Companion May 2012 - BSAVA

More documents

Recommendations

Info

A 18 | companion How to select and collect: feline blood donation Figure 2: A variety of methods exist for feline blood typing including immunomigration assays (such as the Alvedia kit (A and result – Type A) and blood typing cards (B and result – Type B). possible results are Type A, B or AB Figure 2a courtesy of pet Blood Bank B Red blood cell substitutes Oxyglobin (a polymerized bovine haemoglobin solution) was available until recently as an alternative to feline blood for improving the oxygen carrying capacity. Currently out of production, the manufacturers (OPK Biotech) are applying for a licence and production is hoped to re-commence shortly. Prior to cessation of production this product was not authorized for use in cats but had been used “off-licence” in cats with few reported complications. The main advantages of Oxyglobin are that its use avoids the possibility of incompatibility reactions and it is has a greater ability to deliver oxygen to the tissues than erythrocytes. Therefore Oxyglobin is principally useful in cases where type-specific blood is not available or, particularly relevant to cats, when oxygen carrying capacity is needed immediately and the patient cannot wait for the time taken to collect feline blood. The main disadvantage is its short duration of effect (11–82 hours); compared with erythrocytes (maximum circulating lifespan of transfused cells is 4–6 weeks). Furthermore Oxyglobin acts as a plasma volume expander as it is a potent colloid and causes vasoconstriction. Patients, particularly those which are volume-replete, must therefore be carefully monitored to prevent fluid overload. Conversely, Oxyglobin is an excellent choice in patients in which rapid volume expansion is required. Recruiting blood donors Despite there being animal blood banks in the UK, the author is not aware of any currently supplying feline blood. At Pet Blood Bank a pilot project, funded by the Waltham Foundation, has been underway looking into various collection methods, with a conclusion to this project due for publication in <strong>2012</strong>. It is hoped that in the future Pet Blood Bank may be able to provide feline blood products. However, at present, veterinary practices must rely on recruiting their own donors. There are two principle sources. The Animal Blood Register can be used to obtain a list of possible donors in your area (www.animalbloodregister.com). This online register allows owners to register their pets and contact details and allows vets to access them via a secure registration system. Alternatively, practices may choose to use staff pets for convenience or to recruit client’s pets. If feline transfusions are regularly carried out, creating a database of donors will be useful when a transfusion is required in an emergency. The donors should be pre-typed and have had an initial pre-screening of biochemistry and haematology, as well as being tested for feline leukaemia virus, feline immunodeficiency virus and haemotropic Mycoplasma sp. The ideal donor Careful selection of potential donors minimizes both the risk to the donor of the blood collection and to the recipient of the blood transfusion. The owner of the donor should be made aware of the risks associated with sedation and donating blood. All donors should: ■■ Be in good general health. The sedation and collection of blood from the donor can result in hypotension and can exacerbate pre-existing conditions such as cardiac and renal disease. ■■ Undergo initial pre-screening for biochemistry and haematology. They should also have tested negative for feline leukaemia virus, feline immunodeficiency virus and haemotropic Mycoplasma sp. Ideal donors maintain a lifestyle which limits exposure to the viruses, i.e. indoor-only cats. It is recommended that these blood tests are carried out on a yearly basis, whilst the cat is a donor. The owner of the recipient cat should be
