Raccoon Medical Mystery

Article by Juliana Sorem, DVM, Melanie Piazza and Alison Hermance

In this video, Dr. Amy Allen explores the raccoon’s nasal passages endoscopically while WildCare’s Brittany Morse
monitors the raccoon under anesthesia.

The heavy mucus coming from the raccoon’s eyes and nose was caked on his face. Here he is being sedated for a nasal flush. Photo by Alison Hermance

Upon his intake at WildCare’s Wildlife Hospital, our Medical Staff noted that this young raccoon was in severe respiratory distress and he had thick mucus coming from his nose and eyes. Our team’s treatment plan for this raccoon involved careful consideration of all of his symptoms. Little did they know this case was about to turn into a serious medical mystery!

Dr. Sorem takes samples for the distemper test and flushes the raccoon’s nose. Photo by Alison Hermance

Heavy nasal discharge can be a symptom of distemper, a very contagious disease between mammals like raccoons and skunks, so Medical Staff had a volunteer prep an enclosure in quarantine in one of WildCare’s wards. Any distemper species (raccoon, fox, skunk) with these symptoms must be considered a distemper suspect until proven otherwise. The team treated his injuries, hydrated him with subcutaneous fluids, gave him medications for pain, and started him on a course of antibiotics due to the severe blood-tinged nasal discharge.

Over the next several days, the raccoon demonstrated a feisty nature and a great appetite. Unfortunately, Medical Staff saw minimal improvement in his nasal discharge with antibiotic treatment. After five days they sedated him to take radiographs (x-rays), to run bloodwork, and to test for distemper. Blood tests came back showing anemia and elevated blood protein (probably due to inflammation), and the radiographs showed no trauma to skull or nasal passages and clear lungs. Interestingly, they also showed old (healing) fractures in both of the raccoon’s wrists, but we don’t know how those injuries occurred. The raccoon continued to receive supportive care and his nightly routine included creating chaos in his enclosure.

The bright light of the endoscope is clearly visible inside the raccoon’s nasal passage! Photo by Melanie Piazza

As weeks passed, WildCare’s Veterinarian Dr. Sorem and the team became increasingly concerned that none of the treatments effectively resolved the raccoon’s symptoms. He continued to eat well and gain weight, and his attitude remained feisty and wild, which is always a good sign in the Wildlife Hospital. The distemper test came back negative, which was good news, but the mucus continued to cause the animal significant distress.

Medical Staff decided to call upon the expertise of Dr. Amy Allen, a San Rafael-based veterinary Internal Medicine Specialist and owner of Animal Internal Medicine (AIM) Mobile Endoscopy. Dr. Allen brought her equipment to WildCare to examine the raccoon’s nasal passages endoscopically. (WildCare is very grateful to Dr. Allen and her assistant for their generous donation of their time, equipment and expertise to help us diagnose this raccoon!) With her superior instruments, Dr. Allen was able to visualize the full length of the raccoon’s nasal passages all the way back to his larynx. She discovered an enlarged left tonsil as well as a thick band of tissue that divided the nasopharynx, the deepest part of the nasal passages, into left and right halves. Scroll down to see the rhinoscopy photos!

This is not a normal finding in Dr. Allen’s usual patients (dogs and cats) but it was unknown if it was also abnormal for a raccoon. Part of the problem with diagnosing this raccoon’s illness is the lack of concrete veterinary information about his species. The team put out a call to Dr. Pesavento, a veterinarian doing research at the UC Davis School of Veterinary Medicine for her collection of CT scans of raccoon heads to determine the normal shape of a raccoon’s nasal passages. See box for more information on WildCare’s participation in Dr. Pesavento’s ground-breaking research.


In 2012, WildCare data helped Dr. Pesavento discover a new virus called a raccoon polyomavirus that was discovered to be the cause of a certain type of brain tumor in raccoons.

WildCare’s Medical Staff had reported, and had sent to the lab at UC Davis for postmortem testing, a number of raccoons with oddly passive behavior and the symptoms of head trauma without an obvious cause.

The submitted samples came to the attention of Dr. Pesavento, and diagnostic input from WildCare Medical Staff helped her isolate the animals with tumors and ultimately discover the polyomavirus. Read about it in the LA Times here.
As of this writing we are still waiting to see the CT scans and compare those raccoons’ heads with that of our young patient.

Dr. Amy Allen of Animal Internal Medicine and her assistant donated their time and equipment to examine our raccoon patient. We’re grateful! Photo by Melanie Piazza

The other interesting thing Dr. Allen’s endoscopy found was a swollen and reddened mass on the band of tissue, and some areas that looked like they might be fungal growth. Dr. Allen was able to obtain samples from deep within the nasal passages to submit for a biopsy and fungal culture. It is truly wonderful for WildCare Medical Staff to work with specialists on cases like this one, and the opportunity for advanced learning and increased diagnostic capability make medical mysteries a very important learning opportunity for WildCare’s medical team. Scroll down to see the actual photos with descriptions from the raccoon rhinoscopy!

Unfortunately the biopsy results just showed a severe bacterial infection with thickened connective tissue (possibly scar tissue). No fungal organisms were seen on the biopsy and only a small number of likely incidental fungal organisms grew on the fungal culture. These findings raised further the question of whether the structure dividing the raccoon’s nasal passages is a normal feature of raccoon anatomy vs. an anomalous structure that might be contributing to the chronic infection.

Raccoon Rhinoscopy

Click each image to see what Dr. Allen saw during her endoscopic exploration of the raccoon’s nasal passages!

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Medical cases like this give WildCare Medical Staff an invaluable opportunity to learn new skills. Here Dr. Allen works with Clinic Manager Brittany Morse. Photo by Melanie Piazza

Throughout all this, and after over 40 days in care, the raccoon was still eating well and gaining weight but nasal discharge persisted despite empirical use of several antibiotics. Could this be a bacterial infection that was resistant to the antibiotics that are normally effective? Dr. Sorem decided that we should run a bacterial culture but, because the raccoon was already on antibiotics and this could interfere with the culture results, we decided to stop all antibiotics for five days before obtaining a new sample of the nasal discharge.

Once again the team sedated the raccoon in order to get samples of discharge from deep inside his nose. These were submitted for bacterial culture and antibiotic sensitivity testing. The results came back a few days later and showed that the main bacteria growing in his nose (of the klebsiella species) is one that should have been susceptible to one of the antibiotics (enrofloxacin) he was already on. So, we made one last-ditch effort by adding a new antibiotic (doxycycline) that attacks a class of bacteria that is difficult to grow on cultures. Now we had to wait once again to see if there was any improvement.

Finally, good news!

As of this writing, and after eight days on the new antibiotics, the raccoon is showing almost no nasal discharge! The small amount of discharge still present is clear, which is a much less concerning color, and he is healthy enough to move to an outdoor enclosure this weekend! We will continue this medication for two more weeks, and, with luck and ongoing excellent care, this medical mystery will finish with a tremendous amount of new knowledge for our Medical Staff, and the release of a healthy raccoon back to the wild!

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