When faced with a dog that has a severe problem it can be easy at times to overlook the significance that breed plays in susceptibility to a disease. Giacomo Biagi offers a brief overview of some common breed-related problems where diet can play a major role.
Nobody ever said that vitamins are an easy subject to understand – and although they are essential for life, too much or too little of a vitamin can make a huge difference to an animal’s health. Valerie Parker makes it all clear in her excellent review of Vitamin D.
Feeding behavior in cats
We all need to eat to survive. But for humans, eating can be much more than a simple task to be undertaken on a daily basis; our mealtimes allow us to rest and relax, and perhaps catch up with friends or family as we enjoy our food. But from a cat’s point of view, eating is not quite the same, as Jon Bowen explains.
Empathy is at the root of pet keeping; the sense of a shared emotional experience is not only the basis of the human-animal bond but also the origin of its key benefits for pet owners. A recent scientific statement from the American Heart Association noted that pet keeping was strongly associated with a range of cardiovascular health benefits, but these benefits were also linked to the quality of the bond and not merely due to the presence of a pet in the household ( 1 ).
Although research in this area is limited, evidence is accumulating that pets with behavioral problems might adversely affect their owner’s lifestyle and wellbeing. For example, a study of dog owners found that both major behavior problems (such as aggression and separation anxiety) and minor problems (such as leash pulling and restlessness) can have a significant impact on lifestyle and satisfaction with pet ownership ( 2 ). The same kinds of owner-lifestyle impacts would be expected with cats that are unsociable, destructive, or show inappropriate toileting in the home.
Pets provide both an opportunity for owners to receive emotional support from a non-judgmental individual, and to express caregiving behaviors in return. Being expressions of empathy, both giving and receiving care provides similar positive emotional benefits to people, with the offering of food being a primary means of human expression of care ( 3 ). So for some people, and especially for cat owners, offering food and seeing it eaten are important aspects of expressing care, and some individuals, who are out of the house for long periods each day – either with work or for other reasons – may regard feeding as the main point of contact with their pet ( Figure 1 ).
This interaction works perfectly well for a pet species such as the dog, for which feeding is a social activity and meal frequency is flexible. Dogs adapt easily to having one, two or three meals a day, they show appreciation when offered food, and will usually accept restrictions on when and what they can eat. However, the hunting and feeding patterns of cats make it hard for them to adapt to, or show much appreciation for, human attempts to show care through the offering of food ( Figure 2 ). In fact, as we will see, the mismatch between the feeding motivations and behaviors of cats and people can lead to behavioral problems that damage owner lifestyle and the human-animal bond.
What is normal hunting and feeding behavior?
In the wild, and when given free access to food, cats will eat throughout a 24-hour period ( 4 ). Meal frequency can be as high as 20 times per day ( 5 ), although there does seem to be variation between cat breeds; for example, one small study in Bengal cats showed a higher average meal frequency than domestic shorthaired cats ( 6 ).
For feral cats, meal frequency depends upon the availability of food and of hunting success, and therefore upon the availability of prey. Cats will regularly visit a set of hunting sites within their territory, focusing on times when their prey is likely to be active or easily caught. Typically, this means that cats most actively hunt at dawn and dusk, although they also hunt during the night when roosting birds may be more easily caught. Having a visual system that has evolved to work best in low-light conditions, cats also have difficulty coping with bright sunlight, which is why they may be less active during sunny days. Prey size is small, and includes both vertebrates and invertebrates ( 7 ), but since each catch is essentially a small pre-packaged meal which only provides energy for a few hours of activity, satiation plays a minimal role in regulating either hunting or feeding. Having eaten, a cat needs to quickly return to hunting in order to obtain its next meal. Cats do not normally eat large meals because of their limited stomach volume.
At each hunting site, the cat searches for odors and signs of local disturbance which could indicate that prey has been recently active in the area. It will then go to a nearby spot from which it can launch an attack within the area where prey is most likely to arrive. The cat will then wait for a few tens of minutes before moving on to another site. Predatory behavior is also activated by highpitched sounds, and quick movements of prey-sized items; if these are detected the cat will stop moving, adopt a crouched body posture to make itself less visible, localize the prey, wait for it to approach (or move towards it cautiously) and then launch an opportunistic predatory strike ( Figure 3 ). When they occur, such strikes are rapid but brief, and are only over short distances of a few body lengths.
Cats have poorer visual acuity at distances of less than 15-20 cm, so during the final phase of a predatory strike the cat depends on its whiskers and tactile sensation around the mouth. Once the cat has hold of the prey, bite pressure is under the control of local reflexes, so the cat will automatically bite down harder if the prey moves in its mouth. This is one reason why cat bites can be so painful for owners, and why it is important not to use hands and feet to entice cats to play.
