Desperate Measures: Home Mange Cure

Don't Try This

This page describes the successful mange treatment of Bandit, a stray cat in the neighborhood. I was probably a fool for doing it.

I tried to do the right thing. I got out the cat carrier, planning to take Bandit to the vet. After four attempts on two separate days, all we had to show for our efforts was a lot of scratches on us and a feral cat who no longer trusted the only humans who reliably fed him.

I knew I couldn't get Bandit to the vet. I knew if I didn't get him cured, he would die - mange had already killed one of his brothers.

May Bast forgive me, I experimented. I had no choice.

Possible Treatments

Researching on the web provided many different treatments for mange, depending on the type of mange, cost, and other factors. Some choices include:

Organophosphate baths for several months.
A series of 6 or 7 lime sulfur baths
A series of Amitraz (Mitaban) dips.
Ivermectin injection. [This is the treatment preferred by the veterinarian whom we initially contacted.]
Selamectin (Revolution) – A topical medication was designed for flea, heartworm, and intestinal parasite control. Approved for control of Sarcoptic mange mites in dogs.

I also found some things that might help, but didn't promise a cure:

"Pets with mites often make a bad situation worse by opening mite wounds and causing infection. Treat the itch with an over the counter antihistamine (like Benadryl). Give dogs 3mg. per each pound."
"Poorly nourished dogs and cats suffer the effects of mange most often. Upgrading your pet's food quality can help to prevent your pet from contracting mange."

None of the cures looked practical for a feral cat. I decided to use some of these techniques to buy time, while researching an effective home mange cure that could be applied to a feral cat.

Hope

Since a local veterinarian prefers to treat mange with Ivermectin injection, I set about investigating whether or not Ivermectin could be administered orally. If it could, I would simply put some Ivermectin in Bandit's food.

My search for information on oral Ivermectin was instantly fruitful, but not in any really helpful way.

I found a lot of information about oral Ivermectin against mites in other species. I found out how much to give cattle, sheep, and horses. I found out about pigs and guinea pigs. I found out about rabbits, gerbils, hamsters. And dogs. The problem is that all of these different animals have different tolerances for Ivermectin. And there are even differences between breeds. A dose of Ivermectin that does a fast and effective job of curing a beagle of mange might well kill a collie.

And nobody provided information on dosing cats for mange!

I did find some information on Ivermectin against hookworm and/or heartworm infections. The doses looked safe, but I doubted that they would be strong enough to combat mange mites. [When treating dogs for heartworm, much less Ivermectin is used than for mange.]

I eventually prepared Ivermectin for oral administration, following instructions on a site for guinea pig owners. But I used my own dosage.

WARNING

Ivermectin is a poison. That's how it cures mange: it kills the mites. The trick is using enough poison to kill the mites, but leave the pet unharmed.

This means that the dosage must be precisely calculated and carefully measured.

The clinical signs of Ivermectin poisoning are:

mydriasis - excessive dilatation of the pupil of the eye
depression
coma
tremors
ataxia - loss of coordination of the muscles, especially of the extremities
stupor
emesis - vomiting
drooling
death

It is thought there are no long term effects from mild overdoses. Animals showing reactions following recommended doses should not receive further treatment using Ivermectin.

In case of overdose telephone your local veterinarian immediately. Then read Ivermectin Overdose.

Plan Of Attack

The general plan of attack was:

obtain some medication that contains Ivermectin
calculate a safe, but effective dose
measure the dose accurately
put the Ivermectin into Bandit's food

The plan is pretty simple, but the Ivermectin product that I started with is fairly concentrated. A cat-sized dose of strong medicine is a tiny amount, and hard to measure. I had to dilute the Ivermectin - a cat-sized dose of weaker medicine is a larger amount, and easier to measure. This takes a little math.

A Note On Units

The correct metric measure of volume is the milliliter (ml). It is quite common to see volume measured in cubic centimeters (cc), especially in the field of medicine. For all practical purposes, 1 cc = 1 ml. I will use "cc" and "ml" interchangably.
One pound is equal to 0.45 kilograms.

Why Is Math Necessary?

Let's conduct some thought experiments to show why we need to do a little math.

