Esbilac by PetAg 2019 Concerns

Hi everyone. 

Many of you know me personally as Christina Clark and also as the owner of Chris’s Squirrels and More, LLC.  I am not speaking to you as the owner of Chris’s Squirrels and More, LLC. I am speaking to you as the Wildlife Rehabilitator that has been specializing in Squirrel Rehabilitation for the last 24 years. 

This post is primarily intended for wildlife rehabilitators that are using Esbilac by PetAg

I do apologize to everyone for not reaching out sooner to everyone; I have had some family-related emergencies this past week that have taken priority and left me very little time for much else.   Recently it came to my attention that there are some rehabbers that have had high instances of Metabolic Bone Disease (MBD) with their squirrel and opossum babies this year, and that Esbilac is suspected as being a big contributing factor. MBD is caused by a calcium deficiency, caused usually a deficiency in Vitamin D3 because the body cannot absorb calcium without Vitamin D3. This disease is not uncommon in wildlife, especially squirrels and opossums, when they are fed an improper diet (though any animal can be prone to it). Squirrels and opossums can be more prone to MBD while in a rehabilitation setting because they often don’t receive the proper amounts of vitamin D3 and therefore cannot absorb the calcium. Many times we will get calls from rehabbers that are encountering MBD for the first time and while they are treating the animal by giving extra calcium, they see no results because they do not realize they must also supplement the Vitamin D3. Like people, animals get the majority of their Vitamin D from the sun and the foods we eat.  But without it, treating with calcium is useless (this is why most human calcium supplements will also contain Vitamin D3).  

So, with that, let’s get to the issue at hand. 

I haven’t had any issues with my animals this year, nor have I received any calls or questions from my customers directly regarding Esbilac until just recently over the last two weeks, but shortly before that I was contacted by text messages by a couple of rehabbers that I’ve worked with for years letting me know that there was a lot of chatter on social media regarding people’s concerns – specifically that many people have found their young squirrels to have developed MBD and believe the cause to be Esbilac. Also, many people reached out to the manufacturer expressing their concerns and were frustrated that they were not getting the answers that they needed. Since I was made aware of these concerns, I've contacted PetAg myself to see if they had any information to share.

The first thing I can assure you is that they are NOT ignoring the situation. I was told that when they were informed of the concerns being raised, they began taking the steps needed to try to figure out whether or not the Esbilac was the source of the issue.  They were not able to provide an answer or resolution until recently because they didn’t have a conclusive answer yet, but they have found what they suspect the problem may be and while working to resolve it, have asked me to reach out and share the information that they have available.   

PetAg believes that the issue may be that the Calcium in the Esbilac has not been ground finely enough for the animals to absorb it. To be clear, the Calcium itself has NOT changed as far as the source or supplier, nor the amount.  As it was explained to me, the Calcium was not ground into a fine enough powder for that particular batch of formula. 

 Please do not think that I am playing this issue down; the opposite is true. This can be a very serious situation for the animal and frustrating and emotionally draining for the rehabber trying to care for them successfully.  Fortunately, it seems as though this issue is not as widespread as it could be which suggests that more may be contributing to the issue than just the Esbilac.    

 For anyone interested, I have included an explanation of how we mix our Esbilac for squirrels at the end of my letter 

 At my this spring at Chris’s Squirrels and More we took in 14 baby squirrels. All were raised on Esbilac and we had no issues. We keep our squirrels until 18 weeks of age and if Esbilac were the sole cause of MBD in squirrels this year then I would expect that we would have seen it as well.  Also, while our clinic did not intend to take in animals this summer, I do have a new rehabber that I am working with that had a baby gray squirrel, on arrival this baby weighed 12 grams in size and is now 7 weeks old and doing very well. The formula was fresh off of our shelves in my store, so would have been the formula in question. This squirrel has also had no issues but we did always add heavy cream to the formula - from day one. That rehabber has two other squirrels also, but they came in at 4 and 5 weeks old so the comparison would not be as accurate (once these babies are started on the proper solid foods MBD should be non-existent).  A different rehabber this spring did have squirrels with MBD, and she and I were using Esbilac from the same lot number so while I cannot say that the Esbilac was not the cause, I can say that our 14 babies raised on the same batch of formula did not develop MBD.    

 My intention is not to say that adding heavy cream is the solution to the problem that some are having.  I offer it more as information and knowledge that I have gained over my 20+ years of experience rehabilitating squirrels and have found that it has helped ensure success with my animals.  Experience being the great teacher, it often helps for those of us that have already had to learn “the hard way” to share what experience taught, and do our best to spread that information and make this responsibility that we’ve all chosen to share a bit easier on one another.   

