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Veterinary Pathophysiology Student’s Lectures, 5th Semester

Department of Clinical Pathology and Oncology University of Veterinary Medicine

Disorders of the alimentary tract 1. Disorders of food intake and prehension

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QUANTITATIVE DISORDERS OF PREHENSION OF FOOD AND WATER 1.

Prehension: act of seizing and conveying of food and water

Important: hunger appetite

Hunger is a sensation of longing for food.

Appetite is a desire for food but not necessarily prompted by hunger.

In everyday life the meaning of the two words are mixed.

Anorexia Incapability of eating/prehension

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Control of appetite

http://arbl.cvmbs.colostate.edu/hbooks/pathphys/digestion/pregastric/foodintake.html

• Central neural control

• Pregastric factors (appearance of

food, smell, taste, learned experience

and aversions, psychologic factors)

• GI and postabsorptive factors’ effect

on hunger (GI fill ↓, cholecystokinin

↓, ghrelin , leptin, and adiponectin ↓,

glucostatic and lipostatic modell –

glucose, FFA ↓ or )

• Set weight – long term control of

food intake „set point” modell

Basic definitions

• Hypophagia – reduced food intake

• Aphagia – refusal or inability to swallow

• Dysphagia – Medical term for any difficulty, discomfort or pain

when swallowing

• Polyphagia, hyperphagia, bulimia – excessive food intake

– (bulimia – voracious appetite and vomiting shortly afterwards)

• Polydipsia (physical alterations, psychogenic) – excessive water

intake

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Causes for anorexia:

• increase in blood glucose, FFA, VFA, AA concentration (e.g.

Tissue necrosis)

• repletion of the stomach (ballasts)

• hyperthermia, fever, neoplasms, pain, cognition disorders (e.g.

Bevaioural changes – depression, demention), gastro-intestinal

problems etc.

• In older age decrease in sensing

• Psychogenic?!

Causes for incapability of eating:

• disturbance in food intake – prehension, chewing, swallowing

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QUANTITATIVE DISORDERS OF PREHENSION OF FOOD AND WATER

Causes of decreased sense of thirst: haemodilution, lack of

consciousness (behavioural changes, dementia, depression)

Causes of incapability of drinking: see incapability of eating

Decreased sense of thirst incapability of drinking

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QUANTITATIVE DISORDERS OF PREHENSION OF FOOD AND WATER– see

lecture about metabolism

Overfeeding, obesitas Obesitas = energy intake > absolute/relative need

Causes: endogenous e.g. hypothyreosis RARE!

exogenous e.g. tasty, energy dense food

Consequences: obesitas, adipositas = increase of BW

due to fat deposition)

Starving Absolute Partial

serious diseases and decreased food intake,

local causes (e.g. trismus, bad quality food,

incapability of swallowing) malabsorptio,

Rare increased loss (GI, kidneys)

increased need (production),

Frequent forms!

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QUALITATIVE DISORDERS OF FOOD INTAKE (PICA OR CHANGE OF APPETITE) 1.

Allotriophagy (pica)

inorganic: organic: macro- and microelements proteins, AS, vitamins

Ingestion of strange materials not normally considered to be food.

Most cases are the result of dietary deficiencies, which force the animal to satisfy its craving by eating unusual items.

A desire for improper food.

Or: A vitiated appetite that craves what is unfit for food, as chalk, ashes, coal, etc.; chthonophagia. Source: Webster’s Dictionary

Amylophagia (starch)… Coprophagia (faeces)… Geophagia (soil, clay, chalk)…

Hyalophagia (glass)… Lithophagia (a form of geophagia – pebbles, stones)…

Mucophagia (mucus)… Odowa (soft stones – Kenya, pregnant women)…

Pagophagia (ice)… Önkannibalizmus (in humans Lesch-Nyhan syndrome)…

Trichophagia (hair, wool)… Urophagia (urine)… Xylophagia (wood or paper)

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QUALITATIVE DISORDERS OF FOOD INTAKE (PICA OR CHANGE OF APPETITE) 2.

