My search was ultimately successful, resulting in a home mange cure that appears to be both safe and effective. It is also easy and inexpensive.
If it were an option, though, I would have preferred to take Bandit to a veterinarian.
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.
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.
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.
This means that the dosage must be precisely calculated and carefully measured.
The clinical signs of Ivermectin poisoning are:
In case of overdose telephone your local veterinarian immediately. Then read Ivermectin Overdose.
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.
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 mgThe 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.
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 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).
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?
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
Does this make sense to you?
That's the theory. Here's the practice...
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.
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.
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.
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.
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.
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/mlIt 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/mlBut 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.
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.
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.
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.
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:
Bandit’s Ivermectin offered treatment has been:
How much did I give him?
Based on the results I got, it looks like:
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.
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.
In particular, I would like to thank the guinea pig lovers at http://guinealynx.info/ivermectin.html .
You should leave diagnosis and treatment to a veterinary professional. If your pet looks sick or injured, you should be on your way to the vet now.