International Giant Otter Studbook Husbandry and Management

Thyroid Malfunctions: see Chapter 1 Section 2 for more information.
Vomiting: Giant otters, both in captivity and in the wild, have been reported to vomit on
occasion. The occurrence of occasional vomiting does not seem to be a problem for giant otters
in captivity. Three zoos (Philadelphia & Dortmund Zoos and Hagenbeck Tierpark) have
provided comments about vomiting among their giant otters.
At Philadelphia Zoo, in an eight month period (from 1/1997 through 9/1997; 2/97 results were
not available) where the occurrence of vomiting was reported in detail, vomit was found in the
enclosure holding two giant otters about 2-3 times per month on average during three of the
eight months monitored (Sykes, pers. obs. & reports 1996-99). (These three months were not
consecutive and a one and five month period occurred between these occasions. Vomit was
found esp. in the dens when the keepers first arrived to check the animals in the morning,
sometimes it was found outside on exhibit, or the otters were observed vomiting.) In the
remaining months vomiting did not occur or it only occurred once per month. Because two
male giant otters, one approx. four and the other five years old, were held together at that time
and both had been reported to be seen vomiting on occasion, it was assumed that one or the
other otter vomited. The vomit consisted of partially digested or nearly digested fish and
sometimes included a lot of white/gray mucous or it consisted of a yellow colored liquid
substance (bile?) and/or mucous alone. The amount of vomit varied from a lot to a little. After
the conclusion of the aforementioned detailed report, both otters were noted to vomit
occasionally (this was noted until June 1999 at which time this report was concluded). I.e.
sometimes vomit was found one to three times in a month and in most of the other months no
vomit was found or sometimes one such occasion occurred in a month. As well, sometimes the
animals heaved as if they would vomit, but no substance was expressed. Sometimes they also
acted as if they had a fish spine caught in their throat and dry heaving or vomiting (either fully
or just saliva) resulted. The fish spine that was stuck in their mouth/throat was presumably the
cause for this event. Other than the reason just aforementioned, no factor was identified to be
specifically responsible for causing the vomiting and no other health problems resulted from
vomiting.
Some theories about what might have caused this vomiting were posed (Toddes, pers. comm.
1997 & unpublished report, 2004; Osmann, pers. comm. 4/1997; Wünnemann, pers. comm.
3/1997; Sykes, unpublished report, 1997). These theories mainly concerned diet. For example,
it was posed that feeding salt-water fish that was high in fat content, such as esp. mackerel
(Scomber sp.), may cause vomiting (Osmann, pers. comm. 4/1997; Sykes unpublished report,
1997). At Philadelphia Zoo, fresh-water fish formed the main part of the giant otters’ diet,
although salt-water fish were fed for variety. Toddes modified the diet offered in consideration
of this theory. Although in 2/1997 the salt-water fish mackerel and herring (Clupea harengus),
among some other fresh-water fish (i.e. catfish (Ictalurus punctatus) etc.], were eliminated from
their diet and their principal diet was changed to fresh water rainbow trout (Salmo gairdneri),
vomiting still occurred occasionally thereafter. (See the full diet that was offered and the health
problems that occurred in 1997 with the giant otters at Philadelphia Zoo under “Walking
Difficulties Involving the Lower Back and Hind Legs” just below.) Giant otters have been
noted to purposely swallow sand (reported at a few institutions) and even tree bark, although
again this has not been specifically linked to causing vomiting or any other health problems (see
under “Miscellaneous” above). Also, when otters eat fish in an area that contains sand, sand
may stick to the fish and the otters will naturally ingest both (Wünnemann, pers. comm.
3/1997). [It is not known whether feeding fish in the reproductive state (i.e. when they carry
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