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Introduction to nutrition:
Basics & essential nutrients
Nutrition series – 1
Dr. Sarah Wilson

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Introduction to nutrition - Outline
- Essential nutrients for dogs & cats
- Digestion & absorption
- How to evaluate basic nutrition
- Energy requirements – introduction
- Helpful resources & references

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Why is nutrition important?
- Every patient needs food
- Hippocrates
- Let food be thy medicine & medicine be thy food
- If we could give every individual the right amount of nourishment and
exercise, not too little and not too much, we would have the safest way to health

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Essential nutrients
- Essential nutrients are required in adequate amounts from an outside source as the animal cannot make enough (or any) to support their needs

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Essential nutrients
- Basic categories of essential nutrients
- Water
- Energy
- Amino Acids
- Fatty Acids
- Vitamins
- Minerals
- (& others)

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Essential nutrients - Water
- Most important essential nutrient
- Requirements are equivalent to daily energy needs
- Fresh, clean source of water should always be available
- Remember preferences (cats – location, type of dish/flow)

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Essential nutrients
- Energy
- Amino Acids
- Fatty Acids
- Vitamins
- Minerals
- (& others)

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Essential nutrients – Energy
- Energy obtained from macronutrients
- Protein, fat, & carbohydrate
- Calories = kcal
- The first requirement to be met by diet
- Protein & carbohydrate provide ~4 kcal/g
- Fat provides ~ 9 kcal/g (twice as calorie dense!)
- Pet foods use modified Atwater factors for energy conversion
- Protein & carbohydrate (3.5 kcal/g) & fat (8.5 kcal/g)

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Dietary Energy
Gross Energy GE
- Fecal energy lost
Digestible Energy DE
- Urinary energy lost
- Fermentation losses (negligible)
Metabolizable Energy ME
- Dietary thermogenesis

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Essential nutrients
- Amino Acids
- Fatty Acids
- Vitamins
- Minerals
- (& others)

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Essential nutrients – Amino Acids
Amino Acids (or nitrogen source)
Essential AA for dogs PHILL MT VAT
Essential AA for cats PHILL MT VATT
Dietary Protein(plant & animal sources)
-Phenylalanine
-Hisitidine
-Isoleucine
-Lysine
-Leucine
-Methionine
-Tryptophan
-Valine
-Arginine
-Threonine
-*Taurine
-Nonessential amino acids
-Alanine
-Adpargine
-Aspartate
-Cysteine
-Glutamate
-Glutamine
-Glycine
-Hydoroxylysin
-Hydroxyproline
-Proline
-Serine
-Tyrosine

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Essential nutrients
- Fatty Acids
- Vitamins
- Minerals
- (& others)

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"Essential nutrients – Fatty Acids
- Essential Omega 3 & 6 fatty acids
- Linolenic, linoleic, *arachidonic
- Dietary Fat (plant & animal sources)
- Concentrated form of energy
- Facilitates absorption of fat-soluble vitamins
- Enhances palatability

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Essential nutrients
- Vitamins
- Minerals
- (& others)

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Essential nutrients - Vitamins
- Vitamins – organic molecules
- Fat soluble - Vitamins A, D, E, & K
- Water soluble – B-complex vitamins
- Thiamin, riboflavin, niacin, pyridoxine (B6), biotin, folate, cobalamin (B12), pantothenic acid, & choline
- vitamin C – Essential: humans, non-human primates, fruit-eating bats & guinea pigs require
-Dogs & cats can synthesize vitamin C – Non-essential

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Essential nutrients
- Minerals
- (& others)

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Essential nutrients - Minerals
- Minerals – inorganic molecules
- Macrominerals
- Ca, P, Mg
- Na, K, Cl (electrolytes)
- Trace minerals - Fe, Zn, Cu, Mn, Se, I, & possibly others

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Essential nutrients
- (& others)

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Conditionally essential nutrients
- Other nutrients *
- Taurine
- Carnitine
- EPA & DHA * growth & reproduction

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Dietary Energy
Gross Energy GE
- Fecal energy lost
Digestible Energy DE
- Urinary energy lost
- Fermentation losses (negligible)
Metabolizable Energy ME
- Dietary thermogenesis

