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Does your ferret seem itchy? Lethargic? Any one of a variety of external or internal parasites may be pestering your pet.
by Erika Matulich, Ph.D.
Volume 2, Number 3
May / June 1999
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You should not rely on the veterinary advice or information provided on this site for diagnosis or treatment of any specific situation. Always consult your own veterinarian for specific advice concerning the medical condition or treatment of your own pet or animal.

Ferrets can suffer from a number of parasites, both internally and externally. This article will focus on the most common external parasites, which are fleas, mites, ticks, and mosquitos. Unfortunately many of these external parasites can also transmit other parasites of their own, which begin feeding on your ferret from the inside. The remainder of the article will cover major internal parasites.
Ferrets tend to get fleas, particularly when the weather gets warm and humid and when other pets in the house carry them in from outside. Flea eggs can remain dormant for up to two years waiting for a host, so if you have just moved or brought in used furniture or carpeting, your flea infestation can seem to come out of nowhere. If you notice excessive scratching, check your ferrets for fleas by combing with a fine-toothed flea comb and ruffling the fur. Blowing on the ferret’s fur to see various parts of the skin is also helpful. Dislodged fleas are reddish brown to black and about the size of a pencil tip. Dark specks in the fur indicate the flea residue. Look for fleas between the shoulder blades where they are most commonly found. Some ferrets are more allergic to fleas than others, and may develop bald patches or inflamed scabby skin in addition to the itching. Remember that ferrets scratch themselves for other reasons than fleas, so don’t panic until you have confirmed that you have fleas.
To rid a ferret of fleas, bathe with a flea shampoo suitable for kittens and one that contains pyrethins. Don't use anything containing organophosphates, carbamates, or petroleum distillates. Follow the label directions carefully. Shampoo the ferret starting at their ears and working toward the tail. Be careful to avoid the eyes and nose. Use a flea comb to remove fleas from the ferret's face. This may need to be repeated weekly if the flea infestation is very bad. In general, sprays and dips should be avoided because they are much more toxic than shampoos and could harm your ferret.
You will also need to treat the ferret's environment. Change and launder all bedding in hot water, but avoid fabric softeners. Treat floors with flea spray or powder and vacuum frequently. You can use cut-up flea collars in your vacuum cleaner bag to help kill flea eggs that are swept inside. Flea collars, however, cause severe irritation on your ferret's skin and can lead to serious health problems because of the dichlorvos they contain. Flea collars should NEVER be used on a ferret! Also, do not let your ferret in contact with the flea sprays or powders used on your floors until it is safe to do so. Do not put flea powders designed for carpets onto your ferret either. In fact, flea powders designed for dogs or cats should only be used as a last resort, because they may cause skin reactions and lung irritation. Many natural flea repellents contain cedar oils, which are also toxic to ferrets. Check ingredients carefully!
Dr. Bruce Williams, DVM recommends getting a flea bomb from your vet which contains methoprene (a flea growth regulator). This type of premise bomb will allow you to complete the household eradication job in just two applications - one to kill the adults and larva, the second two weeks later to get the ones that have hatched out since the first spray. (Of course, make sure to remove your ferrets from the house at the time of the bombing.
Aside from causing infection and skin allergies, flea bites cause ferrets to lose sleep, lose their appetite, and become irritable and difficult to handle. Also, it does not take many flea bites to cause anemia from lack of enough blood in the ferret's system. Fleas can also transmit diseases, and if a flea is accidentally ingested when your ferret grooms with his teeth, tapeworms, an intestinal parasite, can be a serious problem. Flea infestations can be difficult to solve, but patience and continuous treatments will eventually get rid of these parasites.
Several new flea eradication products are on the market that can provide long-term relief to your ferrets, although none have been specifically tested for use in ferrets. Frontline spray is the product most highly recommended for ferrets by veterinarians. The Frontline products, by Merial, contain a revolutionary new molecule that is highly active against both fleas and ticks. The product kills all insects within 24 hours of application; 96% are killed within 2 hours. The product has a wide margin of safety and has found to cause no problems in kittens at many times the overdosage level. A single dose can last a month or more. The product is not affected by sunlight or shampooing. Product longevity is a potential drawback in the unlikely event your ferret has an allergic reaction to the product because it cannot be washed off. Additionally, many ferrets intensely dislike being sprayed with the product. For these ferrets, Frontline also comes in a "drop on the neck" type product. One dose of Frontline TopSpot for cats and kittens is good for two ferrets. Put the half dose (a few drops or 0.25 ml) between the shoulder blades of your ferret. Some ferrets may develop an allergic reaction to this application, as it is more concentrated than the spray. Advantage (by Bayer) has a similar "drop on the neck" product that lasts a month or more and may be suitable for ferrets. However, toxicology and overdose tests show that the product slightly more toxic than Frontline. However, Advantage is water soluble and will wash off in case your ferret has an allergic reaction. Do not apply these drops if your ferret has a cut or scratch -- the alcohol base will sting. Other products, such as BioSpot and Defend, are more toxic and may not be safe for your ferret. Further studies are necessary on these products before they can be labeled for ferret use. The main advantage of these products is that they kill fleas and ticks on contact BEFORE they bite your ferret and last a month or more between applications.
