I need help figuring out the proper dose for my itchy cat. (incl. what I have tried so far) Can someone help me soon?

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CindyB

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I paid $1 (during free trial) to chat with a vet online.

The vet wants me to give my cat Benadryl for itchiness. He said "You can give benadryl at 1 mg per pound every 12 hours".

My cat weighs 12.4 pounds

So that meant the dose is 12.4mg. Easy, right?

The problem is that I didn't think to look at the medication label and see that the dose is listed as 12.5mg /5ml.

I can't go back and ask for clarification because I cancelled my free trial right after I got the vet's answer.

My cat weighs 12.4 pounds

In order to figure out how to give a metric dose, I figured out my cat's weight in kg:

12.4 / 2.2 = 5.66 kg

Since the label states that it has 12.5mg/5ml, to figure out the number of mg to give I did this:

5.66 kg X 1 mg = 5.66 mg

Now I need to figure out mg/ml (I think):

5.66mg = 1mg per pound

...but the dose is given in ml, so how many mg is in 1 ml? I found this by searching the question on google:

1 mg = 0.001000 ml

So I tried the following and used my calculator. I got:

5.66mg X 0.001000 ml = 0.00566 (that seems wrong!)

Then I tried:

5.66mg/0.001000 = 5,660 (and that also seems wrong!)

...That is where I gave up because I do not want to kill my cat with Benadryl!

I was going to ask here in the forums for help, but first I searched to see if anyone had asked a similar question. I wanted to figure my question out for myself. In the forums I saw a reference to:

DosageHelp.com - Helping Nursing Students Learn Dosage Calculations

Learn dosage calculations with this free tutorial complete with explanations, examples, and practice questions.
www.dosagehelp.com www.dosagehelp.com

From there I copied the following formula:

Example: Phenytoin (Dilantin), 0.1 g PO, is ordered to be given through a nasogastric tube. Phenytoin is available as 30 mg / 5 mL. How much would the nurse administer?

Ordered
Have x Volume Per Have = Y (Liquid Required)

Convert 0.1 g to mg.
mcg ← mg ← g ← kg ( x by 1,000 )
0.1 g x 1,000 = 100 mg

100 mg
30 mg x 5 m = 16.7 mL

So I tried:

1 mg
12.5mg x 5 m =

and didn't know how to figure that out because in the example they use '30 mg x 5 m = 16.7 mL' to figure out ml.
Where does 5m come into play?

I'm really stumped by that now ...and am not even certain that the formulas (formulae?) I've used up to this point are even correct.

Can someone help me please?
 
CindyB said:
… [on] the medication label … the dose is listed as 12.5mg /5ml
Click to expand...
Hi Cindy. That's not the dose. That's the concentration.

5ml of liquid is about 1 teaspoon.

In other words, one teaspoon of liquid coming out of the bottle contains roughly 12.5mg of diphenhydramine (suspended).

The dose is 12.4mg, according to the vet's dosing rate and your initial calculation.

The 12.5mg of drug in a teaspoon of liquid Benadryl is close enough to the 12.4mg dose. (Minor fluctuations in measured weights and measured teaspoons have been taken into account by both the vet and the manufacturer.) Short-term Benadryl use is not highly toxic.

It's safe to give your cat one teaspoon every 12 hours. See this page, for feline precautions.

?
 
For confirmation, I did a search on "benadryl for cats" and found this:

www.petmd.com

Can You Give Cats Benadryl?

Is Benadryl safe for cats? Can it help with cat allergies? Dr. Sandra Mitchell explains why Benadryl may or may not be recommended in certain situations.
www.petmd.com

It says, among other things,

Faught says his office doses Benadryl at about one milligram per pound. For an average sized cat, you’ll probably want to give half of a 25-milligram tablet. A 10-pound cat will most likely need about four milliliters of liquid (available at a concentration of 12.5mg/5ml) to get the right dose, he says.
Click to expand...

And 4 milliliters is a little less than a teaspoon (for a little less than your cat!). So everything is in agreement with the one-teaspoon dose.
 
Dr.Peterson said:
For confirmation, I did a search on "benadryl for cats" and found this:

www.petmd.com

Can You Give Cats Benadryl?

Is Benadryl safe for cats? Can it help with cat allergies? Dr. Sandra Mitchell explains why Benadryl may or may not be recommended in certain situations.
www.petmd.com

It says, among other things,



And 4 milliliters is a little less than a teaspoon (for a little less than your cat!). So everything is in agreement with the one-teaspoon dose.
Click to expand...

I actually read the same information you quoted from Petmd.com. I obviously missed the most important part. ? Thank you Dr. Peterson, I appreciate your help!
 
No one has commented (yet) on my attempt to figure this out on my own. I would really like to have a visual so that I can understand if I did any of the math the right way, and how I could figure something like this out on my own in the future.
 
CindyB said:
No one has commented (yet) on my attempt to figure this out on my own. I would really like to have a visual so that I can understand if I did any of the math the right way, and how I could figure something like this out on my own in the future.
Click to expand...
I do normally like to help people find the error in their work; but that's really been done already: You started out with a wrong understanding of what 12.5mg /5ml meant. It is a concentration, not a dose relative to the size of the cat (as if you were to give 12.5 mg of medicine for each 5 milliliters of cat), so you much of what you did was in the wrong direction. In particular, there is no weight of the cat here, so your correct conversion to kilograms crashed into the ratio and led you to very wrongly equate 5.66 kg to 5.66 mg.

The correct dosage ratio is what the doctor said, "1 mg per pound", so it's just 1 mg/lb * 12.4 lb = 12.4 mg.
 
Harry_the_cat said:
How's your cat now?
Click to expand...
I am still trying to get part of the medicine down his throat. I got about half of it into him before he really started fighting me, so I gave him a break. The benadryl is cherry flavored, so it didn't work too well when I tried to disguise the taste. ?
Thanks for asking though!
 
The cat weighs 12.4 pounds.

The dosage is 1 mg per pound so that is 12.4 * 1 = 12.4 mg.

The concentration is 12.5 mg per 5 ml. So we want about 5ml. 1ml is just about 1/5 of a US teaspoon. So you need a teaspoon.

This kind of calculation is called dimensional analysis. For an introduction, see
www.khanacademy.org

Intro to dimensional analysis (video) | Khan Academy

Sal shows how we can treat units of measurement algebraically, and use these tools in order to convert between different units of the same quantity.
www.khanacademy.org www.khanacademy.org

Try mixing the benadryl in a saucer of cream
 
Otis said:
Can you squirt the liquid, using something like an eye dropper?

\(\;\)
Click to expand...
I'm laughing because I have a syringe type dropper and I shoved it way back near his throat because I know Benadryl tastes bad. I wanted his swallow reflex to kick in quickly. Unfortunately, he got a taste and was struggling not to swallow it. He even started foaming around his mouth. That was when I let him go for awhile. I tried again a couple of minutes ago... just refer to the comic posted by Otis. I might look that bad before we get it done.
 
5.66 kg X 1 mg = 5.66 mg is not correct. It should be 5.66 kg X 1 mg = 5.66 kg*mg whatever that means.
5.66mg X 0.001000 ml = 0.00566 (that seems wrong!)It would be .00566mg*ml
 
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