Respiratory Disease in the Ferret

Katrina D. Ramsell Ph.D, DVM

(Revised February 2006)

Ferrets, like dogs, cats, and other creatures are susceptible to various respiratory tract infections and diseases. Although respiratory ailments are observed less commonly than many other diseases in ferrets, they can be serious and life threatening if not treated appropriately. In addition to infections, inhalation of food and other substances, environmental irritants or allergens, trauma, foreign bodies, and systemic diseases, such as heart failure and cancer can cause abnormal conditions affecting the respiratory system.

Respiratory diseases are frequently localized to the upper or lower respiratory tract. The upper respiratory system includes the nose, nasal passages, sinuses, larynx, and trachea. Sneezing, discharge from the eyes or nose, and open-mouth breathing are all signs of an upper respiratory ailment. Diseases of the lower respiratory tract affect the primary bronchi and the rest of the lung tissues. Labored breathing, coughing, wheezing, and respiratory crackles are signs associated with diseases involving the lower respiratory tract. A healthy ferret should have cold, slightly wet nose and should have a resting respiratory rate around 35 breaths per minute.

General respiratory conditions

Sinusitis
Ferrets can suffer from “sinusitis”, which is a condition where the sinus passages are inflamed and sometimes infected. Signs of sinusitis can include a decreased appetite, nasal discharge, sneezing, noisy breathing, and sometimes open-mouthed breathing. Allergies and an infection at the root of an upper canine tooth can both cause sinusitis in ferrets. Although I recently diagnosed a ferret with a cryptococcus-induced sinusitis, fungal infections rarely cause respiratory disease in ferrets. A ferret showing symptoms indicative of sinusitis should be examined by a veterinarian.

Bronchitis
Bronchitis is sometimes diagnosed in ferrets. Viruses, bacteria, allergens, and inhaled irritants are common causes of bronchitis. Cigarette smoke, scented litters, and wood shavings with aromatic oils should be avoided. Blankets and hammocks in a ferret’s cage should preferably be washed in a detergent free of scents and dyes. Bedding should be washed frequently to prevent accumulation of urine, feces, dust, and other debris, and cages should be cleaned and thoroughly rinsed on a regular basis. Cages should be properly ventilated to help prevent buildup of toxic, noxious odors (such as ammonia from urine), and air filters can help remove dust and other unwanted particles from the air. If you have ferrets that sporadically sneeze, wheeze, cough, or have watery discharge from the eyes or nose, you should examine the environment for a potential cause of irritation and remove the culprit if it is found. If no source of irritation is found and your ferret’s illness is not resolving, or especially if it is getting progressively worse, then your ferret should be seen by a veterinarian and appropriate diagnostic tests should be done. Treatment of bronchitis initially involves identifying and removing the source of irritation, but medical therapy may be necessary to give your ferret some relief, especially if no cause for the condition can be found.

Pneumonia
Pneumonia is rarely diagnosed in ferrets, but it can be serious if a ferret does suffer from the condition. Ferrets that are immunosuppressed, such as those with canine distemper, human influenza virus, or Aleutian disease virus are more susceptible to pneumonia. Several types of bacteria can cause pneumonia in ferrets, and secondary bacterial infections can be life-threatening. Ferrets can also acquire a type of pneumonia called “aspiration pneumonia” from inhaling food, medications, or other substances, and this condition is often secondary to another disease known as megaesophagus (a disease where the esophagus does not push food into the stomach appropriately). Signs of pneumonia include lethargy, labored or difficult breathing, discharge from the nose, fever, and sometimes coughing. Ferrets with pneumonia occasionally die suddenly without showing previous signs of illness. X-rays are helpful in determining if a ferret has pneumonia, and blood tests can further indicate if an infection is present. Ferrets with pneumonia require supportive care and usually require hospitalization with antibiotics and supplemental fluids.

Systemic diseases associated with respiratory conditions

Cardiac Disease
Cardiac (heart) disease is common in ferrets, and middle-aged to older ferrets with respiratory difficulty frequently have underlying heart disease that has progressed to heart failure. Congestive heart failure often results in fluid accumulation in the chest and/or abdominal cavity as well as various tissues and organs. Fluid in and around the lungs can make breathing difficult, as can pressure on the diaphragm. Ferrets with advanced stages of congestive heart failure are often lethargic, have labored breathing, and have poor appetites. Although the disease cannot be reversed or cured, there are medications that can control the symptoms, at least for a period of time, and greatly improve your ferret’s quality of life.

