Papaya enzyme is one of my go-to's at the first one of my rabbits might be having GI issues (usually small or strung together poops clues me in). However the treats them selves are quite expensive (~$10 for 90 tablets). Human papya enzyme tablets cost 5x less (500 for ~$11).
No you should not feed papaya enzyme tablets designed for humans to rabbits.
Papaya tablets are little more than a sugary treat: they contain very little active enzyme
Additionally as there is no rabbit specific dosage listed on the instructions, you should not use it.
Recommended dosages of proteolytic enzymes vary with the form used. Because of the wide variation, we suggest following label instructions
Strung together poops are not necessarily indicative of a GI issue, particularly during a spring or fall shed. I usually consider it a good sign if the hair is moving through.
Susan Brown, DVM, believes that enzyme tablets are not necessary to restore GI motility.
How do we treat a stomach impaction due to reduced GIT motility once it happens? It is important to make sure that all the conditions that may be affecting the rabbit are detected. Your veterinarian may suggest x-rays or other lab work. Since this is an impaction problem, the goal is to rehydrate the rabbit both through the circulatory system and through the GIT. Fluids are administered either under the skin or in a vein along with high fiber and moisture feedings by syringe or tube. Syringe feedings can be made from ground rabbit pellets or powdered alfalfa mixed with blenderized green leafy vegetables and an oral electrolyte solution. In addition, medications to stimulate the GIT to start moving again and analgesics are used. It is rarely necessary to use antibiotics, and in fact these might cause further disturbance to an already compromised GIT. Some people like to use laxatives, and enzymes. I too, have used these products in the past, but have found that they really aren't necessary. I have equal success in treating this condition with or without enzymes. It is important to remember that enzymes of any kind (pineapple, papaya or pancreatic) do not dissolve hair. But the real keys are hydration of the stomach/cecal contents and getting the GIT moving again.
I find that over 50% of the rabbits presented with this condition will take care of it themselves when they are given a big pile of leafy greens to eat. Most of the cases of stomach impaction we see have been on a primary pellet diet and have had little or no access to greens or hay. They are craving fiber and fluids and the leafy greens can be just the ticket. In addition we give all these patients good quality grass hay. We completely remove pellets from the diet (rabbits usually won't eat pellets when they are ill anyway). Whatever treatment is used, one can expect stools to be produced within three days. It is rarely necessary to perform surgery for this condition.
Other causes of GIT disease in the rabbit include partial or complete blockages of the intestine with foreign material (often carpet fibers), post-surgical adhesions, intestinal parasites, toxins (such as lead) and other systemic disease. It is important to have your rabbit thoroughly examined by your veterinarian to determine all the problems prior to instituting the treatment that I have described.
If the cost of enzyme tablets is a concern, you may be better off investing in more leafy greens rather than the tablets which may or may not be effective.