Coprophagy: The ingestion of feaces. This is normal in some species: rabbits, pigs etc. Can be unusual form of depraved appetite, in which the animal tries to correct a dietary deficiency or it may be a vice caused by boredom.

Cannibalism: Any of various vices in which an animal attacks its own kind.

Causes: overcrowding or dietary deficiency. Common in intensively housed poultry and pig farms. Cannibalism of newborn by the dam can occur in some species, especially pigs or dogs, following stress or for no apparent reason. Attacks are often apparently unprovoked and may be sustained, with no relation to the victim

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Allotriophagia – due to boredom

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DISORDERS OF SEIZING, MASTICATION AND SWALLOWING 1.

Reasons: Local diseases of lips, mouth, teeth, tongue,

masseter muscles, mandibular joints are involved + CNS!

1. Seizing difficulties

differences according to species:

Cran. nerves: V, VII, XII

carnivora horse ruminants

http://jama.ama-assn.org/content/vol298/issue1/images/medium/jmn70071fa.jpg

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Rabies – n. trigeminus paralysis

n. facialis - paralysis http://chestofbooks.com/

Paralysis of the

tongue in

botulism www.uwyo.edu

Actinobasillosis („wooden tongue”) http://www.dpi.nsw.gov.au/

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2. Mastication (chewing) disorders – 2.a. muscle disorders

paralysis: impairment of muscle function usually due to cranial

nerve (CNS) lesions (rabies n. trigeminus)

trismus: tonic spasm of the muscles of the jaw (tetanus, strichnine

poisoning)

tic: repetitious, irresistible contraction of muscles (distemper

m. temporalis)

myositis: inflammation of m. temporalis, m. masseter (ie. myositis

eosinophilica)

DISORDERS OF SEIZING, MASTICATION AND SWALLOWING 1.

Scott et al. Dermatology

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Masticatory disorders

Myositis (actinobacillosis),

Trismus (due to tetanus)

A disease characterised by suppurative and granulomatous lesions

Actinobacillus lignieresii.

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2.b. Inability in eating due

to overgrowth of teeth

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2.b. Inability in eating due to overgrowth of teeth

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2.b. Inability in eating due to overgrowth of teeth

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Inability of eating and drinking, joint disorders („hanging jaw”)

Dislocation of mandibula

2.c. mandibular-temporal joint disorders

- paralysis

- joint inflammation

- dyslocatio

- fracture

2.d.Fracture of other bony elements

http://www.vetsurgerycentral.com/

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DISORDERS OF SEIZING, MASTICATION AND

SWALLOWING 2.

3. Deglutition (swallowing) disorders

Dysphagia: difficulties or inability in swallowing

Cause: - degeneration of muscle

- myasthenia gravis – a synaptic disorder

- achalasia of the lower esophageal sphincter (cardia)

- foreign bodies ("choke"),

- persistent right aortic arch (ductus arteriosus Botallo)

- rabies, pseudorabies, botulism glossopharyngeal nerve.

Consequence: regurgitation, vomiting, aspiration pneumonia

meg

aoes

op

hag

us

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Dysphagia: megaoesophagus • large, flaccid esophagus

• severe motility disorder: hypomotility,

dilation, regurgitation (weight loss)

• congenital and acquired

• Congenital megaesophagus in both dogs

and cats - signs are obvious around

weaning time

• Acquired megaesophagus quite frequent

in middle aged to older dogs (esp. large

breeds).