Lymphoma
Lymphoma is a type of cancer frequently observed in ferrets. Adult (lymphocytic) lymphoma is most common in older ferrets and is usually associated with enlargement of peripheral, abdominal, and/or thoracic lymph nodes. Juvenile (thymic) lymphoma is a type of cancer that affects young ferrets primarily less than two years of age and is associated with a cancerous thymus that enlarges and interferes with lung expansion and breathing. Signs of juvenile lymphoma usually come on quite quickly, and obvious signs of debilitation may not be observed before the ferret becomes critically ill. Ferrets with symptoms of difficulty breathing and lethargy should be taken to a veterinarian immediately. Lymphoma is extremely difficult to cure, and the most realistic goal of treatment is to put the cancer into remission for a period of time.

Colds and Flu

With the cold and flu season well under way, many people are probably wondering if their ferrets can catch their cold or the flu. Although ferrets can contract human influenza, there is no evidence to indicate that ferrets can be infected by the human rhinovirus, which is a common cause of human colds. A variety of viruses cause the human “cold”. People frequently believe they have a cold when they actually have a mild case of the flu or a bacterial sinus infection. Rarely do people actually know exactly what type of bacteria or virus is causing their flu-like symptoms. Therefore, although it may be technically correct to say that your ferret cannot catch your cold, if you have the symptoms of a cold or the flu, you should assume your ferret is able to contract your illness.

Human Influenza
Human influenza virus is a common viral cause of respiratory disease in pet ferrets. It is a virus from the family Orthomyxoviridae, and there are several strains of the virus that can infect ferrets. Ferrets contract the flu when exposed to people or other ferrets infected with the influenza virus, and ferrets can transmit the flu to people. Transmission occurs by inhalation of aerosolized droplets and occurs for a few days from the time a ferret spikes a fever.

Influenza results in mostly upper respiratory symptoms in both ferrets and people. In addition to a fever that lasts about 48 hours, sneezing, watery eyes, nasal discharge (clear to mucoid and yellowish-green), lethargy, and a decreased appetite are all signs of influenza in ferrets. Signs of influenza are usually mild in older ferrets, but some strains of the virus can cause more serious disease and result in pneumonia. Ferrets with simultaneous diseases are usually more severely affected. Very young ferrets often develop a much more serious upper respiratory tract infection than adult ferrets and they can die from mucus obstructing their lower airway.

Influenza is usually diagnosed based on a ferret’s symptoms and history of exposure.
Treatment of influenza usually consists of supportive care at home, but severely ill ferrets may require hospitalization. Supplemental feedings and/or fluids may be needed for ferrets that don’t eat or drink adequately on their own. Antibiotics may be necessary to prevent secondary bacterial infections. If your ferret displays symptoms indicative of a cold or the flu, never give over-the-counter medications unless your veterinarian specifically recommends them.

You should seek veterinary care for your ferret if symptoms seem severe or if they persist for more than a few days. Reducing your ferret’s exposure to the influenza virus in addition to providing a clean, sanitary environment will help prevent your ferret from catching the flu. If you have a cold or the flu, wash your hands frequently, especially before handling your ferret. Don’t kiss, sneeze, or cough on your ferret while you are ill.

Other viral causes of respiratory disease

Canine Distemper Virus
Canine distemper virus is another virus that can cause respiratory disease in ferrets. Although canine distemper can initially have signs that are similar to the flu, distinct differences between the two diseases appear within a few days, and their out comes are very different. Whereas influenza generally resolves on its own, canine distemper is almost always fatal in ferrets.

Canine distemper virus is a contagious disease caused by a paramyxovirus. Several families of mammals can contract the disease, including Canidae (e.g. dogs, coyotes, foxes, and wolves), Mustelidae (e.g. ferrets, mink, weasels, otters, and badgers), and Procyonidae (e.g. raccoons, coatis, and kinkajous). Canine distemper is a prevalent viral disease in unvaccinated dogs and neighborhood raccoons. Ferrets are susceptible to the disease when they are unvaccinated and are exposed to an animal carrying the virus or when they come in contact with infected material such as shoes or clothing. You can bring the virus home and infect your ferret after visiting a pet store or walking in the woods or local park. Canine distemper virus has been shown to live for at least 20 minutes on clothing, but the virus can be destroyed by disinfectants, detergents, heat, and drying (e.g. run clothing through the drier for at least 30 minutes). Ferrets can also contract the disease if they receive a canine distemper vaccine that is not appropriate for ferrets. Appropriate canine distemper vaccines stimulate an immune response, which can protect a ferret if it is later exposed to the virus, without actually causing the disease.

Although signs of canine distemper virus are variable, the disease usually initially results in mild eye irritation and clear nasal discharge. A high fever often develops within a few days, and an infected ferret usually becomes lethargic and loses its appetite. Discharge from the eyes and nose often becomes thick and yellowish-green, and the eyes may become matted shut. A prominent sign of canine distemper is a red and swollen appearance to the skin around the lips, chin, and anus. This often progresses to thick, orange-tinged crusting, and the foot pads frequently become very thick and hard. Ferrets may exhibit other signs such as wobbliness, head tilt, odd behavior, and seizures as the disease progresses to later stages. Some ferrets with the disease die from brain damage. Canine distemper virus suppresses a ferret’s immune system, resulting in overwhelming secondary bacterial infections, severe respiratory symptoms, and eventually death.

