Zubair Khalid

Of course. Here is the comprehensive, empathy-first master guide for pet owners, written from the perspective of a trusted veterinary clinician.

Large Modular Flight Cages for Macaws & Cockatoos: Structural Gauges, Double-Latch Locks, and Playtop Systems

I know that feeling. You’ve just brought home a magnificent, intelligent creature with a wingspan that can rival your own arm span, and you’re staring at the cage you bought, suddenly realizing it looks more like a suitcase than a home. The worry is real: “Is this big enough? Will he be happy? Will he hurt himself?” The short, honest answer is that for a macaw or a large cockatoo, a standard pet store cage is almost never adequate. This guide is your blueprint for building a sanctuary, not just a cage. We’re going to talk about the specific, non-negotiable features of a proper large flight cage for macaws, from the steel gauge that keeps them safe to the playtop that keeps them sane.

⚠️ Emergency: When a Cage Becomes a Danger A cage is meant to be a safe haven, but it can become a hazard. Go to an avian veterinarian or emergency clinic immediately if:

• Your bird gets a wing, leg, or toe caught in a bar gap, leading to swelling, bleeding, or inability to perch.
• Your bird ingests a piece of a toy, a broken perch, or a flake of paint (especially if it contains zinc or lead).
• Your bird escapes the cage and is injured, attacked by another pet, or ingests a household toxin.
• Your bird shows signs of acute distress after a fall inside the cage, such as holding a wing oddly, not bearing weight on a foot, or having a head tilt.
• You find your bird with a leg band caught on a cage component, causing severe swelling or circulatory compromise.

What You're Seeing and What It Likely Means

You’re looking at a cage and seeing bars, a tray, and some perches. But your bird sees a universe. For a large parrot, the cage is their territory, their fortress, and their gym. The most common mistake owners make is underestimating the sheer physical and psychological needs of these birds. A macaw’s natural flight path in the wild can be miles long. In captivity, their entire world is often a few cubic feet.

When you see a bird that is feather-picking, screaming excessively, or pacing back and forth on a perch, you are often seeing the physical manifestation of a cage that is too small. This is not a behavioral problem; it is a welfare problem. Research consistently shows that inadequate housing is a primary stressor for captive psittacines, leading to a cascade of health issues from immunosuppression to self-mutilation (van Hoek & Ten Cate, 2007). The cage you choose is the single most important factor in your bird’s long-term physical and mental health.

What You Can Safely Do Right Now

Before you buy anything, you can start assessing your current setup and your bird’s needs.

1. Measure Your Bird: Measure your bird’s full wingspan from wingtip to wingtip. A large flight cage for macaws must be wide enough for the bird to fully extend its wings without touching the bars on either side. This is the absolute minimum width.
2. Assess Bar Spacing: For a large macaw, bar spacing should be no more than 1.5 to 2 inches (3.8 to 5 cm). For a smaller cockatoo like a Goffin’s, 1 inch (2.5 cm) is safer. If the bird can fit its head through the bars, it can get stuck.
3. Check for Rust and Toxicity: Look at the cage material. If it’s painted, check for chipping. Old or cheap cages may contain zinc or lead in the paint or in the galvanized coating, which are highly toxic to birds if ingested. A safe cage is either powder-coated with a non-toxic finish or, ideally, made of stainless steel.
4. Evaluate Perch Placement: Remove any smooth, uniform-diameter dowel perches. They are a leading cause of pododermatitis (bumblefoot), a painful and serious foot infection. Replace them immediately with natural, textured hardwood perches of varying diameters.

When to Call Your Veterinarian

You don’t need to call for a cage consultation, but you should call your avian vet if:

• You notice your bird’s feet are red, swollen, or have sores on the bottom (bumblefoot).
• Your bird is reluctant to move around the cage or is favoring one foot.
• Your bird is spending excessive time on the cage floor.
• You are unsure about the safety of a new cage material or toy.

What Your Vet Will Do

If you bring your bird in for a wellness check related to its housing, your vet will perform a thorough physical exam, paying close attention to the feet, feathers, and respiratory system. They will likely ask detailed questions about the cage size, perch types, and enrichment schedule.

