Thanks for reaching out with your concern. I understand how worrying it can be when your cat isn't using the litter box as expected, especially when traveling.
Cats may experience constipation due to changes in environment, stress, or dehydration—common factors during travel. Ensure your cat has regular access to fresh water, as dehydration can exacerbate constipation. You might want to offer some canned food, which typically contains more moisture than dry food, helping to rehydrate them a bit.
Gently massaging your cat's abdomen might also help stimulate bowel movement. Make sure your cat is given opportunities to move around, as movement can aid digestion.
Keep an eye out for any signs of distress, such as vomiting, lack of appetite, lethargy, or if your cat is trying to defecate without success, as these may indicate a more serious issue that requires medical attention.
If your cat hasn't relieved itself in another day or begins to show any of the concerning symptoms, I recommend booking a video consult with one of our vets on Dial A Vet. They can provide you with personalized advice and support during your journey.
Clinically Approved Standard by Dial A Vet Veterinary Team
Disclaimer: The customer and expert messages presented herein may have been altered with artificial intelligence or modified to enhance readability and safeguard the privacy of individuals. This content is for informational purposes only and is not a substitute for professional veterinary advice, diagnosis, or treatment. If your pet is experiencing a medical emergency, contact your local veterinarian or emergency animal hospital immediately. Talk to a vet now.

