Firocoxib (Previcox or Equioxx) in the pregnant mare
I'm looking for experience from breeders who have specifically used this drug while their mare or mares were pregnant.
Did you have any problems with the foals with it?
I read a very comprehensive report on this that included toxicity reports (low risk for adult horses), but there were some considerable fetogenic deformities and deaths at relatively low doses when tested in rabbits and rats even down to only 1 mg/kg. While I realize horses are not nearly the same as rabbits or rats, it made the researchers concerned enough to totally mark it contraindicated in dogs who are pregnant and nursing.
"Developmental toxicity studies revealed that firocoxib was Embryotoxic/foetotoxic in both the rat and rabbit inducing a variety of external, visceral and skeletal Malformations, anomalies and variations. The rabbit was far more sensitive than the rat to these Effects. Consequently firocoxib is contraindicated for use during pregnancy and lactation in dogs."
They also tested toxicity effects on the humans who were administering the drug and again found enough concern that all women of child-bearing age, pregnant or nursing should NOT handle this drug without using gloves. Washing of hands thoroughly is recommended.
"Also, given the fact that reproductive toxicity was the most sensitive toxicological endpoint, the SPC includes a warning statement concerning use of the product by women of child-bearing age. Women of child-bearing age should avoid contact with, or wear disposable gloves, when administering the product."
An adult horse, I see no problem with giving this drug. At the usual dose of 0.1 mg/kg an adult horse can deal with this drug no problem; however, a fetus is an entirely different thing. Even at late 2nd trimester or 3rd trimester there is active growth of the skeleton and many of the mutations were skeletal in origin, as well as cardiac and gastrointestinal including imperforate anus (sealed anus) being specifically noted. A foal does not have the drug clearance capabilities of an adult horse and their bodies are WAY smaller. As far as I can see, the drug manufacturer went ahead and had it licensed for use in horses without any specific drug testing on horses, specifically with regards to fetotoxicogenic effects!
Specifically what concerns me is that it is already known that the horse is far more sensitive to this drug than even dogs!!!! So, if dogs could have a problem, then why the h3!! would they offer it to pregnant mares??
THUS, I'm looking for information from people who have specifically used this drug IN A PREGNANT MARE.
I have used Firocoxib for pulse dosing in second and third trimester, generally at 2x the recommended dosing (veterinarian feels 2x is more effective on soft tissue). After reading the long term study of 180 days at 5x dosing (with the knowledge there were no pregnant mares in the study) I felt comfortable with pathological findings and blood chemistry results. I have used Firocoxib at 2x recommended dose for as long as 30 days prior to foaling and 7 days post foaling. Mare's delivery of the foal and the placenta were text book. Foal had a CBC, Chem 20, IgG and physical exam at 16 hours, all results were normal. I did not have any developmental/gastrointestinal issues with either the mare or foal.
My concern for using this NSAID was based on the treatment of extensive swelling associated with an older mare who was stocking up and went 18 days past her due date. She was in a 2 1/2 acre grass paddock on full turnout and still had swelling issues. I have also used Firocoxib for injury related treatment of a mare while pregnant also. Firocoxib is my choice based on its selectivity of COX-2 vs COX-1 in the Arachidonic cascade.
That being said I would not recommend using an NSAID for long term use on any pregnant horse. I understood that there can be side effects related to any drug usage. I also understood fully that I was using Firocoxib off label. Also, I have only used Firocoxib long term on one mare which does not make a case study. I have used it short term on other pregnant mares with no ill effect to mare or foal. Every animal's system is different in absorption/metabolism of drugs, i.e. use of any dog or human NSAIDs in felines can be quickly detrimental (with the exception of Meloxicam). In my particular case the pros far out weighed the cons.
My mare started out with a severe allergic reaction to a vaccine on January 11 with systemic-wide pitting edema, hives and difficulty breathing (anaphylaxis) and emergency treatment by the vet with antihistamines, heavy doses of banamine. Vet held off using epinephrine waiting to see if antihistamine did the trick and it did. Treatment of course has limitations based on her pregnancy although if push comes to shove I will always elect to save the mare and sacrifice the foal. We continued the high-dose banamine, but she still developed very severe laminitis as a complication to the reaction. She did not stabilize with the use of deep bedding/confinement, ice and bute nor banamine (plus Regumate). Pain control has been the biggest issue for her, sometimes her pain is so intense she will just collapse and this is on maximum doses of bute 3-4 grams/day!! Or large doses of banamine 10 cc twice a day! She is still not stable and things are rather touch and go. For this mare, she will need to be on rather long-term drugs. Right now, after more intensive discussions with my vet team, I did start her on the firocoxib - she's on 114 mg a day (this is now day 2), but it's not holding her pain and she will be dosed with 10 cc of banamine tonight at about midnight. I've been literally nursing this mare intensively round-the-clock for 51 days. I'm getting kinda tired. But, she is still fighting and so I'll keep fighting for as long as she does. If she starts to give up, and she doesn't respond to encouragement to keep fighting, then I will let her go. For now, she wants to fight, so we fight. Sometimes I go out and she tosses her little red head and shows some attitude. Sometimes, she's rather flat. She's at day 225 of her pregnancy so we have a long ways to go yet. Farrier is coming out yet again on Tuesday. She very much is still in the destructive phase of laminitis as her hooves have stopped growing as evidenced by my line of bright red nail polish applied immediately under her coronet band. No growth for 51 days. When her hooves finally start to heal, then she will grow and we will know she is finally starting on the very long road of mending.
