cats become withdrawn
- Signs of diabetes: increased thirst, weight loss despite appetite — check bloodwork periodically
Get a Prednisolone prescription or refill in your state
RexVet is licensed in Florida, New York, and Virginia. Our veterinarians can examine your 18 lb cat by video, calculate the right Prednisolone dose for their specific situation, and either fill the prescription through our in-house pharmacy or send it to a local pharmacy near you.
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Learn more about Prednisolone
Prednisolone — Full Drug Guide
Uses, side effects, drug interactions, refills, and how it compares to alternatives.
Frequently asked questions
Frequently asked questions
How much Prednisolone can I give my 18 lb cat?
Prednisolone is preferred over prednisone in cats because cats convert prednisone to prednisolone less efficiently. Dosing varies widely by indication: anti-inflammatory dosing typically 0.5-1 mg/kg/day; immunosuppressive dosing can range 2-4 mg/kg/day. Dose is tapered over weeks, never stopped abruptly. For a 18 lb (8.2 kg) cat, this gives a range that a licensed vet will narrow down based on the indication, your cat's age, kidney/liver function, and any other medications. RexVet vets serve Florida, New York, and Virginia and can calculate the right dose for your specific cat in a $64.99 video visit.
Is Prednisolone safe for a large adult cat like mine?
Prednisolone (prednisolone) is widely used in cats in the 18 lb range, but "safe" depends on the specific cat, not just the weight. Cats over 15-18 lb are often a mix of genuinely large breed (Maine Coon, Norwegian Forest) and excess body fat. Drug dosing for these cats is calculated based on LEAN body weight — not total weight. Many medications are over-dosed in overweight cats when total weight is used. A vet calculates the lean-mass-adjusted dose during the exam. A licensed vet will check your cat's history, current medications, and any underlying conditions before prescribing.
What should I watch for after giving my 18 lb cat Prednisolone?
The most common things to watch for are: Increased thirst, urination, and appetite (expected with steroid use); Weight gain — closely monitor; obese cats are at higher diabetes risk; New or worsening infections (steroids suppress immunity). If you see anything concerning, contact a vet. For large adult cats specifically: Cats over 15-18 lb are often a mix of genuinely large breed (Maine Coon, Norwegian Forest) and excess body fat.
Can a RexVet online vet prescribe Prednisolone for my 18 lb cat?
Yes — if your cat is in Florida, New York, or Virginia and the medical situation is appropriate. Prednisolone is one of the medications RexVet's licensed veterinarians can prescribe via a $64.99 video visit. The vet will examine your cat by video, ask about history, and either prescribe Prednisolone at the right dose for your cat's weight (18 lb) or recommend a different approach if needed.
Can I get a Prednisolone refill in Florida, New York, or Virginia online?
Yes. RexVet is licensed in all three states and can refill Prednisolone prescriptions for cats already established on the medication. Refill visits are also $64.99. Prescriptions are filled through RexVet's in-house pharmacy (RexVetRx) or can be sent to your local pharmacy. Same-day delivery is available in most ZIP codes in FL, NY, and VA.
Prednisolone dosing for other cat weights
Other medications dosed for a 18 lb cat
Sources
Last fact-checked: 2026-06-01. Reviewed by Dr. Tiffany Delacruz, DVM. RexVet (Rex Vets Inc.) is licensed in Florida, New York, and Virginia.
Get the right Prednisolone dose for your 18 lb cat
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