Diagnosis of canine distemper is made based on a ferret’s symptoms and a history of exposure of an unvaccinated ferret to the virus. There is no known treatment for this disease, and ferrets with canine distemper almost always die. Having your ferret properly vaccinated against canine distemper is the best way to prevent your ferret from contracting the disease. Ferrets should be vaccinated starting at 8 weeks of age and should continue receiving vaccinations every 3-4 weeks until 14 weeks of age. If a ferret is over 14 weeks of age, or if the vaccine history of the ferret is unknown, the ferret should receive two vaccinations 3-4 weeks apart. All ferrets should be revaccinated on an annual basis. Three distemper vaccines are commonly used ferrets: Fervac-D (United Vaccines, Inc, Madison, WI ), Purevax (Merial, Athans, GA), and Galaxy-D (Schering-Plough Animal Health Co, Omaha, NE), with the first two being USDA approved for use in ferrets. Fervac-D has been used for quite a few years in two large U.S. ferret breeding facilities. As of January 2006, United Vaccines, Inc. will cease production of Fervac-D. You may want to discuss ferret vaccine protocols with your veterinarian, and you can also contact the American Ferret Association for current vaccine recommendations.

Aleutian Disease Virus
Aleutian disease virus can sometimes cause respiratory symptoms in ferrets. This is a contagious disease in ferrets and is caused by a parvovirus. Aleutian disease was first reported in mink in the 1940s. Although the mink virus can infect ferrets, at least three other strains of the virus have been documented in ferrets. When the virus is present, the body makes antibodies to try to fight off the virus, forming antibody-virus complexes. Deposition of these immune complexes in various organs results in clinical signs, such as progressive weight loss, hind end weakness or paralysis, tremors, and respiratory disease. Aleutian disease is suspected based on a ferret’s history of exposure, clinical signs, and a high blood globulin level. A definitive diagnosis can be made based on a positive blood test together with a high globulin (gamma) level or characteristic histopathologic findings.

Many ferret shelters routinely test new arrivals for the Aleutian disease virus. Although there are a few different methods for testing a ferret for the disease, one blood test often used by shelters (the counterimmunoelectrophoresis test (CEP or CIEP) – United Vaccines, Inc., Madison, WI) that has been shown to be an effective method for identifying ferrets with antibodies to Aleutian disease, will no longer be available after January 2006. Another type of test, known as an ELISA test, is currently available for testing blood and saliva samples (Avecon Diagnostics Inc., Bath, PA), but there are no studies published about the specificity or sensitivity of the tests in ferrets. The presence of the antibody in a ferret is not necessarily diagnostic of the disease, as some surveys have indicated that ferrets can be antibody positive without showing signs of Aleutian disease. There is currently no vaccination available and no definitive treatment for Aleutian disease virus. Although testing and removal of infected animals is considered a way of controlling the disease in some shelters, some individuals and shelters handle the situation differently; for example they may confine ferrets that test positive for the disease to isolated areas or specific Aleutian disease positive households. Research is ongoing to facilitate our understanding of this complex disease.

Warning Signs
There are several indicators that a ferret is having difficulty breathing, such as coughing, choking, and rapid and shallow or deep breathing. A ferret experiencing difficulty breathing that also has muddy brown or bluish gums (which indicates poor oxygenation to tissues) should be considered an immediate emergency. A ferret that is coughing up blood or has blood coming from the nose should be seen by a veterinarian immediately. Do not administer anything orally to a ferret that is having difficulty breathing. Your pet could inhale the substance into its lungs, making the condition worse.

A ferret with an object obstructing its trachea (windpipe) may initially panic and run around or paw at its mouth. It may lose consciousness as oxygenation to the brain decreases. If the ferret does lose consciousness, open its mouth to look for the obstructing object. Avoid lodging the object farther down and making the situation worse, or being accidentally bitten. A ferret in this situation requires immediate medical attention. Note: Sometimes ferrets breaths oddly and/or paw at their mouth if they have a piece of food stuck in the roof of their mouth. They may require a little assistance to dislodge the piece of food, however care must be taken to avoid being bitten.

Prevention and early treatment of diseases is key
Keeping your ferret current on recommended vaccinations and practicing good sanitation habits will help prevent your ferret from contracting contagious diseases. It is important to observe your ferret on a daily basis, and being aware of common signs associated with respiratory conditions and recognizing when your ferret is suffering from a respiratory ailment will help you better care for your pet. A ferret knowledgeable veterinarian should be contacted if you have questions or concerns regarding your ferret. If you suspect your ferret is ill, you should take it to your veterinarian as soon as possible for an examination.