She is in a standing paddock outside, sheltered from the elements, but this allows her to see the comings/goings on the farm and be with buddies. She is bedded very deeply in shavings. Farrier put pads on with frog supports, but she still wants to stand with her toes pointed definitively downhill, so this means she is wanting thicker pads at the heel, so the farrier is in the middle of fabricating special pads for her which will be installed on Tuesday. The priority is pain control. We will worry about contractions later. We can only deal with one problem at a time and saving her life is numero uno. If we can't get her pain under control we will lose her (never mind the foal). Vet team is very much in full agreement with farrier's plan, based on her xrays and such. Her x-rays show considerable rotation, but it's the ligament (? or tendon, can't remember, too tired to think straight) attached to the heel of the coffin bone that is doing a lot of damage as it is pulling the coffin bone downwards, literally shearing the laminae off the bone at her toe and front of hoof. Sounds painful even to describe it! So, the theory is we will add 3/4 inches of padding at her heel (which she is trying to do herself by standing downhill) and reduce the pull of the ligament or tendon (whichever it is attached there) for the next few months giving the lamina time to heal, strengthen and start to grow down. And then, after that, 5-6-7 months down the road, we can re-do x-rays (again and again) and the farrier can start reworking her trim to bring the coffin bone in the right alignment to the ground. Oh boy, I hope this works. She will soon let us know as she has been extraordinarily good about letting me know what works and what doesn't. Here's hoping this attempt is the one that does the trick for her.
Even though her issue has nothing to do with metabolic anything or other, we have radically changed her diet. She has timothy hay that was already tested to be 11.7 NSC, but we still soak it. She gets beet pulp (soaked/rinsed) and no-calorie preg mare minerals that look and taste like sand (I taste test everything these days it seems). She eats it though. To this I add human-grade Omega 3, 4000 mg, and 2000 IU vitamin E. She is on an extra 2.5 grams of magnesium and the vet just started her on ranitidine for her gut because of all the bute and banamine she's been on. And that's it. Her diet is very bland. It will stay that way until she has been good and stable for quite a while before I even attempt to think about ways to increase her protein (for baby). She's not "due" until mid-late June so we have time yet. Someone suggested split peas for protein since this mare is also sensitive to soy. That might be worth investigating. And BOSS although while she has lost some weight in the last 50 days, she's still at a pleasant body score for her pregnancy. If she loses more, BOSS might be worth looking at, but frankly right now I want to do little and/or nothing with her diet until she settles.
In early February, because she wasn't settling, I brought up the subject of forcing abortion of the foal, but the repro vet team said no way because the drugs required and the radical shift in hormones when she was already in very severe acute laminitis could send her off over an edge from which she may not recover. Only if she started to go into kidney failure would it even be worth considering. So, we held off and waited to see and so far she's been hanging onto her foal. She went into mild kidney failure mid February, but she self-recovered and she's been okay since, as per blood work. You don't even want to know what I've paid out for her medical bill thus far...
Even confined 24/7, she has zero behavior issues and isn't even cribbing, so I'm rather amazed (or concerned, haven't decided which I should be yet - concerned only because it means she is still too sick to even consider being naughty). She always has been a sweetheart, but to have her some attitude would mean she is starting on the mend and feeling a whole lot better. Attitude and playful naughtiness is really something I'd prefer to start seeing really, really soon!
On the advice of my vet, I used low dose Previcox on a very late term broodmare with an abscess in her hind foot. She was uncomfortable and it was hard for her to get around. It was short term use, and she delivered her foal with no issues for the foal or her.
My vet recommended Equioxx when my mare was very foot sore in her 9th month of pregnancy. I guess we'll see if there are any long term effects, but it worked well and she was only on it for a couple of days. I try to stay away from drugs, but sometimes it's necessary.