Page 173 - WSAVA2017
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X-rays can be carried out under sedation/anaesthesia. Most fish will tolerate 5-10 minutes easily outside of water so long as they are kept moist. Useful to look at boney structures, the swim bladder, some tumours but most internal organs are usually hard to differentiate.
To get true sampling for culture and sensitivity it is best to take the sample from the kidney. Requiring sacrifice
of the fish and often not acceptable to the client. When swabbing an external ulcer, even if the sample is taken correctly, may not reveal the true cause. There are further issues which tend to mean you can end up with the incorrect information on the type of bug to the wrong sensitivity profile.
Surgery
There are some differences to fish surgery compared
to mammals with the first being that fish need to be
kept moist and for short procedures, a damp towel covering the fishes’ eyes is suitable (Note that towels
and handling can damage the fish’s mucous layer). Site preparation consists of a gentle wipe with sterile saline swab followed by one wipe of dilute povidone iodine swab. Traditional scrubbing damages the non-keratinised skin. It is acceptable to carry out no site preparation
- think of fin snips – with no detrimental effects such
as wound dehiscence or post-op infection apparent. Traditionally scales should be removed (one or two rows) from the incision site otherwise delayed healing/post-op infection may occur. This also provides easier placement of sutures so less iatrogenic trauma. However, current thinking is that this is not a necessity. If removing external masses healing will be by secondary intention.
To enter the coelomic cavity a ventral midline incision
can be made posterior to the pelvic girdle (attachment of pelvic fins) ending anterior to the vent. The pelvic girdle can be incised and the incision extended anteriorly to
the pectoral fins but the pelvic girdle may require wiring back together in larger fish. After the skin incision, blunt dissection with scissors of the musculature tends to decrease haemorrhage (remember fish blood volume is considerably less than mammals). Haemostasis must
be good. If removing abdominal masses then no more than debulking maybe achieved as delineation between tumour and normal tissue is difficult to determine without using CT or MRI scans. If the tumour is within the gonads then complete removal should be undertaken. Fish up
to 12” in length can be sutured in a single layer using
4.0 nylon (preferred) or equivalent monofilament with a 12 – 16mm cutting needle. Single interrupted, horizontal mattress or X mattress patterns can be used. Wound healing usually within 21 – 30 days (partly temperature dependent) and suture removal is preferable if possible.
Hospitalisation
Providing hospitalisation can be problematic as maintaining fish systems requires an actively working filtration system which needs time to mature. Stripping down and sterilizing the system between patients is not an option or having tanks empty between patients. Using a plastic paddling pool can be an option although it is labour intensive. Maintaining the system with a resident population to keep the filter ticking over can be useful although this means the filter is not routinely sterilized, the resident population maybe at risk from infections, and still requires a lot of work to maintain making it expensive. One simple and effective solution is to do away with filters and replace them with trays of fast growing plants (think of aquaponics). Mature Busy Lizzie plants (Impatiens spp.) are cheap and effective. This removes the nitrogenous waste. At the end of a patient’s hospitalisation period they can be discarded leaving just the tanks and pipes to be sterilised.
Dispensing
Routinely used chemicals for the treatment of parasites such as potassium permanganate, malachite green
and formalin maybe better obtained by the client from the local aquatics shop. As perhaps will salt (a useful
first aid treatment) and chloramine-T used either as a disinfectant or antiparasitic. Still leaving several veterinary endo/ectoparasiticides, aquatic disinfectants, antibiotics, NSAIDs that can be dispensed amongst the 300 or so drugs that are currently used in ornamental fish medicine.
Medications can be applied topically, by short dips, longer term baths, prolonged immersion, injection and in-feed. In selecting a medication thought should be given as to how it can be given. Most fish are inappetant when ill although using appetite stimulants can help. To minimize volumes, antibiotics should be given by injection and used as a last resort. As fish are poikilothermic treatment duration and frequency of repeat are affected by water temperature. Increasing the water temperature particularly in Coldwater fish will improve immune function. It is also good practice to include supportive treatments along with the actual medication. Vitamin C and levamisole increase immune function, using a water disinfectant decreases pathogen load within the system and salt decreases osmotic stress.
An Urban Experience
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