Capture Myopathy

  • Capture Myopathy – Also known as overstraining- or white muscle disease

  • It is an important cause of death in game captured for translocation

Causes

  • Unnatural overexertion and stress (e.g. continuous pursuing of animals with helicopter/vehicle/motorbike)

  • Additional factors include

    • Exposure to strange and loud noises and smells in captivity

    • Close proximity of vehicles, people and other perceived dangers

    • Unnatural confined spaces of capture bomas, crate and/or transport truckso Close proximity of other animals that are equally stressed

    • Effects of drugs/antibiotics/tranquilizers administered during the capturing process

    • Injuries and bruising in addition to stress and over exertiono Inability to adapt to new surrounding which include unfamiliar sight, smell, sounds and dieto Anorexia (not eating/drinking after release)

  • An inability to escape from the above mentioned factors causes an unnatural and continuous state of stress.

  • Severe panic, fear and/or anxiety (combined with or in the absence of physical exertion)

  • Stress factors can work cumulatively and eventually have a detrimental effect on the animal

  • In the case of chemical immobilization, exhaustion can occur due to error e.g.

    • Less than the full dose is injected

    • Too weak dose

    • Misfiring of dart

    • Blocked needle

    • Poor dart penetration

How it works / Dynamics

  • Due to the fight or flight response

  • Overexertion causes irreparable damage to muscles and organs (including the heart)

    • Myoglobin from the muscles is released into the bloodstream

    • Muscle glycogen is broken down and an excess of lactic acid is formed which acidifies the blood

    • Changes in the chemical composition of the blood occurs

    • Reactions take place in the damage tissues that affects the kidneys ***

    • Most animals die either as a result of heart failure or degeneration of the kidneys

Degrees of Severity

  1. Hyper-acute: Death from heart failure shortly after capture. Initial symptoms are of restlessness and agitation before depression sets in and the animal dies. Death within an hour after capture

  2. Acute: The animal shows some of the above mentioned symptoms a few hours or days before death

  3. Chronic: Lameness, stiffness and/or partial paralysis can be observed a few weeks (or even months) after exposure to stress. Animals show signs of depression, anorexia, constipation, and weight loss. Further exposure to stress can develop into acute capture myopathy and result in death due to heart failure. Occurs more frequently than expected. Animals can appear to be healthy

Sensitive Breeds

  • Nyala’s – tranquilizers should be administered immediately after the animals have been captured in nets

  • Tsessebe – highly susceptible, especially during excessive pacing in holding pens in an attempt to escape

  • Roan Antelope – highly susceptible, individual chemical immobilization recommended

  • Red Hartebeest – can succumb to capture myopathy even weeks after relocation

  • Springbok – tranquilizers should be administered immediately after the animals have been captured in nets

  • Kudu

  • Giraffe

  • Impala females – Bent necks (torticollis) are often observed in impala as a physical manifestation stress

Increased Susceptibility

  • Age – young and old are most susceptible

  • Condition – over or underweight animals

  • Diseased / infected animals are at a disadvantage

  • Parasitic load – can lead to anaemia and weakness therefore and increased susceptibility to capture myopathy

  • Pregnancy – heavily pregnant females are more susceptible than non-pregnant animals

  • Weather conditions – warm/cold weather, rain and high humidity can play a role

Time Frame

Few minutes after over-exertion (e.g. Impalas caught in a net) to 5 – 7 days after release

  • One often hears of gemsbok and other game dying within five to seven days of release where the cause of death is incorrectly given asheartwater or due to plant poisoning. Heartwater has an incubation period of 10 – 20 days and can only be confirmed by microscopic examination, and game do not voluntarily eat toxic plants like gifblaar hence Posoning is unlikely

Symptoms

  • Lameness and/or stiffness of one or more limbs and moving with difficulty

  • Exhaustion – unable to get up

  • Shivering

  • Rapid breathing

  • Depression

  • Pain and anxiety – the animal appears to be uncomfortable

  • Bent neck (torticollis) – may occur in both slender necked (e.g. impala, kudu) or thick necked (e.g. gemsbok, zebra) animals

  • Anorexia (loss of appetite)

  • Constipation

  • Dark coloured urine – due to the broken down haemoglobin in the urine (myoglobinuria) (this is a very important and prominent symptom of capture myopathy and over exertion)

  • Muscle paralysis caused by muscle cramps or spasms

  • Death

Treatment

Chances of successful treatment is poor, handling of animals to administer treatment is impractical and increases adds to the already stressful environment.

Prevention

  • Quick and professional capture and handling of animals in as calm and quiet environment as possible

  • Chemical immobilization (under veterinary supervision) eliminates most of the stresses

  • Make use of tranquillizers in highly stressed species e.g. Tsessebe and Red Hartebeest

Post Mortem Signs

Post Mortem (PM) examinations or autopsies must be carried out on every animal that dies after capture or transportation. This is to establish if death was caused by capture myopathy or by some other underlying disease. The PM should be done while the carcass is fresh and the lesions can be seen easily – usually within 12 hours of death. Post mortal changes can cause confusion and samples collected for microscopic examination to confirm a diagnosis may then be useless. Remember to provide a detailed history of the animal before its death! Any samples taken may be sent to the nearest private or state veterinarian who will forward it to a pathologist.

  • Sub-cutaneous haemorrhage and bruising (bleeding and bruising under the skin)

  • Haemorrhage and bruising in muscles of the hind and/or front limbs

  • Dull or pale appearance of some muscles

  • HEART: Haemorrhage on the outer and inner surfaces of the heart

  • LUNGS: Congestion or redness of the lungs

  • LUNGS: Accumulation of fluid in the lungs (also froth in the trachea and lungs)

  • LIVER/KIDNEYS: Congestion and degeneration of the liver and kidneys

  • BLADDER: Dark-coloured urine (myoglobinuria) due to the myoglobin (muscle pigment) which is produced by damaged muscles

  • In Hyper-acute cases: Haemorrhage of skeletal muscle (especially the heart)

  • In Acute cases:

  • In Chronic cases:o Grey coloured areas on heart and kidneys and pale or lightly coloured areas on muscle. This indicates areas of muscle which were previously damaged and had healed as a result of the formation of connective tissue

  • For microscopic examination collect samples of approximately 1cc of the affected areas in the following organs and tissues (preserve it in sample bottles containing 10% formalin)o Heart (including a sample from the the apex)o Lungso Livero Kidneyso Adrenal glando Spleen

Remember to write the following detail on the label of the bottle:

• Name and address of the owner

• Type of animal, age and sex

• DOB (date of birth)

• Type of sample