Bleeding disorders Flashcards
Ddx for bleeding disorders
Common conditions causing bleeding disorders (but generally quite rare in farmed spp):
- Disorders of coagulation/miscellaneous coagulopathies
- Thrombocytopaenia
- Bracken toxicity (localised and is more common in some areas, causes a coagulopathy)
Rare disorders, unlikely to come across in GP farm practice:
- Mycotoxicosis (some mycotoxins associated with bleeding disorders)
- Rodenticide toxicity
- Mouldy sweet clover toxicity (more common in USA where they feed it)
- Factor XI deficiency (rare inherited condition of Holstein cattle)
- Disseminated intravascular coagulation (DIC) (rarely seen in farm spp and usually end stage of other severe illness)
- Bovine neonatal pancytopaenia
- BVD type 2 virus (type 2 BVD virus rarely seen in UK, more common in USA
BVD type 1 vs type 2
- BVD itself is common in the UK but it is BVD type 1 virus that we usually see, and this does not typically result in bleeding disorders
- By contrast, BVD type 2 virus is associated with bleeding disorders, but this type has only been reported in the UK a small number of times and is more common in the USA
- Therefore, bleeding disorders associated with BVD are rare in the UK.
Causes of acute/peracute haemorrhage in cattle
Common conditions:
- Abomasal ulceration
- Trauma/injury/laceration
- Calving injury, including vaginal or uterine artery rupture
Medium-likelihood conditions:
- Caudal vena cava syndrome
- Pulmonary aneurysm (ruptured)
Rare conditions:
- Rupture of the corpus luteum
- Splenic rupture
- Mesenteric vessel rupture
Treatment of acute haemorrhage in cattle
- Haemostasis
- Restoration of circulating volume
- Blood transfusions
- Supportive care
- Specific tx
Haemostasis
- Cessation of bleeding is the most important first aid treatment to perform in these cases
- If a farmer calls to report a bleeding animal, they should be advised to apply pressure to the area until the vet arrives
- Bleeding can be stopped by applying pressure (this can be digital pressure, use of haemostats, or a pressure bandage), cautery, or ligation of offending vessels
- Haemostatic material may also be used if it is available but in farm practice this may not be the case
- Sometimes the vessel that is bleeding cannot be identified
– An example of this is laceration of a vaginal artery after calving
– In these cases the vagina is packed with clean material (e.g. a bedsheet) to apply pressure and achieve haemostasis - Effective haemostasis may be a life-saving intervention and should be attempted first, before other treatments or investigations
- However, if there is internal bleeding first aid treatment to stem the bleeding may not always be possible.
Restoration of circulating volume
- If animals are hypovolaemic, restoration of circulating volume should be attempted
- It is important to stop the haemorrhage before doing this wherever possible
- For smaller ruminants IV fluid therapy alone would be appropriate
- Colloids achieve rapid expansion but are rarely available so crystalloids are more commonly used
- For large ruminants (i.e. adult cattle), provision of large volumes of fluids through the IV route can be impractical
- Therefore administration of IV hypertonic saline immediately followed by oral fluids can be a more efficient method of providing fluids to these patients.
Blood transfusions
- A blood transfusion can be an effective way of increasing circulating volume and replacing factors lost through haemorrhage that are not replaced if colloids or crystalloids are used (e.g. red blood cells, clotting factors etc.)
- PCV of <10% is an indication for blood transfusion in almost all cases
- PCV 10-15% is an indication to consider blood transfusion in some cases - clinical judgement is needed
- Donor considerations: Healthy, adult cattle that are not heavily pregnant or recently calved are suitable donors
- Blood volume is calculated as 7-8% of adult bodyweight and a maximum of 25% can be collected (but collection of this amount of blood is rarely performed)
- For a 650kg cow, this equates to ~13L, so collection of 6 L for transfusion can be performed safely
- Recipient considerations: For most cases in adult cattle, 5-6L of blood is transfused
- Transfusion reactions are rare (especially for the 1st transfusion) and cross-matching is not typically performed due to the large number of blood groups in cattle.
Supportive care
Supportive care (i.e. good nursing) is always warranted and can make a substantial difference to the recovery of a patient
Examples of good supportive care are:
* Ensure adequate, fresh feed is readily available
* Ensure clean, fresh water is always available
* Isolate the animal so it can receive individual attention and is not competing with others in the herd (e.g. for feed/water)
* If outside, bring the animal inside into comfortable, dry housing. If this is not possible, erect some shelter over the animal (this may be as basic as a tarpaulin) to keep the animal dry and sheltered from adverse weather
* If inside, move to a straw yard for more comfortable lying
Specific treatments
Depending on the underlying cause of the haemorrhage, specific treatments directed at correcting this will be indicated
This may include:
* Longer-term haemostasis (e.g. ligation or surgical repair)
* Analgesia
* Antibiosis
* Anti-toxin treatments (e.g. vitamin K might be indicated if the diagnosis is warfarin toxicity)
* Rarely cessation of some treatments might be needed (e.g. if abomasal ulceration is present, and the cow is being treated with NSAIDs, it would be prudent to stop NSAID treatment as NSAIDs can exacerbate abomasal ulcers)
* Very rarely it might be indicated to surgically remove a ruptured organ (e.g. if there has been a splenic rupture, a splenectomy could be performed. However, this is not field surgery and should only be attempted if there are appropriate facilities and experienced surgeons available).
* Euthanasia might be warranted in some cases