Let's say that you have a headache. You want to take some aspirin, and know from experience that a single pill with 325 mg works well for you. But you are at a friend's house, and all your friend has are some low-strength 81 mg pills. Instead of a single large pill, you can take 4 of the smaller ones, because

81 mg X 4 = 324 mg

The point here is that the strength of the medicine (concentration) makes a difference. More concentrated medicine - use less. Less concentrated medicine - use more.

Next, it helps to know the weight of the patient. That aspirin will flow throughout your body, even though you only need it to reach the hurting part. So, the bigger the body, the more medicine you need in order to flow through the rest of your body to reach the hurting part. The best way to accommodate larger and smaller patients is by the weight of the patient. In theory, a man who weighs 200 pounds will require twice as much aspirin as a man who weighs 100 pounds. [Most over-the-counter medication does not bother with this. Instead, it suggests doses based on the age of the patient - making the assumption that the older you are, the bigger you are. This is a poor assumption, but it is close enough to be workable, especially when the package says you can take another pill if the first dose doesn't help.]

Now we know how to scale the dose up and down. But we still need a number to start with. The most accurate way to measure medicine is to use a dose per unit of body weight.

Let's recap that, returning to cats. There are three numbers that figure into the dose.

Concentration of the medicine.
If the medicine is half as strong, you have to use twice as much. If the medicine is ten times as strong, you must use 1/10 as much.
The weight of the cat.
The medicine will go throughout the body, and the larger the body, the more medicine that you need to fill it. A cat that weighs 10 pounds will take twice as much as a cat that weighs 5 pounds.
Medicine is usually computed in the metric system. One pound is equal to 0.45 kilograms (kg).
Amount of medicine you want to get per given weight of cat.
This is where you figure whether the dose will be strong or weak.
This amount is often specified in milligrams (of the medicine) per kilogram (weight of the patient). An example is 0.2 mg/kg.

How do these numbers work together?

my standard dilution contains 1.0 mg Ivermectin/ml
let's say a cat weighs 8 pounds = 3.6 kg
I got good results with 0.2 mg/kg
3.6 kg X 0.2 mg/kg = 0.72 mg

That's how much Ivermectin (0.72 mg) is necessary for a cat of that weight. If the cat weighed (say) twice as much, we would need twice as much Ivermectin.

But how do we measure out that 0.72 mg? "mg" is a weight in milligrams. And we have a bottle of diluted stuff. The answer is in the first number - the concentration.

The concentration is 1.0 mg/ml. That means if you squirt out 1 ml of volume (which equals 1 cc) of this stuff, it will contain Ivermectin weighing 1.0 mg. This means you don't need a scale. You don't have to weigh tiny amounts. You just have to measure a small volume. We want 0.72 mg

0.72 mg / 1.0 mg/ml = 0.72 ml = 0.72 cc

(Dividing something by one just gives the original number back. It's easy - which is one reason why we picked the concentration of 1 mg/ml to begin with.)

So a cat

that weighs 3.6 kg (8 pounds)
would get 0.72 ml
of 1.0 mg/ml medicine
in order to reach 0.2 mg/kg

Does this make sense to you?

That's the theory. Here's the practice...

Preparation Of Medication

Ingredients

I assembed the following ingredients and tools:

Horse Paste
Horse Paste is used to kill worms and other internal parasites in horses. There are different formulas and ways of packaging.
The type that I bought was an Ivermectin-based formula called Eqvalan. It comes in an oral syringe - you stick it down the horse's throat and squirt. This is enough to worm a 1250 pound horse.

Horse paste can generally be found at local feed stores or online. I bought mine from Pet Supplies 4 Less.
Warning: If you are tempted to try this, be aware that the information that I have recorded here corresponds to my experience with this exact type, brand, and dosage of horse paste.
Carrier Liquid
A small tube of horse paste treats a large animal. It isn't practical or precise to measure the tiny amounts of horse paste necessary to treat small animals. So one must dilute the horse paste to a lower concentration that can be more easily measured. I did this by mixing the horse paste with a carrier liquid.
Web pages treating other animals suggested diluting with water, vegetable oil, or propylene glycol. Propylene glycol is said to mix the best, but I didn't have any. Water is easy to get, but you can't keep the mix around for followup doses.
I originally decided on vegetable oil.

