I have infected the mice foot pad with Mycobacterium marinum and my goal is to monitor the footpad swelling using digital caliper and then check the footpad cfu after termination.
My question is where exactly on the footpad should we measure? as the swelling kind of starts in the mid footpad region and then spreads towards the tarsal joint and digits.
Has anyone done this kind of study? from which region of footpad do you measure the swelling or do you just average the total by measuring front, mid and back of the footpad?
Dear Saptha,
You should be expecting granuloma if they have been vacinated with BCG, otherwise first exposure would elicit an inflammation that would have cells next to hyperemic areas.
Mannan
Hi Abdul,
I injected marinum by footpad s.c. I do see inflammation on the footpad.
My question was more on which region of the foot pad do you measure for checking the foot pad inflammation? I mean closer to the digits or the center region or the region near close to the tarsal joint?
maybe this article be useful:
Comparison of three tests for measuring footpad swelling in the mouse.
link: https://www.ncbi.nlm.nih.gov/pubmed/6352814
Choose two positions, I would say close to the digits and the center region of the foot pad and go on measuring always those positions. You should also measure the controlateral footpad injected only with saline to assess the individual variability.
Hi Maestroni,
Thanks for your response. I have done something similar to what you have mentioned. I measure near the digits, center and near the joint. I see an increase in swelling in all three measurements.
How do you plot the increase in foot pad thickness?
I mean in your case you are measuring near digits and center. So do you take an average of both measurement and minus that from the thickness of control, plot the final value or percentage swelling? or is there another way?
Yes, I would do exactly what you said but not percentage swelling , because in this case you will get in trouble with statistics
I would go for a uniform mid-foot injection, and a uniform mid-foot measurement. This region has anatomical planes that swell up visibly during inflammation. Using a consistent anatomical locus will also generate a more consistent, easily-analysable data.
After measuring with the caliper and killing the mouse you should cut loose the foot and weight it. That will give you an additional and accurate measure of the edema
Thanks Olakunle and Ivar for your responses.
I do check the weight of the footpad so I can express the bacterial cfu count/g of tissue. Using that information for estimation of edema sounds good
To get a true measurement of inflammation, I would suggest using plasma extravasation technique using Evan's blue. It is a more accurate measure of inflammation than microcaliper. The microcaliper puts pressure on the tissue causing some of the inflammation (fluid) to displace during measurement. Using this method you would also get a total measurement of inflammation, regardless of placement of the device. The protocol for this techniques can be found here.
http://www.nature.com/protocolexchange/protocols/1919
Please read Microprocessor-assisted plethysmograph for the measurment of mouse paw volume by Webb & Griswold.
Journal of Pharmacological Methods 12(2):149-53 · October 1984
DOI: 10.1016/0160-5402(84)90032-9 · Source: PubMed
Abstract
A sensitive and reproducible method of measuring mouse paw volume was developed by interfacing a Mettler DeltaRange top-loading balance with a microcomputer. This methodology combined ease of operation and precision with the advantages of computer-controlled data processing and archivable storage of data.
Leonard's suggestion is also a better way to measure inflammation than microcaliper.
In the 1960s and 1970s measurements of the thickness of footpads in mice or rats were performed using a relative simple, but sensitive mechanical device (see added picture). For a description of the technique: J.C. Bonta & C.J. De Vos, Acta Endocrinol., Vol. 49, p. 403-411, 1865; T.H. Van Der Kwast & R. Benner, Ann. Immunol. (Inst. Pasteur), Vol. 128 C, p. 833-840, 1977.