The first major use of MWDs by the US military occurred doing World War II, when nearly 15,000 trained dogs were in the American military inventory.1 The dogs that fought in World War II were privately owned pets that had been volunteered for service through an organization called “Dogs for Defense.”2 When the war was over, the dogs were put through stringent demilitarization training and returned to their owners.
The most widely publicized use of MWDs in American history, however, occurred during the Vietnam War, with as many as 1,600 dogs deployed in Vietnam at one time. Many dog handlers expected their assigned dogs to return home with them, but military policy at that time was that as handlers finished their tours and returned home, their canine counterparts would remain behind and be reassigned to new handlers. In 1970, the Department of the Army implemented a return policy for these dogs, but because ehrlichiosis (tropical canine pancytopenia) was endemic in Vietnam, the policy included strict criteria for determining which dogs were eligible to be returned so that there would be no risk of transmitting ehrlichiosis to the US dog population. Under these strict criteria, only 150 to 200 dogs were eligible for return to the United States. The remaining dogs were left in Vietnam, where they were transferred to the Vietnamese military or euthanized.3
Public concerns and the growing animal welfare movement have caused the military to readdress how MWDs are discharged from service. This culminated in the passage of a federal statute in 2000 allowing for adoption of suitable MWDs by members of law enforcement agencies, former handlers, and other persons capable of caring for them.4 With input from the local kennel master and Army veterinarian, the unit commander is responsible for deciding whether any particular MWD is a candidate for adoption under this provision. An extensive disposition packet including pertinent medical and training records and letters of support is submitted for candidate dogs to a central MWD Evaluation and Disposition Committee for a final decision. This committee's purpose is to maximize utilization of MWDs, eliminate those that do not meet military standards, identify unsafe dogs, and identify potential nonmilitary dispositions for dogs that do not pose a safety hazard.5
Most dogs destined to become MWDs are purchased from selected American and foreign breeders. Dogs must be between 12 and 36 months old; pass brief but extensive temperament and physical evaluations; and be considered trainable, although not fully trained, at the time of purchase. Purchased dogs must complete training and certification standards prior to being placed in military service and must maintain those standards to remain in service. In 2000, a pilot breeding program with Belgian Malinois was initiated at the MWD Training Center to augment current methods for procurement of dogs that could be used as MWDs. By 2005, 68 puppies were produced through this program. Puppies from the program receive age-appropriate medical and behavioral evaluations and are considered candidates for adoption if they fail to meet appropriate criteria.6
In 2005, there were more than 2,900 dogs in the Department of Defense's MWD inventory. In recent years, all agencies within the department have been increasing their use of these dogs. Thus, although there are no currently published estimates of the number of MWDs needed, the increased use of these dogs in conjunction with considerations of reasonable working life span means that it will be necessary to expand the MWD force. According to the Department of Defense, a preliminary analysis of the need for MWDs across the military services suggested that it would be necessary to increase the number of new dogs produced by 50% each year for the next 2 years and by 40% the year after that to meet the forecasted supply shortfall. With an average of 400 new MWDs currently being produced each year, this represents an increase of almost 200 additional dogs each year for the next 3 years to keep up with anticipated demand.
Working dogs that leave military service represent not only the loss of valuable assets but also the loss of the resources used to purchase, train, and care for those dogs. The purpose of the study reported here was to determine the primary causes, other than death, for the discharge of MWDs from service since the new discharge procedures were mandated in 2000.
Criteria for Selection of Cases
The Department of Defense Dog Center Disposition Board database was searched to identify all MWDs approved for discharge from December 1, 2000, through November 30, 2004. For purposes of the present study, MWDs were considered to have been approved for discharge if they had been classified by the MWD Evaluation and Disposition Committee as suitable for adoption by law enforcement agencies or the general public. No attempts were made in the present study to determine disposition of dogs following classification as suitable for adoption (ie, whether dogs were subsequently adopted, transferred, or euthanized because of a lack of adequate placement outside the Department of Defense).
Dogs produced through the Department of Defense puppy breeding program that passed the equivalent of the prepurchase examination required for dogs obtained as adults and also passed post-training certification standards were included in the adult MWD study population. Data for dogs produced through the puppy breeding program that failed to meet prepurchase or certification standards were analyzed separately from the data for the adult MWD population.