 At our clinic at Chris’s Squirrels and More, we prepare our Esbilac the following way: 


  1. We mix 1 Part Esbilacto 1.5 Parts Water!  The instructions on the label that read “1 part Esbilac to 2 parts water” are intended for PUPPIES, not squirrels!!  Since we are technically using the Esbilac “off-label” when using it for squirrels, we as rehabilitators need to take into consideration the modifications that may be necessary to meet the needs of the species of animal we are caring for.  
  2. We add a small amount of heavy cream to the formula at all stages, neonate right through weaning off of formula. The heavy cream has calcium and vitamin D3 in it, reducing the risk of a shortage or non-absorption of the calcium. Depending on the age of the squirrel: 
  • Neonate: Newborn add one 24thor a couple drops to each feeding to the above. With my neonates I start very gradually with the heavy cream to be sure they can handle the cream, and I do watch for bloat but we do not normally have any issues with the cream with our neonates.
  • 3 weeks: 24thpart cream added to the formula
  • 5 weeks: 1/8thto ¼ part cream added to the formula

 Other Important things to keep in mind: 


  1. Always prepare your milk replacers several hours in advance, regardless of which manufacturer’s product you use - PLEASE let your formula sit for at least 4 hours (preferably 8-12).
    A. It is critical that formula be premixed and allowed to sit in the refrigerator to break down all of the ingredients.  Doing so will result in better absorption by the animal’s gut. This is a case where “fresh” is not always “best”. We are commonly fooled into thinking if we make it fresh and feed it fresh it will be “better”, but the longer it sits, the better the animal can absorb it.  
    B. As far as preparing it and then being concerned that it is not going to be good until you finish that particular batch, at our clinic we make the formula the night before we need it. Generally, our formula has sat anywhere from 8-12 hours before we use it, then refrigerate it. 
    C. Both initially and when using the pre-prepared formula, you must shake it very well as the formula will have sediment at the bottom. When we have more mouths to feed, we will prepare the formula in larger containers and freeze it.  It is safe to freeze, and this way it has been allowed to sit and you always have the formula available.

    D.  Please do not microwave your formula ever. At our clinic, we will use a container of very hot water, and let the formula sit in something like a specimen cup or a plastic cup and place it in the cup of hot water. We never have, nor ever will, microwave our formula.

    Please make sure your weaning diet is always nutritionally “correct” for the specie that you are rehabilitating. Weaning diet is critical always and is specie specific.  For those of you that are either concerned about MBD presenting with the use of Esbilac  or are worried about oncoming issues using the present lot numbers of Esbilac, I would suggest any of the following: 


  1. Continue to use the Esbilac on hand and add a supplement that contains calcium or add calcium carbonate powder.  For example, we carry a calcium that is usually sold for nestling songbirds and opossum as those are two animals that normally need an extra calcium source. We have been using this particular calcium for several years now with excellent results.  
  2. If treating a squirrel, then I would recommend a small pinch every other day for preventative treatment. 
  3. If you actually have squirrels or opossums in your care with swollen limbs or lumps olimbs then I highly recommend that you consult with your veterinarian and if they advise it, have the veterinarian administer injectable calcium at their discretion. Please advise the veterinarian that this could be Metabolic Bone Disease.  
  4. DO NOT administer injectable calcium or D3 on your own. This could be truly deadly to the animal if not dosed properly. This is not something that rehabilitators should be experimenting with without the guidance of a veterinarian.   
  5.  Switch to GME (Goats Milk Esbilac). The GME has been used for many    years as an alternative to using Esbilac for animals that may have a more    sensitive stomach. The fat and protein are the same as Esbilac but the        formula itself is a bit easier on the stomach.  
  6.  I have been told that some people are switching to the Fox Valley for Squirrels 5 weeks and older. Which formula you choose/prefer comes down to personal preference.  I would add, however, that the switch from Esbilac to GME would be an easier transition for the animal for digestion reasons, being that they are manufactured by the same company (so the ingredients will be very close in comparison).  


  7.  Adding a supplement such as Nutrical which does contain a small amount of Calcium and Vitamin D3 may be helpful, keeping in mind that too much of a good thing is not always the best. Example: 6 week old squirrel I would administer the size of a small pea mixed into formula once a day or every other day.

     Also, remember that when changing any food source for baby animals, it should always be done gradually over at least a 24-hour time frame. Changing instantly will most likely only result in diarrhea or constipation.  

     Together, as wildlife rehabilitators, let’s work together to save our animals!  I urge everyone to be careful of falling into some of the more negative aspects of social media, such as harmfully criticizing one another, or shaming those whose opinions or experiences are not the same as our own.  While social media gives us the opportunity to share our knowledge with one another, we lose that opportunity to learn when we take away the platform where people can ask their questions without fear of embarrassment.  I think we all know that it only takes one instance of someone “setting us straight” in a critical, harsh, or rude manner to ensure that we never as that person or group seek help again.  We all have valuable information to share and can all learn from one another if we take the opportunity to do so and continue to focus on the fact that we are all doing this for the same reason - to save and care for our wild babies. So let’s just do it! 

     Also, aside from what I stated before, I had not received any additional calls or contact from anyone raising their concerns about this issue (if I had, I would absolutely have reached out to PetAg sooner than last week) other than people that are reaching out because of what they have heard on Social Media. 

    Chris Clark 

    Wildlife Rehabilitator first, business owner second