[April 2005 update:]
The first few times I had to do this, I mixed the horse paste with vegetable oil. The paste doesn't really dissolve in the oil. The best that you can hope for is to stir for a long time, breaking up the horse paste into tiny bits that stay in suspension. Since then, I have experimented with mixing horse paste with glycerin, and it works a lot better.
Glycerin is pretty easy to find at drug stores. It may be with the cosmetics. Make sure that the glycerin is pure, not some fancy stuff that merely contains some glycerin.
accurate measurement of 22 ml. - for the carrier liquid
Remember: Ivermectin is a poison, that must be carefully measured. One mustn't just use a teaspoon here.
I happened to have a lab-quality graduated cylinder on hand, and used that.
One could also use a large oral syringe.
accurate measurement of 2 ml.
Remember: Ivermectin is a poison, that must be carefully measured. One mustn't just use a teaspoon here.
I used a small syringe. It was designed for injection, but I just removed the needle.
a small container that comfortably holds 25 ml and can be tightly sealed
Note that you will have to vigorously stir the contents, so the container should not have a small mouth.
I used a pill bottle with a wide mouth and a lid that seals tightly.

Calculation Of Standard Dilution

Horse past is concentrated. The tube isn't that big, and it treats a huge beast. In this highly concentrated form, it is impossible to measure the tiny amount necessary for a correct cat dose. The first step is to take a small amount of the horse paste and dilute it with lots of carrier liquid (glycerin or vegetable oil). This makes a much weaker solution, that requires more volume in a dose, which is easier to measure.

I prepared Ivermectin for oral administration, following instructions on a site for guinea pig owners. This required a standardized dilution that would contain 1.0 mg Ivermectin/ml.

The horse paste that I bought comes in a tube marked for various weights of horse by pound. A whole tube contains enough ivermectin to treat a 1250 pound horse (for worms, not mange).

The plunger is marked in five increments, each one corresponding to 250 pounds of horse.

The whole tube of horse paste contains contains 6.08g of paste, which contains 1.87% Ivermectin. So the active content of the past is 113.7 mg Ivermectin. Since the whole tube contains contains 113.7 mg Ivermectin, each of the 5 increments on the plunger corresponds to 22.8 mg Ivermectin. So, how do we get from there to a nice standard of 1.0 mg Ivermectin/ml?

This dose (1/5 of the whole tube) contains 22.8 mg Ivermectin. I added 22 ml of carrier liquid (glycerin or vegetable oil). Ignoring the volume of the horse paste itself, I then had:

22.8 mg Ivermectin / 22 ml carrier = 1.04 mg/ml

It isn't really precise to omit the volume of the horse paste itself. But it's hard to estimate. If the paste took 1 ml, the solution would have:

22.8 mg Ivermectin / (22 ml carrier + 1 ml paste) = .991 mg/ml

But we don't really have enough precision to carry that to three significant digits. So I'll just say that this dilution is pretty close to 1.0 mg Ivermectin/ml.

Preparation Of Standard Dilution

I closely examined the markings on the tube of horse paste. Into a pill bottle, I carefully measured enough horse paste to treat a 250 pound horse.

I added to the bottle 22 ml of carrier liquid. The first time, I used vegetable oil. I later discovered that glycerine mixes better.

Now it's time to stir thoroughly. This takes a long time, because the Ivermectin paste just plain won't dissolve in the vegetable oil. The best I could do was to break up the white paste into thin threads, evenly dispersed through the oil. Each time that the mixture is allowed to settle out and is stirred again, the threads get smaller, until there is a cloud of tiny particles suspended in the oil.

Several web sites said that solutions using propylene glycol can be refrigerated and used at a later date (check expiration date on product). They suggested that solutions made with water be discard after use. Nobody really knew about vegetable oil, but they suggested discarding it for the sake of safety.

I decided that I would keep the vegetable oil solution in the refrigerator for up to a month and then discard it.

Treatment

Dispensing

Having prepared the standard dilution, we should discuss dispensing it.

Every time I got ready to dispense some Ivermectin solution, I had to stir it well. I immediately drew off the desired dose and squirted it into a dish. (Don't give it time to settle!) I then added canned cat food, mixed thoroughly, and gave it to Bandit.

