A big challenge to rehabbing cottontails is getting them to eat. They are some of the fussiest babies. They know we are not their mom and they are not cooperative.
Bunnies are at the bottom of the food chain, which makes them ever alert to danger. This poses a challenge because to the bunny, we are the enemy. You must gain the trust of your cottontails or you will only add to their stress.
The final challenge to the cottontail is their sensitive digestive system. The transition from formula to solids will claim the lives of many cottontails if proper steps are not taken to prepare them for the switch.
In order to successfully rehabilitate cottontails you must understand the challenges and keep working to find a way to overcome them. Hopefully the tips that have worked for me can help you come up with new ideas to overcome these challenges and help more bunnies.
Cottontails are born with no fur and their eyes closed. Their ears are sealed at birth. There are usually 4 to 6 babies per litter, but I have seen litters as small as 2 and as large as 13! Babies typically weigh 30-35 grams at birth.
By 2-3 days old, the babies are starting to get noticeable fur and their ears are no longer sealed, but are still held back against the head. They still have no fur on their bellies. they typically weigh 40-50 grams at this age.
At 5-6 days old the babies are fully furred bu the fur is still very short. They may start holding their ears up, but for the most part they are still back against the head. At this age they typically weigh 50-60 grams.
At 7-10 days old their eyes open and they are holding their ears up more and more. They will begin exploring on shaky legs. It is normal for their head to wobble a little while they walk at this age. They should weigh 60-80 grams at this age.
At two weeks old, cottontails in the wild would begin leaving the nest for short adventures. This means that it is time for a larger cage. It is also time to start introducing greens. They should weigh between 80 and 100 grams at this age, but it can vary greatly.
At three weeks old they should be weaned and gaining weight well on the greens, oats, and timothy hay. A healthy weight at this age is anything 90 grams and up.
When the bunnies are four weeks old, they are ready to head to an outside cage. They should weigh at least 100 grams, typically closer to 150 grams, but some will come in emaciated and be a little behind. They should be active and alert by this time and fearful of all humans, including you!
At five to six weeks old they are ready for release. I wait until they have outgrown the sit and hide strategy and are confident they can outrun a predator (instead of sitting their with their ears back not moving when you approach, they will sit and then take off when you get too close, like a cottontail would do in the wild). They should weigh over 150 grams at release, typically 200-300 grams. They should be released in the evening (I release around 6 when it is still light enough for them to find their way around, but late enough that it is close to their natural active time), in a brushy area. You should release at a time when good weather (no rain) is predicted for at least 2-3 days.
I have experimented quite a bit with cottontail formulas and have found that Zoologic 33/40 mixed evenly with Zoologic 30/55 or multi-milk (both are the same thing) works the best for me. To mix the formula, I combine the two formulas then mix at 2:1 for full strength. So, if I was using a tablespoon as my measure, I would add 1 tablespoon of Zoologic 33/40 powder with 1 tablespoon of Zoologic 30/55, and 4 tablespoons of water.
Some of the formulas that I have tried but did not like are Fox Valley formula 32/40 and Esbilac with Multi-milk. My cottontails on the fox valley formula tended to either bloat or get diarrhea on the 2:1 strength, so I had to keep them at 3:1 and then their weight gain was not very good. If heavy cream or multi-milk were added to this formula it might be OK for bunnies though.
I have also tried using Esbilac mixed with Multi-milk, since I used to use Esbilac for my squirrels before the processing changed and my cottontails seemed to do well at first, but later some became very weak and even lost use of their back legs before dying. They seemed to have very weak bones.
Some formulas I have not tried but would consider trying if the bunnies had issues with the Zoologic formula is Fox Valleys 30/50 formula for Beaver. That is closer to a cottontails needs than the 32/40 formula designed for cottontails. I would also consider trying Zoologic 33/40 with heavy cream added. I have heard from several rehabbers that hand feed their cottontails (I tube feed all eyes closed cottontails) that their bunnies love heavy cream and that KMR with heavy cream is readilly accepted by the fussy babies. KMR alone in my opinion is too high in protein and too low in fat for cottontails, but with the addition of the heavy cream, that would increase that fat and it should be a good choice nutritionally.
There are many formula options and what works for me may not work best for you; so experiment with the formulas until you find something that you are happy with. The protein and fat content should be roughly 30 and 50 respectively so in order to ensure your babies grow up healthy and strong, try to stay as close as possible to those numbers.
