Muscle Disease Overview in Animals

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary substance released into circulation during acute rhabdomyolysis?

Troponin

Creatine

Lactate

Myoglobin (correct)

Which enzyme is considered muscle-specific and indicates muscle integrity when elevated?

Lactate dehydrogenase (LDH)

Alanine aminotransferase (ALT)

Aspartate transferase (AST)

Creatine kinase (CK) (correct)

How soon after injury does creatine kinase (CK) typically peak following muscle damage?

48-72 hours

1-2 hours

4-6 hours (correct)

12-24 hours

What is the typical half-life of elevated creatine kinase (CK) levels after muscle injury?

2-4 hours Signup and view all the answers

Which condition is NOT classified as a cause of acute rhabdomyolysis?

Chronic fatigue syndrome Signup and view all the answers

What is indicated by a significant increase in CK levels after sub-optimal exercise?

Underlying pathology Signup and view all the answers

What does the presence of myoglobin in urine indicate?

Muscle cell damage Signup and view all the answers

Which of the following tests is necessary for differentiating between haemoglobinuria and myoglobinuria?

pH laboratory analysis Signup and view all the answers

What condition is caused by Vitamin E or Selenium deficiency in farm animals?

White muscle disease Signup and view all the answers

Which of the following would NOT be used to diagnose muscle disease?

Exercise tolerance test Signup and view all the answers

Which type of muscle injury involves a complete tear of muscle fibers?

Muscle tear Signup and view all the answers

What condition is most likely associated with episodic or progressive weakness due to upper motor neuron lesions?

Spinal trauma Signup and view all the answers

What type of muscle wasting is primarily associated with a loss of motor neuron input?

Neurogenic atrophy Signup and view all the answers

What is a potential complication related to selenium or vitamin E deficiency?

Muscle wasting Signup and view all the answers

Which of the following is a common neuromuscular disease characterized by progressive weakness?

Equine motor neuron disease Signup and view all the answers

What is one main role of skeletal muscle in animals?

Maintaining posture Signup and view all the answers

Which aspect of muscle physiology contributes to an animal's athletic capacity?

VO2 max Signup and view all the answers

What percentage of a Thoroughbred horse's body is made up of muscle?

55% Signup and view all the answers

Which of the following is NOT a common clinical presentation of muscle disease in animals?

Excessive grooming behavior Signup and view all the answers

What does a higher VO2 max indicate about an athlete?

Higher aerobic capacity Signup and view all the answers

Which of the following can contribute to muscle disease?

Neuromuscular input Signup and view all the answers

Which factor is most likely to influence the long-term prognosis of muscle disease?

Presence of other comorbidities Signup and view all the answers

What is an important aspect of the diagnostic approach to disorders of skeletal muscle?

Problem-based clinical methodology Signup and view all the answers

What is a common nutritional deficiency that can lead to muscle disease?

Selenium/Vitamin E deficiency Signup and view all the answers

In addition to movement, how else does skeletal muscle contribute to an animal’s physiology?

Functions as an active metabolic organ Signup and view all the answers

Which clinical sign indicates a possible muscle disease?

Muscle atrophy Signup and view all the answers

Acquired disorders of muscle diseases can be caused by which of the following?

Infectious agents Signup and view all the answers

What is a key difference between hereditary and acquired muscle disorders?

Hereditary disorders are only found in certain breeds Signup and view all the answers

Muscle fasciculation is often associated with which clinical situation?

Neuromuscular disorders Signup and view all the answers

What condition is commonly referred to as 'tying up' in horses?

Exertional rhabdomyolysis Signup and view all the answers

Which of the following is NOT considered a clinical sign of muscle disease?

Increased joint flexibility Signup and view all the answers

What type of muscle fibers are primarily found in postural muscles?

Type I Signup and view all the answers

Which of the following conditions is a differential diagnosis for locomotor muscles?

Polysaccharide storage myopathy (PSSM) Signup and view all the answers

What is one of the long-term sequelae of muscle disease?

Fibre necrosis Signup and view all the answers

The prognosis for patients with muscle disease is generally favorable under what condition?

With appropriate management Signup and view all the answers

What factor does NOT affect the prognosis of muscle disease?

Type of muscular fiber present Signup and view all the answers

What diagnostic methods may be necessary to reach a diagnosis for myopathies?

Serum muscle enzymes and muscle biopsy Signup and view all the answers

Which mechanism is associated with the loss of muscle fibers as a consequence of muscle disease?

Fibre necrosis Signup and view all the answers

Which factor is essential in establishing the cause of a myopathy?

Species and breed along with clinical history Signup and view all the answers

Study Notes

General Approach to Muscle Disease

Muscle disease encompasses various disorders impacting skeletal muscle.
The presentation and diagnostic approach vary across species.
A thorough understanding of muscle anatomy and physiology is crucial for accurate diagnosis and management.
Common clinical presentations include pain, heat, swelling, muscle cramping, abnormal limb positions, weakness, fatigue, poor performance, muscle fasciculation, atrophy, sweating, and myoglobinuria.
Diagnostic considerations include the onset and nature of clinical signs, activities prior to symptom onset, exercise tolerance, gait abnormalities, muscle loss (atrophy or wasting), progression, and other signs of illness.