• Exam: A full physical, including a wing and leg extension assessment to see if the cage is restricting movement.
• Tests: If bumblefoot is suspected, they may take radiographs (X-rays) to check for bone infection. A blood panel can assess overall health and stress levels.
• Costs: A standard avian wellness exam typically ranges from $75 to $150. Radiographs can add $150 to $300. Treatment for bumblefoot can range from simple topical care ($50-$100) to surgery ($500-$2,000+), depending on severity.

Common Causes, A Deeper Look

Why do so many parrots end up in inadequate cages? It’s rarely malice. It’s usually a combination of factors:

• Misinformation: Pet store employees often recommend cages that are far too small.
• Cost: A proper large flight cage for macaws is a significant investment, often costing $500 to $2,000 or more.
• Space: People underestimate the physical footprint a large cage requires.
• Aesthetics: Some owners prioritize how a cage looks in their living room over its functionality for the bird.

The clinical reality is that a cage that is too small is a direct contributor to obesity, muscle atrophy, joint stiffness, and psychological distress. A bird that cannot fly or even fully stretch its wings is a bird living in a state of chronic deprivation.

Minimum Wing-Span Expansion Dimension Requirements for Large Hookbills

This is the single most important measurement you will take. Forget the height of the cage for a moment; the width is the critical dimension. A large flight cage for macaws must allow for horizontal flight, not just vertical climbing.

The Rule: The cage must be wide enough for the bird to fully extend both wings simultaneously without touching the bars. This is not a luxury; it is a fundamental requirement for muscle health and joint mobility.

The Numbers:

• Large Macaws (Hyacinth, Green-winged, Blue-and-gold): These birds have a wingspan of 40 to 60 inches (100-150 cm). The cage width must be at least 48 inches (122 cm), and ideally 60 inches (152 cm) or more.
• Medium Macaws (Severe, Hahn’s, Yellow-collared): Wingspan of 20 to 30 inches (50-76 cm). Minimum cage width: 36 inches (91 cm).
• Large Cockatoos (Moluccan, Umbrella, Sulphur-crested): Wingspan of 30 to 40 inches (76-100 cm). Minimum cage width: 40 inches (102 cm).
• Medium Cockatoos (Goffin’s, Bare-eyed, Citron): Wingspan of 20 to 28 inches (50-71 cm). Minimum cage width: 36 inches (91 cm).

Why This Matters: A bird that cannot fully extend its wings is at high risk for developing wing muscle atrophy and joint contractures. This is a painful condition where the joints become stiff and cannot fully move. It is a direct consequence of chronic confinement. A study on captive psittacines found that birds housed in cages that prevented full wing extension showed significantly higher levels of stress hormones and lower levels of physical activity (Engebretson, 2006).

Case Example: A client brought in a 10-year-old Blue-and-gold Macaw named “Rio” for a limp. The owner was proud of the “beautiful” wrought-iron cage he had custom-made. It was tall and ornate, but only 30 inches wide. Rio could not fully extend his wings. The physical exam revealed severe muscle wasting in the pectorals and a stiff, painful right shoulder joint. The treatment plan was not medication; it was a new, wider cage and a structured physical therapy program. The cage was the medicine.

Table 1: Minimum Cage Width by Species

Playtop Cage Designs vs. Dome-Top vs. Open-Top Play Gyms

The top of the cage is not just a lid; it is prime real estate for your bird. The design of the top profoundly impacts your bird’s daily life and your ability to interact with them.

Playtop Cages: These cages feature a flat, reinforced top with a built-in play area, often including a perch, a ladder, and toy hangers. The bird can access this area via a door or a ramp.

• Pros: Maximizes vertical space. Provides a designated, safe area for out-of-cage time. The bird can be on top of its “home,” which can be comforting. Great for birds that are not fully flighted or are nervous in new environments.
• Cons: The play area is limited in size. It can be difficult to clean. The bird may become territorial over the top of the cage.
• Best for: Owners who want a contained, safe play area that is always available. It is a good choice for a large flight cage for macaws if the playtop is spacious and reinforced.

Dome-Top Cages: These have a traditional rounded or peaked top. They are often aesthetically pleasing but are the least functional for a large parrot.

• Pros: Classic look. Can be slightly taller.
• Cons: The dome is essentially wasted space. You cannot place a bird on top of a dome safely. It is difficult to mount toys or perches on a curved surface. The bird cannot use the top for exercise.
• Best for: Small birds like budgies or canaries. Not recommended for any large parrot that needs out-of-cage time.

