Friday, September 2, 2016

Ear Mites


 
One morning while doing your rabbit chores, you notice that your rabbit is shaking it's head, or scratching it's years. Upon closer examination of the rabbits ears you may notice small blisters and small areas of yellow crusting scabs in the lower portion of the ears known as 'ear mange' or 'ear canker'. At this point there is only culprit responsible for this condition, the common ear mite. Ear mites are a member of the Psoroptes or Chorioptes family. They are a blood sucking parasite that burrow into the flesh of the rabbits ears and lay their eggs in small tunnels as they suck blood from the skin. When your rabbit feels the mites biting it's ears it begins shaking it's head and scratching at it's ears which can cause more damage to the ears.

The good news is that by themselves ear mites are not deadly, however, untreated they can cause significant damage and discomfort to your rabbit and they can easily be spread from one rabbit to another unknowingly by you the breeder. In worse case scenarios, the infestation can cause the rabbit's immune system to weaken making it more susceptible to other bacterial infections. If the inner or middle ear becomes infected the rabbit(s) infected may develop wry neck (torticollis) which usually results in the death of the rabbit.

So how did your rabbits get infected with ear mites? There are many vectors that could be responsible. Mites can be transported by a number of rodents including mice and rats, as well as your barn cat if you have one. They can live in straw and or the cracks of wooden hutches for a long time and continue to re-infest your herd. They can be transmitted by the breeder by unknowingly rubbing or scratching the head and ears of a rabbit that has mites and then handling another rabbit without washing their hands in between. Your rabbit can even acquire them from any activity in which there are a large amount of rabbits present such as a rabbit show, after all it only takes one newly infected bunny to spread the mites to many others. However, the most common way mites gain access to your rabbitry is when you bring a newly infected rabbit into your rabbitry that has mites, but does not yet show any signs or symptoms of the infestation. This is what happened in our case. Fortunately, we soon discovered the problem and because the rabbit was isolated, we were able to eradicate the mites without any problem, and the rabbit involved is doing fine.

Now there are many different ways to treat ear mites. The most common non-medication treatment option is the use of mineral or olive oil (way to expensive, keep it in your kitchen) to coat the scabs and drown the mites. There are also a few different “off-label” medications that can be used to effectively kill the mites as well as their eggs. Each technique has it's advantages and disadvantages whether it be cost, length of treatment time, or possible side effects. The goal of this article is to share with you the many alternatives that you may choose to eradicate the mites from your herd should you find that you have a rabbit with ear mites.




Non-Medical Treatment

The most common non-medication type treatment for ear mites is called the 'triple 3' or 3-3-3 treatment. This treatment involves coating all the scabs on the ear with mineral oil once a day for 3 days to drown or smother the mites. The easiest way to do this is to use a small medicine dropper to place 3 or 5 drops of oil in ear year and then gently massage the ear. If there are a significant amount of scabbing noted, then dip a q-tip in the oil and gently coat the scabbed areas and carefully remove as many of the scabs as possible without causing further injury to the rabbit.

Then apply the mineral oil every other day for three applications. By this point the ears should be looking much cleaner. After three applications, continue to apply oil to the ears once a week for a total of three more weeks. Hence the name 'triple 3' or 3-3-3. This technique not only kills any active mites that may be infesting the rabbits ears, it will also kill any mites that may hatch from eggs that were still in the ear.

This process works by actually drowning the live mites with mineral oil causing them to die, the reason you have to perform so many applications of the mineral oil is that the initial application does not destroy any eggs that may be in the tunnels of the skin in which they are laid. These eggs incubate for a total of four days then new mites are hatched. So while one dose of mineral oil may kill the adult mites, four days later any eggs left in the ear will hatch and the process will continue unabated. Therefore to be effective you most perform multiple applications of mineral oil as directed.

