14/09/2025
We were recently asked to take a look at cow #520, a 9 year old Jersey cow, who had been noticed to be off-milk at morning milking. 520 had calved without any trouble 3 weeks ago, and had been doing just fine until now.
We headed out to the farm to take a look and see what was wrong with her.
When we arrived, 520 had wandered only a few meters from the shed and had sat down on the concrete - this is not normal behaviour for a dairy cow, and indicates she is feeling quite unwell.
We began our examination by taking her temperature- this came back at 39.8 degrees celsius - a fever. This helps us narrow down what the problem is, because a fever will usually indicate we firstly need to find an infection source, as opposed to the raft of other functional and metabolic issues which could be going on.
We listened to her heart and lungs. She had a heart rate of 100 beats per minute which is high. Her respiratory rate was 25 breaths per minute which is normal. Her heart sounded normal and rhythmic, and her lung sounds were clear and normal.
She was slightly sunken-eyed and moderately dehydrated.
We listened to her gut, along both the left and right sides of her body - everything seemed to be in good working order, with no pings or sloshing present.
At her back end, a vaginal exam revealed a thick, ropey clear discharge - nothing unusual for 3 weeks post calving, and probably indicating a very recent estrus event.
So what was going on with #520, and what was the cause of her fever?
One aspect of an examination for any sick cow, but particularly for a down dairy cow, should always be to check her udder. Doing this is quite awkward as their leg tends to get in the way, and their udder is squashed against the ground. However, all 4 quarters should still be checked - both the udder itself palpated and the milk inspected.
Both of 520s' right quarters were easy to check as they were on top - they were soft and empty, and with normal milk present. She was sitting on her left quarters so with some effort we could feel them - they felt soft. We stripped the back left and found more normal milk. However, the front left quarter gave us dark yellow milk containing fine clots - mastitis!
Source of infection identified ✔️
The final check we did was to measure her blood ketone levels to ensure no secondary Ketosis was present. Her blood ketone level was 0.8, which is fine.
Luckily at this point #520 decided she did have the energy to stand, so we were able to move her to the crush for milk sampling and treatment.
As you can see from the milk samples, the front left milk was noticeably different to the rest. If we had used the RMT paddle on it, if would have thoroughly stuck to the plate!
520 then received 35L of warm water for rehydration, with electrolytes, calcium and magnesium added.
She was given an IV dose of antibiotics to help combat the mastitis infection, as well as IV antiinflammatories to combat toxemia.
In order to full understand what is happening with a mastitis case, we culture all milk samples in our lab. In many cases like this we can have an answer before the end of the day, to help guide the cows ongoing treatment.
In this case, #520 grew E.coli from her mastitic milk.
E.coli is a gram negative bacteria which is a common cause of mastitis in dairy cattle. It is an environmental bacteria which loves wet, dirty conditons, such as what most farms experience over spring.
The bacteria causes such a massive immune system reaction, that cows will usually develop a fever and toxemia as they battle with the bug. Dehydration can be severe, and this is the reason that giving large volumes of fluids via stomach tube is so important in the management of an E.coli mastitis case.
We let ' owners know what she was dealing with, and they were prepared to give her more fluids and antiinflammatories over the next few days as required.
What we think happened is that #520 had been on heat the day before and that the high estrogen levels combined with a day of being distracted from eating, had given the E.coli a window of opportunity to invade her udder, while her immune system had been slightly down.
It was great to hear from her owners a few days later, that 520 was doing well and was well on the road to recovery 🌟🌟🌟