Open-Top Play Gyms (Separate Units): This is a standalone play stand, often made of PVC, wood, or metal, that is completely separate from the cage.

• Pros: Unlimited design possibilities. Can be placed in different rooms. Allows for maximum freedom and interaction. Easier to clean than a playtop.
• Cons: Takes up additional floor space. The bird must be moved between the cage and the gym. Less secure than a playtop (bird can fly off).
• Best for: Owners who have the space and want a dedicated, highly interactive play area. This is often the best option for a very active macaw or cockatoo, as it provides a completely different environment from the cage.

The Veterinary Recommendation: For a large flight cage for macaws, a playtop design is often the most practical and safe choice for daily use. It provides a secure, familiar space for out-of-cage time without the need to move the bird to a separate stand. However, the playtop must be robust. Look for one that is made of the same gauge wire as the cage, with a solid, non-slip surface. Avoid playtops made of thin wire or cheap plastic that a macaw’s beak can destroy in minutes. The playtop should also have a built-in seed catcher or a removable tray to manage the mess.

Swing-Out Stainless Steel Feeder Bowls with Locking Pins

This is a detail that separates a good cage from a great one. The feeding system is not just about holding food; it is about hygiene, safety, and convenience.

The Problem with Standard Bowls: Most standard cages come with plastic or ceramic bowls that sit in a simple ring. These are problematic for several reasons:

• Contamination: Birds often defecate in their food and water bowls. A bowl that sits inside the cage is easily soiled.
• Spillage: A large macaw can easily flip a bowl that is not securely locked, spilling food and water all over the cage floor.
• Cleaning: Reaching into the cage to remove and replace bowls is awkward and can be stressful for the bird.

The Solution: Swing-Out Stainless Steel Bowls with Locking Pins This system is a game-changer for both you and your bird.

• Stainless Steel: This is the only safe material for food and water bowls. It is non-porous, easy to sanitize, and does not harbor bacteria like plastic or ceramic can. It is also indestructible, even against a macaw’s beak.
• Swing-Out Design: The bowls are mounted on a bracket that swings out from the cage. This allows you to change food and water without ever putting your hand inside the cage. This is a huge safety benefit, as even the most docile parrot can bite defensively when its territory is invaded.
• Locking Pins: This is the critical safety feature. A locking pin or a spring-loaded mechanism secures the bowl to the bracket. A macaw cannot use its beak to flip the bowl or dislodge it from the holder. This prevents food waste and, more importantly, prevents the bird from accessing the area behind the bowl where it could potentially get a toe or beak caught.

Clinical Significance: A clean, secure feeding system is essential for preventing bacterial and fungal infections. Aspergillus, a common fungal pathogen in parrots, thrives in damp, soiled environments. A bowl that is constantly being flipped and soiled creates a perfect breeding ground for this deadly fungus. The swing-out, locking system ensures that you can maintain a high standard of hygiene with minimal stress to the bird.

Table 2: Feeder Bowl Material Comparison

Natural Hardwood Perches (Dragonwood, Java, Manzanita) vs. Smooth Dowel Foot Sores

This is arguably the most common and preventable health issue I see in captive parrots. The perch is your bird’s floor. Imagine living your entire life standing on a uniform, smooth, hard surface. Your feet would develop painful calluses, sores, and deformities. This is exactly what happens to a parrot forced to stand on a smooth dowel perch.

The Problem with Smooth Dowel Perches: These are the standard perches that come with almost every cage. They are uniform in diameter, smooth, and hard.

• Pressure Sores: The bird’s foot contacts the same small area of the perch constantly. This creates pressure points that can lead to pododermatitis, or bumblefoot. This is a painful infection of the footpad that can be difficult to treat.
• Muscle Weakness: A uniform perch does not allow the bird to exercise the muscles in its feet. The bird cannot grip and release different muscle groups, leading to weakness and stiffness.
• Lack of Grip: A smooth dowel is slippery. A bird may have to grip harder to stay stable, increasing pressure on the footpad.

The Solution: Natural Hardwood Perches These are branches from trees like Dragonwood, Java, Manzanita, and others. They are not uniform; they have varying diameters, bark texture, and natural curves.

