“Doc – Do Mares Get Milk Fever Like Cows Do After They Calve?”
© A.J. Neumann, D.V.M.
published in The Draft Horse Journal, Spring 2002

They sure do. The condition in the mare is called “eclampsia.” It probably is one of the most under-diagnosed conditions following foaling in the mare.

Postparturient eclampsia is much more common in the draft horse than in the light horse breeds. In my experience I have seen and treated many cases in the draft mares; very, very few in light horse mares, and not a single case in a pony mare. It may occur in pony mares, but I have never seen a case in these breeds.

Eclampsia can occur in a mare anytime after foaling, up through weaning. One time I diagnosed and treated the condition in a big Belgian mare about one week before she foaled. Her case was very different, in that I treated her for two more foalings. It occurred the same way, just about seven to ten days prior to foaling.

Generally speaking, however, eclampsia will occur in the mare seven to fourteen days after foaling.

So what do we see happening in these postparturient mares as they develop eclampsia?

The first symptom a sharp-eyed horse person will notice is that the animal seems to be a “little nervous.” It may act anxious and be very restless, moving about the stall or paddock as if it wants to leave the foal and just go somewhere else. One may notice rapid breathing, and occasionally the mare will sweat lightly.

At this point, the animal may often show signs of colic. It will lie down, stretch out, roll up and look at its flank, then get up, only to walk around and repeat the process again.

Another set of symptoms may follow the initial stage of anxiety. The animal may appear to walk slightly “stiff.” This may be followed in an hour, up to two hours, with a staggering gait. The mare will fall to the ground and is unable to regain her feet. The head and neck become extended, as well as the feet and legs. The latter may be rigid, or the animal may be making feeble running motions.

Sometimes the entire musculature may be hard and rigid, with short periods of relaxation. Occasionally the affected mare will be found down, unable to rise, and she will show periodic spasms of the muscles or convulsions.

Just before the animal goes down, its breathing becomes labored, and the body temperature may rise to 105 or 106 degrees Fahrenheit. At this stage of the game, the pulse becomes very rapid and weak.

The total time elapsed from the onset of the first symptoms to the “down stage” could be from one hour up to twelve or fifteen hours.

If one has time, a blood sample can be taken from the patient and a blood calcium level test performed. In the draft mare, the normal blood calcium level is 9 to 15 mg per 100 ml, the average being 12 mg. The stricken mare may have blood calcium as low as 4 to 7 mg per 100 ml. It is also interesting to note that while the blood calcium level is low, the phosphorus blood level will be high. It is a very good idea to check the blood phosphorus level as well as the blood calcium level when running the blood sample taken from the mare.

Most veterinarians cannot take a laboratory with them into the country when making calls. I learned a long time ago to kind of fly by the seat of my pants. I have found a diagnostic symptom that is present in these afflicted mares, as well as in the cow with milk fever and in the bitch with eclampsia. It is the reflex time of the pupil of the eye when a bright spot of light is focused on it.

Take a pen light, and focus it on the eye. Those mares with the eclampsia syndrome will have a very retarded constriction of the pupil of the eye. Now, don’t be so foolish as to ask me what the length of time is! Try your light on normal horses’ eyes. Get a feeling for the pupil constriction time. Then when you try it on the suspected eclampsia mare, you will immediately recognize the fact that the pupil is slow in constricting.

The history and symptoms of the patient, including the slow constriction of the pupil in the eye, should be diagnostic of eclampsia, or so – called “milk fever” of the mare.

The treatment is easy. I have never lost one of these afflicted mares, treated while undergoing an acute attack. Calcium gluconate in a 20 percent solution is given very slowly intravenously to the patient. If the mare is down, the foal should be removed until the mare is on her feet. A dose of 750,000 to 1,000,000 units of vitamin D is also administered into the muscle of the hip of the mare.

Occasionally the calcium gluconate solution will have to be administered more than once to secure complete recovery. When the mare has recovered, her grain ration is fortified with a correct balanced mineral and vitamin D. I have never had to wean a foal from a mare that has suffered from eclampsia.

I believe the condition can be prevented to a large extent by providing an adequate ration, complete with the necessary amounts of calcium, phosphorus, and vitamin D, to the pregnant mare during gestation, and on through the nursing period.

It is interesting to note that the old literature on horse diseases, lameness, etc., contains no mention of so-called milk fever or eclampsia. Yet, my old mentor, Dr. Roach, (who graduated in 1902) told me he treated this condition successfully in some mares after foaling with large doses of bone meal and codliver oil given orally. The downed mare was tubed, he said, and given a solution made of bone meal and water.

A veterinarian called me a few months ago concerning a draft mare (that was nursing a foal) which appeared to be foundered, as she was walking stiff and seemed to be sore on her front feet and legs. He said he was not acquainted with the draft horse, but he had a good light horse clientele. After listening to the history and symptoms of the animal, I suspected the mare might have eclampsia. I instructed him to get a pen light and do the eye test, and I told him if the pupil was slow in contracting down, to give the mare some calcium solution slowly in the vein.

He called back and told me the eye test was positive for eclampsia, and he gave the calcium intravenously after making the diagnosis. Recovery of the “foundered” mare was almost instantaneous.

So I often wonder how many draft mares suffering from eclampsia, but with symptoms often mistaken for founder or acute colic, have been mistakenly diagnosed with such, by well-meaning veterinarians without draft horse experience. Also, it is one thing to suspect eclampsia two to four weeks after foaling, but how about the nursing mare who is found down in the paddock early in the morning, three months after foaling?

Give her the old eye test; it may separate the sheep from the goats.