Procedures
Information obtained for dogs included in the study consisted of breed, sex, neuter status, age at discharge, and primary cause for discharge. Archived medical and training records at the Department of Defense Dog Center were consulted when further clarification or detail was required. For the present study, age at discharge was defined as the age at which a dog was approved for discharge, rather than the age at which the dog was actually discharged from active duty status. Thus, for some dogs, age at discharge may not have been the actual age at which the dog was moved to a new facility or home.
For each dog included in the study, the primary cause for discharge was classified as behavioral or medical. A dog was classified as having been discharged for a behavioral cause if it was reported to have exhibited any behavior that inhibited its training or had a deleterious effect on the performance of its duties and the dog could not be retrained to eliminate the behavior. Behavioral causes for discharge included a wide range of problem behaviors, such as a lack of sniffing behavior, being building or explosive shy, having low drive, being overor underaggressive, having a weak bite, and other training problems. In general, however, information was not available on specific deficiencies identified in individual dogs discharged for behavioral reasons. For this reason, all dogs discharged for behavioral reasons were grouped together.
A dog was classified as having been discharged for a medical cause if it was reported to have had a specific medical abnormality that inhibited its training or had a deleterious effect on the performance of its duties. For each dog, the specific medical cause for discharge was determined on the basis of the attending veterinarian's assigned diagnosis and corresponding entries in the dog's medical record. In some dogs, obtaining a definitive diagnosis was not possible or was impractical and the presumptive diagnosis was used. Dogs that were discharged after a marked decline in performance or quality of life that did not have other defined medical or behavioral problems were classified as geriatric. When > 1 medical cause for discharge was listed, the medical record was examined to determine the most important or irreversible condition leading to discharge from military service.
As a matter of policy, all female dogs obtained during the time of the study were spayed at the time of procurement. Male dogs were kept sexually intact, unless a medical or behavioral problem prompted castration.
Statistical analysis—Because of a bimodal distribution for age at the time of discharge among the adult MWD population (ie, dogs that had been purchased as adults or that had been obtained through the Department of Defense puppy breeding program and had passed prepurchase and certification standards), this group was divided into MWDs from 1 to < 5 years old at discharge and MWDs ≥ 5 years old at discharge. Dogs were grouped on the basis of breed, sex, or cause for discharge, and median age at discharge was compared between groups. The Wilcoxon rank sum test was used for comparisons involving 2 groups, and the KruskalWallis equality-of-populations rank test was used for comparisons involving > 2 groups. The χ2 test of independence or Fisher exact test was used to compare distributions of nominal data. All analyses were performed with standard softwarea; values of P < 0.05 were considered significant.
Results
During the 4-year study period, 268 MWDs had been classified as suitable for adoption. Of these, 23 had been obtained through the Department of Defense puppy breeding program but had failed to meet prepurchase or certification standards (puppy population). The remaining 245 had been purchased as adults or had been obtained through the Department of Defense puppy breeding program and had passed prepurchase and certification standards (adult population).
For the puppy population, median age at discharge was 1.50 years (range, 0.61 to 2.08 years). All 23 of these dogs were Belgian Malinois. There were 16 (70%) spayed females (median age at discharge, 0.72 years; range, 0.61 to 2.08 years), 6 (26%) sexually intact males (median age at discharge, 1.61 years; range, 1.51 to 1.81 years), and 1 (4%) castrated male (age at discharge, 1.81 years). Twenty-one of the 23 (91%) were discharged for behavioral causes (median age at discharge, 1.52 years; range, 0.61 to 2.08 years), and 2 (9%) were discharged for medical causes (degenerative joint disease; ages at discharge, 0.96 and 1.13 years).
For the adult population, median age at discharge was 8.05 years (range, 1.09 to 14.05 years). Eighty-five of these 245 (34.7%) dogs were 1 to < 5 years old at discharge, and 160 (65.3%) were ≥ 5 years old at discharge (Table 1). Overall, 120 (49%) of the dogs in the adult population were German Shepherd Dogs and 100 (40.8%) were Belgian Malinois, with the remaining dogs representing a variety of breeds. The proportion of adult dogs < 5 years old at discharge that were German Shepherd Dogs (59/85 [69.4%]) was significantly (P < 0.001) greater than the proportion of adult dogs ≥ 5 years old at discharge that were German Shepherd Dogs (61/160 [38.1%]). Within the subgroup of dogs ≥ 5 years old at discharge, median age at discharge for the German Shepherd Dogs (8.59 years) was significantly (P < 0.001) less than median age at discharge for the Belgian Malinois (10.61 years).