Mineral Oil
Strength: Do not dilute
Dose: 3 to 5 drops (Enough to coat the scabs on the initial treatment)
Cost: $2.00 for 16 ounce bottle (more doses then I want to count)
Availability: Can be purchased at any drug store or supermarket.

The advantages of this form of treatment is that it is extremely cheap and relatively easy to perform. The disadvantages are that it is labor intensive, and the process takes the longest time to eradicate the mites, and you may have to perform the compete process more than once for severe infestations. If you have a lot of animals it will take you along time to treat them all.


Medical Treatment Options

There are several fifferent medications that can be used to treat ear mites in rabbits, with the exception of 'Eradimite' all of them are considered 'off-label'. That is that the medication or treatment option is effective for treating ear mites in rabbits, but that is not what the original intended use of the medication was created for. Other than Eradimite, the two most common forms of medical treatment used to treat ear mites in rabbits is the use of the anti-parasitics ivermectin and selamectin.


Eradimite


Is a topical ear solution that uses pyrethrins (0.15%) and piperonyl butoxide (1.50%) as it's active ingredients to kill the mites in dogs, cats, and rabbits. Pyrethrins come from the chrysanthemum flower and have been used in many insecticides since the 1950's, piperonyl butoxide is a chemical that keeps the insects from being able to degrade the posion therby enhancing the effectiveness of pyrethrins. The remaining ingredients (98.3%) is essentially aloe vera. Pyrtethrins are a form of nerve agent which excites the nervous system of any insect that eats or touches it. This quickly leads to their paralysis and eventually kills them. My research into this product indicates that it does nothing to destroy the mites eggs, therefore it has to be repeated several times in order to kill all of the mites in your rabbits ears.

The recommended dosage is to place 8 – 10 drops of the mediation in each ear, which means that a 1 oz bottle will probably only be good for two to four applications before you need to purchase another bottle. The instructions for use state “Repeat every 2 days until the condition has cleared up or as directed by your veterinarian.” As far as I can tell, eradimate will kill mites in their various stages of growth, but it does not effect the eggs which is why multiple applications are needed.

I have read on may forums that pet owners claim that 8 to 10 drops are way to many for their dog, cat, and or rabbit and they usually recommend only 3 to 4 drops. As I have never used this medication, and do not know of anyone who has done so, I cannot verify if the lesser dose is effective or not. There appears to be no specific 'weight based' instructions for this medication, the only caveat is that it is not to be used on dogs, cats, and rabbits less than 12 weeks old.

Eradimite (Fort Dodge)
Strength: Do not dilute
Dose: 8 to 10 drops per ear
Cost: $17 – $20 for a 1 ounce bottle (about two to four applications)
Availability: Can be purchased on-line or at some pet stores.


Ivermectin 1% (Anti-parasitic)


Some would say that the use of anti-parasitic agents is the easy way out, however it does require the purchase of medication as well as syringes, and you need to know the proper way to administer the medication to your rabbit. The medication of choice is Ivermectin (Stromectol). Ivermectin is a broad-spectrum anti-parasitic used to treat head lice, scabies, and ear mites among other things in both humans and animals. The effective dosage of ivermectin for rabbits is 0.018 to 0.025 ml of a premixed 1% sterile solution for each pound that the affected rabbit weighs. While a smaller dose may be effective, for rabbits with a severe mite infestation, it is recommended that the dose used be 0.025 ml's for each pound your rabbit weighs. Some of the brand names for ivermectin that you will find not only on the internet, but at retail farm supply stores such as Tractor Supply include: Ivomec 1%, Vetrimec 1%, and Agri-Mectin among others.

Name: Ivermectin 1% Injectable
Strength: 10mg/ml
Dose: 0.018 – 0.025 ml per pound of rabbit
Cost: $25 – $35 for 50ml bottle (about 400 – 450 doses)
Availability: Can be purchased on-line, or locally at Tractor Supply, or at almost any farm and ranch supply store.