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Digestion & Absorption
- Digestion breaks down larger complex molecules into simplest form of essential nutrients
- Mechanical digestion – mastication, mixing, & peristalsis through gastrointestinal tract
- Chemical digestion – splitting chemical bonds of complex nutrients via metabolic enzymes

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Digestion & Absorption
- Gastrointestinal tract (GIT)
- Mouth – food mixes with saliva, bolus of food with little to no chewing;
- *taste sweet/bitter
- Esophagus – megaesophagus, strictures
- Stomach – storage & chemical digestion, as well as some peristaltic movement
- Pyloric sphincter controls rate of passage of food (influenced by fat, volume, fiber, etc.)
- Small Intestine – fat digestion, nutrient absorption at brush border of microvilli
- Nutrient absorption via passive diffusion, facilitated diffusion, & active transport
- Large Intestine – Colon – main function to absorb water & electrolytes
- Microbiome – may digest indigestible fiber (and other nutrients)
- Vestigial cecum - cat

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Digestion & Absorption
- Important factors affecting absorption
- Vitamin/mineral interactions – excesses, nutrient sparing
- Patient health status – chronic enteropathies, surgery

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How to evaluate basic nutrition
WSAVA Global Veterinary Development
Nutritional Assessment Guidelines

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How to evaluate basic nutrition
- Nutritional Assessment
- Patient evaluation – Physical examination
- Bodyweight history
- Body condition score
- Muscle condition score

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How to evaluate basic nutrition
- Body Condition Score BCS – every visit
- Two scales
- 1-5
- 1-9
Images from: https://wsava.org/WSAVA/media/Documents/Committee%20Resources/Global%20Nutrition%20Co mmittee/English/Body-Condition-Score-cat.pdf & https://wsava.org/WSAVA/media/Documents/Committee%20Resources/Global%20Nutrition%20Co mmittee/English/Body-Condition-Score-dog.pdf

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How to evaluate basic nutrition
- Muscle Condition Score
MCS – every visit
- Scale
- Normal, mild, moderate, & severe muscle loss
Image from: https://www.wsava.org/WSAVA/media/Documents/Committee%20Resources/Global%20Nutrition%20Co mmittee/English/Muscle-Condition-Score-Chart-for-Dogs.pdf & Cats.pdf

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How to evaluate basic nutrition
- Any red flags – investigate further
- Further history details
- Possibly diagnostics
- radiographs, bloodwork
- Need to implement a plan
- Diet (+/- treats, supplements)
- Feeding plan with details
- Monitoring & follow - up
Images from: https://wsava.org/WSAVA/media/Documents/Committee%20Resources/Global%20Nutrition%20Committee/English/ Nutritional-Assessment-Checklist.pdf

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Energy requirements - introduction
- Resting Energy Requirements (RER) – the energy needed for a normal unfasted animal at rest under normal temperature conditions
- Maintenance Energy Requirements (MER) – the energy needed to keep an animal in a maintenance state
- Includes activities necessary for work, growth, reproduction, lactation
- Also referred to as Daily Energy Requirement (DER)\

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Energy requirements - RER
- RER calculations (provide an estimate of daily resting energy requirement)
- 30 x (Body weight in kg) + 70
Or
-70 x (Body weight in kg)0.75 Metabolic body weight = kg0.75
- Example: 10 kg dog (M/N, 3 y, BCS5/9)
- 370 kcal / day RER
- 394 kcal / day RER

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Energy requirements - MER
MER = RER x Factor = estimate of maintenance energy requirement
Canine
- Intact Adult 1.8
- Neutered Adult 1.6
- Puppies < 4mos 3.0
- Puppies >4 mos 2.0
- Obese prone 1.4
- Low activity 1.4
- Weight loss 1.0
- Critically ill 1.0
Feline
- Intact Adult 1.4
- Neutered Adult 1.2
- Kittens < 4mos 3.0
- Kittens >4 mos 2.0
- Obese prone 1.0
- Low/No activity 1.0
- Weight loss 0.8-1.0
- Critically ill 1.0

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Energy requirements - MER
- MER = RER x Factor = estimateof maintenance energy requirement
- Neutered Adult 1.6
- RER (previously calculated)
- 370 kcal / day (linear)
- 394 kcal / day (allometric)
- Example: 10 kg dog (M/N, 3 y, BCS 5/9)
- MER = 592 kcal / day
- MER = 630 kcal /day

