ANS 210: Animal Health and Toxicology

Why is it important for livestock producers, pet owners and anyone who works with animals to understand pet health?

Recognition of healthy versus diseased animals, disease prevention, identifying animal welfare concerns and for financial reason

Why is understanding animal health important financially?

Healthy animals are more productive

What can be some animal welfare concerns?

Over-crowding, boredom and cruelty

What are some things that can be done to prevent disease?

Biosecurity programs, vaccination, sanitation and ventilation

Define health:

A state of physical and psychological well-being and of productivity

Define disease:

A condition that results from any structural defect or functional impairment in the body

What are the six sections of a clinical exam?

Complaint, signalment, history, observation, sample collection

What is the complaint section of the clinical exam?

Why the animal is being evaluated

What is the signalment section of the clinical exam?

The age, breed and sex of an animal

Where might you observe an animal as part of a clinical exam?

In a group, in their environment and in the clinic

Why is knowing how to preform a physical exam important as a veterinarian?

It’s necessary to evaluate the animal to help determine symptoms and diagnose

Why is knowing how to preform a physical exam important as a producer?

It can help to determine which conditions may need closer, veterinary evaluation

What is a physical exam?

The evaluation of the body and it’s functions using inspection, palpation and auscultation

What is auscultation?

Listening to something in the body

Why is it important to develop a consistent when performing an exam?

It ensures everything is examined and nothing is missed

What tools are required for a physical exam?

Your senses, a stethoscope and a thermometer

What should be listen to on both sides of the body?

The lungs, heart and gut

Why should the heart be listened to from both sides?

To best hear all valves

What are purposes of physical exams?

To document health, determine cause of ill health and specific purpose exams such as pre-purchase exams and breeding soundness exams

What goes into a subjective assessment

Animal demeanor and how the animal stands and moves

What does BAR stand for pertaining to demeanor?

Bright, alert, responsive

What elevated vital signs can indicate pain?

Pulse and respiration rate

What kind of data are vital signs considered?

Objective data

Why is it important to have base line values and see changes over time during treatment and in general?

They can be used to evaluate general condition, disease progression and treatment overtime

What are mucous membranes?

Linings of body cavities that are filled with lots of capillaries

What is the normal color of mucous membranes?

Pink

What do pale mucous membranes indicate?

Blood loss (trauma), low red blood cell production and anemia

What are blue or purple mucous membranes called and what do they indicate?

Cyanotic and they indicate cardiac or pulmonary disease

What are yellow mucous membranes called and what do they indicate?

Icteric and they indicate liver disease

True or false: Mucous membranes can be used to determine hydration status

True

What does capillary refill time indicate (CRT)?

Blood perfusion to peripheral tissue

How long indicates poor blood perfusion when taking the capillary refill time?

>2 seconds

What can cause poor perfusion/slow capillary refill time?

Shock and anemia

What is the skin tent test used for?

To assess hydration

How long should it take for the skin to snap back when taking a skin tent test?

It should return immediately

What can be causes of dehydration?

Inadequate fluid in take (from inadequate access, stress, poor water quality and unpalatability) and excessive fluid loss (from profuse sweating, diarrhea, vomiting)

Why might sudden death occur?

Catastrophic problem with an organ or body system (ie ruptured aorta), infectious disease (severe bacteria or viral infection), trauma and toxins in feed, water and plants in pastures

How is the cause of sudden death diagnosed?

Necropsy

Define: toxicology

The study of how natural or man-made poisons cause undesirable effects

Define: toxicity

The degree to which a substance can cause injury

What factors does the level of toxicity factors depend on?

Dose, duration and route of exposure, nutritional and health status, life stages and genetics

Define: Toxicants

Any poisonous substance of microbial, vegetable or synthetic chemical origin that interacts with specific cellular components to kill cells, alter growth or development, or kill an organism

Define: Toxins

Toxicants produced by biological organism

What is a threshold dose?

The maximum dose at which there is no observable toxic effects

What is a dose and how is it usually expressed? Why?

It is the amount of substance an organism is exposed to and is usually expressed as mg per kg because the severity of toxicity is usually related to body weight

What is lethal dose 50 (LD50)?

The amount of a substance which causes the death of 50% of the population of an organism in testing

Is LD50 looking at acute or chronic toxicity?

Acute, it usually comes from studies after one exposure

True or false: The threshold dose can also be the minimum lethal dose

True

True or false: all substances are toxic depending on the dose, including nutrients

True

What is the desired dose?

When health benefits from a substance reach it’s maximum before it begins to have adverse effects

What is a Margin of Safety (MOS)?

