Dog Digestion, Portosystemic Shunt, and Cleft Palate

Canine Dentition

Canine teeth for gripping; molars and premolars for cutting

Digestive Organs

Simple stomach, short large intestine

Dog Diet

Mostly carnivorous, omnivorous if available; eat small canidae (parts of whole carcasses of rabbits and rodents, even the poorly digestible parts); eat apples, grasses, persimmons, etc

Resting Energy Expenditure for Dogs

70 x W(kg)^0.75

Protein Digestibility in Dogs

From most to least: Meat, casein, soy, field beans, keratin

Arginine

Required in dogs (though not as much as cats); so cats cannot eat dog food but dogs can eat cat food

Fat

Dogs are good at digesting this; almost all of it is digested in the small intestine and emulsified with bile

Blood Transport

Similar to other species

Fat Metabolism in Dogs

2x the human rate; adapted for aerobic form of this; atherosclerosis/heart attacks are rare because fat is transported differently in dogs

Lipoprotein Distribution Percent

Lipid inside, outside hydrophilic

HDL

Less of it makes you more prone to heart attacks

LDL

More of it makes you more prone to heart attacks

Unsaturated Fatty Acid Metabolism

n6 Linoleic Acid —> n6 Arachidomic acid

n3 alpha-linolenic acid —> n3 EPA —> n3 DHA (VERY important for diet)

Carbohydrate

Central metabolic role for glucose; no pregastric amylase; disaccharides

Carbohydrate Digestion

Dogs & people can use amylase to break a (1,4) bond (starch)

Dogs & people cannot break a (1,6) bond (cellulose)

Fermentable Polysaccharides

Can be digested/broken apart

Pregnancy Experiment

In pregnant females with low protein diets and no carbs, they became hypoglycemic and had ketosis & fetal death, but with high protein diets and no carbs, they were okay; carbs are NOT necessary if there is enough protein

Undigested Starch

Fermented and becomes volatile fatty acids in the colon

Volatile Fatty Acids

Source of energy (only about 5% b/c colon is short); butyrate is preferred fuel of colonocyte; promote sodium and water absorption; stimulate blood flow & cell turn over; prevents diversion collitis

Soluble Fiber

Creates firmer feces

Feces

Need a good balance of soluble fiber, fermentable carbs, and fat

Vitamins and Minerals

Dogs do not require Vitamin C but require Vitamin D; salt requirements are low b/c dogs don’t sweat and losses from panting are small; dogs just need water (no salt)

Sources of Energy

ATP & Creatine (bad for long distance), anaerobic glycolysis (glycogen), glucose oxidation (protein), fat oxidation

Glycogen

Amount is important for stamina

Muscles Types

High oxidative; slow twitch and fast twitch (greyhounds have almost all fast twitch)

Effect of Diet on Stamina in Beagles

Low fat diet - didn’t do well

High fat diet - did well

Fat Adaptation

Prolongs exercise with little food

Portasystemic Shunt Cast (Examination)

Visual impairment, can’t walk; after a few hours, could walk but was still visually impaired; after a few hours, normal

Abnormal Cerebral Function

Aimless walking, blindness, disorientation

Impaired Peripheral Nerves

Recumbency and problems walking

Metabolic Disturbance

Fluctuating Clinical Signs

Portasystemic Shunt Case Study (Hypothesis)

Issue with prosencephalon due to metabolic disorder; hypoglycemia, hypoxia, hyperammonemia

Portasystemic Shunt Case Study (Second Hypothesis)

Lab tests suggested abnormal liver function; hypothesis is hepatic encephalopathy

Portal Venogram

X-Ray

Portal scintigraph

Camera

Portasystemic Shunt

When one or several vessels connect the portal vein to the caudal vena cava or Azygous vein; blood is shunted past the liver to the heart

Extrahepatic Shunts

Causes toxins because it allows blood to bypass the liver

Acquired PSS

Surgical correction is very difficult/not possible

Surgery for Extrahepatic Shunt

Use an aneroid constrictor to slowly close vessel

PSS Surgery Complications

High blood pressure, 15% will develop additional shunts, infection, possibility of seizures, 85% surgical success rate

Cleft Palate

Could be congenital based on breed (purebreds and brachycephalic breeds) or congenital based on pregnancy conditions (viral illness, hypoxia, pesticide exposure, cortisone use, excessive vitamin A)