How Heat Stroke and Diseases Affect Livestock Systems

Health in livestock refers to the state where animals are free from diseases. A disease is a deviation from normal body functions or structures. In this article, we are going to learn about some of the causes of diseases, terms used in animal health, and body systems in animals.

Causes of diseases.

  i). Endogenous causes:

Endogenous diseases are caused by internal factors, often linked to genetic defects. Lethal genes or hereditary conditions can predispose animals to specific illnesses or metabolic disorders.

 ii). Exogenous causes

Exogenous causes originate from outside the animal. These can be viable (living organisms) or non-viable (physical, chemical, or environmental factors).

a). Viable causes

Microorganisms- these are organisms that can only be seen with the help of a microscope, like viruses, bacteria, protozoa, fungi, and rickettsia.

Macro organisms- these are organisms that can be seen with our naked eyes, like internal and external parasites.

b). Non-viable causes

1. Physical damages- these may depend on the nature of the object. It may be sharp or blunt.
2. Thermal heat- this may be a 1st-degree burn, 2nd-degree burn, 3rd-degree burn, or 4th-degree burn.
3. Frost-like Liquid Nitrogen.
4. Poisoning – these may be poisonous chemicals, poisonous plants, or poisons from snake bites.
5. Metabolic causes- like faulty metabolism, such as ketosis.
6. Nutritional deficiency- like avitaminosis and mineral deficiency.
7. Allergy- this is the reaction of the body against foreign substances like pollen, bee venom, or food, which forces the immune system of the animal to produce substances known as antibodies.
8. Photosensitization - This is an ailment in which the skin becomes abnormally sensitive to bright sunlight after the stock has eaten certain toxic plants. This, in most cases, affects the white parts of the skin of an animal.
9. Environmental causes: these may be polythene bags and nails.

Terms used in animal health

Clinical signs- these are objective terms for describing abnormalities that are detected during a clinical observation or examination of an animal.

Pathognomonic sign- This is a particular sign whose presence means that a particular disease is present beyond any doubt while examining an animal.

Lesion: a functional/structural abnormality in an animal. Lesions are described by: Location, size, shape, consistency, color, appearance of the cut surface, and quantification.

Pathogenesis is the progression from the normal state to the abnormal form or structural state.

Diagnosis is the ability to recognize a lesion in a dead or live animal.

Prognosis is the expected outcome of a disease.

Incubation period- This is the period from the invasion of the host by infectious organisms up to when clinical signs appear.

Prepatent period- This is the period from the invasion of the host by the parasite up to when a demonstration of the presence of the parasite can be done by laboratory means.

Infestation- This is an invasion of the body by macro-organisms.

Infection- This is an invasion of the body by microorganisms.

A Carrier- This is an animal that is infected and sheds infectious organisms without showing signs.

Incubatory carriers- These are animals that shed organisms during the incubation period.

Convalescent carriers- These are animals that shed organisms when clinical signs have disappeared.

Epidemic- This is the occurrence of a disease over its expected level.

Endemic- This is the occurrence of disease at the usual frequency.

Pandemic- This is a geographically widespread epidemic, and it affects many populations.

Inflammation- This is the reaction of tissue to injury/ infection.

NB: Cardinal signs of inflammation include redness, pain, heat, swelling, loss of function, and production of exudates such as gastritis, and nephritis.

General systemic states in animal health.

Hyperthermia/heat stroke:

It is the elevation of body temperature above a critical point. It is due to excessive heat production or absorption, or deficient heat loss.

The causes of Hyperthermia/heat stroke are entirely physical.

a). Toxaemia. This is the presence of toxins in the bloodstream, and it may be caused by bacteria or metabolic products.

b). Fever.  This is a symptom complex where hyperthermia and toxemia are produced in the body by substances in the bloodstream. It may be septic or aseptic.

c). Septicaemia. This is a disease state where toxemia and hyperthermia are present, with a large number of organisms present in the bloodstream.

d). Dehydration. This occurs when there is a water imbalance in the body. There is an increase in the metabolism of fats and proteins in the body to make water. There is an increase in acid metabolites.

Body systems that are mainly affected by diseases in livestock.

1. Alimentary system

Functions: The primary functions of the gastrointestinal tract include prehension of food and water; mastication, salivation, and swallowing of food; digestion of food and absorption of nutrients; maintenance of fluid and electrolyte balance; and evacuation of waste products.

Abnormalities in this system might include;

a). Diarrhea.

This is an increased caudal flow of ingesta and decreased transit time.

Causes of diarrhea.

Microorganisms, excitation, indigestible materials, and incomplete digestion.

Treatment of diarrhea:

Fluid therapy.

b). Constipation.

There is decreased gut mobility and increased transit time. The frequency of defecation increases.

Causes of Constipation.

Partial obstruction, terminal pregnancy, lack of fiber in the diet, and painful conditions of the anus.

c). Vomiting.

This is the movement of the ingesta in the reverse direction. The purpose is the removal of excess ingesta or toxic material.

There is projectile and true vomiting. In projectile vomiting, a lot of fluid is produced without effort. In true vomiting, little fluid is produced, and there are retching movements and extension of the head.

d). Disturbances in appetite and food intake.

Hunger is a local subjective sensation arising from gastric hypermobility due to lack of stomach distension by food.

1. Hyperorexia- is an increased appetite due to hunger
2. Polyphagia- Increased food intake.
3. Inappetance- decreased/lack of appetite.
4. Anorexia- improper feeding with indigestible feeds
5. Pica- is a depraved appetite and it leads to the ingestion of materials rather than food.
6. Dysphagia- Painful swallowing.
7. Starvation-  This is the complete deprivation of food, and it leads to the depletion of glycogen and increased fat metabolism.
8. Malnutrition- Is partial starvation.
9. Thirst- Desire for water and which is shown by polydipsia (excessive water intake).

