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Why Environmental Enrichment is important for lab animals

In addition to the legal requirement for psychological enrichment of primates, it is generally accepted that environmental enrichment is beneficial for all research animals. Both the new Guide and the 3rd edition of the Agricultural Guide place more emphasis on environmental enrichment for all species as providing “sensory and motor stimulation… to enhance well being”.

The ability to form social groups, exhibit species specific behaviors and occupy time in pleasurable pursuits reduces stress and therefore stereotypical and self-injurious behaviors. In the wild, feeding, breeding and hunting activities occupy the animal’s time; in the lab, all of these things are provided. Lab animals lack the opportunities to channel energy into activities that challenge and interest it for any length of time. This can lead to a number of negative behaviors including aggression, self-biting, anorexia, and failure to thrive. The Guide also cites studies that indicate the possibility of abnormal brain development. Any of these stress reactions can compromise animal research results.

Zoos have been the leaders in environmental enrichment. Organizations such as the Association of Zoos and Aquariums have long been proponents of natural environments, varied enrichment devices, and social groupings based on behavioral study. According to the AZA, the goal of enrichment is to increase behavioral choice and control of the environment based on their behavioral biology. Providing enrichment allows animals to retreat from threat or danger (shelters, visual barriers), keep warm (nesting materials), challenge intellect (manipulation, puzzle toys) and fill time.

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Presentation is everything with Animal Enrichment

Presentation is everything.

Have you ever introduced a new enrichment item and been disappointed by the animal’s reaction?  Do they explore it briefly and then ignore it?

The new Guide for the Care and Use of Laboratory Animals addresses animal enrichment and cage spatial considerations.  It proposes that using only floor area to calculate space requirements may not be sufficient to determine adequate cage size.  According to the Guide, for some species, cage volume and spatial arrangement may be more important.  This determination can be useful when locating enrichments in the primary enclosure.

Some animals, most notably primates, cats and arboreal animals use vertical space to a great extent.  For these animals, the placement of enrichment devices at a variety of levels exploits natural behaviors and provides the opportunity to present enrichment items in a variety of ways.   Items can be suspended from enclosure ceilings, shelves, and perches or placed in locations that require the animal to find them by moving throughout the enclosure.

The addition of hammocks to the enclosure provides another opportunity to use the volume of the enclosure to remove themselves from a group, collect items or provide a vantage point.  Think up.

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The Person at the other end of the Enrichment

When providing animal enrichments, don’t forget the human involved.  For many larger animals, the person with the toy or treat in hand is part of the animal’s overall enrichment experience.   Two that come quickly to mind are dogs and primates. They anticipate your arrival, and will often greet regular caregivers.

Most people, either consciously or unconsciously, talk to their animals. In fact, it seems to be second nature.  We don’t realize how many conversations we have with our charges as we clean, feed and otherwise interact with them.  Tone and intensity level are important, so pay attention to your voice; loud noises bouncing off of hard surfaces are not calming.

Enrichment items can be actively introduced to animals as playtime; a ball tossed into enclosures encourage animals to give chase, and pull toys can be playfully tugged.  Any type of interactive activity enhances the animal’s environment.

Don’t forget the human touch. Animals will respond to a head pat or a kind stroking.  If it is safe and permitted, this tactile enrichment can be provided while performing physical health checks.  In fact, some studies suggest that this interaction is good for both the human and the animal.

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Safety and Environmental Enrichment for Lab Animals

We may unwittingly introduce risk into the animals’ environment by our use of enrichment devices. Foraging may lead to aggression in some species. Competition for toys may elicit dominance behaviors. Items may fall on animals or be used as a weapon if not properly secured.

As with small children, enrichment devices with small pieces should be avoided to lessen the possibility of swallowing or choking. It is also possible that an animal could become wedged between an enrichment item and the enclosure or have a head or appendage stuck. Selecting the right sized enrichment is important for animal safety.