Getting Your Cottontails To Eat
Cottontails are the fussiest babies when it comes to drinking their formula. They are one of the few animals that would rather starve than take formula from you. I hand fed my first litter of cottontails and it took me an hour to get 1 cc into them. I was spending all my time feeding them and I only had 2! When another litter came in I knew there was no way I could help them unless I found a better way. That is when someone recommended tube feeding and now I recommend tube feeding all bunnies that do not yet have their eyes open. Tube feeding will save you time and is easier on the bunnies. With hand feedings you run the risk of aspirating the bunnies and then they will most likely develop a respiratory infection, which can easilly be fatal. The only risks with tube feeding are getting the tube into their lungs and then filling the lungs with milk, which would be fatal, and puncturing the soft pallet and filling the neck cavity with formula, which is also often fatal. Both can easily be avoided though.
I use a 3.5 F tube for bunnies that are 1-3 days old and weighing under 40 grams and a 5 F tube for any babies 40 grams and up. When tube feeding, hold the bunny so that it is facing you and use your dominant hand to push the tube down. Use your other hand to hold the bunny's head still. Before you begin tube feeding, be sure to mark the tube with a line so you know when the tube is down in their stomach. To do this, lay the tube against the bunny with the tip just below the rib cage and follow the tube up to the mouth and mark a line where it is at the mouth. this marks the distance that the tube needs to go to get to the stomach.
Now you are ready to tube the bunny. Hook the feeding tube to the syringe and draw the formula up through the tube into the syringe (the idea is that if the formula draws up the syringe, it shouldn't clog going back out). Make sure to get rid of all air bubbles and push the air out of the end of the feeding tube before putting the tube down the bunny. When you tube the bunny, the tube should go down the bunny's left side, which is your right if the bunny is facing you. Gently push the tube down until you get to the line you made on the tube. If the tube will not go all the way to the line, you may be in the lungs, so bring the tube back out and try again. If you continue to have trouble, remeasure the distance to the stomach and make sure that the line is in the right place. When you get the tube down near the line, gently push until you feel it stop, that is when you are in the stomach. To begin feeding, put just .1cc down the tube and wait a little bit to make sure no milk comes out the bunny's nose. If none does, slowly feed the bunny the amount that it should get for the feeding. The bunny should move its mouth like it is drinking the formula. If it does not, wiggle the tube a little in its mouth to see if it starts. If it doesn't move its mouth, that could be a sign that something is wrong and you should take the tube out and try again.
I always use a 3 cc syringe for bunnies under 40 grams and feed just 3 ccs. and I use a 5 cc syringe for bigger babies and never exceed 5 ccs per feeding. I feed my cottontails 8-10% of their body weight 3 times a day until they are 70 grams, then I cut back to 2 feedings a day. At 80 grams I cut them back to 1 feeding a day, and I wean my cottontails (provided they are eating greens well and at least maintaining their weight without formula) at 90 grams.
Managing stress will be a major key to success with cottontails. Even babies that come in eyes closed and are used to you caring for them can stress out and die. You never know what will freak a bunny out. It can be anything from a dog barking to even a plastic bag or the noise of a tarp, the beeping of an alarm, you just never know.
A few pointers that work well for me are:
- Put sheets or pillow cases over their aquariums
- Move them to another room when vaccuming
- Establish and maintain a schedule
- Keep the area as quiet as possible and find an area out of the way that won't constantly have people walking through it.
- Don't house near predators or other noisy animals
The number one issue for eyes closed bunnies is digestive issues. Many bunnies will seem healthy and then suddenly get diarrhea or bloat and die shortly after starting to eat solid foods. The cause of this is typically a lack of gut flora needed to digest greens and other solid foods.
I have found that using cecotropes from an adult domestic rabbit can prevent this in nearly all cases. Cecotropes contain the enzymes and bacteria that cottontails need to digest regular food. Baby bunnies are born with a sterile gut and their mother's milk is acidic, which keeps bad bacteria from taking over and making the bunny sick. Then when the babies open their eyes, they eat their mother's cecotropes and are weaned onto a diet of greens with no issues.
