Can I Give My Cat MiraLAX?

Yes, with care
Polyethylene glycol 3350 is commonly referenced for cats at published doses. Published guidance for cats: 1/8 - 1/4 tsp in wet food, every 12-24h. Commonly used for feline constipation. Straining WITHOUT producing urine is an emergency (blocked cat), not constipation. ER now.
Source: Veterinary Partner (VIN)
Get the exact range for your cat's weight

Skip it or ask a vet first if

suspected obstructiondehydrationstraining with no urine (cats). ER

The safe habit

Confirm any medication decision with your veterinarian, who knows your cat's health history and other medications. VetDose shows published reference data, not prescriptions.