While a serous, runny nasal discharge may only be a sign of infection caused by bacteria or viruses, a discharge that contains mucus, pus or blood can be indicative of nasal cancer in dogs. Young puppies and kittens must be checked for a cleft palette if they are discharging milk from their nasal passages.
The nasal cavity in dogs is a complex structure consisting of nostrils that open up in two air passages that are lined with scrolled spongy bones called turbinates. A clear serous discharge coming out from both the nostrils may also be caused by the presence of small mites but mucoid and purulent (pus-filled) discharges need to be investigated since they can be signs of any of the following:
- Foreign matters, such as grasses or weeds that may have enter the nose while sniffing
- Dental infections, especially in the roots of upper teeth
- Fungal infection
- Nasal cancer
If blood is present in the discharge, it is almost certain that the cause is either a fungal infection or nasal cancer that is taking root in the passage. Cats with fungal infection in the nose must be checked for prevalence of feline cancer or the leukemia virus. Final diagnosis is done only after ruling out that the bleeding is not caused by violent sneezing since that can also result in temporary bleeding.
Nasal cancer usually occurs as paranasal sinus fibrosarcomas (a sarcoma derived from fibroblast cells, often able to generate collagen) or paranasal sinus chondrosarcomas (a malignant neoplasm of cartilage cells). Both types of sarcomas grow slowly but are progressive and invasive in nature.
Diagnosis of nasal cancer involves routine blood and urine tests, biochemical profiling, biopsy and CT scans. Apart from the nasal discharge and bleeding, other symptoms that dog owners should keep watch out for include:
- Excessive sneezing
- Bad breath
- Loss of appetite for a long period
- Facial deformity
- Bulging eyes
- Seizures that indicate metastasis to the brain
Nasal tumors usually do not respond to chemotherapy and other anti-cancer drugs. Surgery is also a difficult procedure since the structure of the nose is extremely complex. Therefore it is difficult to remove the tumor from the nose. Radiation therapy is available in select cities and veterinary schools, but this method usually reduces the size of the tumor only. It is dangerous to ignore treatment as nasal tumors can spread to the brain and cause seizures, and the condition may also breakout through facial bones and distort the dog’s appearance permanently.
Like all types of tumors, the cause behind nasal tumors is also not known. As with the symptoms of liver cancer in dogs, your observation of the symptoms and detection are the only ways to institute medical intervention in early stages to manage nasal cancer in dogs.