Explanatory model of cattle death by starvation in Manitoba: forensic evaluation

Abstract

Cattle death by starvation is a persistent annual event in Manitoba. Herds with more than 10% overwinter death loss are usually identified in the late winter or early spring. Field and postmortem findings suggest that there is complete mobilization of fat followed by inability to maintain adequate thermoregulation and death by cardiac arrest. Carcasses show only mild evidence of muscle catabolism and are in excellent preservation if located prior to or around the time of spring thaw. A forensic diagnosis of death by starvation-induced exposure can be made with a high level of confidence when considering field data, whole carcass appearance, and postmortem evaluation of residual fat stores.

Figure 1

Image of a cow in Body Condition Score 1 (Ref. 2) as she meets the emaciation criteria of BCS 2 with the addition of weakness which prevents her from standing up. a) Cow is bright and alert (rectal temperature was not taken). Image was captured January 24, 2003 at 11:51 AM. b) In this image you can visualize the spine of the right scapula. This cow died at about 15:30 the same day. There was no manure build up behind this cow. Average hourly environmental temperature for the previous 10 days was −20.6 ± 5.5°C (Max −7.1, Min −32.2°C); Wind chill average −29.5°C − 5.7°C (Max −14°C, Min −43°C) [Environment Canada, Gimli MB weather station (1)].

Figure 2

a) Image of a cow in Body Condition Score 2 (presumably 1, as probably weak prior to death); b) field evidence collection, image of thigh muscle reflected and middle of femur exposed, muscle tissue is bright pink and significant muscle tissue remains; c) image of split femur bone showing serous atrophy of fat (photo Mark Swendrowski).

Figure 3

Field photographs of carcasses of a presumed cow calf pair. a) pair as found in situ in a wooded area April, 2008 (photos courtesy C. Marion), there is no fecal build-up behind the calf carcass (foreground) suggestive of recumbency quickly followed by death. b) same pair of carcasses, image captured from about 4 meters away. There is significant evidence of intestinal emptying of the cow, suggesting she initially became recumbent in the lower edge of the photo and over several days crawled into position to die in contact with the carcass of her calf.

Figure 4

a) Gross postmortem of excised normal heart, kidney, and split femur from a feedlot heifer which had died of blackleg (photos, courtesy M. Swendrowski). b) similar image of a heart, kidney, and split femur from a similar aged animal which had died of starvation.