Physiological consequences of alternative diets

Question 1

What are the physiological consequences of a vegetarian diet

Answer 1

Deficiencies in essential amino acids can lead tosevere disease and deatrh
- arginine is required by the urea cycle to convert toxic ammonia to urea
- ammonia is a by-product of protein metabolism
- if a cat eats a meal without arginine, this can result in hyperammonemia which may be seen as vocalisation, vomiting, ataxia, cyanosis and death

- taurine is an essential nutrient for cats and deficiency results in heart disease
    - cats can only synthesize minimal taurine due to lacking enzymes and therefore must obtain from diet
    - taurine is found primarily in animal based products
    - taurine is used to conjugate bile salts into bile acids
    - deficiency is associated with retinal degeneration and blindness, dilated cardiomyopathy, reproductive problems, abnormal skeletal development in kittens

Cats have low conversion efficiency for beta carotene to be processed to vitamin A
- the retinal form (found in animal sources such as liver) of vitamin A is required
- cats lacking vitamin A may have poor coat and eye health

Cats are unable to synthesize vitamin D
- they must consume animal fat and tissue
- vitamin D deficiency can lead to secondary nutritional hyperparathyroidism

Cats cannot synthesize arachidonic acid from linoleic acid
- arachidonic acid is needed for cell membranes
- a vegetarian diet would be devastating if fed to a kitten

Question 2

What are the physiological consequences of a diet entirely composed of raw fish

Answer 2

Thiamine deficiency may be seen due to a raw fish diet as they contain thiaminase, an enzyme which breakdowns the thiamine
- cooking the fish destroys the thiaminase
- thiamine is a water soluble vitamin required for formation of thiamin pyrophosphate which serves as a coenzyme in carboxylation reactions in carbohydrate and amino acid catabolism
- clinical signs include anorexia, weight loss depression, progressive mydriasis, ataxia, weakness, seizures and eventually death
- myocardial degeneration is also described

Vitamin E deficiency may also result
- fish contains PUFAs that are easily oxidised
- Vitamin E is an antioxydant that prevents oxidation of fatty acids in cell membranes

Question 3

What are the physiological consequences of a diet entirely composed of liver

Answer 3

Vitamin A toxicity can occur
- chronic hypervitaminosis A is characterizzed by formation of exostoses on the cervical vertebrae causing ankylosis, deformation and crippling
- also possible: growth retardation, abnormal dentition and neurological deficits as a result of nerve entrapment from hyperostoses

Hypervitaminosis D may occur as vitamin D is abundant in liver
- excess can result in hypercalcemia which may lead to PUPD, anorexia, vomiting and constipation, seizures