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Energy requirements - MER
- National Research Council (NRC, 2006)
- Uses a multiplier & metabolic body weight
- DOGS
- Active ME maintenance = 132 kg0.75 kcal/day
- CATS
- Lean cats ME maintenance = 100 kg0.67 kcal/day
- Overweight cats ME maintenance = 130 kg0.40 kcal/day

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Energy requirements
- Remember that calculations for RER & MER are estimates
- Can be used as a guide to evaluate patient needs – starting place
- Energy calculations can differ up to +/- ~50% of actual individual needs

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Helpful internet resources & references
- World Small Animal Veterinary Association (WSAVA) Global Nutrition Guidelines - https://www.wsava.org/Guidelines/Global-Nutrition-Guidelines
- American College of Veterinary Nutrition
- https://acvn.org
- American Academy of Veterinary Nutrition
- https://www.aavn.org
- Academy of Veterinary Nutrition Technicians
- http://nutritiontechs.org

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Helpful internet resources & references
Table 2 Useful web sites for client and starff education
1.AAFCO Association of American Feed Control Officials(Nutrien profiles,feeding trials,ingredients)
http://www.aafco.org
2.AAHA American Animal Hospital Association
http://www.aahanet.org
3.AAVN American Academy ofo Veterinary Nutrition
www.aavn.org
4.ACVN American College of Veterinary Nutrition(Specialty college for board certification; list of institutions that provide consultation; continual updates of links to resources for diet formulation and analysis)
http://www.acvn.org
5.AVNT Academy of Veterinary Nutrition Technicians
http://nutritiontechs.org
6.European Society of Veterinary Clinical Nutrition
http://esvcn.com
7.FDA Center for Food Safety and Applied Nutrition(regulatory and safety issues,adverse event reporting,meetings,industry infomation)
http://fda.gov/AboutFDA/CentersOffices/CFSAN/default.htm
8.FDA Pet Food Site(information,links,food safety issues,recalls,pet food labels,selecting nutritious food,handling raw foods)
http://www.fda.gov/AnimalVeterinary/NewsEvents/CVMUpdates/ucm0480630.htm
9.European Pet Food Industry(Nutritional guidelines,guide to good food practice)http://www.fediaf.org
10.Indoor Pet Intiative(Comprehensive recommendations for environmental enrichment for dogs and cats.)
http://indoorpet.osu.edu
11.NRC National Research Council(Nutrient Requirements of Dogs and Cats)
http://www.nap.edu/banr/petdoor.html
12.NRC Downloadable booklets.Your Cat's Nutritional Needs and Your Dog's Nutritional Needs.Versions for pet owners:BANR Board on Agriculture and Natural Resources Petdoor Nutrient Requirements of Dogs and Cats.
http://dels-old.nas.edu/banr/petdoor.html
13.NIH Office of Dietary Supplements(Evaluating supplements,internet health info,and more)
http://ods.od.noh.gov
14.University of California Davis Diet History Form(Downloadable Word document)
http://www.vetmed.ucdavis.edu/vmth/small_animal/nutrition/newsletters.cfm
15.Pet Food Institute(Information on ingredien definitions,labeling regula-tions,etc.)
http://www.petfoodinstitute.org/Index.cfm?Page=Consumers
16.United SStates Pharmacopeia Dietary SUpplement Verification Program(voluntary program)
www.usp-dsvp.org
17.USDA Food and Nutrition Information Center(General supplement and nutrition information,links to a variety of dietary supplement websites)
http://www.nal.usda-gov/fnic/etext/000015.html
18.USDA Nutrient Database(full nutrient profiles on thousands of human foods)
http://www.nal.usda.gov/fnic/foodcomp/search

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References
- Small Animal Clinical Nutrition 5th Ed. (Hand et al., 2010)
- Nutrient Requirements of Dogs & Cats (NRC, 2006)
- Applied Veterinary Clinical Nutrition (Fascetti & Delaney, 2012)
- Association of American Feed Control Officials (AAFCO, 2018)
- Manual of Veterinary Dietetics (Buffington et al., 2004)
- Canine and Feline Nutrition, A resource for companion animal professionals (Case et al., 2011)