I'm here to tell you that this diet related death myth is total BS and pure hogwash!
I always tell new caregivers of baby squirrels to be forewarned. Do not get too attached to them for at least 2 weeks! This is the voice of experience from the realization that, unless you know first-hand that the babies did not suffer any injuries from when they fell from its mother's nest, there is always the possibility of a baby squirrel going down-hill suddenly and dying. They can be fine one day, and dead the next.
Unknowing and ignorant Rehabbers are quick to blame new squirrel caregivers with a guilt trip about feeding them the wrong formula. But, my 40+ years of Surgical and Emergency experience has carried over to my avocation as a Squirrel Rehabber.
I learned early-on that there are people out there that don't know what they are talking about with their "knee-jerk" assumptions. The reason I know is that I know how to conduct an autopsy to find a cause of death! I've seen enough of them, and participated in enough of them and scrubbed in on enough trauma cases and know enough physiology to know that people and animals don't go down-hill and die suddenly from drinking or being fed milk or formula.
When baby squirrels are fine one day and the next they go into shock and die, I know it is more than formula that killed them! So, I open them up to see what kind of problem caused the death. Most times it was delayed internal bleeding from blunt trauma to the abdomen. Internal organs have a tough membrane around them called "fascia," which will contain bleeding into the organ when it is injured. Baby squirrels are tough little troopers in that they can act completely normal with an injured liver, spleen, or kidney. The problem comes when either the fascia or the organ starts to fail.
If there is a significant amount of bleeding into an organ, and the fascia breaks down, it causes the organ to leak blood. The animal rapidly becomes so anemic that they die of hypovolemic shock. These babies suddenly stop eating because free blood in the abdomen is very nauseating. They also become difficult to keep warm because peripheral blood is being shunted to the internal organs to keep them going. So, the baby feels cold to the touch.
Organ failure is a little slower but the end result is the same! I've only had one baby that had me stumped. I would find it sleeping outside of the blanket nest every morning. Soon, I realized that it was breathing rapidly and seemed short of breath and needed to be out where there was more oxygen. After another week I found it dead.
Since shortness of breath and rapid respiration were its primary symptoms, I suspected a lung contusion. I checked it's internal organs and found them to be in perfect shape, so I extended my investigation to the chest cavity and found the lungs to be in perfect shape. I was about to chalk-it-up to "unknown" until I separated the lungs to look at the heart.
There it was! The fascia surrounding the heart was full of dark blood, a condition called "Pericardial Tamponade." A very small blood vein had been torn loose and very slowly leaked blood into the pericardial sac. It eventually built up enough pressure to start squeezing the heart so that it became difficult to pump blood. If blood isn't pumped efficiently through the lungs, shortness of breath and tachypnea, (rapid breathing,) become the symptoms.
I say all this not to brag, but to let you know that I know what I'm talking about, and to assure you that if your squirrel suddenly goes downhill and dies, it's not your fault or what you fed them.
I wrote a Blog article 5 years ago about feeding babies. I never bought the myth that milk was bad to feed a baby squirrel nor that a baby needs vitamins during its nursing phase. Because I learned back in College during "Early Childhood Care 101," that all suckling mammals synthesize everything they need for growth and development from the fat, protein, carbohydrates, calcium, and simple sugars contained within their mother's milk or formula.
When a baby is born, it is only developed enough to live and breathe outside the womb. But, it is far from fully developed and there are tissues and organs that still need to develop and mature. The liver during this time is also immature, but, being the master chemist of the body, has a unique ability during this time to synthesize everything that is needed to complete the maturation and development of the tissues and organs from these simple raw ingredients.
I can still hear my professor tell us that, " All vitamins do during this time of synthesis is make expensive urine!" I've searched and searched online for corroboration of what I learned back 40+ years ago, but current textbooks conveniently leave this out!
But, I did manage to dig up an ancient study of squirrel breast milk conducted by the Ohio State University that proved that cow's milk with added milk fat is the closest thing you can find to squirrel breast milk. Between this study and another separate study, they found that squirrel breast milk is up to 24% milk fat. This study is what I base my formula recipe upon.
Here is the link to my Blog article. The link to the Ohio State Study is in the article. Please draw your own conclusions!
The thing I want you to take away from this article is that if your baby squirrel suddenly died for no apparent reason there actually was a reason that was not your fault. And don't let anyone try to convince you that it is!!
I'm not in the pocket of any formula manufacturer so I have no financial ties or interest in promoting their products unlike State Rehab organizations that receive funds for promoting certain products.