Of the three medical treatment options, this is the cheapest as a 50ml bottle of ivermectin will supply you with enough medication for about 400 – 450 doses for a 10lb rabbit making the cost around $0.065 per application. The advantage of this treatment is that it 99.6% effective after the administration of three doses. In addition to killing ear mites, it also eradicates any fur mites the animal may have. The disadvantages is that you need to also purchase insulin syringes (which are relatively cheap) and you need to know how to give a subcutaneous injection to your animal as you will need to administer this treatment once every two weeks for a total of six weeks.


 
Breeders Note: Using insulin syringes to administer ivermectin is just about the only accurate way to administer the correct dosage of medication to your rabbit. Insulin syringes are broken down into a scale known as units. There are 100 units in 1 ml (millileter). I have taken the original recommended doses from the chart in the book 'The Rabbit Problem Solver' and added a column to the chart indicating the number of units of medication you should administer to your rabbit based on the rabbits weight. If you want to perform your own calculations simply take the dose in ml's and multiply by 100 (0.25ml x 100 = 25 units), it that simple.



Ivermectin should be administered subcutaneously once every two weeks for 6 weeks (total of 3 doses). To administer a subcutaneous injection, pinch up the skin over the shoulder blades of the rabbit and clean the area with a q-tip dipped in alcohol, or with a cotton ball soaked in alcohol. Then inject the required amount of medication into the tented area of the skin that you have just cleaned. Keep in mind that ivermectin is a thick and viscous medication and it takes a while to fill the syringe, and it will take a bit of pressure to inject it into to nape of your rabbits neck. Having a partner to hold the rabbit you wish to medicate is definitely an added bonus.

Breeders Note: There are a couple of other forms of ivermection such as pour-on, pastes, and even powders, none of which I have used. While there are a number of videos on YouTube from people who have given their rabbits ivermectin 1.87% horse de-wormer orally to treat ear mites, I cannot validate the effectiveness of the dose which is often described as "pea sized." I may delve into these other types of ivermectin in a future article, but for know, know that the subcutaneous route is safe and effective when administered correctly.


Revolution (Selamectin 15mg topically)

Revolution for dogs and cats can be used as an 'off-label' medication to treat ear mites in rabbits. According the article 'Efficacy and safety of Selamectin (Stronghold / Revolution) used Off-Label in Exotic Pets' in The Journal of Applied Research in Veterinary Medicine (JARVM), Stronghold and Revolution for puppies and kittens (5lbs and under) can be used as an effective treatment for ear mites in rabbits.

In two independent clinical trials a 15mg application of selamectin killed all of the mites in rabbits whose ears were infested. In the first study, when applied to the skin at the base of the neck either once or twice after a single application of 15mg of selamectin (1 tube) no live mites were recovered from day 7 through day 56. In the second case study four 4-month-old dwarf rabbits who shared a cage all with ear mites were treated with 15mg of selamectin, no mites were detected after 7 days.

Revolution (Mauve Colored Box)

Name: Revolution for Puppies and Kittens < 5lbs (Mauve Colored Box)
Strength: 15mg per tube, 3 tubes per box.
Dose: 1 15mg application (3 doses per box)
Cost: $25 – $30 (about $10.00 per application)
Availability: Can be purchased on-line, or locally from Pet supply stores such as Petsmart, Petco, or from your local veterinarian. 



Of the three medical treatment options, this is the most expensive as one box contains only 3 does (15mg per tube) of the selamectin making the cost about $10.00 per application. The advantage of this treatment is that it is 99.5% effective after the administration of one to two doses. It is easy to administer and takes no medical knowledge to do so. The major disadvantage is the cost. If you are only treating one or two animals this may be the route you want to go, but it is far to costly to try and treat more than a few animals.


