Metabolic, Nutrition Flashcards
Define metabolizable
energy (ME).
ME of a nutrient is the amount of energy available to the animal after taking into account losses from digestion (nutrients in foods are not 100% digested),
urine losses, and losses in exhalation of gases.
Average ME for protein vs fat vs CHO in whole food vs commercial dog food?
Protein & CHO: 3.5kcal/g (dog food), 4kcal/g (whole food)
Fat : 8.5kcal/g (dog food), 9kcal/g (whole food).
Recommendations for minimum dietary protein intake in working dogs?
22-24% ME
(25-28% or higher if maintaining muscle, extreme working envt)
What energy sources do dogs use predominantly during low, moderate & intense exercise?
Exercise at </=40% of max aerobic capacity: predominantly fat (aerobic metabolism)
40-70%: CHO (from protein oxidation) & fat
> 70% (e.g. sprinting): glucose (anaerobic metabolism)
Causes of hypercobalaminemia in dogs & cats?
Dogs - overall 3% incidence of high B12. DDx chronic GI signs (48%), hypoA (uncommon)
Cats - chronic enteropathy (65%), acute/chronic pancreatitis (24%), cholangiohepatopathy, gastric lymphoma (6%), hyperT (3%).
Short chain fatty acids
- Produced by which bacteria?
- Name the main SCFAs.
- Name 5 key roles.
Ruminococcus, Faecalibacterium, Turicibacter - ferment dietary CHO to SCFAs.
Butyrate, acetate, propionate.
Roles:
* Nutrients
* Regulate satiety
* Anti-inflammatory properties
* Regulate intestinal motility
* Downregulate intestinal pH to create an environment that is not suitable for pH-sensitive enteropathogens.
Dietary copper - what forms are available, and which form is recommended?
Copper sulfate recommended, more bioavailable vs copper oxide.
Describe copper metabolism.
Copper absorption occurs in the upper SI via membrane transporters –> transported to liver in free & protein-bound forms –> uptake by hepatocytes –> added to transcriptional products, bound to metallothionein or cupriproteins for storage, OR shuttled to canaliculi for bile elimination.
Describe roles of copper.
Required for function of the following metalloenzymes:
- Lysyl oxidase - essential for molecular cross-linking of collagen & elastin
- Cytochrome c oxidase - essential for electron transport chain that generates ATP –> mitochondrial energy generation
- Copper–superoxide dismutase - role in antioxidation, dismutates superoxide anions that otherwise cause oxidative damage to local protein & lipid cell constituents.
AAFCO recommendation for minimum daily copper intake for maintenance adult dog diet?
How does this compare to prescription copper restricted diets?
1.83 mg/1,000 kcal = ~Cu intake of ~0.067 mg/kg/day
(0.9 to 1.1 mg/1,000 kcal, ranging from approx 0.04 to 0.07 mg/kg/d)
What is a disadvantage of feeding a hepatic diet to dogs with copper storage/necroinflammatory liver disease vs dogs with PSS or HE? (Hint: copper & protein content)
Most dogs with CSH or NIH don’t have hepatic failure or HE - so protein restriction is not ideal as these patients can be expected to have heightened nitrogen turnover secondary to inflammatory cytokines & catabolism.
Consequences of phosphorus deficiency? (Name 3)
Hemolytic anemia
Decreased mobility
Metabolic acidosis
Consequences of phosphorus deficiency? (Name 3)
Hemolytic anemia
Decreased mobility
Metabolic acidosis
What dietary factors may affect phosphorus bioavailability?
Form of phosphorus (inorganic Na/K phos salts more available than organic e.g. meat, bone meal) - feeding highly available phos with too low Ca can cause renal damage in cats.
Dietary Ca content (Ca:P ratio) - high Ca:P ratio (1.5-2:1) results in less increase in serum P
Dietary Mg content - high dietary Mg content (>0.32g/1000kcal ME) reduces P intestinal absorption by 13%. Unknown mechanism.
What dietary factors may affect phosphorus bioavailability?
