Miscellaneous Diseases/Disorders (TV4102, Lecture 38 Notes)

Discuss udder oedema

- Common in periparturient dairy cattle, especially heifers

- Compression of abdominal veins and lymphatic vessels by large fetus or developing udder, causing increased capillary blood pressure with oedema of udder and ventral abdomen

- Causes discomfort, difficulty in attaching milking cups, difficulty in extracting all milk from gland, permanent damage to suspensory ligament and udder attachments

Discuss treatment and prevention of udder oedema

- Start milking prior to calving

- Diuretics (e.g. frusemide) and NSAIDs after calving

- Restrict the amount of salt in the diet

- Avoid excessive body condition and high energy feeding during late gestation

Discuss anaphylaxis

- Release of chemical from mast cells and basophils, affecting the vascular system and smooth muscles

- May be due to blood transfusions, vaccines, insect bites, lignocaine, procaine penicillin or long-acting corticosteroids

- Present with sudden severe dyspnoea, muscle tremors, anxiety, increased temperature, salivation, bloat, diarrhoea and urticaria

- Administer adrenaline

Discuss heat stress

- Exposed to environmental temperatures >25C with high relative humidity or sunshine

- Fat cattle (e.g. feedlot) are at greater risk

- B. taurus cattle are more susceptible than B. indicus

- Assess the temperature-humidity index

List milk production effects with heat stress

- Decreased milk yield

- Decreased milk fat %

- Decreased milk protein %

- Elevated somatic cell counts

List reproductive performance effects with heat stress

- Delayed first ovulation after calving

- Reduced expression of oestrus (i.e. lower submission rates)

- Lower conception rates

- Impaired oocyte quality and embryo development

- Loss of normal follicular dominance patterns

- Impaired transport of sperm in the oviducts

- Reduced uterine blood flow and endometrial dysfunction

- Embryonic death

- Reduced birth weight of calves

- Reduced body condition at calving

List conception rate effects with heat stress

- Excessive heat load during weeks-4 and +1(2) of day of service are associated with a reduced chance of conception

- Effects of daily heat stress during this period are cumulative

- AI and natural service are equally susceptible to the depressing effect of heat load on conception

- Larger declines occur in higher-producing cows

List clinical signs of heat stress

Discuss management of heat stress

- Provide shade and cool water

- Adjust diet with high-quality fibre, buffers, extra sodium and betaine

- Encourage evaporation with sprinklers

- Reduce handling, consider adjusting milking times

Discuss bovine ephemeral fever (three-day sickness)

- Transmitted by mosquitos with the direct intravenous deposition of infected blood

- Vasculitis of small blood vessels in synovial membranes, tendon sheaths, muscles, fasciae and skin

- Long-lasting immunity obtained following natural exposure

- Laboratory confirmation with paired serology

List clinical signs of ephemeral fever

Mild = high fever, inappetence, discharge from eyes/nose, shivering, temporary shifting lameness, sudden severe drop in milk production and heavily pregnant cows may abort.

Moderately severe = animals are sitting down and are reluctant to move, there is joint swelling, loss of rumen motility, and subcutaneous oedema.

Severe = paralysis of the limbs, profuse salivation, may lead to coma and death.

Discuss treatment of ephemeral fever

- Treatment involves NSAIDs, calcium injection may assist down animals in getting up

- Animals that go down need shelter, nursing, watering and feeding

- Swallowing reflex impaired, do not drench or force feed

- Vaccines (live or inactivated) are available

List implications of three-day sickness

- Downer cattle may suffer permanent paralysis due to spinal cord damage

- Lactating cows may dry off completely

- Bulls may become temporarily infertile, lasting 3-6 months

- Naive, introduced stock are at high risk of becoming infected

- Mustering during an outbreak may increase mortality

Discuss Akabane virus

- Spread by biting arthropods especially midge Culicoides brevitarsis

- Problem when infection occurs for the first time during pregnancy

- Virus multiplies in rapidly dividing cells of the foetus, especially the brain and spinal cord, with maximal damage occurring at 12-16 weeks of gestation

- Present with abortion, premature births, stillbirths or severe damage to the foetus rendering it unviable (including arthrogryposis and hydranencephaly)

Discuss navel-ill

- Predisposing factors include poor colostrum management, calving in unhygienic conditions, using dirty trailers for transporting collected calves, failure to dress the navel and poor housing

- Calves are unthrifty, debilitated, dull, inappetent with swelling of the navel and/or surrounding tissues

- Systemic signs include polyarthritis and meningitis

- Provide antibiotics, may require surgical intervention

Discuss umbilical hernia

- May be uncomplicated, irreducible hernias with localised abscessation/subcutaneous infection occurring concurrently or associated with infection of the umbilical remnants

- Self-resolve or require surgical intervention

- Heritable condition, do not breed animals