International Giant Otter Studbook Husbandry and Management

It is very important that giant otter milk composition be analyzed to determine which milk
replacer formulas are best for this species. The specific composition of giant otter milk (i.e.
percentages / types of fat, protein, lactose, etc.) is either unknown or unreported. The
nutritional content of giant otter mother’s milk needs to be studied for comparison to the variety
of milk replacers available/used for this species. This information could then be used to
formulate and/or recommend types or brands of milk replacers that are most optimal to rear
giant otters specifically. [Note: Although, staff at Dortmund Zoo (Germany) have trained a
giant otter to allow milk samples to be drawn after litter loss. Unfortunately, the only sample
drawn was lost due to technical reasons, but further study and training will be continued. It is
important that other captive females, world-wide, be trained to allow similar procedures (only
after litter loss) to gather additional vital information for study and comparison. See Chapter 1.]
The research on formulas currently used for giant otters should be expanded and studied in more
detail. For example, studies should be conducted to determine if the formulas currently used
have been successful on every handreared cub and to what degree are the cub’s total nutritional
needs met with these formulas. The existence of lactose intolerance should be studied, as well
as, if or when vitamin, mineral, oil, rice cereal supplements are necessary etc.. Concerning an
effective milk replacer for giant otter cubs less than approx. one month old, either no
information is reported, or formula fairly tried and found successful. It is as well, most
important to develop/find formulas that could be used successfully in these cases, and/or if a
successful formula is already known but not reported, handrearers are encouraged to share this
vital information with the professional community.
River otter milk composition for the species Lontra/Lutra canadensis has been studied. Pet-Ag,
Inc. (manufacturer of artificial milk replacers for pet, zoo, and wild animals) and handrearers
alike have used this information, combined with successful experiences, to formulate and/or
recommend specific brands of commercially prepared milk replacers that are best for rearing
river otter species. Esbilac TM is produced by Pet-Ag, Inc. (see additional information below) and
it is recommended for use with river otters. “The formula of choice amongst those who have
handreared mustelids is Esbilac.…Esbilac seems to be close enough in composition to mustelid
milk to adequately raise any infant.” (Burnette 1994).
It is commonly recommended and emphasized that milk replacer formulas used for human
babies (commercially prepared or otherwise and usually derived from cow’s milk) and/or cow’s
milk (for human consumption, fresh, powdered, evaporated etc.) should not be used to raise
river otter cubs. The reasoning is they do not contain the appropriate nutrient composition and
ingredients (i.e. those that are similar to mother’s milk). For example, their fat content, which is
the major source of energy for neonates, is too low or it may be an inappropriate type etc..
These formulas therefore may not be satisfactory to rear cubs (Kirk 1994; Cain-Stage 1992/93
citing Evans 1986). Although however, 5 of the 6 handrearers/institutions known, successfully
rear/reared giant otter cubs, with either a commercial milk replacer for human babies or cow’s
milk (for human consumption) (Sykes-Gatz unpublished report). The 6 th handrearer
successfully used goat’s milk. These cubs ranged in age from approximately one month old and
older. [Note: The multiple handrearing experiences at Dortmund Zoo are not included in these
statistics. Inherited thyroid malfunctions due to severe inbreeding were likely to have prevented
the survival of all of the handreared (and parent-reared) cubs born at this zoo. See below.]
Other river otter species, especially in areas where commercially prepared formulas were not
available, have also been successfully reared on cow’s milk (homogenized whole milk or
diluted evaporated milk) and buffalo milk, and goats milk has been used to rear mustelids as
well (Burnette 1994). Some handrearers have recommended goat’s milk for river otter cubs
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