Prevention

The old adage, “prevention is always the best medicine” still applies to ear mites. When bringing any new livestock into your rabbitry, the best practise is to isolate them from the rest of your herd for a minimum of two weeks, but four weeks is better. This will allow you to determine not only if the animal has any ear mites that may have been undetected by both the breeder and yourself when you initially examined the rabbit. Keep in mind that no breeder that I have ever known intentionally sold a rabbit infested with mites, but it does happen. After you have treated your rabbits and they are mite free, you will need to remove them from the cages and clean and disinfect your cages and any plastic resting boards.

The following instructions will demonstrate how we clean our cages here at TAP rabbitry. We clean and disinfect our cages about every 6 months and whenever necessary. We clean and disinfect our cages with both heat and bleach. I use a butane torch and burn off any old hair from the wire cage. Then I spray the cages with simple green and remove any additional stuck on stuff with a plastic bristle brush. The cages are then rinsed with the water hose and I spray the entire cage with a 1:10 bleach solution (1 part bleach, 10 parts water) and place the cages in the sun to dry.

Make sure you also clean and disinfect any plastic resting boards that may have been in cages with infected animals. For this, I clean them with simple green, and soak them in a container filled with a 1:10 bleach solution. Any wooden, sheet rock or other porous type resting boards that cannot be disinfected with bleach should be thrown away and not reused as the mites can live in the cracks and crevasses of these items.


Conclusion

If you have the time, and you are only treating a couple of rabbits, then the non-medical treatment may be the choice for you. Of all the treatment options it takes the most time and if you have a rabbitry of any size it will take you some time to treat all your livestock. It will work, but it has the lowest success rate, (most often due to human error) and may need to be performed more than once. It is however the cheapest option, and the only non-medical option that I am aware of for treating ear mites. I am not so sure that the use of eradimite is any more effective than simply using mineral oil as eradimite does not kill the eggs and you still have to perform multiple applications just as you would if you were using mineral oil. If these were my only two choices, I would definitely try mineral oil first before ponying up the money for eradimite, but this is just my humble opinion. If you are not wanting to medicate your rabbits then the use of mineral oil is definitely the only avenue you have other than destroying the animal and or animals concerned.

If you do not mind the use of anti-parasitics then Ivermectin is a good choice, especially if you have to treat multiple animals. It is an inexpensive solution when you figure the number of doses you can get from one 50ml bottle, and with a 99.6% success rate it is hard to beat. The downside is that you will have to wait for a minimum of two months before you can butcher any treated animals for human consumption to give the medication time to get out of their system. Revolution (for dogs and cats) has about the same success rate as Ivermectin, it is easier to administer, but is far more costly per dose, but if you only need to treat a few rabbits, it is the easiest of the three to administer. Like Ivermectin, a two month waiting period is recommended to allow all of the medication to thoroughly leave the rabbits system before butchering them for human consumption.

It should be noted that I am not a veterinarian, and I do not endorse any of the products that are in this article regardless of whether I have used them or not. Proper care should be taken whenever administrating any medications to your rabbits and you do so at your own risk. I have done my best to provide you with the necessary information so that you can make an informed decision regarding how you may wish to treat your rabbits if and when they become infected with ear mites. I encourage you to do any additional research that you think may be necessary regarding the side effects of he aforementioned medications. As always, if you have enjoyed this article or have found it informative, then please share it with your friends. Don't forget to send us a friend request on Facebook or Google+ so that you will not miss any of our latest articles.


Resources:

Bennett, Bob, Storey's Guide To Raising Rabbits, (North Adams, MA: Storey Publishing, 2009).

Fisher, Maggie DVM, Beck, Wieland DVM, Hutchinson, Melanie J. DVM, “Efficacy and safety of Selamectin (Stronghold / Revolution) used Off-Label in Exotic Pets” in The Journal of Applied Research in Veterinary Medicine (JARVM), 2007 (pp 87-96)
Patry, Karen, The Rabbit Raising Problem Solver, (North Adams, MA: Storey Publishing, 2014).