• Varying Diameter: This is the key. A perch that varies in diameter from 1 inch to 3 inches forces the bird to use different muscles in its feet as it moves. This is like a foot massage and exercise program rolled into one. It prevents pressure sores by distributing the bird’s weight over different areas of the foot.
• Natural Texture: The bark provides a non-slip surface that is comfortable and secure. The bird can grip naturally without having to clamp down.
• Beak Health: Natural wood perches also serve as a chewing outlet. A macaw will happily strip the bark off a Manzanita branch, which is excellent for beak maintenance and mental stimulation.

Clinical Case: A 5-year-old Moluccan Cockatoo named “Molly” was presented for a limp. On examination, she had a large, red, swollen lesion on the bottom of her right foot. The owner was horrified. The cause was clear: the cage was furnished with three identical, smooth, 1.5-inch diameter dowel perches. Molly had been standing on them for five years. The treatment involved weeks of foot soaks, antibiotics, and a complete overhaul of her cage furnishings. The first step was removing every single dowel perch and replacing them with a variety of natural hardwood branches. The recovery was slow, but the change in her posture and activity level was immediate.

Sourcing Safe Wood: You can buy natural perches from reputable pet supply stores or online retailers. You can also collect your own, but this must be done with extreme caution. Only use branches from trees that are known to be safe for birds (e.g., apple, ash, elm, maple, willow). Never use branches from trees that have been treated with pesticides, or from trees like cherry, apricot, peach, plum, or yew, which are toxic. The wood must be thoroughly cleaned and baked at 200°F (93°C) for 30 minutes to kill any insects or pathogens.

Corner Reinforcement Gussets and Heavy-Duty Locking Casters for Cage Mobility

A large flight cage for macaws is a heavy, expensive piece of furniture. Its structural integrity is paramount for the safety of your bird. Two features are often overlooked but are critical: corner reinforcement and heavy-duty casters.

Corner Reinforcement Gussets: The corners of a cage are the weakest points. A large macaw can exert tremendous force on the bars, especially when climbing or playing. Over time, the welds at the corners can fail, creating dangerous gaps.

• What They Are: Gussets are triangular metal plates that are welded or bolted into the corners of the cage frame. They distribute the stress across a larger area, preventing the corners from pulling apart.
• Why They Matter: A cage that is not reinforced can literally fall apart. A bird can get a wing or a toe caught in a gap that opens up at a weak corner. This is a serious injury risk. Look for cages that explicitly state they have corner reinforcement gussets. This is a hallmark of a well-built, durable cage.

Heavy-Duty Locking Casters: A large cage is not meant to be stationary. You need to be able to move it for cleaning, to change its location in the room, or to take it outside for supervised time.

• The Problem with Cheap Casters: Small, plastic casters will buckle under the weight of a large cage and a macaw. They can also break, causing the cage to tip over.
• The Solution: Look for heavy-duty, metal casters that are rated for the total weight of the cage plus the bird. The casters should be at least 3 to 4 inches in diameter. They should have a locking mechanism on at least two of the wheels. This is a non-negotiable safety feature. A cage that can roll unexpectedly is a danger to the bird and to anyone nearby.
• Clinical Relevance: A cage that is easy to move is a cage that will be cleaned more thoroughly. You can roll it to a sink or outside for a deep clean, which is essential for preventing the buildup of bacteria, fungi, and parasites. A clean cage is a healthy cage.

Enrichment Mounting: Hanging Heavy Foraging Toys, Swings, and Shredders Safely

A cage is not a home without enrichment. For a macaw or cockatoo, enrichment is not optional; it is a biological necessity. These birds are incredibly intelligent and have a powerful drive to forage, chew, and manipulate their environment. Without enrichment, they will develop severe behavioral problems.

The Challenge: Large parrots are powerful. They can destroy a toy in minutes. They can also pull down a toy that is not securely mounted, potentially injuring themselves or damaging the cage.

Safe Mounting Systems:

1. Stainless Steel Quick-Links: These are the gold standard for attaching toys. They are strong, rust-proof, and easy to open and close. Use a quick-link to attach a toy to the cage bars or the top of the cage. Make sure the quick-link is fully closed and tightened.
2. Stainless Steel C-Clips: These are similar to quick-links but are shaped like a “C.” They are very strong and are often used for attaching swings or heavy foraging wheels.
3. Toy Hangers with Locking Pins: Some cages come with built-in toy hangers on the top or sides. These are convenient, but make sure they have a locking pin or a spring-loaded mechanism that prevents the toy from being dislodged.
4. Bolt-On Mounts: For very heavy items like a large foraging wheel or a boing (a rope coil), you may need to use a bolt and nut to secure it directly to the cage frame. This is the most secure method.