2. The skin and associated structures.

Primary skin conditions are restricted to the skin, but they can spread to other organs, for example, wounds and burns. Secondary skin conditions are those that arise from disease in other organs, e.g,. in Lumpy Skin Disease.

Skin lesions may be discrete (when they are localized) or diffuse (when they cover the whole body).

Abnormalities of the skin

1.  Jaundice - yellow coloration of the skin.
2. Erythema- the reddening of the skin
3. Cyanosis- is the blue/purple coloration of the skin
4. Parlour- the pale mucous membrane of the skin
5. Alopecia- hair loss on the skin
6. Pruritis- an itching condition of the skin.
7. Photosensitization - is an ailment in which the skin becomes abnormally sensitive to bright sunlight after the stock has eaten certain toxic plants. This, in most cases, affects the white parts of the skin of an animal.

3. Respiratory system

1. Dyspnoea: difficult breathing.
2. Hyperpnoea: Increased respiratory rate.
3. Apnoea: means completely no breathing
4. Oligopnoea: Decreased respiratory rate
5. Epistaxis: Nose bleeding
6. Coughing: It is a deep expulsive action to remove substances from the respiratory tract.
7. Nasal discharge: Mucus discharge produced from the nostrils.

Abnormal respiratory sounds

1. Coughing- It is a deep expulsive action to remove substances from the respiratory tract.
2. Snoring due to pharyngeal obstruction
3. Sneezing occurs when there's irritation of the nostrils
4. Yawning-prolonged respiration

Anoxia

This is a deficiency of oxygen. There are 4 types of anoxia.

1.  Anoxic anoxia-Inadequate oxygenation in the pulmonary circuit and which is caused by diseases of the lungs.
2. Anemic anoxia-The oxygen-carrying capacity is decreased, and it occurs when there is anemia.
3. Stagnant anoxia- blood flow through the capillaries is reduced, as occurs when there is an obstruction to blood flow in the veins. It leads to the stagnation of blood.
4. Histotoxic anoxia-There is the failure of tissue oxidative systems, and tissues cannot take up oxygen. It occurs in cyanide poisoning.

Pulmonary emphysema

It is the excessive distension of the lungs due to the rupture of the alveoli.

4. Musculoskeletal system

This system can be affected by diseases manifest by decreased activity and abnormal posture, such as those listed below:

1. Lameness
2. Loss of support
3. Insufficient movement
4. Stiffness of muscles
5. Lack of flexion of limbs

Abnormal postures in livestock.

1. Persistent recumbency
2. Dog-sitting position
3. Arching of the back (lordosis, kyphosis)
4. Abduction of limbs is a sign of chest pain.
5. Kicking at the belly
6. Rigidity of limbs
7. Severe systemic disease can lead to weakness, pain, and incoordination.
8. Recumbence may be due to paralysis, or it also occurs in milk fever.

Diseases affecting the musculoskeletal system:

These are classified according to the aetiological, clinical signs, and pathological features-

1. Inflammatory diseases, for example, arthritis
2. Degenerative diseases, for example, myopathy,
3. Proliferative diseases, for example, neoplasms (rare in animals)
4. Developmental defects are seen in newborn animals. but not common.

5. Nervous system

The function is coordination. It comprises  4 systems, namely;

a). Sensory-motor system – maintains posture and gait

b). Autonomic nervous system-homeostasis

c). Special senses system- controls the activity of special senses

 d). The psychic system controls the mental state.

Manifestation of nervous system dysfunction

a). Disturbance of the mental state

1. Mania - an excitation state where the animal performs abnormal movements with vigor.
2. Frenzy- an advanced stage of mania.
3. Coma (syncope) - a state of depression or mental state
4. Involuntary muscle movements
5. Tremor- continuous repetitive twitching of the skeletal muscle.
6. Convulsions- violent muscular contractions

b). Abnormal postures. These include: paralysis, persistent recumbency, disturbances of special senses, hyperaesthesia, and hypoaesthesia.

6. Urinary system

1. Renal insufficiency- partial loss of function
2. Renal failure- complete loss of function
3. Pre-renal causes- Congestive Heart Failure
4. Renal causes- nephritis

Manifestations of failure of the Urinary system

a. Abnormal qualities of urine

1. Polyuria - excessive urine as occurs in diabetes inspires.
2. Oliguria- decreased quality of urine as occurs in nephritis.
3. Anuria- no urine at all, as occurs in urethral obstruction.
4. Dysuria- difficulty in urination, the animal feels pain. E.g pyelonephritis

b. Abnormal constituents of urine

1. Haemoglobinuria- hemoglobin in the urine
2. Proteinuria- the protein in the urine.
3. Haematuria- blood in the urine
4. Myoglobinuria - myoglobin in the urine.
5. Pyuria- pus in urine.

c. Other conditions in the body (in the bloodstream).

1. Uraemia- a syndrome resulting when waste materials usually passed out in urine are retained
2. Urinary caliculi -stones found in the kidney, they are salts (oxalates and carbonates of calcium). Stones may also be found in the stomach, especially in animals on a high-grain diet.

7. Circulatory system

There are two functional units in the Circulatory system, i.e., the heart and blood vessels

1. Heart failure-problems with the heart signal that there is a problem with the blood vessels.
2. Congestive heart failure- The ventricular output is not equal to venous flow.
3. Acute heart failure- There is the sudden cessation of the heartbeat.
4. Peripheral circulatory failure- There is the pooling of blood in the peripheral circuit.
5.