Lecture 15- Dog nutrition Flashcards
What is canine digestive physiology?
- Cats & dogs have relatively similar digestive tracts • Dogs have a larger small intestine length
- Dogs are carnivores but cats are obligate carnivores
- “obligate” = by necessity
- Also true for mink, tarsiers, dolphins, seals, sea lions, walruses etc.
What is dog’s feeding behaviour?
- Wild dogs hunt in packs • Cooperative hunting
- Dogs will eat intermittently
- Gorge after a hunt and not eat for an extended period after
- Competition between pack members causes rapid consumption • Food hoarding / burying
What is dog’s mouth like?
- Dogs (& cats) do not masticate food as much as other species • Often swallow large boluses whole
- Although dogs & cats have the same number of incisor (6) & canine (2) teeth on each jaw dogs have more premolars & molars
- Chewing/crushing plant materials (omnivore?)
- Dogs lack the α-amylase enzyme in saliva that initiates starch digestion • Saliva is very important for evaporative cooling
What happens in the esophagus in dogs?
- Cells secrete mucus to lubricate food
- Stimulated by the presence of food in the mouth
- Striated muscle
- Rapid passage of peristaltic waves • Takes only a few seconds
- Cardiac sphincter
- Junction between esophagus & stomach • Relaxes to allow food into the stomach
What is stomach like in the dog?
• Storage of food
• Important as dogs are ‘meal feeders’ & eat large amounts at one feeding event • Proximal stomach expands to store food
• Initiates protein digestion
• Major enzymes pepsin & lipase
• Mixes food with gastric secretions
• Volume of gastric secretion controlled by the volume of the meal, its protein content &
hormones
• Entry into small intestine • Controls rate of entry
• Gastric emptying is controlled by:
• Volume, energy content, viscosity, density, particle size, temperature, body
weight, amount of acid in duodenum, water intake, meal size & diet type • Higher density particles move slower
• Ave time (half empty) 72-240 mins
What happens in the small intestine?
- Chyme mixed with intestinal secretions
- Enzymatic digestion of protein, carbs & fats
- Dog SI has a simple microbial population
- Important for preventing colonisation of pathogenic microorganisms
- SI transit time influenced by diet type / size • Difficult to quantify
- 30-300 mins
What happens in the large intestine/colon?
- Dog’s cecum cat
- However bacterial digestion of fibre is minimal • ~8% total digestion
- Water absorption from the LI is important • Also electrolytes
- Fecal characteristics influenced by diet type & quantity of indigestible matter • Bacterial digestion → gases (amines indole & skatole, H2S)
- H2,CO2&CH4
- ~12 hr retention time
What are dog’s nutrient requirements?
- Deficiencies are rare in companion animals
- BUT overfeeding & excessive supplementation is common
- NRC published tables for dogs & cats • Same as other species
- Generally balanced by pet food companies
- Most companion animals are fed commercial diets
What is feeding behaviour like in dogs?
- Domestication has made dogs & cats dependent on humans for food • Although there are feral species
- Dogs hunt in packs & have broad feeding habits
- Dogs can rapidly consume their daily energy requirements in one meal
- A Labrador reportedly ate 10% of its bodyweight of a canned food in one sitting
- If allowed dogs eat fewer & larger (& more variable in size) meals than cats • Dogs drink more water than cats
- If fed one kind of food for 1st 6months of life puppies will not try novel foods when offered
- Not seen in pups fed a mixed diet
- Dogs are neophilic
- Flavour fatigue / monotonous
- Will select new flavour when fed one repeatedly
- When given a choice dogs will select 25-30% of their calories as protein
- Dogs will eat rancid foods
- Dogs respond well to umami flavours
What is the dry diet type of dogs?
• Dry (10-12% moisture):
• Dry-expanded: mainly extrusion processed which gelatinizes starch making it
more digestible. Fat generally added post-processing (sprayed on) • Meal: round or reduced in particle size
• Pelleted: grain normally heat treated to improve starch availabilty • Kibbled: similar to baking.
• All can provide entire ration if designed well
What is the semi-moist diet type for dogs?
- Semi-moist (25-35% moisture): • Cooked via extrusion
- Shelf life stability controlled by water activity • Similar basic ingredients to dry feeds
- Addition of meat or meat slurries
What is the soft-expanded diet type for dogs?
- Soft-expanded (27-32% moisture):
- High level of meat & fats
- Take on expanded appearance after extrusion
What snacks and treats for dogs?
- Snacks & treats
- Not regulated as tightly as complete diets
- Do not need to provide feeding directions
- Do not need to be complete & balanced
What is the situation with canned food?
- Canned (74-78% moisture) • Shrinking market?
- High % meat or meat by-products
- Textured protein = meat analogue (soy/wheat etc)
- High energy density
- Complete meal but often fed with dry foods
- Processing is complex
- Thiamine often lost (heat treatments)
What about table scraps?
- Ok to feed but should not be the whole diet • Difficult to quantify/qualify
- Are you meeting nutritional requirements?
- Can be dangerous
- Toxic foods for dogs
- High sugar / salt etc
- High fat can → pancreatitis
- Balance & moderation are key