Form of phosphorus (inorganic salts more available than organic)
Dietary Ca content (Ca:P ratio) - high Ca:P ratio (1.5-2:1) results in less increase in serum P
Dietary Mg content - high dietary Mg content (>0.32g/1000kcal ME) reduces P intestinal absorption by 13%. Unknown mechanism
Apart from neurological signs, what does mucopolysaccharidosis (liposomal storage disease) typically cause?
Skeletal & ocular changes.
What IV drug can be used to activate lipoprotein lipase? How does it work?
Ettinger
Heparin, used in a liproprotein lipase activity test.
Heparin activates lipoprotein lipase (LPL) by releasing LPL from vascular endothelium where it is normally anchored.
Also activates hepatic lipase (HL). Overall enhances plasma lipolytic activity & elevates FFA levels.
What are the roles of adiponectin? What is the effect on obesity on it?
Ettinger Chap 176
Adiponectin = synthesized by mature adipocytes.
Roles vary depending on organ. Increases insulin sensitivity, lowers serum glucose [ ], reduces liver & muscle triglyceride concentrations.
Anti-inflammatory & insulin-sensitising hormone.
Serum concentrations are decreased with obesity (possibly inhibition by inflammatory cytokines)»_space; results in insulin resistance.
What is leptin & its effects? What is its status in obese cats?
Adipokine (secreted by fat). Long term regulation (suppressant) of food intake/appetite.
Crosses BBB > binds to leptin receptors in hypothalamus > decreased fat storage –>
- Decreases hypothalamic secretion of appetite stimulants (NPY / ARGP)
- Activates POMC neurons
- Increases production of hypothalamic hormones that decrease appetite
- Increases SNS activity > incr metabolic rate
- Decreases insulin secretion; modulates insulin sensitivity.
Obese cats/dogs are leptin-resistant (high circulating leptin [ ] but less response)
Glycogen storage diseases - types, breeds affected, CSx?
Glycogen storage dz – deficient or defective activity of the enzymes responsible for metabolizing glycogen.
- Type Ia = Maltese (von Gierke dz); deficiency in glucose-6-phosphatase (gene mutation)
- Type II = Lapland dogs (Pompe dz); deficiency of lysosomal acid a-glucosidase
- Type III = GSD and Curly-coated retrievers (IIIa) (Cori’s dz) deficiency of glycogen debranching enzyme amylo-1,6-glucosidase»_space; Curly coated affects liver and muscle (AGL gene)
- Type IV in Norwegian Forest cats (Anderson’s dz), deficiency in glycogen branching enzyme glycogen accumulation in skeletal m, cardiac m, nervous system
- Type VII = English springer spaniel (Tauri’s dz) deficiency in PFK»_space; hemolytic anemia, hemoglobinuria
Tryptophan
- Metabolic pathways & roles
- Significance in which diseases
Allenspach VCNA 2021 PLE review
- Essential AA in dogs/cats, largely absorbed in SI
- 2 main metabolic pathways in host:
1. Kynurenine pathway (90%) = energy metabolism: precursor for kynurenine
2. Serotonin pathway (5%) (90% in ENS, 10% in brain): metabolized to serotonin
- Melatonin pathway (pineal gland, GIT)»_space; metabolized to melatonin
3. Small % reaches colon»_space; metabolized by luminal bacteria to metabolites (indole, skatole indicant, tryptamine ‘SIT’).
- Microbial metabolites play an essential role in counteracting intestinal inflammation (induce anti-inflammatory cytokines e.g. IL-22).
PLE, canine CIE
What are the major roles of leptin & where are its receptors located? What factors can influence circulating leptin levels?
Type of adipokine.
Roles
- Suppress appetite
- Inhibit apoptosis (mitogen)
- Stimulate angiogenesis
- Pro-inflammatory, modulate T cell responses
- Repro - incr during puberty, causes FSH & LH release
- Pro-thrombotic
- Inhibits adiponectin (opp effects)
OB-R in hypothalamus (satiety centre), also hematopoietic SCs
Circadian rhythm
Amt of fat mass (linked to BW) - increases leptin expression but causes ‘leptin resistance’
Food (post prandial levels = 2-3x fasting levels)
Breed (Shelties higher)
GCS tx (dex incr, pred no effect, methylpred high dose suppress but low dose incr)
What are the top 2 major endogenous sources of angiotensinogen?
1 white adipose tissue (WAT)
#2 Liver