The last new product is Program by Ciba (lufenuron). This product is a monthly oral tablet that puts flea-killing chemicals in the ferret's bloodstream. Use the cat dosage per pound for your ferret, and feed with a meal. When the flea bites the ferret and drinks the blood, the flea lays sterile eggs. The disadvantage is that fleas must bite your ferret first, and it takes several months for the breeding cycle to be broken. In the meantime, your ferret can suffer from severe medical problems. Additionally, the long-term toxic effects of lufenuron in the ferret's bloodstream has not been studied. Program can be used in conjunction with Advantage or Frontline without any harmful effects. All three of these product need to be purchased at a veterinary facility.
If you live in a wooded area, or your ferret has access to the outdoors, ticks may be a problem. The Frontline spray mentioned in the Flea section are helpful in eradicating and preventing ticks. Ticks can cause anemia just like fleas, and carry other diseases, such as Rocky Mountain Spotted Fever. Lyme disease may also be a serious threat, but not much is known about Lyme disease in ferrets. Be careful when pulling ticks off your ferret, as the tick's head or mouthparts can stay lodged in the skin and can cause serious infections.
Ferrets can suffer from three different types of mites: earmites, sarcoptic mites, and demodex mites. Earmites are by far the most common and are often known as the "ferret social disease."
Earmite infestations are frequently found acquired at birth or when the ferret has close contact with other ferrets, dogs, or cats. The mites are too small to be easily seen with the naked eye, but the dark, crumbly or black waxy debris they create in the ears of their host is often abundant. The mite debris is often smelly. The presence of the mites can be irritating to the unfortunate ferret who may respond by rubbing and scratching at his ears or vigorous head-shaking (although these symptoms are usually not as dramatic as in dogs and cats). Occasionally the mites may spread to other parts of the head and body; under extreme infestations the mites may burst the eardrum and cause much deeper, middle or inner-ear infections.
Diagnosis is usually made by collecting some of the ear debris and examining it under a microscope by a veterinarian. Either the mites or their eggs will usually be found in abundance. One method of treating earmites consists of applying miticide (labeled as safe for kittens) and cleaning the ear debris periodically with an ear lotion or peroxide. If mites have spread outside the ear, flea powder may be necessary on the skin. The miticide method requires diligence to get the daily drops rubbed into a struggling ferret’s ears and may take a number of weeks of treatment to completely cure the problem. A veterinarian can also apply drops of ivermectin or can give an ivermectin injection once a week for 2-3 weeks, if your ferret does not enjoy a daily treatment. Ivermectin treatments should not be used on pregnant ferrets.
On at least two occasions, Oterna ear mite drops from Pitman-Moore Ltd England (containing betamethasone BP, neomycin BP and monosulifiram) have caused damage to the outer ears of ferrets, necessitating the surgical removal of part of the ear. Avoid using this medication and check other medications for those ingredients.
Because ear mites are so contagious among ferrets, cats, and dogs, all household pets must be treated at the same time. Treat even those pets who do not have the obvious mite infestations, because the treated pet may be reinfected immediately after the end of treatment by those animals who were not treated.
Sarcoptic mites are more common in feral ferrets in Europe, but has been reported in domestic ferrets in Australia and the United States. These mites can be caught from infected rabbits, ferrets, or bedding. Your ferret will display intense itching accompanied by a scabby yellow and red rash. This rash may appear on the face and ears, or be confined to the feet and toes (which is why it is sometimes called "footrot.") Diagnosis can be difficult, and multiple skin scrapings by your veterinarian may be necessary. Treatments consist of removing scabs and any diseased portions of skin and claws and applying sulfa drugs topically. Ivermectin injections may help, and topical corticosteroids can also help with itching and inflammation. This mite is highly contagious to other ferrets and to humans.
