The main function of a ferret’s respiratory system is to breathe in oxygen and to exhale out carbon dioxide. The respiratory system includes the nose, nasal cavity, pharynx, larynx, trachea, bronchi, and lungs. Unfortunately several diseases and conditions can cause problems with a ferret’s respiratory system.
The Upper Respiratory System
A ferret’s upper respiratory system contains the nose, nasal cavity and the pharynx, which is sometimes called the throat. The nose and nasal cavity filters, warms and humidifies the air. Filtering the air helps to remove viruses, bacteria, and other infectious agents before these reach the lungs and cause infections. The pharynx is a short tube that transports air into the larynx. Like the nasal passages, the pharynx helps to filter the air. In addition, the pharynx contains the tonsils, which also help to prevent infectious organisms from entering the lungs.
The Lower Respiratory System
A ferret’s lower respiratory system contains the larynx, trachea, bronchi and lungs. The larynx is often referred to as the voice box, but its main role is to transport air into the trachea. It also prevents food and liquids from entering the ferret’s trachea and lungs, and it helps to filter the air.
Air passes from the larynx into the trachea. The trachea is often called the windpipe. The trachea is made of C-shaped rings of cartilage. A ferret’s trachea contains from 60 to 70 rings; humans have only 15 to 20 rings in the trachea.
The trachea splits into the left and right bronchi. The bronchi further divide into even smaller tubes called bronchioles. The trachea, bronchi and bronchioles help move mucus upward toward the pharynx.
The ferret has six lung lobes while humans only have five lobes. A ferret’s left lung is composed of two lobes, but the right lung is made up of four lobes. Within the lung lobes, the bronchioles continue to divide into smaller passages and eventually into tiny alveolar sacs. These sacs are made up of very tiny alveoli.
The alveoli are where oxygen is delivered to the bloodstream and where carbon dioxide enters the respiratory system. The oxygenated blood goes back to the heart and is pumped out to the rest of the ferret’s body, and the carbon dioxide is exhaled out through the nose or mouth.
Diseases Of The Respiratory System
Ferrets are susceptible to many viruses that can cause infections in the respiratory system. The human influenza virus is the most common virus involved in ferret respiratory infections.
Ferrets are quite susceptible to most human influenza viruses, including the seasonal type A, the new 2009 H1N1 flu (swine) and the avian flu. Because ferrets can get the human flu and their lungs are similar to humans, ferrets are frequently used in human flu research. Ferrets can get the flu from people who have the flu or from other ferrets that have the flu. In a very recent case, a pet ferret in the Portland, Oregon, area got the swine flu from its owner. Thus, it is very important to avoid playing with or handling your ferret if you have the flu.
Most seasonal type A flu cases are mild in adult ferrets, but type A flu may cause more serious illness in young or old ferrets. H1N1 (swine) flu and avian flu can cause mild to fatal disease in ferrets regardless of age.
Ferrets with the flu usually have a fever, sneeze or cough, are lethargic, have a discharge from the nose and eyes, and eat less than normal. Treatment of the flu can include anti-influenza medications such as Tamiflu, along with an antibiotic for secondary bacterial infections, fluid therapy and supportive care.
The canine distemper virus is another virus that ferrets are very susceptible to. Signs of distemper start in the respiratory system, with fever, anorexia and a discharge from the nose. With time, skin rashes and neurological problems develop. Because distemper is almost always fatal in ferrets, vaccinate your ferret to protect against this fatal disease.
Aleutian disease is a parvovirus infection that can cause serious to fatal respiratory disease in very young ferrets (kits). In young kits, the parvovirus causes damage directly to the lungs, which can cause the kit to develop a fatal case of pneumonia. In adult ferrets, it can cause a chronic cough that does not respond to cough suppressants or antibiotics. Unfortunately, there is no vaccine for Aleutian disease.
The coronavirus is another viral disease that can cause serious to fatal respiratory disease in young ferrets. Most of the time, the coronavirus causes just a mild illness of the gastrointestinal tract; however, some ferrets develop a coronavirus infection that spreads through the blood to other organs. This systemic coronavirus infection can go to the lungs and cause pneumonia and death. Treatment can include drugs to suppress the immune response, antibiotics for secondary bacterial infections, fluid therapy and supportive care.
Ferrets can also have bacterial infections of the respiratory system. Bacteria can infect the nose (causing rhinitis), nasal cavity (causing sinusitis) and lungs (causing pneumonia), but most cases of bacterial infections of the respiratory system are secondary to a viral infection. Viral infections such as influenza and distemper can cause damage to the respiratory system and immune system, which allow bacteria to infect the respiratory system. Strep, E. coli, Klebsiella, Pseudomonas and Bordetella have all been reported in cases of bacterial pneumonia. Bacterial infections can be treated with antibiotics, fluid therapy and supportive care.
Fungal infections of the respiratory system are possible, but they are rare in pet ferrets that are kept indoors. Fungal infections may be more common in ferrets that are kept outdoors or are working ferrets that are exposed to the fungal spores in the soil.
Another cause of pneumonia is aspiration of food or liquids. Aspiration pneumonia is most commonly seen in sick ferrets that are being force-fed. Ferrets with megaesophagus are also prone to aspiration pneumonia. Treatment of aspiration pneumonia includes antibiotics, fluid therapy and supportive care.
Cancer can also invade the respiratory system. Lymphoma is the most common type of cancer in the respiratory system. By the time lymphoma spreads to the lungs, the ferret is usually in bad shape and may need to be euthanized.
One last problem in the ferret respiratory system is trauma. Ferrets are at risk for traumatic injuries from dog bite wounds, rocking chair injuries, falls and damage from falling objects. Trauma can cause injuries to the lungs and even death, so be careful when your ferret is out of its cage.
The ferret’s respiratory system is very similar to the human respiratory system with the two main differences being the number of tracheal rings and the number of lobes in the right lung. Ferrets are also susceptible to a lot of viral and bacterial infections, with the human influenza virus being the most common problem. Fortunately most respiratory infections are treatable or preventable.