Dietary Behavior in Cats

The teeth have an essential influence on the cat’s general health. They have a role to play in many different functions, such as hunting, grasping and breaking food, self-defense and competition. There are few precise epidemiological studies describing the oral health of cats. Data on cats are mostly extrapolated from dogs, although the oral-dental pathology of cats in all their diversity has special particularities that veterinarians need to know.

Periodontal diseases are common in cats but are often underrated by veterinarians and treated superficially. Recent advancements in feline veterinarian dentistry have provided new tools for their evaluation and diagnosis, as well as more effective prevention tools. All this information must be at the center of the care agreement between the clinic and the owner and aimed at minimizing pain and associated infections.

Nicolas GIRARD
DVM

Nicolas Girard graduated from the National Veterinary School of Alfort in 1987. After practicing general veterinary medicine for small animals for approximately twelve years. Nicolas is now a practicing veterinary dentist and ear, nose and throat specialist in the southwest of France. Nicolas is in charge of the dentistry consultation at the National Veterinary School of Alfort. He is also responsible for the scientific committee of the Veterinarian Dentistry Study and Research Group Office (GEROS), a component of the French Association of Veterinarians for Companion Animals (AFVAC). Nicolas is also a member of the European Veterinary Dental Society (EVDS).

Eric SERVET
MEng, Royal Canin Research Center in Aimargues, France

Eric Servet graduated in engineering from ENITIAA in Nantes, specializing in dietary ingredients and technologies. In 1999-2001 he worked on the pilot development and formulation of commercial dairy products. He subsequently spent a year in the United States at Royal Canin USA, working in product stability and palatability. Since 2002 he has been a research engineer at the Royal Canin Research and Development Center in Aimargues, France. His main fields of feline and canine research are dental hygiene, joint cartilage nutrition, and obesity.

1. Dietary Behavior in Cats

Anatomical and Pathological Specificities

Cats are genuine carnivores and their dentition is the same as the major Felidae (Figure 1). They have four types of teeth [incisors (I), canines (C), premolars (PM) and molars (M)] but unlike dogs and other carnivores, cats do not have any chewing teeth – upper molars (Figure 1 and Figure 2).

In the various sequences of dietary behavior, the role of teeth is to capture and dismember small prey, using groups of differentiated teeth.

• The shape of the incisors enables them to cut, hollow out and hack.
• The canines are profiled to pierce and grasp prey.
• The premolars serve to transport the food and to break it into small pieces.

Figure 1. Profile view of the dentition of an adult cat.

Figure 2. Front view of dental occlusion in the cat.

The oral cavity of cats can be opened wide to enable the canines to grasp the prey, while facilitating the powerful action of the carnassials. Once the prey has been broken up into pieces, it is swallowed (Wiggs & Lobprise, 1997).

The movements of the jaws are limited sagittally (no transversal masticatory movement). This extreme specialization of the jaws and the temporomandibular joints in cats guarantees great efficiency with respect to the forces exercised when prey is grasped and broken down (Orsini & Hennet, 1992). In domesticated cats, the canines apply around 23 kg of pressure, the carnassials around 28 kg (Buckland, 1975). Joint integrity is maintained by powerful lateral ligaments covered by an effective jaw musculature. Typically, while the carnassials break the food up, the temporomandibular joints twist and rotate it, doubling the effect. The fibrous symphysis connecting the two branches of the mandible enables the distinct movements of the right and left jaw according to the needs and the side used by the cat (Harvey & Emily, 1993).

Varied Oral Prehension Techniques

In nature, the diet of a wild cat comprises mostly of small rodents, rabbits, birds and some lizards. After catching its prey, step-by-step the cat cuts and swallows it in small pieces.

While domestication has changed their behavior to a degree, domesticated cats still have the ability to return to their wild life, as they retain the hunting instinct, separate from the feeding function. Only 13% of tracked prey is actually caught (Kays & DeWan, 2004). A study shows that, even properly fed housecats with outdoor access will continue to hunt and eat prey, although the proportion of such prey in the total ration is clearly lower than in that of cats that permanently live outdoors (66 g/day vs. 294 g/day) (Liberg, 1984).