For adult dogs < 5 years old at discharge, the most common cause for discharge was behavioral problems (70/85 [82.3%]; Table 2). In contrast, for adult dogs ≥ 5 years old at discharge, the most common cause for discharge was spinal cord disease (48/160 [60.0%]), followed by degenerative joint disease alone or in combination with spinal cord disease (42/160 [26.3%]). Of the medical reasons for discharge, only heat stroke was significantly (P < 0.01) overrepresented among adult dogs < 5 years old at discharge, compared with dogs ≥ 5 years old at discharge.
In breed-specific analyses, behavioral problems was the most common cause for discharge of German Shepherd Dogs < 5 years old at discharge (Table 3). This proportion was significantly (P = 0.016) higher than the proportion of Belgian Malinois < 5 years old that were discharged for behavioral problems. Median age of German Shepherd Dogs discharged for spinal cord disease, degenerative joint disease, or both (9.31 years; range, 5.06 to 13.15 years) was significantly (P < 0.001) less than median age of Belgian Malinois discharged for these reasons (10.58 years; range, 5.63 to 12.78 years). Twelve of the 82 (14.6%) Belgian Malinois discharged at ≥ 5 years of age were classified as geriatric (median age at discharge, 11.50 years), whereas none of the German Shepherd Dogs were classified as geriatric (ie, discharged because of a marked decrease in performance or quality of life without any other defined medical or behavioral problems).
Females were significantly (P < 0.001) overrepresented in the puppy population (16/23 [70%]), compared with the adult population (81/245 [33.0%]). Sexually intact male dogs were significantly (P < 0.001) more likely to be discharged for behavioral problems than were neutered male or female dogs, but median age at discharge for dogs in the adult population discharged for behavioral problems did not differ significantly (P = 0.068) among groups (sexually intact males vs castrated males vs spayed females).
Breed and sex distributions for 245 MWDs discharged from service between 2000 and 2004.
Causes for discharge of 245 MWDs discharged from service between 2000 and 2004.
Causes for discharge of Belgian Malinois and German Shepherd Dogs discharged from military service between 2000 and 2004.
Discussion
Results of the present study suggested that behavioral problems were the most common reason for discharge of MWDs from service. Breed-related differences in reasons for discharge and age at discharge were also identified.
In the present study, 21 of the 23 (91%) dogs produced by the puppy breeding program that were discharged were discharged because of behavioral problems. In most instances, this did not represent true behavioral abnormalities or a lack of trainability. Rather, these dogs were most often discharged because they failed to achieve the high standards required for entry into the MWD training program or were thought to be unlikely to readily achieve certification standards. Most dogs bred at police dog breeding centers are found to be unsuitable for use,7 representing a challenging obstacle in raising potential security and police dogs. Anecdotally, it has been suggested that female dogs in particular commonly fail to meet aggression standards.
Median age at discharge for the 245 dogs in the adult population in the present study was 8.05 years. By comparison, in a previous study,8 mean age at death for MWDs in active service was 10.06 years. Thus, discharge of these MWDs represented nearly 500 years of productive life lost. Prepurchase standards have been used in the MWD program for many years in an attempt to select dogs that will work with their military handlers for many years, and all MWDs are currently dual-trained in protection work and substance (ie, explosives or narcotics) detection. Discharge from service indicates failure to achieve or maintain required standards of performance and represents the loss of months or years of training time.5
In the present study, 93 of the 245 (38.0%) adult dogs were discharged for behavioral reasons. During the prepurchase examination of potential MWDs, extensive behavioral testing is performed to evaluate each dog's current level of training and future trainability. Each dog must demonstrate aptitude in protection work and must show satisfactory progress in initial training for substance detection. For dogs that pass this initial evaluation and are accepted into the program, several months of additional training are required to reach defined certification standards as patrol and detection dogs, and for many dogs in the present study, discharge for behavioral reasons likely indicated a failure to attain or maintain certification standards, rather than a true behavioral abnormality. As an example, MWDs that pass either protection or detection certification, but not both, may still be used in military service, but such dogs may have limited deployability, particularly if their aggression level (or lack thereof) poses a safety risk to their handlers. As a result, these dogs may be discharged for behavioral reasons. Military working dogs must perform protection work in a controlled manner and must terminate an attack or attack run on command. Dogs that do not maintain a desired level of aggression may not perform protection work adequately, causing them to be discharged for behavioral reasons.
