Abstract

A female pygmy sperm whale had been in rehabilitation since it and its mother had stranded and the mother had died almost 21 months earlier. The calf had chronic constipation and chronic gastric ulcers over most of its life, but had otherwise been doing very well. The whale developed severe diarrhea for a four-day period, after which defecations decreased in frequency. During the diarrhea, the whale became somewhat lethargic, and the lethargy increased over the next few days as the appetite decreased. About six days after the start of the diarrhea, the whale began vomiting and undigested food items were found in the stomach although the calf had not eaten solid food for several days. Blood work showed elevated creatinine and liver enzymes. Over the next two days, the whale worsened, and despite all treatment, it quietly died. On necropsy, there was a total torsion involving the cranial half of the ink sac, the entire large intestine, and a large segment of the small intestine. Although much of the twisted segment appeared fairly normal, a section of about one meter in length was necrotic and had ruptured, causing a severe acute peritonitis and death. In some species, the condition may be linked to gut hypermotility and aerial spinning. Although this whale was not trained to breach, she would occasionally have breaching periods, especially when it rained.

About four months later, an orphaned male pygmy sperm whale calf that had been in rehabilitation for three months and was estimated to be about six months of age developed an intestinal blockage thought to be due to constipation. For about a month, the calf had vomited occasionally, although its appetite appeared good, and it was treated for gastric ulceration. The animal was not yet on solid food and was given extra oral fluids, mineral oil, and later metoclopramide (0.1 mg/kg IM bid) for the constipation. After about three days of treatment, the animal died. Necropsy revealed that the cause of death may have been a disseminated intravascular coagulopathy and a gastric perforation, but a partial torsion was found involving the cranial ink sac and the caudal large intestine that appeared to be developing at the time of death. A section of the large intestine about 20 cm in length was thickened and involved in the partial twist. It appeared that a chronic colitis had been present, and the volvulus may have been related either to the colitis or to the use of metoclopramide in this case. This whale would also breach on occasion, but not nearly as much as the previous case.

Pygmy sperm whale calves in captivity appear to have almost continuous gastrointestinal problems. Whether this is related to their diet, to captivity itself, to their inability to dive in captivity, or some other factor is unknown at this time. From these two cases, it would appear that lesions in the lower large intestine where it joins the ink sac may lead to what appears to be a slow developing twisting of the GI tract in that area.