Learning Objectives

Relate muscle anatomy and physiology to clinical presentations and investigations of muscle diseases.
Understand common clinical presentations in animals with muscle disease.
Outline the diagnostic method for skeletal muscle disorders using a problem-based clinical approach.
Explain the potential long-term implications of myopathies and factors influencing disease prognosis.

Role of Skeletal Muscle

Maintains posture.
Generates movement (power, strength, speed).
Enables precise coordination.
Acts as an active metabolic organ.

Muscle Anatomy

The provided images highlight the structures involved.

Physiology

The presentation briefly mentions Lance Armstrong (and his racing cyclist history) and horse VO2 max levels.
VO2 max in Thoroughbreds is approximately 140-180ml/kg/min.
55% of a Thoroughbred's composition is muscle.

What Can Go Wrong With Muscles?

Skeletal muscle diseases arise from disorders within the neuromuscular input, muscle cell membrane, myofibre proteins, and metabolic functions.
This section highlights acquired versus hereditary factors.

Approach to Investigating Muscle Disease / Clinical History

Signalment (species, breed, age, sex).
List of common myopathies (e.g. equine: exertional rhabdomyolysis, metabolic disorders, atypical myopathy).
Factors such as diet (nutritional deficiencies - Selenium/Vitamin E deficiency), access to pasture, exercise and husbandry, breed history, and other recent diseases.

Establishing The Problem

Onset of clinical signs (acute vs. chronic).
Activities prior to symptom onset.
Detailed nature of clinical signs (e.g. weakness, exercise intolerance, gait abnormalities, muscle loss, progression, other signs of illness—comorbidities).

Clinical Signs Associated With Muscle Disease

Pain, heat, and/or swelling on palpation of muscle.
Muscular cramping.
Abnormal limb position (e.g. muscle tears).
Gait abnormalities.
Weakness.
Fatigue or poor performance.
Muscle fasciculation.
Muscle atrophy.
Sweating.
Myoglobinuria.

Problem-Based Approach (Examples)

Muscular cramping with exercise: Overexertion, electrolyte/energy depletion, exertional rhabdomyolysis, tying up in horses, racing greyhounds, myotonia congenita, delayed relaxation of contracted muscles, fainting goats.
Persistent or permanent gait abnormalities: Muscle injury (e.g., tears, strains), fibrotic myopathy (can occur in any species).
Episodic or progressive weakness: Neurological or neuromuscular causes (e.g., upper/lower motor neuron lesions, spinal trauma), equine motor neuron diseases, myasthenia gravis, disorders of cell membrane function (e.g. Selenium/Vitamin E deficiency, hypokalemia. hypothyroidism).
Muscle wasting/atrophy: Neurogenic atrophy, disuse atrophy, equine motor neuron disease, immune-mediated polymyositis, infectious myositis (e.g., Lyme disease).
Acute rhabdomyolysis: Exertional rhabdomyolysis, infectious myonecrosis, toxicities (e.g. hypoglycin A, lonophore poisoning), circulatory disturbances, post-anaesthetic myopathy.

Diagnosis of Muscle Disease

Serum Muscle Enzyme Activity: Creatine kinase (CK), aspartate transaminase (AST) - elevated levels suggest muscle damage.
Urinalysis: Myoglobinuria indicating muscle damage, haemoglobinuria
Specific blood tests: Vitamin/selenium assays for possible deficiencies (white muscle disease).
Immunology testing: Myasthenia Gravis (anti-AChR antibody titre).
Genetic tests: DNA extraction for conditions such as Polysaccharide Storage Myopathy (PSSM1), Hyperkalaemic Periodic Paralysis (HYPP), Myosin heavy chain myopathy (MYHM), Glycogen Branching Enzyme Deficiency (GBED), Malignant hypothermia.
Diagnostic imaging: Ultrasound, MRI for assessing structure, injuries, and infection foci.
Muscle biopsy: Histopathology, biochemical analysis (often used in horses).

Muscle Biopsies

Differences between postural and locomotor muscles. Location & fibre type relevant for diagnoses.

Muscle Histopathology

Images demonstrating normal healthy muscle tissues contrast with those found in various muscle diseases.

Long-Term Sequelae of Muscle Disease

Fibre necrosis (death of muscle fibres).
Loss of muscle fibre number.
Fibrosis of muscle tissue.
Reduced muscle contractile and expansive functions.

Prognosis for Patients with Muscle Disease

Generally favourable with appropriate management.
Factors influencing prognosis include: underlying conditions, severity of muscle pathology, clinical signs, use of animal (e.g., athlete vs. companion), breeding implications of hereditary conditions.

Summary

Understanding muscle anatomy and physiology are crucial for investigating, diagnosing, managing, and assessing prognosis in animals with myopathies.
Thorough clinical history, species, and signalment are vital factors to establish cause.
Myopathies cause a wide range of clinical signs from poor performance to severe pain.
Diagnostic tests (Enzymes, biopsies, imaging).

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Explore the intricate world of muscle diseases affecting skeletal muscles in animals. This quiz focuses on the relationship between muscle anatomy, clinical presentations, and diagnostic methods used for various disorders across species. Test your understanding of symptoms, diagnostic approaches, and common challenges in managing muscle diseases.