Nursing sickness in lactating mink (Mustela vison). I. Epidemiological and pathological observations.

In a retrospective survey, the epidemiological characteristics of nursing sickness in Standard Black and Pastel mink (Mustela vison) were examined in a Danish fur research farm. Based on the clinical diagnosis of the disease, the overall morbidity in a total of 1774 lactating females amounted to 14.4% and the case fatality rate to 7.8%. Apparently healthy females weaned an average of 5.0 kits per litter, while dams suffering from nursing sickness raised and weaned an average of 5.4 kits per litter (p less than 0.01). Based on logistic regression analysis, the increasing age of the lactating dam, followed by littersize and female weight loss, appeared to be major determinants for the development of nursing sickness. The impact of additional covariates such as litter weight gain and female color type were remarkably low. At weaning (day 43) the mean individual live weight of the kits of either sex did not differ between healthy and sick dams. In Standard Black, the total biomass of the offspring raised by sick dams was significantly larger than that of the healthy controls (p less than 0.01). During the final two weeks of lactation, apparently healthy dams lost on average 14% of their body mass, whereas those affected by nursing sickness had a mean weight loss of about 31% (p less than 0.001). Postmortem examination of 25 dams with severe nursing sickness verified the clinical findings of progressive dehydration and emaciation. The gastrointestinal tract was empty and gastric ulcers and melaena were frequently present. Other common findings included small livers,enlarged adrenals and pitted kidneys.(ABSTRACT TRUNCATED AT 250 WORDS)