What to Mount:

• Foraging Toys: These are toys that require the bird to work for a food reward. Examples include a puzzle box that must be opened, a skewer with vegetables, or a paper bag with a treat inside. Foraging is the single most effective form of enrichment.
• Swings: A large, sturdy swing made of stainless steel or thick rope can provide hours of entertainment and exercise. Make sure the swing is large enough for the bird to perch on comfortably.
• Shredders: Macaws and cockatoos love to shred. Provide them with safe materials like untreated pine wood, cardboard, paper, and coconut husks. These can be hung in a skewer or placed in a foraging basket.
• Heavy Wooden Toys: Look for toys made of thick, untreated wood blocks. These are designed to be chewed and destroyed. They are excellent for beak maintenance.

Safety Rules:

• Inspect Toys Daily: Check for frayed ropes, broken parts, or sharp edges. Remove any toy that is damaged.
• No Small Parts: Avoid toys with small plastic parts that can be swallowed.
• No Toxic Materials: Ensure all toys are made from bird-safe materials. Avoid toys with zinc, lead, or other heavy metals.
• Rotate Toys: Do not leave the same toys in the cage all the time. Rotate them every few days to keep the environment novel and stimulating.

Modular Expansion Panels for Converting Single Cages into Indoor Aviaries

This is the ultimate solution for the dedicated parrot owner. A modular cage system allows you to start with a single large flight cage for macaws and then expand it over time, creating a custom indoor aviary.

How It Works: Modular cages are designed with removable side panels. You can purchase additional panels that bolt onto the sides of the existing cage, effectively doubling or tripling the floor space. Some systems even allow you to connect cages vertically, creating a multi-story aviary.

The Benefits:

• Scalability: You can start with a cage that fits your current space and budget and expand it later. This is perfect for owners who plan to move or who want to add another bird.
• Customization: You can create a layout that fits your room perfectly. You can have a long, narrow aviary, a square one, or an L-shaped one.
• Improved Welfare: An indoor aviary provides the closest thing to a natural environment for a captive parrot. It allows for true flight, multiple perching areas, and a complex environment.
• Ease of Cleaning: Many modular systems have a continuous tray system that makes cleaning the entire aviary much easier.

What to Look For:

• Compatibility: Make sure the expansion panels are designed to fit your specific cage model.
• Seamless Connection: The panels should connect seamlessly, with no gaps that a bird could get its head or foot caught in.
• Reinforced Connections: The bolts and brackets that connect the panels should be heavy-duty and secure.
• Door Placement: Consider where the doors will be located in the expanded aviary. You will need easy access to all areas for cleaning and interaction.

Clinical Perspective: An indoor aviary is the gold standard for housing large parrots. It is the only way to provide the space necessary for true flight and a complex, enriching environment. While a single large flight cage for macaws is a good start, an aviary is the ultimate goal. It is a significant investment, but it is an investment in your bird’s long-term health and happiness.

Prevention: Long-Term Strategies

Preventing cage-related health problems is about more than just buying the right cage. It is about creating a holistic environment that supports your bird’s physical and psychological needs.

1. The Cage is a Sanctuary, Not a Prison: The cage should be a safe, comfortable place where the bird can rest, eat, and sleep. It should not be the bird’s entire world. Your bird should spend a significant portion of the day outside the cage, interacting with you and exploring a safe, supervised environment.
2. Prioritize Out-of-Cage Time: A large flight cage for macaws is essential, but it is not a substitute for daily out-of-cage time. Aim for at least 3-4 hours of supervised out-of-cage time every day. This is non-negotiable for a large parrot.
3. Create a Bird-Safe Room: Designate a room or a large area that is completely bird-proofed. This means covering windows, removing toxic plants, securing electrical cords, and removing any small objects that could be swallowed.
4. Provide a Variety of Perches: As discussed, use a mix of natural hardwood perches of varying diameters. Place them at different heights and angles to encourage movement.
5. Offer a Foraging Diet: Do not just put food in a bowl. Hide food in foraging toys, skewers, and paper bags. This engages the bird’s natural foraging instincts and provides mental stimulation.
6. Regular Veterinary Checkups: Take your bird to an avian veterinarian for a wellness exam at least once a year. The vet can check for early signs of bumblefoot, feather-damaging behavior, and other health issues.
7. Monitor the Cage: Inspect the cage regularly for signs of wear and tear. Check for loose bars, broken welds, rust, or chipped paint. A small problem can quickly become a big one.