NOTE: Ivermectin tastes bitter. Animals won't eat this by choice. You either have to force it into them (not easy with a feral cat) or mix it well into food to disguise the taste. I fed Bandit late in the evening, so he would be hungry, and gave him only the dosed food. When he finished that, I was willing to give him seconds of unadulterated food.

Schedule

The treatment schedule was clear: Ivermectin does not kill the mite eggs, so the dose must be repeated to kill the emerging mites. One source suggested 2 doses, spaced 7 to 14 days apart. Another suggested at least two doses, 7 to 10 days apart. I decided on three doses, 7+ days apart.

I decided to dose Bandit in the evening. If he got wobbly from the Ivermectin, he could sleep it off before going about his business in the morning. I didn't want a cat with tremors, ataxia, or stupor wandering around in the street.

Amount

My web research said nothing about how much oral Ivermectin to give a cat. It did suggest that the bioavailability of Ivermectin is similar when administered orally and subcutaneously (injection).

Note that the dose is specified in mg Ivermectin per kg of the animal's body weight.

Lacking concrete information on oral Ivermectin dosage for mange in cats, I started at .2mg/kg, something that I considered a conservative dose. A few days later, I stumbled on a vet who was kind enough to suggest:

single dose: 0.4 mg/kg – 0.6 mg/kg
repeat 1 week later
optional repetition one week later

[This suggestion was probably based on subcutaneous injection. But since bioavailability of oral Ivermectin appears similar, it's a reasonable guess.]

Bandit’s Ivermectin offered treatment has been:

20030722 - .2mg/kg – first treatment at guessed level, ate about half
20030723 - .1mg/kg – more, because he didn’t eat it all yesterday; taken together, the two doses approximate a full dose consumed at .2mg/kg.
20030726 - .4mg/kg – treatment at low end of suggested range
20030802 - .4mg/kg – didn’t eat significant amount
20030803 - .4mg/kg – ate just about all of it
20030809 - .4mg/kg – didn’t eat significant amount
20030810 - .4mg/kg – ate just about all of it

Bandit’s actual Ivermectin consumption has been:

20030722 - .1mg/kg
20030723 - .1mg/kg
20030726 - .4mg/kg
20030803 - .4mg/kg
20030810 - .4mg/kg

How much did I give him?

We estimated Bandit's weight at 10 pounds (4.5 kg).
My standard dilution contains a concentration of 1.0 mg Ivermectin/ml.
Amount to use (ml) = Weight (kg) x dose (mg/kg) / concentration (mg/ml).
In Bandit's case: Amount to use (ml) = 4.5 kg x .4 mg/kg / 1.0 mg/ml = 1.8 ml.

Based on the results I got, it looks like:

0.2 mg/kg - oral Ivermectin does have a theraputic effect against mange
0.4 mg/kg - didn't do any visible harm, and may have resulted in a faster recovery
0.6 mg/kg - doesn't seem necessary to go this high

Note: For dogs, it is well known that some breeds tolerate Ivermectin better than others. Collies are known to have problems with Ivermectin. It would be reasonable to assume that different breeds of cats might also have different Ivermectin tolerance. One web site went so far as to say that "Ivermectin can be toxic in cats." So, it's a good idea to use the minimal dose that really works.

January 2005 update:
The Merck Veterinary Manual recommends 0.2 mg/kg, and cautions that "Sudden death in association with the use of ivermectin in kittens has been reported." What age range should be considered a "kitten?" I don't know what Merck uses, but I would estimate from birth through 4 months.

Results

Bandit showed no signs of side-effects from the Ivermectin. He made a full and complete recovery from mange.

Bandit was visibly better one week after the initial low dose of Ivermectin (.2mg/kg). His face was the first to improve. Ears got better next. His neck took the longest, probably because he was scratching at the irritation as it healed.

Another page shows photos of his recovery.

Thanks

Bandit's successful treatment and full recovery are largely due to the wealth of information I found on the web about treating animals with oral Ivermectin. Although I found no information specific to cats (perhaps this page is the first), the wealth of information on other animals was certainly helpful to me.

In particular, I would like to thank the guinea pig lovers at http://guinealynx.info/ivermectin.html .