anatomy and physiology digestion and absorption. mastication mechanical reduction of the ingested...

Anatomy and Physiology

Digestion and Absorption

Mastication

• Mechanical reduction of the ingested food particles

• Food is mixed with saliva forming a bolus• Tongue (muscular organ) moves food around

mouth to form and push bolus down esophagus

Tongue

• Taste buds – more discriminatory when food is in a native or unprocessed state (able to distinguish between harmful and proper foods)

Taste Buds

• Humans: – 5-6 types of taste buds: sour, bitter, salty, umami

(meatiness) and sweet (possibly fat)– sweet receptor made up of two coupled proteins

generated by two separate genes• Tas1r2 and Tas1r3

Cats Can’t Taste Sweet• Cats have about 470 taste

buds• lack 247 base pairs of the

amino acids that make up the DNA of the Tas1r2 gene– does not code for the

proper protein

Why do you think it is a good thing that cats can’t taste sweet things?

Cats Can’t Taste Sweet• cats can taste things

humans cannot– ATP– signal for meat

• most major pet food manufacturers use corn or other grains in their meals– Cat food = ~20%

carbohydrates– Is this causing diabetes in

cats?

Cats Can’t Taste Sweet

• The suggestion that cats may have difficulty adapting to high-carbohydrate meals appears to be based on two observations:– (1) cats lack glucokinase, an enzyme used to

phosphorylate glucose inside cells– (2) cats lack salivary amylase and, compared with

dogs, may have lower activities of the enzymes involved in carbohydrate digestion

Cats Can’t Taste Sweet

• For glucose to be used by a cell, it must enter the cell and be phosphorylated by glucokinase

• Lacking glucokinase activity, cats rely on other enzymes, including hexokinase– less efficient than glucokinase when glucose

concentrations are high, cats have considerably more hexokinase, phosphofructokinase and pyruvate kinase enzyme activities than dogs

Dogs Can’t Taste Salt

• Dogs have only about 1,700 taste buds that people (~10,000) do, and their distinct sense of taste is actually quite poor

Diseases of the Oral Cavity

• Oral Tumor: can arise from the bone, teeth or soft tissue structures of the lower (mandible) or upper (maxilla) jaw, or the tongue or pharynx

Oral Tumors

• most are malignant• malignant melanoma

and squamous cell carcinoma are the most common oral tumors in dogs

• squamous cell carcinoma is the most common oral tumor in cats

Oral Tumors• Diagnosis

– Physical exam– Blood tests– Aspiration– MRI– Chest X-rays

• Treatment– Surgery– Radiation– Chemotherapy

Periodontal Disease

• Preventable• Shows up at 3-4 years

of age• Clinical Signs– Inflamed gums– Tartar build up– Loose teeth– Difficulty eating– Halitosis

Periodontal Disease• Mainly caused by bacteria: Peptostreptococcus, Actinomyces, and

Porphyromonas• Treatment:

– Dental cleaning (vet)– Brush teeth daily (home)– Diet (tartar contro, i.e. T/D)– Tooth extraction

Stomatitis

• Painful, inflammation of the mouth• Potential to be fatal

Periodontal Disease

• Periodontal disease can lead to heart diseaseand kidney disease if left untreated