Welcome to Justanswer! I am Dr. Altman and happy to assist you both today!
First, congratulations on your rescue adoption! I hope you have many happy years together!
There are a handful of causes of urination that has mucus in it:
1.) A urinary tract infection
2.) Bladder stones that traumatize the bladder and cause irritation
3.) A bladder tumor, most likely in a senior pet
4.) Trauma- hit by car, muscle trauma of some kind
Ideally until you are able to get to your veterinarian, please increase water intake. You can do this by supplementing the dry food with water and flavoring the water (maple syrup or no salt broth for example) as well. Increasing the water intake will help "flush" out the bladder and reduce the pain associated with the mucoid discharge.
Collecting a first morning sample in a tupperware container and refrigerating the sample if more than an hour old to have your vet evaluate the sample will help determine the cause of the mucus in the urine.
Your vet will run a urinalysis, potentially do a urine culture to look for bacteria, an X-ray to rule out a bladder stone, and bloodwork to ensure there is not a metabolic cause or kidney issues causing the symptoms
Diagnosing the issue will help determine how best to treat the discharge to get your pet comfortable swiftly
Please let me know if you have any additional questions I can assist with!
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