The palatability of commercial food has been studied in detail to continually improve product quality. Dry kibbles in various shapes, sizes, textures and densities are given to cats to evaluate their reaction. Analyzing videos of the feeding behavior of different breeds of domesticated cats (Figure 3) has enabled the characterization of how cats grasp their food in general, while also identifying several kibble prehension methods (Figure 4):

• Supra-lingual mode: using the upper side of the tongue
• lLbial mode: using the lips and jaws
• "Shovel" mode: using the incisors
• Sub-lingual mode: using the lower side of the tongue

The kibble prehension method varies with the breed. A certain degree of adaptability in terms of prehension and mastication behavior is observed depending on the kibble shape and size (unpublished internal Royal Canin studies, 2002).

Figure 3. Video analysis of the oral prehension method of Persian cats. Analysis conducted in association with Royal Canin, École Nationale des Arts et Métiers d’Angers (ENSAM) and Ecole des Mines d’Alès (EMA).

Figure 4. Different oral prehension methods observed in cats.

Observing brachycephalic breeds (e.g., Persians), it is clear that they have difficulty grasping standard- sized, round kibbles, particularly with the incisors. Persians use the tongue to trap a standard kibble in 80% of cases (60% lower tongue (Figure 5) and 20% upper tongue). They use their lips just 20% of time, while the ‘shovel’ method is not observed.

Figure 5. Comparative jaw conformation between a brachycephalic cat (persian) and a mesocephalic cat. (Source: Royal Canin Research Center, 2002).

- Dolichocephalic cats (e.g., Siamese) like to use their incisors (Figure 6). The ‘shovel’ method is observed in 30% of cases, which is more efficient when the kibble bowl is full. Prehension tends to progress towards the upper tongue method as the bowl empties (to ensure the tongue grasps the kibble). Siamese cats use the upper tongue method in 70% of cases.

Figure 6. Traditional food prehension method used by the Siamese cat. The sequential analysis of 4800 prehension sessions shows that the Siamese uses its incisors in 30% of cases. The jaws open at a very wide angle. (Source : Centre de Recherche Royal Canin, 2002).

- Mesocephalic cats (e.g., Maine Coon) make almost equal use of upper tongue and lips at the start of the meal (in 57% and 42% of cases respectively) (Figure 7). The upper tongue method may become more prevalent during the course of the meal or if the kibbles are smaller (83% tongue vs. 17% lips).

Figure 7. Traditional food prehension method used by the Maine Coon cat. (Source : Centre de Recherche Royal Canin, 2002).

The influence of anatomical particularities related to breed also affects others aspects of feeding behavior. After grasping a standard kibble, Persians chew in only around 10% of cases, whereas the chewing percentage is 90% among Maine Coons and Siamese cats (unpublished internal Royal Canin studies, 2002).

Hence, prehension methods differ significantly from one breed to the other, and especially from one maxillofacial biometric to another.

Feeding Rhythm in Domesticated Cats

Domesticated cats habitually divide up much of their daily food. When different types of dry food are offered, the frequency and average duration of meals varies according to the breed and the food (internal Royal Canin studies, 2006).

On average, a cat fed ad libitum will feed a dozen or so times a day. Each session lasts about two minutes, with the cat consuming around 6 g of food. In one 24-hour period, the cat therefore devotes an average of 20 minutes to eating and digesting 50-60 g of kibbles (Table 1). Nocturnal consumption accounts for 30% of all food ingested. At night, meals are generally larger and take longer. A strong correlation between breed and feeding rhythm (Figure 8) and the quantities ingested at each meal has been shown.
Figure 8. Influence of breed on the average duration of meals in cats fed with a dry food.

The influence of maxillofacial biometric variations on the feeding method of the domesticated cat is accordingly self-evident. The significant differences observed between facial morphologies provide more proof of different prehension methods, feeding rhythms and quantities of food ingested. The low adaptability of jaw movements (see above) requires them to adapt the natural sequences of prehension and ingestion to suit the food.

Domesticated cats have however retained the principle features of their wild feeding behavior. This feeding behavior continues to be studied frequently to evaluate the impact of commercial food on the oral health of cats as precisely as possible.