22 – Comparing Nutritional Needs of Dogs & Cats

Question 1

Carnivora

Answer 1

• Dogs and cats are in it
• But there are also omnivores in it

Question 2

What drove development of differing nutritional requirements in dogs compared to cats?

Answer 2

• Dogs are NOT wolves or carnivores
  o Share ancient ancestors, but exact ancestry is unknown
  o Have more genes to handle starches
• Dogs domesticated by and co-evolved with people
  o Genome derived from modern wolves
  o Fed by or scavenging from humans
  o *adapted mostly/partially to omnivore diet
• **in between carnivore and omnivore (facultative or ‘adaptive’ carnivore)

Question 3

Feline: what drove their adaptation?

Answer 3

• *Life-style
• Likely self-domesticated
• Genome WELL CONSERVED
• Hunting=10-20 small meals/day
• *obligate or ‘true’ carnivores
  o Need certain animal products for essential nutrients in natural diet

Question 4

Cats: obligate carnivores

Answer 4

• INCREASED PROTEIN requirements
  o Increased N and AA demands
  o Increased Arginine requirement
  o Taurine=ESSENTIAL
• INCRASED fat requirements
  o Arachidonic acid (AA)=ESSENTIAL
• Alterations in starch and glucose metabolism
• Dietary fiber still beneficial, but lower total ‘capacity’ (shorter colon) compared to dogs

Question 5

What drives higher protein demand in cats?

Answer 5

• Nitrogen demand=urea cycle and aminotransferases
• Glucose and energy needs=gluconeogenesis

Question 6

Cats vs. dog: urea cycle and aminotransferases

Answer 6

• *enzymes always active=always using AA
• Cats are UNABLE to downregulate activity as low as dogs
  o Urea cycle enzymes=increase Nitrogen requirements
  o Aminotransferase activity=increases in some AA requirements

Question 7

Cats and AA

Answer 7

• Very adept at utilizing AA rapidly and efficiently via gluconeogenesis to meet their endogenous glucose demands
• Maybe b/c they have a larger brain compared to body size
• *cats usually have higher AA profile requirements than dogs
  o Need arginine: for urea cycle (otherwise=ammonia toxicity)

Question 8

Arginine

Answer 8

• Indispensable/essential AA
• Cats=higher dietary requirement
  o Dogs can synthesize some arginine
• Need it to convert ammonia to urea
• Plants are lower in Arginine

Question 9

Methionine, cysteine, taurine (sulfur-containing AA)

Answer 9

• Cats: highest requirements for these
• Methionine + cysteine:
  o Cysteine non-essential but spares methionine
• Taurine
  o Made from cysteine
  o *essential in feline diet

Question 10

What is feline compound?

Answer 10

• Made form cysteine
• Produced by feline kidneys
• Give cat urine characteristic odour

Question 11

Taurine

Answer 11

• **BETA-sulfphonic AA
• NOT incorporated into proteins
  o Remains ‘free’ in tissue or conjugated to non-protein compounds
• Not degraded, oxidized or metabolized by mammals
  o BUT microbes can
• Synthesized from sulfur alpha-AA (met and cys)
• *daily loss of taurine determines DIETARY REQUIREMENT
• **always essential in cats
  o Can be conditionally essential in dogs

Question 12

*What are the sources of daily loss of taurine?

Answer 12

• ***BILE ACIDS
  o Bile acids are obligatorily conjugated to taurine in cats and dogs (not in other animals)
  o Entero-hepatic recycling occurs but ~10% still normally LOST daily
• Gut microbes
• Kidneys

Question 13

What are dietary requirement for taurine affected by?

Answer 13

• Bile acid losses and degradation by gut bacteria
• TYPE OF DIET
  o Affects gut hormones, bile acid recycling, gut microbiome
  o Canned cat food requires TWICE as much taurine as dry diets
• *individual variations in metabolism an physiology (breed variations)

Question 14

What are the general causes of taurine deficicency?

Answer 14

• Dietary
  o Insufficient methionine and cystine in diet
  o Insufficient taurine in diet (cats, some dogs)
• *ileal resection or loss of ileo-ceco-colic valve
• Increased loss of protein

Question 15

What are the consequences of taurine deficiency?

Answer 15

• Dogs and cats: DCM
• Cats
  o Central retinal degeneration
  o Reproductive impairment or developmental defects
  o Poor survival and slower growth of kittens

Question 16

Essential FAs

Answer 16

• Omega-6: linoleic acid (18C)
  o Essential DOGS and cats
  o *delta-6 desaturase very low/inactive in cats=arachidonic acid essential in cats
• Omega-3: alpha-linolenic acid (18C) (ex. flax seed)
  o Conditionally essential in growing animals
  o DHA: retina and brain (dogs and cats)
  o Supplement EPA and DHA=high in marine forms
   Animals don’t die if they don’t eat them though, but recommended

Question 17

Cats: starch and glucose metabolism

Answer 17

• *Evolved as carnivores but still use CHOs
• Inability to taste sugar
• Salivary amylase inactive
• Lower pancreatic amylase activity
• Lower intestinal amylase and disaccharidase activity than dogs
• Glucose absorption saturates sooner
• *dogs have a better capacity compared to cats
  o Have HIGHER GLUCOKINASE activities
• *cats have a limited capacity to handle fructose (FRUCTOSURIA)

Question 18

*Cats and thiamine (B1) deficiency

Answer 18

• *most susceptible species
• All carnivores have high requirements
• Require 3-4x more compared to dogs
• *severely hyporexic or starved patients will deplete thiamin relatively quickly
• Fatal if untreated
  o Neurological signs
  o Increase pyruvate=type B lactic acidosis
  o Impaired TCA cycle and ATP synthesis
  o Weakness
  o **VENTROFLEXION OF HEAD AND NECK

Question 19

Cobalamin (B12) importance and signs of deficiency

Answer 19

• *important co-factor n enzymes
• Signs
  o *Decreased appetite
  o *Lethargy
  o Anemia
  o Neurologic signs (humans)
  o Pancytopenia (not common)
  o *Inability to respond to treatment

Question 20

*What are some cause of colbalamin (B12) deficiency in dogs/cats?EXAM

Answer 20

• Insufficient INTRINSIC FACTOR (ex. pancreatic disease: EPI, chronic pancreatitis)
  o Cats: exclusively made in pancreas
  o Dogs: mostly from pancreas, less from stomach
• Problem with ILEUM (ex. enteropathy, ileal resection)
• Other: uncommon (inborn error of metabolism, B12 not liberated from food (humans))

Question 21

Niacin (vitamin B3)

Answer 21

• Higher dietary requirement in CATS
• Deficiency reduces NAD/NADH
• 4 D’s (pellagra)
  o Diarrhea
  o Dementia, disorientation
  o Dermatitis (‘black-tongue’ in dogs)
  o Death

Question 22

Fat soluble vitamins

Answer 22

• Vitamin D3: dogs have higher dietary requirement but also LOWER safe upper limit
• Vit E: increase with higher dietary fat
• Vit K: healthy microbiome can produce it, but cats eating fish-based diets require pre-formed vit K in diet

Question 23

Vit A

Answer 23

• Beta-carotene is INACTIVE in CATS
• *cats need to ingest preformed Vit A in diet
  o If eat a lot of liver=could develop Vit A toxicity and develop bony malformations