The predatory activity patterns of cats involve a lot of travel between hunting sites, foraging, and waiting. After catching its prey, the cat will take it back to its core territory where it can be eaten in private. For domestic cats, this may mean bringing prey home to eat, because this is a safer and more relaxing place to be; it is not that the prey is a “present” for the owner or a sign that the cat is dissatisfied with its food. It is also why some cats remove food from the bowl to eat it elsewhere; they want more privacy when they are eating. Owners should treat this as an indication that the food bowl is in the wrong place for the cat, or that it is frustrated by having to share a food bowl with other cats in the household. Free-ranging cats tend to locate their latrine, hunting and resting sites away from each other, so in the domestic home these may be too closely related, which also leads to cats not wanting to eat from the bowl they are given. Owners should therefore be encouraged to site feeding bowls and litter trays away from each other wherever possible.
“The hunting and feeding patterns of cats make it hard for them to adapt to, or show much appreciation for, human attempts to show care through the offering of food.”Jon Bowen
Larger, more dangerous, prey may be dispatched immediately, using a kill bite that severs the cervical vertebral column. Carnassial teeth are then used to shear flesh from the carcass (4). If the cat is not hungry, and the prey is small, the cat may keep the prey alive for longer in order to practice predatory behavior with it. Cats will typically eat small mammals starting with the head and then moving onto the body and legs. They take time to chew the prey into digestible pieces and may not consume the whole animal; the aim is to refuel and then return to hunting and other behaviors. Less palatable parts of the body, such as the intestines, may not be eaten. If a cat catches a surplus of food, it may cache some of it by burying it in a patch of dry earth or leaves. This acts as a temporary food store for a few hours, and may explain why some domesticated cats perform “digging” behaviors around a food bowl after they have eaten.
What tastes do cats like?
Like other carnivores, cats have major areas of taste loss ( 8 ); for example, they are insensitive to fruity-sweet and salt tastes ( 9 ). They are more strongly sensitive to the flavor of amino acids and nucleotides; they tend to reject the taste of certain amino acids (such as l-tryptophan, which humans identify as bitter tasting) and are attracted to the taste of others (such as l-glycine). Owners sometimes comment that their cats are attracted to salty items like nuts or crisps, and sweet items like cakes or biscuits, but this is probably because of subtle amino acid flavors that we are not even aware of, because our perception of salt or sugar flavors is so overwhelming. Although cats taste food in a completely different way from us, this does not mean that human and feline preferences will not sometimes overlap! For example, cats will often reject bitter-tasting foods, as it is a means of avoiding the consumption of something that is potentially toxic ( 10 ).
Initial food preferences develop as kittens observe and replicate their mother’s eating habits. However, this changes when cats become independent and are exposed to the range of foods available in the environment or provided by their owners. Some individual cats are regarded by their owner as being quite fussy about what they will eat. This can be due to limited early experience of different foods and flavors, leading to neophobia. However, cats also exhibit a “monotony effect” in their food selection ( 4 ); they experience a growing aversion to familiar foods (and also prey), which may lead to a preference for novelty and dietary diversity (within the range of foods and flavors that the cat is already familiar with). This monotony effect encourages the cat to maintain a nutritional balance by eating a wide range of food/prey, and is greater in freeranging cats than pets that have been reared on commercially prepared nutritionally complete diets ( 11 ). It probably explains the tendency for some pet cats to periodically lose interest in their regular diet, which then forces owners to try alternatives.
What dictates feline behavior?
Probably the most important aspect of feline hunting and feeding behavior, and indeed behavior in general, is that it is regulated primarily by environmental and internal factors, and not by social interaction. When a cat is within its territory, its behavioral patterns are not influenced by other cats; hunting, feeding, and self-maintenance (grooming, resting) are all solitary activities. Environmental cues, such as light level and vegetation type, provide information that enables the cat to predict when and where prey will be available. The decision to hunt is then dependent on the cat’s physical condition and the balance of competing internal motivational states (e.g., the motivation to self-maintain versus finding a mate or hunting for prey).
Free-ranging cats tend to establish quite rigid personal temporal and spatial routines of hunting, feeding, territorial and self-maintenance behavior ( Figure 4 ). One reason for this is that, unlike dogs, cats do not have specific behavioral mechanisms for regulating conflict around shared resources. Instead, they use scent marks (e.g., urine and claw marks) and distance maintaining signals (e.g., threatening body postures, eye contact and vocalization) to keep apart from each other. Cats do voluntarily form colonies in areas where there is a surplus of shelter and food, but this still does not involve cooperation of the kind which can be seen in a group of dogs. Instead, it reflects the increased level of social tolerance that members of such groups possess; socially tolerant cats can coexist and take advantage of an area of increased prey and shelter availability, whilst
• Cats eat up to 20 small meals each day
• They eat throughout a 24-hour period.
• Hunting and feeding are not social activities that are regulated by the presence of other cats.
• Cats follow strict individual routines of hunting, feeding and self-maintenance.
