Injury Related to Environmental Enrichment in a Dog (Canis familiaris): Gastric Foreign Body

Abstract

A pregnant 7-y-old Beagle crossbred dog (Canis familiaris) presented with clinical signs of lethargy, dehydration, and occasional vomiting. The dog was managed with fluids, antibiotics, and supportive care for several days in an effort to maintain the pregnancy. The bitch aborted the pups at approximately 50 d of gestation and was euthanized due to her poor reproductive performance and age. Necropsy revealed a compact mass of plastic pieces in the pylorus of the stomach. The gastric foreign body was discovered to be the vinyl covering of a bed that was in the dog's run as part of the environmental enrichment program for this animal. The use of that type of dog bed was discontinued. This case emphasizes that any type of enrichment can cause harm and the risks must be assessed carefully before implementing any enrichment device.

Since the Animal Welfare Act was amended in 1985 to require exercise for dogs to promote health and welfare,^5,8 many facilities have taken additional steps to comply with this mandate and enrich their environment. Our institutional animal care and use committee, in conjunction with the veterinary staff, created a comprehensive environmental enrichment program that included social housing, social interaction with caretakers, toys, and the inclusion of elevated resting boards in the primary enclosure. The elevated resting boards created ‘variable-height resting spots’ and are viewed as valuable components of canine housing.⁷

Enrichment items carry risk for unintended negative consequences.^1-4,6 In particular, dogs occasionally chew and ingest items that can cause harm, a behavior sometimes colloquially described as ‘dietary indiscretion.’ In our experience, dogs kept as pets have ingested a wide variety of inappropriate items including fabric, plastic, toys, bones, and rocks. Frequently, these gastrointestinal foreign bodies pass through the digestive tract without ill effect. However, ingested items can cause damage and potentially result in obstruction or perforation of the gastrointestinal tract that can lead to life-threatening sequelae. In light of the potential for this sort of behavior and the potential negative outcomes, the selection of the toys and resting boards by our facility included a thorough assessment of their durability and risk of ingestion. We ultimately concluded that the benefit from the enrichment devices would be much greater than any associated risk, although we acknowledged that risk for unintended negative consequences remained.

We report a case of a pregnant bitch that ingested material from a resting board placed in her run to promote her wellbeing. The ingested material ultimately caused gastric obstruction. The case management was complicated by the pregnancy, research objectives of the laboratory, and absence of any evidence suggesting a gastric foreign body at initial presentation. This case highlights the importance of balancing the good intentions of enrichment devices with the potential for harm that can arise from such devices, particularly in larger species such as dogs.

Case Report

A 7-year-old intact female Brittany spaniel, Beagle crossbred dog (Canis familiaris) was reported for lethargy and dehydration. This dog was part of a colony maintained to study hereditary canine spinal muscle atrophy, a disease of the motor neurons that occurs in Brittany spaniels, is inherited as an autosomal dominant trait, and serves as a model of amyotrophic lateral sclerosis in humans. This dog was heterozygous for this trait and showed no neurologic deficits at presentation. She was at approximately gestational day 45 at the time of presentation. The dog had carried only 1 previous litter to term and had been a successful foster mother for an orphaned litter of puppies. She was group-housed in a slatted floor run, which contained a dog bed with a 40-oz. vinyl fabric resting surface (Kuranda USA, Glen Burnie, MD) and several toys. The dog beds had been in use for approximately 2 y when this case presented. The dog was maintained in accordance with standards set in the Guide for the Care and Use of Laboratory Animals.⁵ All research conducted with this dog was approved by the Institutional Animal Care and Use Committee of Emory University.

Initial physical exam showed that the dog was quiet, alert, and responsive and exhibited mild dehydration estimated at 5%. The abdomen was moderately distended with a palpable fluid wave. The abdominal distension was more than that expected for day 45 of gestation. Her breathing appeared labored, but the lung sounds were normal on auscultation, and pressure from the abdomen was deemed the cause of the labored breathing. She had yellow discharge from her vulva; digital palpation of the vagina was otherwise normal. No other abnormalities were noted on physical exam.

Abdominal ultrasonography revealed at least 3 puppies with strong heartbeats. Free abdominal fluid was not apparent. Blood was collected for a complete blood count and chemistry. Packed cell volume, total protein, and blood smear results were unremarkable. The bitch was started on intravenous lactated Ringers solution at a maintenance rate. We were unable to contact personnel in the research laboratory to discuss a treatment plan (the time of presentation was late in the afternoon on the day preceding a long holiday weekend). The immediate plan was to stabilize the dog through continued conservative fluid therapy and further develop any treatment plan based on diagnostic test results and emerging clinical signs.

