Puzzling lab results, mastitis, please help!

[Obsidian_Fire]

Last Tuesday (a week ago) I arrived at the barn to find my mare in a full-blown mastitis event. Udder swollen, goo hanging from the teats, edema from the udder forward almost a foot.
Straight to vet we went. Vet milked out the most disgusting yellow chunky goop ever, and sent it to pathology. Put mare on SMZ’s.
SAA was over 700.
Took miss mare several days to act “normal”, and not punky. She is still not really eating like normal.
Yesterday, Monday, I talked with vet. Pathology came back and it GREW NOTHING. Vet is very puzzled by this and is going to call the lab to ask questions.

How do you have an obvious infection, yet grow nothing from a culture? What is (or might be) going on here?

[Rosewatt]

I have no idea, but am interested in hearing other experiences or ideas on this matter.

I did find this, which was an interesting read for me: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6417605/

[trubandloki]

Jingles for your mare. That sounds so uncomfortable.

(I can’t answer your question, but just wanted to add support.)

[Obsidian_Fire]

Yes, the usual suspect in these cases is “inappropriate lactation” but in my mare’s case that is not so.

Vet said opportunistic bacteria entered thru the teat hole, and voila!, infection.

[victoriakent]

This is one of my favorite papers. " Idiopathic inappropriate lactation" makes me chuckle every time. My TB mare also randomly lactates year round with no found reason and I always say “well, she is an idiot sometimes so that sounds right.”

[Skip_s_Rider]

Many milk samples from cows with mastitis do not show any growth when cultured. Usually they suspect the infection to be caused a gram negative bacteria, which the cow has cleared on her own. Therefore, there are no live bacteria remaining in the milk. These infections, however, can cause quite severe systemic symptoms such as lethargy, fever, and poor appetite in addition to signs present in and around the udder. These cows often will receive supportive care involving fluids and antiinflammatory drugs.

[Simkie]

Not everything out there cultures. Not every sample is handled appropriately from animal to lab. Not every sample taken is representative of the spectrum of stuff that may grow.

I’d be totally comfortable to chalking this up to “if it walks like a duck, and talks like a duck, it’s a duck” and continue to treat like a mastitis. If it doesn’t improve or respond to your current treatment, repeat the culture. Maybe with a few samples.

Fwiw, when I had a dry mare develop a mastitis, it also took her quite a while to really feel better. We had her on doxy for a month, I think.

[JBCool]

UGGGHH!! Poor mare mare. That sounds awful! Sorry, not more helpful.