Cats, horses – dysautonomia: a profound

failure of both sympathetic and

parasympathetic functions across several

organ systems (nucleolysis, swelling of

neurons – Cl. botulinum C type toxine?) http://vet.uga.edu/

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• Anticholinesterase Ig - Myasthenia

gravis

• Distemper

• Esophagitis

• Gastric food retention

• Genetic, hereditary

• Hypoadrenocorticism

• Hypothyroidism

• Polymyopathy

• Polyneuritis

• Vascular ring anomaly

Persistent ductus Botalli, megaoesophagus

http://jama.ama-assn.org/content/vol298/issue1/images/medium/jmn70071fa.jpg

Megaoesophagus etiology

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Oesophagus motility disorders Esophageal dysmotility in young dogs - Esophagealis dysmotility

without megaesophagus – young terriers, symptomatic or

asymptomatic, possible cause – slower maturation

J Vet Intern Med. 2006 Nov-Dec;20(6):1314-8.

Esophageal achalasia and secondary megaesophagus in a dog

Can Vet J. Mar 2003; 44(3): 232–234. (5 yeras old, neutered, golden male)

pre-operative esophagogram:

strong contraction (open

arrows) – normal upper

motility; lower sphincter

does not open (closed

arrows)

11 days after surgery

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Dysphagy/-ia : oesopagal obturation

Most frequently at locations with physiological narrowing (see anatomy)

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Function of saliva Range: reptiles - a venomous drop, ruminants - 100 quarts

1. Functions varying: grooming and cleansing to nest-building

2. Oral digestion - marginal importance

3. Preparing food for mastication, for swallowing

4. Normal taste perception

5. Lubricating and protecting the soft and hard tissues: against desiccation, penetration, ulceration, and potential carcinogens by mucin and anti-proteases.

• Encourage soft tissue repair - reducing clotting time and accelerating wound contraction.

• Maintenance of the ecological balance in the oral cavity via: (1) debridement/lavage; (2) aggregation and reduced adherence by both immunological and non-immunological means; and (3) direct antibacterial activity.

• Possesses anti-fungal and anti-viral systems.

• Effective in maintaining pH in the oral cavity - helps neutralize reflux acids in the esophagus.

• Maintenance of tooth integrity: (1) mechanical cleansing and carbohydrate clearance; (2) post-eruptive maturation of enamel.

Mandel ID: Function of saliva.J Dent Res. 1987 Feb;66 Spec No:623-7.

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DISORDERS OF SALIVATION

1. Quantitative disorders

a, ptyalosis, sialosis - increased production of saliva ( sialorrhoea, ptyalorrhoea or salivation, that can be caused by lack of swallowing)

Can be cause by parasympathomimetic effects!

b, xerostomia - dryness of the oral mucosa due to a diminished excretion or decreased production of saliva

– Causes difficulty in food prehension (and talking), dysphagia

– Decreases taste perception, anorexia

– Mucosal erosions, necrosis may occur

– Problems caused by gastro-oesophagial reflux may worsen

– Increased production of plaque and tartar

– Slowing down of woundhealing

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Hypersalivation caused by lesions

in the oral cavity

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Plants causing xerostomia

Datura stramonium

(Thorn Apple)

Effective alkaloids: atropin, hyosciamin (parasympatholytic compounds)

Hyosciamus niger

(Black Henbane)

Atropa belladonna

(Deadly Nightshade)

• Autoimmune disease e.g. Sjogren syndrome

• Drug adverse effects: atropin, H1-antagonists

• STRESS! The cortizol concentration of the saliva increases

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DISORDERS OF SALIVATION

2.Qualitative disorders

Importance of the salivary pH: bicarbonate (HCO3-) and phosphate

buffers are present to control

• In acidosis tha pH of saliva also decreases.

• Decreased saliva production and buffering capacity in IDDM

Increase likelyhood of salivary calculus formation!

Salivary K+, Na+ and urea reflects the blood concentration of these

elements

• The saliva urea concentration (SaU) is a trustworthy uraemia biomarker

(Cardoso et al. Scandinavian Journal of Clinical and Laboratory

Investigation, Volume 69, Number 3, May 2009 , pp. 330-334(5))

• In ruminants – there is substantial protein recirculation through the urea

content of saliva (approx. 65% of the urea content of blood)