Non-food enrichment items need to be routinely inspected for damage and discarded as required. Items with sharp edges can cause injuries or become a harborage for bacteria. Ropes and cloth items can fray over time, possibly resulting in ingestion, strangulation or entrapment.

When selecting enrichment items, care should be taken to select those that can be easily sanitized. Items should be constructed to withstand the cage washer and common chemicals. Where ongoing sanitation is an issue, disposable enrichment items may be a better choice.

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Elicit Hamsters Natural Behaviors

The best animal enrichments are those that elicit the animal’s natural behaviors. Animals that are arboreal will naturally use the vertical height of an enclosure. Animals that burrow will look for similar hiding places in bedding or structures. Nesters will spend much of their time fluffing, arranging and rearranging materials into a comfortable sleeping area. Collectors, such as Syrian hamsters, will remove feed blocks from feeders to store them in the bedding in some other area of the cage. Hamsters are uniquely adapted for this behavior by the presence of cheek pouches which allow the animals to stash and carry.

In the wild, hamsters live independent lives in deep burrows, where they may store several pounds of grain. Foraging trips may cover up to 8 miles. Males and females come together only for mating, and the female raises her young alone. Nesting materials and a den provide privacy for newborns. They are active in the dark and will run a wheel for the equivalent of long distances. Hamsters will fight less if housed together, sex separated, at weaning, or by providing hiding places to allow an animal to remove itself from the group.

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Guinea pigs present a special challenge for enrichment

Guinea pigs present a special challenge for enrichment. These animals exhibit unusual rigidity in behavior, and do not welcome changes to food, feeders and water containers. Some common enrichment items may be met with skepticism or even fear. Guinea pigs may protest these intrusions by refusing to eat.

What types of enrichment items are acceptable? Food enrichment, such as hay blocks, dried corn on the cob, and corn husks allow the animals to graze throughout the day, occupying time and offering variety. Fresh greens such as kale are a nutritional treat, providing an additional source of vitamin C. Guinea pigs are chewers, tasting everything in sight. Make use of this behavior by offering chew sticks and other small but sturdy items.

Guinea pigs are timid by nature; shelters offer a sense of security. PVC tubing large enough to accommodate the animal provides a comfortable haven, allowing the animal to choose to be alone. Other types of shelter are also well accepted. Guinea pigs are not nesters, but do much better on contact bedding because of their delicate feet. And of course, another guinea pig is a great form of enrichment.


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Environmental Enrichment for Farm Animals

Farm animals present special challenges for environmental enrichment.

Safety is a big issue as some species are stronger and more destructive than the average laboratory animal. Special care should be taken to ensure that limbs, horns, lips or feet cannot become trapped or injured. In some cases the enclosures themselves are challenging due to configuration, drain size and feeding vessels are uniquely shaped.

It is key, for those interacting with these animals to understand the natural behaviors expected from each species.

Enrichment items should be made of non toxic materials and not allow limbs and body parts to become trapped. They should not pose a danger to pen mates or damage the pen itself. Ruggedness and flexibility are important from a safety perspective, as these large animals may be injured by ingesting parts and pieces that can be chewed off.

Can the enrichment product withstand the rough activity and conditions where the animals are housed? For example, if the animals are housed in pastures, can the item withstand weather conditions, mud, and most importantly can they be cleaned and sanitized in accordance with regulations?

With few exceptions, agricultural animals are social. If social contact is not possible, human interaction is a good substitute.

In some cases music, mirrors or videos can enhance their environment.

Training and desensitizing are valuable for all species. Using gentle, positive training will acclimate and empower the animals to feel more secure in their environment. Understanding how the animal normally would react to stress, fear, hunger, etc is the key in a successful enrichment program.

Gentle touch is important, as some animals, such as cattle, can recognize individuals, and will respond negatively to instances of rough handling.

One cautionary note: competition for the item can stimulate aggressive behaviors, so social groups should be monitored after introduction of a new enrichment item.