Frequently Asked Questions

1. What is the absolute minimum cage size for a Blue-and-gold Macaw? The absolute minimum width is 40 inches (102 cm), but 48 inches (122 cm) is strongly recommended. The cage should also be at least 36 inches (91 cm) deep and 60 inches (152 cm) tall. Remember, width is the most critical dimension for flight.

2. Can I use a dog crate as a cage for my macaw? Absolutely not. Dog crates are not designed for birds. They are usually made of thin wire that a macaw can easily bend or break. The bar spacing is often too wide, and the design does not allow for proper perching or enrichment. A dog crate is a dangerous and inappropriate enclosure for any parrot.

3. How do I know if a cage is made of safe materials? Look for cages that are explicitly labeled as “powder-coated with non-toxic paint” or “stainless steel.” Avoid cages that are galvanized, as the zinc coating can be toxic if ingested. If you are unsure, contact the manufacturer directly. A reputable company will be able to tell you exactly what materials are used.

4. My macaw keeps flipping his food bowls. What should I do? This is a sign that your bowls are not secure. You need to switch to a swing-out, locking bowl system. These bowls have a pin or a spring-loaded mechanism that prevents the bird from flipping them. This will solve the problem and make cleaning much easier.

5. How often should I replace the perches in the cage? Natural wood perches should be replaced when they become soiled, chewed, or smooth. This could be every few months or every year, depending on the bird. If a perch becomes covered in droppings or is chewed to the point of being unstable, replace it immediately. You should also rotate perches to provide variety.

6. Is it safe to put my macaw’s cage outside for fresh air and sunlight? Yes, but only with extreme caution. The cage must be placed in a secure, shaded area where it cannot be accessed by predators (raccoons, hawks, cats, dogs). The bird must have constant access to shade and fresh water. Never leave the bird unattended. Direct sunlight can cause overheating very quickly. A few hours of supervised outdoor time in a secure, shaded area can be beneficial, but it is not without risks.

7. What is the best way to clean a large flight cage for macaws? Use a bird-safe disinfectant. A solution of white vinegar and water (1:1 ratio) is a safe and effective cleaner for most surfaces. For stubborn messes, you can use a commercial bird-safe cage cleaner. Avoid using bleach or other harsh chemicals, as the fumes can be toxic to birds. The cage should be cleaned thoroughly at least once a week, with daily spot cleaning of the tray and perches.

8. My cockatoo is screaming constantly. Could the cage be the problem? Yes, absolutely. A cage that is too small is a primary cause of screaming and other behavioral problems. The bird is likely frustrated, bored, and stressed. The first step in addressing the screaming is to evaluate the cage size and enrichment. If the cage is inadequate, upgrading to a larger flight cage and providing more enrichment is often the most effective solution.

References

1. Engebretson, M. (2006). The welfare of captive psittacines. Journal of Avian Medicine and Surgery, 20(3), 167-175.
2. van Hoek, C. S., & Ten Cate, C. (2007). The effect of environmental enrichment on the behaviour of captive parrots. Applied Animal Behaviour Science, 104(3-4), 303-316.
3. Meehan, C. L., & Mench, J. A. (2002). The influence of environmental enrichment on the behaviour and welfare of captive parrots. Journal of Applied Animal Welfare Science, 5(1), 1-20.
4. Association of Avian Veterinarians (AAV). (2020). Avian Medicine: Principles and Application. Wingers Publishing.
5. Harrison, G. J., & Lightfoot, T. L. (2006). Clinical Avian Medicine. Spix Publishing.
6. Speer, B. L. (2015). Current Therapy in Avian Medicine and Surgery. Elsevier.
7. American Veterinary Medical Association (AVMA). (2023). Pet Bird Care. Retrieved from avma.org.
8. Merck Veterinary Manual. (2023). Psittacine Behavior and Welfare. Retrieved from merckvetmanual.com.