Collecting the Cecotropes
Cecotropes are a special poop that is excreted only at night or in the early morning. It is softer than their regular poop and will not have the strands of undigested plant material in it like the regular daytime poop has. You will need to put an Elizebethan collar (E collar) on the rabbit to get the cecotropes because they eat them themselves each night. You will need to put the bunny in a wire bottomed cage with clean newspaper underneath to catch the cecotropes. I usually put the collar on the bunny at around 7:00 in the evening and usually there is poop in the bottom by midnight, if not then by 5 or 6 AM. You want to get the cecotropes as soon as you can because they tend to dry out and harden up if left for too long. I will collect cecotropes from my bunny for up to 3 days in a row with no ill effects. You do not want to go much more than that, though, because they need the cecotropes themselves to maintain their gut flora.
I keep the cecotropes in a ziploc bag in the refridgerator for up to 1 week. I have not tried freezing them or keeping them in the fridge for longer than a week. I usually have 20-30 baby bunnies at one time so the cecotropes are usually gone before a week.
Giving the cottontails the "Chocolate Milk"
Some bunnies will eat the cecotropes, but most will not. iF they will not eat them, you must mix it into their formula and hand feed it to them. There are two ways to do this and both work equally well. If you hand feed your cottontails the regular way you can measure out 1 cc of formula per bunny and then add 1-2 cecotropes per bunny to the formula and feed each bunny 1 cc of the "chocolate milk" as I call it. The mixture will be very thick and you should ensure that the bunnies chew up the pieces. Each bunny needs to get 1 cc of the mixture 1 time a day. Then you can give the rest of the feeding as regular formula.
If you tube feed, like I do, you can measure out the formula needed for the full feeding and mix in 1-2 cecotropes per bunny. This needs to be mixed thoroughly and you should mash the cecotropes with a spoon and make sure all the chunks are broken up. Since this still jams the tube up, I put the mixture through a sieve. Then, when tubing, I always attach the tube to the syringe and then draw the formula up through the tube because if it can go up the tube, it shouldn't jam coming back out. Then each bunny should get the regular amount of the "chocolate milk" that it gets for a full formula feeding. The bunnies need to get the chocolate milk mixture once a day.
When to give the Cecotropes
I use to wait until my cottontails opened their eyes and then I would give them the "chocolate milk" for 3 days before starting them on solids. This works fine for the older eyes closed bunnies that come in at 5 days old or older, but I found that the tiny little guys that came in at 1-3 days old still developed digestive issues despite having been given cecotropes. Then, three years ago, I got in one 2-3 day old bunny and five 5-6 day old bunnies and put them all together since I didn't have hany other young bunnies. When the older bunnies started opening their eyes, I did not want to delay giving them the cecotropes, so I decided to give it to all the bunnies including the tiny guy. What I did was I alternated between giving the cecotropes and adding LA 200 to their formula each day. I would add the LA 200 to the formula for the day so they got it at every feeding and then the next day I wouldn't add the LA 200 but would give the cecotropes in the milk at one feeding that day. I did this until the little guy opened his eyes. Then I gave the cecotropes once a day for 3 days and started giving them greens, oats, rabbit food, and timothy hay. That little guy was my first tiny little grey guy (that is what I call the 1-3 day old bunnies that have no fur, but have the greyish color) to survive to be released and now using this technique my success rate with newborns is the same as any other age (about 70%).
Something else I do with cottontails when I am very busy in the summer and don't ahve time for the cecotropes feeding every day is I will add LA 200 (a probiotic sold by fox valley) to the formula instead of cecotropes every other day. So they get cecotropes and LA 200 on olternating days. The bunnies MUST get the cecotropes at least three times after their eyes open before getting any regular food though. I have tried other probiotics (Bene-bac and a laccobacilus tablet from a health food store) and it doesn't seem to work as well so I am sure to always keep LA 200 on hand. I mix it more concentrated than the directions say to. I just add 1/2 teaspoon to their formula for the day (usually 6 tbsp. of ready to feed formula).I have tried just using the LA 200 and no cecotropes and some of the older cottontails (6-7 days old with their eyes opening within a couple days) survived, but none of the babies under 3 days old survived.
I have also found that the domestic donor bunny must be at least 6 months to a year old or older. When my bunny died and I got a baby bunny and tried to use the cecotropes, they seemednot to work and I lost quite a few bunnies to digestive issues and had to borrow a bunny from a friend after which my success rate returned to normla. I used the same donor that I had issues with the following year and had no bunnies with digestive issues. The bunny was tested for parasites when I was having issues and came back negative. I think they must be older to have enough bacteria to be beneficial to the babies.