Hello, my name is***** and I have over 20 years of experience as a veterinarian. I understand that you are concerned about Lollipop's sneezing bloody mucous, snoring, wheezing and hacking and I'd like to help.
Is his gum color a nice bubblegum pink, or are they every pale/white? A nice pink color tells me her bleeding wasn't a significant amount.
Heart disease does not lead to nasal congestion, so it makes sense her heart and lungs sounded OK.
Possible reasons for these symptoms are bacterial, fungal, tick borne or viral infections, a foreign body in the nose, a polyp or mass in the nose or a tooth root infection. Rarely the cause is a clotting disorder, but I would have expected her to have other symptoms of that including blood in her urine, bruising under the skin, and difficulty breathing due to blood in his chest. Dogs with a clotting disorder also tend to bleed equally from both sides of the nose. Is that the case with her?
I understand that she saw her veterinarian and they didn't see anything unusual on physical examination, but sometimes we need to perform some diagnostic testing to figure out the cause of their symptoms.
Sneezing and reverse sneezing with nasal congestion are signs of nasal and pharyngeal irritation.
With nasal irritation we can also see a nasal discharge which can be yellow, white, green, mucoid or even bloody in character. In some cases with long term infections or a mass we can even see nasal bone destruction and swelling or changes in nose conformation or around the eye.
Diagnosis of a the problem behind these symptoms can be complicated. We may need to perform radiographs of the nose and sinuses looking for changes in the bones or full sinuses, nasal flushes and scoping to collect culture and biopsy specimens and sometimes blood titers to look for the infection (especially if we are suspicious of a fungal infection).
Things that you can do that aren't too expensive include checking a complete blood count and biochemistry profile. I would also recommend checking her blood pressure.
If those tests come back normal then looking for a tooth root infection, a foreign body or polyp with a nasal scope and radiographs of his tooth roots, nose and sinuses under sedation would be recommended. Even if the crowns (top of the teeth above the gumline) look normal we can have root abscesses/infections that cause nasal irritation and congestion/bleeding.
If you decide that you cannot or would not run any further diagnostics, her color remains good and her physical examination is relatively normal then trying an antibiotic such as Clindamycin or Clavamox could be an option. These antibiotics are good for treating tooth and respiratory tract infections.
If you have lots of ticks in your area then a course of Doxycycline could be given instead as Doxycycline is good for tick borne and respiratory tract infections.
Benadryl (diphenhydramine) is an antihistamine that is used for allergies. Dogs rarely have nasal congestion with allergies, they usually get itchy skin. And I have never seen an allergic dog sneeze blood. Benadryl can also raise their blood pressure and dry out already sensitive nasal mucosa, perhaps leading to more bleeding. But if you wish to try it the dose would be 1mg per pound of body weight every 8-12 hours. Or 1/2 of a 25mg tablet per 7-12 pound dog every 12 hours.
Best of luck with Lollipop, please let me know if you have any further questions.