Demodex mites are the least common mite. Ferrets with compromised immune systems or long-term illnesses are more susceptible to these mites. Yellowish skin, dandruff, and baldness are symptoms of these mites. Your veterinarian can diagnose these mites under the microscope and may prescribe regular dipping in a .0125% amitraz liquid.
Ferret owners must be aware that heartworms can attack their ferrets and cause fatal heart disease. The ferret, whose natural immune system seems to be particularly intolerant of infection, contracts heartworms through mosquito bites. Due to the warm winter and damp spring in southern areas, mosquitos are always in abundance. This raises the risk of heartworm infestation considerably. This is one reason that outdoor cages are not recommended for ferrets. Most ferrets are housed indoors and have little to no exposure to mosquitos. However, if you get mosquitos in your house, your ferret may need to be treated. Your vet can prescribe a heartworm preventive to be administered orally throughout the spring and summer months. This is usually a once-a-month medication, such as Heartguard, in tablet or cube form. You can get a dosage for a small cat, and halve this dosage. Heartworms are seldom curable in ferrets; prevention is the key. Additionally, standard canine tests for heartworms are not very reliable in ferrets. Dr. Deborah Kemmerer, DVM, has had more success in using the CITE Snap heartworm test.
Ringworm is not actually caused by worms. This skin infection is caused by dermatophytes, or a type of fungus. The symptoms are usually one or several round, itchy patches of hair loss. A reddish ring commonly appears. It can also cause scaling of footpads, or toenail thickening. Ringworm is highly contagious to humans and other animals. Treatments is with anti-fungal creams or ingestible tablets. Treatments typically last six weeks.
"Helminths" are parasites that have a lifecycle that typically goes from eggs to larvae to some type of worm. Eggs can be ingested by your ferret (usually from the feces of another infected animal) and the life cycle begins within the ferret host. Larvae and worms migrate within the ferret and feed off your ferret from the inside. Ferrets can be infected by nematodes, hookworms, roundworms, tapeworms, and flukes. Ferrets are also susceptible to trichinosis if they are fed uncooked meat products. These intestinal worms are evidenced by a dull hair coat, a pot belly, weight loss, and diarrhea. A veterinarian can determine if your ferret has an intestinal worm with a standard fecal flotation test. Oral wormers such as mebendazole or ivermectin can be administered by your veterinarian. Ferrets can also get lungworms.
Another potentially serious parasite is the fluke, which is like a small leech that attaches itself to intestinal walls or the liver. Flukes are usually caught when a ferret ingests feces of another animal, usually a dog or cat. Veterinary assistance is required. Symptoms are quite variable, from gastrointestinal upset, to urination problems. If you have other pets in your house, and your ferret has access to their droppings, this may be good to test for.
Ferrets can also suffer from diseases from microscopic parasites called protozoa. These parasites cause diseases such as giardia, coccidiosis, and cryptosporidiosis. The parasites causing these problems attack the intestines.
Giardia is usually caught by ferrets drinking stagnant, unclean, or aquarium water. It also can be caught from (and given to) cats dogs and humans. In humans, this is known as "Montezuma’ Revenge" and in ferrets is characterized by severe gastrointestinal upset. Antibiotics, such as metranizidole, are usually given. All surfaces the ferret has contact with must be disinfected with bleach.
Coccidia comes in several forms and most often causes lethargy, poor appetites, diarrhea and weight loss. The infection is highly contagious among ferrets. Some ferrets may show few signs of coccidia, but may become chronic carriers and continue to reinfect themselves, other ferrets, and sometimes humans. Ferrets with proliferative bowel disease are more likely to succumb to this parasite. A fecal flotation test performed by your veterinarian can determine if your ferret needs treatment. Usually the treatment is sulfa drugs.
Cryptosporidiosis can come from poorly filtered water, raw meat, or fecal contact. The oocytes (eggs) passed in the feces are resistant to disinfectants and can survive for a long time and continue to be infectious. The infection can be easily spread to humans and other domestic animals. Healthy ferrets can fight off this infection, but those who are already ill or have compromised immune systems can succumb to the infection. Drugs seem to be ineffective against this parasite, so prevention is important.
By using a few preventive measures, your ferrets can be free of both external and internal parasites. New research continues on ways to treat these parasites, so keep up with the latest findings for having a happy and healthy ferret.