Threshold of toxicity divided by nutritional requirement

When is a nutrient considered relatively safe by it’s margin of safety?

10 or greater

How many kg does 1 lb equal?

0.45

How many lbs does 1 kg equal?

2.2

How many micrograms (ug) are in a gram?

1,000,000

How many nanograms (ng) are in a gram?

1,000,000,000

What is risk assessment?

A comparison of between dose/exposure and effective dose

What are common ways of expressing concentration in toxicology?

w/kg or w/L, % (w/w or w/v), ppm and ppb

What is 1 ppm equal to in feed?

1 ug/g or 1 mg/kg

What is 1 ppm equal to in water?

1 mg/L

How many grams is 1 liter of water equal to?

1000 g

What percentage of the total body is water?

60%

What is the majority of the fluid inside your body?

Intracellur fluid

What makes up the minority (33%) of fluid in mammals bodies?

Extracellular fluids including interstitial fluid (25%) and blood plasma (8%)

What is the most important nutrient?

Water

What is the most important property of water for biochemical reactions?

Electrolyte concentration

What do electrolytes do?

Plays crucial roles in maintaining fluid balance, nerve function,and muscle contraction throughout the body

What is the ideal range of plasma osmolality?

275-290 mOsm/kg

What concentration in the plasma is an indicator of electrolyte balance?

Sodium

Which species has the lowest range of plasma sodium concentration?

Horses (134-142) and cattle (134-144)

Which animal has the high range of plasma sodium concentration?

Cats (149-158)

How large is the range for plasma sodium concentrations?

7-11 mEq/L

What is it called when sodium level get too low?

Hyponatremia

When is hyponatremia?

<130 mEq/L

Do freshwater or saltwater fish have a larger range of the plasma sodium concentrations?

Freshwater fish but both have the same maximum (170mEq/L)

What do electrolytes regulate?

pH levels, biochemical reactions, maintaining fluid balance between the inside and outside of cells, blood volume, blood pressure and tissue repair

Which element can cause sudden cardiac deaths at low and high levels?

Potassium

What does dehydration lead to?

Hyperosmolality

True or false: Slight dehydration is normally managed by hormones

True

What constitutes mild dehydration?

Losing 3-5% b.w.

What constitutes moderate dehydration?

Losing 5-10% b.w.

What constitutes severe dehydration?

Losing >10% b.w.

What happens during severe hydration?

Sudden death

What are risk factors for dehydration?

Lack of water intake, diarrhea, vomiting, sweating

What are the physiological effects of dehydration?

Low blood pressure, lack of oxygen supply to tissues and organs, nerve and muscle dysfunction causing lethargy, fainting and death

What are other words for water toxicity?

Water toxication, hyperdration, overhydration, water toxemia

Which species are most cases of water toxemia in?

Ruminates and human children

What causes water toxicity?

Consuming a large amount of water in a short time

What is the threshold dose of water toxicity?

It’s highly uncertain in individuals

What can water toxemia cause?

Electrolyte diffusion and dilution, hyponatremia, dysregulation of all biological functions, nerve and cell dysfunction causing lethargy, partial paralysis, seizures, coma and death and hypervolemia which can lead to pericarditis, heart failure, delayed wound healing, tissue breakdown and decreased bowel function

What determines susceptibility to water toxicity?

Dose (amount, frequency, rate of exposure) electrolytes and hormonal state

What are risk factors for water toxemia?

Excessive water intake and dehydration

What is simple acute overhydration? Describe

Excessive and rapid water intake - it has a slow onset and is life threatening if not diagnosed and treated timely

What is complex acute overhydration? Describe

Dehydration followed by rapid water intake - timely diagnosis and treatment are rarely possible and often results in sudden toxicity and death

True or false: eyeball recession can indicate dehydration

True

What hormones play a key role in regulating fluid and electrolyte balance?

Antidiuretic hormone (ADH or vasopressin), aldosterone (ALD), renin-angiotensin system, natriuretic peptides, epinephrine, norepinephrine and cortisol

Where is ADH, aldosterone and renin-angiotensis secreted from?

It is produced from the hypothalamus and released from the posterior pituitary gland

Where and when is aldosterone secreted from?

The adrenal cortex when blood pressure is low and potassium concentration is elevated

Where is renin-angiotensis secreted from?

Angiotensis is secreted from the liver and renin is from the juxtaglomerular cells in the kidney

Where is Angiotensis-converting enzyme (ACE1) produced?

Vascular endothelium throughout the body