Welcome to Justanswer! I am Dr. Altman and happy to assist you both today!
I am so sorry that your dog has straining and diarrhea. First please no immodium, some dogs can have a reaction to this medication and although most are breed related there are a few that are unrelated to breed and can cause significant illness so I do not advise use of this medication. Unfortunately azo is really not effective in dogs and can also be toxic for them as it can cause the red blood cells to break down.
There are a handful of causes of straining to urinate:
1.) A urinary tract infection
2.) Bladder stones that traumatize the bladder and cause bleeding
3.) A bladder tumor, most likely in a senior pet
4.) Trauma- hit by car, muscle trauma of some kind
5.) Kidney changes
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 bleeding.
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 blood 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 straining to urinate and to get your pet comfortable swiftly
Please let me know if you have any additional questions I can assist with!
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