# Fasting Before Blood Testing



## Dallas Gold (Dec 22, 2007)

Penny & Maggie's Mom mentioned in another thread that her vet doesn't require any fasting before drawing blood work on her dogs. Every veterinarian we've used has required a fasting before blood tests. Now I'm curious what is the common practice for this. Please indicate if your vet's requirements for routine blood work and for thyroid testing. Thanks!

OK, I messed this up, I should have made separate threads for routine and for thyroid testing.:doh: Please just pick one and explain. Sorry about that!


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## Rainheart (Nov 28, 2010)

We usually do say to fast, but a lot of times the dog is getting an annual exam and the owners opt for bloodwork, so in that case, they probably aren't fasted. We do like them to be fasted, though.


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## kwhit (Apr 7, 2008)

The vet I use now requires fasting for 12 hours before Chance's blood work to check his liver, (he's on Rimadyl). My last vet said it wasn't necessary.


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## BayBeams (Jan 3, 2010)

None of the vets I have ever gone to over 20+ years with dogs has ever required a fasting blood draw. My current vet has never mentioned the need to fast for regular or thyroid blood testing.


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## Penny & Maggie's Mom (Oct 4, 2007)

As mentioned in another thread, we do not fast for normal lab work or for thyroid ( hemopet/Dr Dodds does not require it). If lipids or glucose were abnormal, perhaps we would follow up with fasting if needed. Also, I've heard that fasting can actually elevate BUN readings. Would be interested to hear our member vets input. The need to fast seems to be different depending on vet??????


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## Dallas Gold (Dec 22, 2007)

Just found this for thyroid testing through Michigan State Diagnostic Center for Population and Animal Health
_Additional Information

Profile includes: TT4, TT3, FT4, FT3, TSH, TgAA, T3AA, T4AA

*Fasting sample is best to avoid lipemia.* 2 mL of serum, NOT WHOLE BLOOD, pour serum off into plastic tube. The sample can be mailed regular mail and does not need to be on ice. Freezing will not affect the sample after the serum has been separated. If the sample is frozen it can be kept almost indefinitely. Slight to moderate hemolysis is okay, but gross hemolysis or lipemia will greatly affect results (increased TT4 especially). Lipemia may affect other tests (decrease TT3, increase FT3, and increase T3AA). If sample is still lipemic after fasting, indicate on the form and send anyway. WHOLE BLOOD is not acceptable for any tests. Spin down and draw off the serum. If a clot separator tube is used, pull off the serum after it has separated. These tubes do not always hold up during shipping._


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## Dallas Gold (Dec 22, 2007)

I did a check of a few of the regular blood chemistries offered on the MSU website and nothing mentions fasting for them. I wonder if it's just easier for vets and staff to require fasting just in case they need to draw a more specialized test based on the in clinic examination?


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## lgnutah (Feb 26, 2007)

Every time I am supposed to get Brooks' thyroid tested, I ask if they want me to do anything like make sure it has been 4-6 hours since he had his thyroid pill, or that he hasn't eaten. Always the answer is NO. I talked with the vet and said I thought I read that...... and he said, No, it doesn't matter.


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## Belle's Mom (Jan 24, 2007)

Now that I think about it - I never asked our current vet as our old vet requested it so I just stuck with the same regimen with our current vet.


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## fostermom (Sep 6, 2007)

No fasting from any of my vets either, though the last time we had Jasper's thyroid tested, I set the appointment for more than 4 hours after he had eaten and had his soloxine. But that was after reading that the thyroid test could be different if he was tested right after getting the soloxine.


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