FELINE trauma has seen a number of key developments in knowledge and opinion with regards to supportive medical care. According to Tim Hackett of Colorado State University, the cornerstones of this care are simple: adequate nutrition, good analgesia and attention to nausea and gastrointestinal disorders with anti-emetics.
The key is, Dr Hackett explained, “to do all we can to prevent organs from getting into trouble”. Previously, it was not unheard of for feline trauma patients to go 4-5 days without eating, but it is now understood that getting a cat to eat as soon as possible after a major event has two major beneficial effects: better healing and an improved immune response.
Dr Hackett advocates the use of a 40kcal/cat/day calculation and, practically speaking, tends to fit an oesophagostomy tube in many cats that have had a general anaesthetic and surgery. Drugs such as appetite stimulants and anti-emetics also play a vital role.
In the US, mirtazapine, a drug which was developed for use as a antidepressant in human medicine, is being used as an effective appetite stimulant which acts for much longer than the traditional UK treatment, valium.
Another key area of supportive therapy is fluids and how cats can easily be “volume overloaded”. This was one of the core points brought up by speaker after speaker at the congress.
“Cats have a poor response to fluids in shock,” said Tim Hackett. “We want to give them fluids but if we give them too quickly or give them an inappropriate fluid they can have problems. Cats are more prone to developing pulmonary oedema than any other species that we deal with.”
Cats that are particularly at risk are those that are not suffering from a hypovolaemic shock such as that seen with heavy blood loss. Also, cats that have gone into cardiogenic shock will not be able to regulate their blood volume well.
The trick with administering fluid in a shocked cat is to monitor regularly. Liz Leece, of the Animal Health Trust, recommends crystalloid fluids at a rate of 10ml/kg over 15 minutes with a careful monitoring for signs of pulmonary oedema or deterioration. These include: dyspnoea, bluish mucous membrane, pulmonary crackles on auscultation and wetness around the mouth and nose. At the end of the bolus dose the cat is reassessed and the fluids adjusted accordingly.
Liz said: “You want to be there when that 40ml runs out… Essentially we are aiming to titrate the fluids to effect and not necessarily give a fixed textbook volume or rate.”
The use of antibiotics in open wounds has been a controversial subject. In theory antibiotics should not be used unless infection is present but Dr Sandra Corr of the RVC acknowledged that it can be very difficult in practice to avoid their use.
Dr Corr said: “Realistically, if you have huge soft tissue damage and open wounds, it’s entirely fine to put them onto broad spectrum antibiotics.” At the RVC they use intravenous antibiotics such as Zinacef and Augmentin. If you do use antibiotics, they should be stopped if a wound swab and culture comes back clear or when granulation tissue, which is “quite resistant to infection”, covers the wound. But, the take-home message with regards to antibiotic use is that it in no way substitutes for excellent flushing and wound decontamination.
Dr Corr said: “If I was given a choice between not cleaning [a wound] properly and using antibiotics, and cleaning properly but not using antibiotics, I would choose cleaning properly every time.”
Tim Hackett gave delegates a brief overview of considerations in feline blood transfusion. He explained how it is possible to carry out a “one-time” transfusion in dogs but not in cats because of the existence of two distinct blood types with pre-existing antibodies in the latter species.
If you give type A blood to a type B cat, or vice versa, this can result in an immunological reaction which can cause haemolysis and death.
According to Dr Hackett there are approximately 3-5% type B cats in the feline population but this is breed-dependent. Breeds that are more likely to be type B are the British Short Hair and the Rex (incidence of type B cats can run up to 50% in some populations of these breeds).
It is recommended that all feline donors and receivers are typed for blood. Donors should also be screened for FeLV, FIV, Bartonella spp and Haemobartonella spp (now Mycoplasma spp). In choosing a blood donor, one that has received good flea control and, ideally, lives an all-indoor lifestyle is best. They should have an up-todate vaccination record, be on no current medication and have never received a transfusion themselves.
Donor cats should be big – Dr Hackett describes a “lean, large cat” greater than 6kg in weight – as they can be at risk from hypovolaemia. A maximum of 40-50ml should be drawn and the donor should be given subcutaneous (or intravenous if necessary) fluids after the transfusion.