Results of a Survey Among Ranchers Concerning Unexplained Animal Deaths
In 1996 and 1997 the National Institute for Discovery Science (NIDS) conducted
a survey among ranchers in two southwestern states in the US. The objective
of the study was to establish the incidence and the patterns of the unexplained
animal death phenomenon. The results provided several significant conclusions.
A total of 1,606 questionnaires (see the attached form) were mailed to ranchers
and 183 of them were returned, equaling a 11.39% return rate. Of the 183 responses
from ranchers, 20 (10.92%) reported unexplained animal deaths. The total number
of reported cases was 27.
By looking at the size of the ranches on which unexplained deaths were reported
it results that most of them – 122 (67.03%) occurred on ranches over 100 acres
(see Figure 1).
Figure 1 – The size of the ranches in acres
Our analysis shows that ranches with over 20 animals were most frequently affected
by unexplained deaths – 145 = 79.23% (Figure 2).
Figure 2 - Number of the animals on the ranches
The species of animals on ranches are shown in the Figure 3. A number
of 149 ranches (81.42%) had cattle, 17 (9.28%) had sheep, 117 (63.93%) had
horses and 11 (6.01%) had swine. Some of these ranches had two or more animal
species.
Figure 3 – Species of animals on ranch
27 animals dead because of unexplained causes were bovines. Of these 20 (74.07%)
were females and 7 (25.92%) were males (Figure 4).
The age of the animals dead because of unexplained causes is revealed by
Figure 5.
The reported missing parts of the body are presented in Figure 6.
In 5 cases (18.51%) it was reported that no blood was visible at the site
of missing body parts or around the carcass.
In 3 cases (11.11%) it was reported that no tracks around the carcasses were
noticed.
In one case (3.70%) it was mentioned that tissues looked to have been cut
with a sharp instrument.
In one cases (3.70%) strange behavior of wild animals (predators and scavengers)
were reported.
The seasonal incidence is presented in Figure 7. All unexplained deaths
occurred in warm months, from May to October.
Figure 4 – The sex of animals dead because of unexplained causes
Figure 5 – The age of animals dead because of unexplained causes
In 11 cases (40.74%) it was established that the death occurred during the
night, while in 16 cases 59.25%) the time when the animal death happened could
not be established.
The time lapse between the animal death and the discovery of the carcass
varied between 3 hours and several days. In 8 cases (29.62%) the carcass was
discovered after less that 6 hours and in 19 cases (70.37%) after more than
6 hours. This means that only in a third of cases tissue samples, if collected,
would have been proper for laboratory examinations.
A necropsy by qualified veterinarian or a sample collection for laboratory
analysis was not performed in any of the 27 reported cases. This shows, once
more, the lack of interest and involvement of veterinarians in investigating
unexplained animal deaths by a thorough scientific approach.
Figure 6 – Pattern of unexplained animal deaths
Figure 7 - Seasonal distribution of unexplained deaths
Size of the ranch:____________________ Number of animals:_________________________
Animal species owned:_________________________________________________________
Cattle: Yes
No
Sheep: Yes
No
Horses: Yes
No
Swine: Yes
No
Other (specify):_______________________________________________________________
Has your ranch ever experienced unexplained animal deaths? Yes
No
If yes, how many times? __________________When did it happen?____________________
When did it happen?__________________________
Do you know if the death occurred during a particular time
of the day/night?_____________
Species involved:__________________ Sex of animal(s):____________________________
Age of Animal(s):___________________Approximate date of occurrence:______________
Approximate time elapsed between death and carcass discovery:_____________________
Was a necropsy performed by a veterinarian? Yes
No
If yes, was the cause of death established? Yes
No
Were samples collected for laboratory examinations? Yes
No
Was an official investigation done? Yes
No
Do you know the results? Yes No Were body parts missing? Yes
No
Vulva/Vagina: Yes
No
Rectum: Yes
No
Teats: Yes
No
Udder : Yes
No
Tongue: Yes
No
Penis/Testicles: Yes
No
Lower jaw: Yes
No
Lips: Yes
No
Eye; Yes
No
Ear: Yes
No
Tail: Yes
No
Other parts of the body (specify):
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
Details about circumstances in which the unexplained death
occurred:
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