Other dogs discharged for behavioral reasons in the present study likely had behavioral problems similar to those described for pet dogs, such as poor socialization towards humans and other dogs, incessant barking, fear of loud noises (eg, thunder or gunfire), separation anxiety, inappropriate aggression, or inappropriate chewing and destruction of property. Although some behaviors that might be considered a problem in a pet dog can be tolerated in an MWD, any behavior that inhibits training or has a deleterious effect on the performance of the dog's duties will result in discharge if the dog cannot be retrained to eliminate the behavior. In such instances, consideration is given not only to the time and money needed to retrain the dog to eliminate the behavior but also to the possibility that the behavior would cause the dog to pose a risk to human life either at the training center or when deployed.
Unfortunately, information on the specific deficiencies identified in dogs discharged for behavioral reasons was not available to the authors. Thus, all dogs discharged for behavioral reasons were grouped together. Because behavioral problems was the most common reason for discharge of dogs in the present study, additional study of the specific behavioral problems leading to discharge is warranted.
In the present study, German Shepherd Dogs that were < 5 years old at discharge were significantly more likely to be discharged for behavioral problems than were Belgian Malinois. It could not be determined whether dogs of either breed spent substantially more time in training before being discharged. However, because 64 of the 120 (53.3%) German Shepherd Dogs were discharged for behavioral reasons, additional study is merited to define specific behavioral problems related to discharge, to determine whether potential trainability concerns were identified during prepurchase evaluations of these dogs, and to establish whether prepurchase criteria should be reevaluated for this breed.
Debilitating, but not life-threatening, diseases that limited deployability resulted in the medical discharge of many MWDs in the present study. Neurologic and orthopedic diseases consistent with breed, age, and use were the primary medical reasons for discharge. Spinal cord disease may be due to compressive or degenerative lesions,9 and lumbosacral stenosis and degenerative myelopathy have been previously documented in MWDs.7,10 Manifestations of these and other conditions, such as degenerative joint disease, are associated with advancing age.11,12,13 Although some improvement may be obtained with anti-inflammatory or analgesic medications, MWDs with these conditions are still required to perform their duties with the same speed and skill expected of unaffected dogs. Medical discharge provides a humane outcome for MWDs that cannot perform their duties because of a debilitating illness.
Of the medical reasons for discharge, only heat stroke was significantly overrepresented among adult dogs < 5 years old at discharge, compared with dogs ≥ 5 years old at discharge, in the present study. Although only 9 of the 245 (3.7%) dogs in the adult population in the present study were discharged because of heat stroke, heat stress is a major concern for dogs training and working at the MWD Center in south Texas. Once heat stroke occurs, some dogs appear to be prone to repeated hyperthermic events, rendering them unsuitable for intensive or highly exertional work. Breed, body mass, and hair coat may be potential risk factors.14
Other medical conditions accounted for the discharge of relatively low numbers of MWDs in the present study. Loss or excessive wear of the crowns of the canine teeth affects the holding capability of MWDs during bite work and can be justification for discharge. Diseases requiring regular medication, such as epilepsy, pannus, or endocrine deficiencies, may limit the deployability of affected dogs, and those that cannot be used as training aids in handler classes may be discharged for medical reasons.
There were several limitations to the present study. Some key statistics regarding demographics of the MWD population during the study period were not available. For example, there was no way to identify the average yearly population of MWDs during each of the 4 years of the study and, thus, no way to determine what percentage of dogs was discharged each year or whether this percentage changed over time. Also, there was no system during the study period for determining the number of dogs that entered the MWD training and certification program each year. These issues have been identified, and it will be recommended that a method to query such archived data be developed.
Importantly, the present study was not designed to determine the success or limitations of the adoption program. It would be appropriate to create a study to determine the final disposition of dogs that have been approved for adoption and to determine how well these dogs are performing in their new locations.
Military working dogs are both partners and companions for their handlers,15 and the final disposition of MWDs has been a concern of dog handlers and the public for many years.16 The present study represents the first retrospective evaluation of the reasons for discharge of MWDs from service. Although it is possible that the number of dogs discharged for medical reasons cannot be reduced, the number of dogs discharged for behavioral reasons could potentially be decreased. Further evaluation of prepurchase criteria may lead to refinements that increase the probability that selected dogs will attain certification requirements and be able to maintain those requirements throughout their working lives.
ABBREVIATIONS
| MWD | Military working dog |
STATA, version 9.2, StataCorp, College Station, Tex.
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