made aware that despite testing for infections such as feline leukaemia virus, false negatives are possible and there is a chance that the recipient cat could become affected with one of these disorders. ■■ Be regularly vaccinated and regularly treated for endo- and ecto-parasites. ■■ Not have travelled abroad, therefore preventing the need for testing for ‘foreign diseases’. ■■ Not have received a previous transfusion because of the risk of development of antibodies to other blood types which would complicate a future transfusion. ■■ Be between 1–8 years of age. Over 8 years old, sub-clinical diseases will be more likely. ■■ Weigh over 4.5 kg with good body condition. ■■ Be of calm temperament. ■■ Not be pregnant, nor have had previous pregnancies. ■■ Ideally have a packed cell volume greater than 35%. This should be checked prior to each collection. In practice cats with a PCV in the normal range meeting all other criteria are suitable donors. Restraint during collection In the author’s experience all cats will require sedation for blood collection, unless the cat undergoes substantial and adequate training and is very calm. Ethically, it is vital that the procedure is as stress-free as possible, as the donor cat is undergoing a procedure which is not of any personal benefit. The drugs used for sedation are dependent on operator preference. The staff handling the collection should be familiar with the drugs to ensure the sedation can be managed safely. The drugs should be short acting, dosed to effect or be reversible. It is advisable to avoid acepromazine due to the hypotension it causes and the difficulties this may cause during collection. Sedative drug combinations which are commonly used in the author’s practice for blood collection are: ■■ Medetomidine 20 µg/kg and butorphanol 0.2 mg/kg i.m. – reverse with atipamezole 50 µg/kg i.m. ■■ Ketamine 3–5 mg/kg, midazolam 0.2 mg/kg and butorphanol 0.2 mg/kg i.m. These provide up to 30 minutes of sedation, commencing 5 minutes after intramuscular administration. The feline blood donation The acceptable donation volume in cats is 10–12 ml/kg and this typically results in a total donation of ~50 ml. Donations should not be more frequent than every 3 months. With frequent donors it is advisable to alternate between the left and right jugular veins. It is important to keep accurate records of the donors and of each donation. From these records it can be ensured that regular health checks are carried out and that any reasons why the cat should not donate are identified. Notes on the donor’s reaction to dosages of drugs used for sedation can be made which will aid future donations. Aseptically prepare the equipment (Box 2) by flushing though the butterfly needle and three-way tap with CPDA and drawing up 2.5 ml CPDA into the 20 ml syringes and 1.25 ml CPDA into the 10 ml syringe (a 1:7 ratio). Set up the fluids ready for administering post donation. ■■ Once the donor checks are successfully completed, place an intravenous catheter and sedate the donor. ■■ The assistant should restrain the donor in lateral or sternal recumbency, with the head extended to expose the jugular vein. If the patient is in lateral recumbency then placing padding under the patient’s neck may aid visualisation and access to the jugular vein. ■■ The hair is clipped and the skin surgically prepared. BOX 2 The following is required for the donation: ■■ Suitable sedative drugs ■■ Clippers ■■ Surgical scrub and spirit ■■ Sterile gloves ■■ Equipment for intravenous catheter placement ■■ 19 G butterfly needle and three-way tap ■■ Citrate phosphate dextrose acid (CPDA) anticoagulant obtained from standard human blood collection bag ■■ 20 ml syringe x 2, 10 ml syringe x 1 ■■ 19 G needles to cap the filled syringes ■■ 100 ml blood collection bag and 19 G needle (optional) ■■ Hartmann’s fluids and giving set ■■ The phlebotomist and two assistants companion | 19
Page 1 and 2: Celebrating Congress In pictures P4
Page 3 and 4: Surveillance - now is the time With
Page 5 and 6: FounDIng FAtHer. BSAVA welcomed the
Page 7 and 8: Party Night pArtY nIgHt. packed out
Page 9 and 10: Disease Requirements for humans Req
Page 11 and 12: Up to 8% of Daubenton’s bats carr
Page 13 and 14: What initial investigations would y
Page 15 and 16: Evaluate the CT (Figure 3). Are the
Page 17: donor can be difficult. Practically
Page 21 and 22: Scottish Congress · 31 AUGUST - 2
Page 23 and 24: Figure 2: Positioning for a dorsopr
Page 25 and 26: ance, Nurse’, after passing a sui
Page 27 and 28: and/or urine is a preferred method.
Page 29 and 30: A busy World Congress During WSAVA/
Page 31 and 32: lungworm in donkeys and my continui
Page 33 and 34: Focus on... BSAVA East Anglia Regio
Page 35 and 36: evening Meeting - South WeSt region

Companion May 2012 - BSAVA

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?