I would be very concerned about this cat. Obviously she is an older cat if you have been caring for her for the last 15 years. If she is drinking excessively, she may be dehydrated, have kidney or liver problems, be diabetic, or have a hormonal imbalance such as elevated thyroid levels. The diarrhea could be a result of improper nutrition, infection, internal parasites, inflammatory bowel disease, cancer as well as any of the above listed diseases. The respiratory congestion could be an upper respiratory infection, feline herpes virus, feline asthma, pneumonia, heart failure or even lung cancer. Weight loss and lack of appetite in an older cat is always of concern and could indicate any number of diseases. Finally, feral and outdoor cats have an increased risk of acquiring the feline leukemia and feline immunodeficiency viruses, which can both suppress the immune system and increase their risks for developing cancer. I understand the difficulty you have because she is a feral cat and is not easily captured or handled, unfortunately I suspect she may have something more serious going on, in which case the over the counter treatments may not be successful. For diarrhea, you can try a short term diet of chicken and rice (use boneless, skinless cooked chicken breast without seasoning and steamed white rice), the addition of a small amount of shredded cheese can sometimes help firm things up and a small amount of yogurt can add intestinal probiotics, however dairy products can also cause diarrhea so keep them to a minimum. You can also try over the counter pet anti-diarrheal treatments such as bentonite clay or an over the counter pet dewormer for internal parasites. For the congestion, you can try steam treatments by keeping her in an enclosed bathroom with the hot water running for 10 to 15 minutes. Saline nose drops for infants once daily can also help loosen up secretions and congestion to help her breathe a little easier. Sometimes cats do not eat well if they cannot smell their food. Over the counter antihistamines can also sometimes help with decongestion, but you will need to contact your veterinarian for proper dosage based on her weight. If she does not show some improvement quickly, I would encourage you to find some way to bring her to your veterinarian for more intensive care.  [less]

Yes, in small amounts this should be fine. After they are weaned from their mothers, kittens lose the ability to digest lactose (the main milk protein) and become lactose intolerant. If fed large amounts of dairy products, this could result in diarrhea, cramping and gas. In small amounts, however, there should not be a problem. Yogurt has the added benefit of providing probiotics (beneficial intestinal bacteria such as lactobacillus and acidophilus), which can help maintain the health of the gastrointestinal tract, although there is some argument as to whether the bacteria actually survive the stomach acid to make it through to the lower intestine where they are of most benefit. Start with just a small amount of yogurt and watch her stools carefully, if she shows any signs of diarrhea or intestinal upset, discontinue using the yogurt.  [less]

A foreign body such as grass blades in the nostrils is a common reason for persistent sneezing, however they usually do not cause a swelling of the side of the face unless there is an infection and an abscess of the tissues around the nose. Another possibility would be an abscessed tooth. The roots of the upper teeth are very close to the nasal cavity and an abscessed root could cause both swelling on the side of the face as well as an infection that breaks through the bone into the nasal passages causing a persistent sneeze. Fungal infections in the nose are also known to cause swellings on the side of the nasal passages and can sometimes cause severe deformities of the nose, usually in cats. In an older dog, however, I would be very concerned about the possibility of a tumor. I would strongly recommend an examination with your veterinarian to have the swelling evaluated and probably an anesthetized oral and nasal examination with x-rays of the nose and teeth as well as a biopsy of the area if cancer were suspected. Early diagnosis and treatment is key to a successful outcome whenever you are dealing with cancer.  [less]