The next day, the dog appeared to be quiet, alert, and responsive. Diarrhea and vomitus were present in the cage pan. Her appetite was markedly decreased, and she appeared to be polydipsic. The blood work revealed a moderate azotemia and various electrolyte abnormalities. These findings were attributed to the dehydration, and fluid therapy was continued. In addition, treatment with cimetidine (200 mg IV) once daily was initiated. Over the next 2 d, the dog appeared to be more bright and alert. However, blood became apparent in the diarrhea, and firm black flakes that appeared to be plastic, but of unknown origin, appeared in the vomitus. Fluid therapy and cimetidine were continued. Treatment with ceftriaxone (400 mg IV) once per day was started.

On day 5, no changes were noted during physical examination. Blood was collected to repeat the CBC and serum chemistry. Urine for urinalysis was collected by free catch. Repeat ultrasonography confirmed that the puppies were still viable. Contact was made with research personnel at this point, and diagnostic options such as exploratory laparotomy and a barium study were discussed. The research laboratory's priority was maintaining the pregnancy, and they requested conservative treatment of symptoms. Later that day, green-black discharge was noted around her vulva. No puppies were felt on digital palpation in the birth canal, and subsequent ultrasonography revealed the absence of fetal heartbeats, indicating that the puppies were no longer viable. On the morning of day 6, 2 dead puppies were found in the kennel, and the research personnel were informed of this development. Due to the poor prior reproductive success and age of the bitch, euthanasia was elected.

Necropsy revealed the presence of approximately 1 cup of firm black and green pieces of plastic condensed at the pylorus of the stomach. The mucosa of the pylorus had several areas of petechiae with no ulceration. The edges of the liver were rounded. Three dead puppies were found in utero. No other abnormalities were seen. The diagnosis of gastric foreign body with obstruction was made. Inspection of the animal's enclosure showed that the black pieces of plastic found in the vomitus and later in the dog's stomach at necropsy were part of the vinyl covering from her dog bed (Figure 1).

Figure 1.

Several pieces of the vinyl covering from the dog bed that were found in the pylorus of the dog's stomach.

Discussion

We present here a case whereby an enrichment device intended to promote health and wellbeing ultimately caused harm. Although enrichment items represent some of the best efforts of care providers to increase animal welfare, modifying the environment always carries the risk of an unintended outcome (such as ingestion) with certain species. For example, several reports document environmental enrichment-related gastrointestinal foreign bodies in nonhuman primates housed for research purposes. A cynomologus macaque (Macaca fasciularis) developed septicemia and peritonitis after ingesting pieces of a sisal rope that were hung on the cage as an enrichment device.³ The pieces of shredded rope acted as a linear foreign body, which caused mechanical ulcerations and erosions of the small intestine. In another case, a baboon (Papio hamadryas) ingested a piece of bark mulch that was used as a foraging substrate on the enclosure floor.⁴ The large piece of mulch perforated the colon and punctured a kidney, resulting in a renal and hepatic abscess. A rhesus macaque (Macaca mulatta) ingested multiple pieces of wire from an automobile tire used as enrichment in its enclosure.² Some of the wires perforated through the stomach and caused a localized peritonitis. All of these cases impress upon animal care personnel the need to inspect devices regularly and evaluate the safety of enrichment devices for possible unintended consequences to determine whether the risk is acceptable.

The case presented here was challenging diagnostically because of the specific wishes of the investigator and the fact that all clinical signs initially were attributed to complications associated with the pregnancy. Moreover, neither the patient nor any other dog in the colony was ever observed consuming the resting board material that ultimately led to the gastrointestinal obstruction. Animal care personnel had noted previously that the resting boards were becoming worn but concluded that the boards were simply wearing from normal use (such as digging, jumping, and climbing), due to the lack of evidence for chewing or consuming behavior. Only on conclusion of the case at necropsy did it become clear that the worn areas of the resting boards (Figure 2) were due at least in part to chewing by this particular dog and perhaps others in our colony. We postulate that the animal dug at the hammock portion of the resting board, thus causing the vinyl to crack and loosen. The dog then was able to peel off the vinyl covering and ingest the pieces. The vinyl pieces became lodged and compressed in the gastric pylorus and resulted in a gastric obstruction. Were it feasible to observe colony animals continually, consumption might have been observed. However, a challenge in any research facility is that, because of finite resources, animals are observed only periodically throughout each day. Such limitations should be considered when choosing enrichment devices.

Figure 2.

The frame dog bed with a 40-oz. vinyl fabric resting surface. The green vinyl apparently was torn, presumably by digging, from the underlying canvas and ingested by the dog.

The purpose of environmental enrichment is to increase the complexity of an animal's environment and promote wellbeing. Any item placed in an animal's enclosure has the potential to cause harm. This case reinforces the importance of evaluation of enrichment devices for safety and routine monitoring for signs of wear and tear. Despite the fact that the manufacturer of the resting boards discussed here guaranteed them to be ‘chewproof,’ any enrichment device needs to be examined regularly for wear. When items appear worn, the best course of action may be to discard them.