Box 1. A summary of feline eating behavior.
socially intolerant cats would never choose to live in such groups. This combination of individualism and facultative sociability enables the feline species to inhabit a wide range of environments. A short summary of feline feeding behavior is given in Box 1 .
How easily do cats adapt to domestic living?
This article started by considering the idea that offering food is an important aspect of caregiving for people. All sorts of social conventions surround this in humans, and usually the recipient of the food is expected to somehow show that their needs have been met. In some cultures it is polite to leave a tiny amount of food at the edge of the plate, in order to show that one’s appetite has been more than satisfied. In others it is considered rude not to eat absolutely everything and then round off the meal with a loud belch. Either way, consumption is evidence of satisfaction, and dogs are usually more than happy to comply with this social norm.
Cats, on the other hand, are more concerned with food as a refueling stop between other activities. Feeding has no social significance, and cats will often take only a couple of mouthfuls before walking away from the bowl. Owners can misinterpret this as dissatisfaction, and may feel obliged to offer increasingly attractive alternatives. In itself, this may not be a major issue, but in some instances it could lead to accidental over-feeding and can be frustrating for the owner.
A more serious problem is the timing and frequency of meals. Putting out food for cats twice daily will only work if the food remains fresh and is available throughout a 24-hour period. Otherwise there will be periods when the cat has no access to food.
Meal-fed cats will try to adapt to this pattern of feeding by consuming a much larger than normal amount of fresh food at each mealtime, which may be uncomfortable for them. The situation is worse in multi-cat households in which cats share food bowls, because this leads to cats queuing for food. To understand what this must be like, imagine that instead of having your own portion of breakfast, lunch and dinner every day, you were given one single massive meal randomly once or twice a week, shared with other people who were equally hungry and desperate to get their share of the food. Feeding on-demand is equally bad because the owner will be asleep or absent at key times when cats are at their most active and need to eat (e.g., at dawn and dusk).
• Cats need free access to food so that they can eat small regular amounts throughout the day and night.
• It is normal for cats to eat a small amount and then walk away from the bowl.
• Feeding a single main foodstuff, with occasional small amounts of novel food items, is probably the most natural pattern for cats, and the relative monotony may help to reduce the risk of overconsumption.
• Activity feeders help to provide mental stimulation, and should be used to prevent over-consumption in ad-lib fed cats.
• Owners need to find other ways to show care, such as playing hunting games and talking to their cats!
Box 2. Tips for better eating habits.
Apart from an inappropriate feeding frequency, meal and on-demand feeding tether the cat’s routine to that of the owner. Given the fairly strict routines that cats follow, having an owner who gets up or arrives home at different times during the week can create a stressfully unpredictable routine for the cat.
As a demonstration of how important this can be, at least two studies have investigated the importance of routine and predictability in the lives of cats. Both found that an irregular pattern of feeding, lighting, heating, cleaning and social contact led to an increase in stress-related behaviors. One study that looked at cats exposed to an unpredictable routine reported that the animals showed elevated urinary cortisol, reduced exploratory behavior, and increased arousal and hiding patterns ( 12 ). Another study found that a similarly disrupted routine led to a 60% increase in urination outside the litter box, and a near ten-fold increase in defecation outside the litter box ( 13 ). This is an important finding, because the deliberate variations in routine the cats experienced in these studies are very similar to what the average cat has to tolerate. Apart from varying food availability, cats often experience abrupt and unavoidable owner-generated changes in lighting, heating, the presence of stimulation, and human contact.
When a cat starts defecating outside the litter tray, the owner will often look for a significant change or stressor that might be responsible; while many factors can be implicated, it may be the result of an overall lack of routine and predictability. Within this general lack of environmental predictability, feeding is probably the most critical aspect, as it is the area in which human and feline needs are the most incompatible. It is also the easiest thing to fix, and in many cases of inter-cat conflict and house-soiling the key to remedying the problem s to provide the cats with free access to food. It is also, however, important to consider the siting of the feeding area within the house ( Figure 5 ).
Owners are often concerned about offering free access to food, as they assume this will lead to obesity. In most cases this is not an issue, as long as access to food is through some kind of activity feeder that slows food consumption ( Figure 6 ), and the food is of sufficiently high-protein content. Cats appear to eat to satisfy a protein intake requirement, and as long as they consume their food slowly enough to allow them to reach satiation they tend not to over-consume. Although indoor cats are at greater risk of obesity because of a lack of activity, this is best tackled by providing a more stimulating environment, along with appropriate food control, rather than relying solely on dietary restriction.
By providing free access to food using activity feeders, we can provide a more natural feeding experience for cats that will reduce stress and frustration. However, owners may not feel comfortable with this because it removes an opportunity for caregiving. One solution that satisfies both owner and cat is to provide food through “hunting games”. For example, playing a game with a fishing toy ( Figure 7 ) that starts with stalking the toy as it appears and disappears behind furniture, and gradually progresses through the hunting sequence until it ends with a hidden tasty treat.