How abscesses come about

My friend Carrie snapped these candid shots of two cats making a ruckus in her neighbourhood - a close-up reveals that the encounter is anything but friendly. Fighting between cats is common as our cities create a highly dense feline population which felines typically don't appreciate (they like their personal space). Fighting not only leads to abscesses, which are incredibly painful and can make cats extremely ill - but its also how feline AIDS is transmitted.

Happy New Year!

Everyone loves a clean slate and we hope 2009 is just that for you...here in small animal land we're taking some time out to plan the next twelve months or so, resolving to read more, take more photos of interesting cases (instead of having a mental debate and missing the moment) and spend a bit more time chillaxing.

Meanwhile given we're in tick season (a bit of a misnomer these days since we're seeing more ticks in the traditionally "tick-free" months of the year) I wanted to share an interesting case with you. A young Border collie pup who presented to me with a history of vomiting and profound depression and bradycardia (a slow heart rate - it was sitting at around 40-60 beats per minute when a dog her age and size should be around 120-160). She could hardly move. To all intents and purposes she looked like a dog suffering from tick paralysis. The night before her loving family had decided to prevent tick envenomation - washing her with an anti-tick shampoo then adding an anti-tick collar just to be sure. Well, being the age she was she ate part of her collar. The active ingredient in the collar, amitraz, prevents ticks...but being an alpha-2 agonist, it has sedative properties when eaten. Vets use alpha-2s to induce sedation or as part of an anaesthetic protocol in animals. These days they're used more in zoo and large animal medicine, but have been larely superseded in small animal medicine. Fortunately though, because vets have the need to reverse sedation, the drugs used to reverse these agents can also reverse side effects of amitraz ingestion - as I discovered when I spoke to Dr Mark Kelman, technical services vet for the manufacturer of the collar.

The full case report, together with a discussion on the pharmacokinetics of amitraz, is written up in the latest issue of the Australian Veterinary Practitioner. The good news is that after a few days hospitalisation, during which I painstakingly waited for the dog to poo out the ingested remnants of collar, the patient made a full recovery and her loving family bought her back in the next week to show us how bright and happy she was.

Fawcett AF and Kelman M (2008) Amitraz toxicity in a dog following ingestion of amitraz-impregnated collar. Australian Veterinary Practitioner 38(4):142-145.

Occupational hazard?

My friend K, a brilliant vet, is currently in hospital on three different intravenous antibiotics following a dog bite she received almost nine days ago. The patient, a rottweiler, is trained as an attack dog but was not wearing a muzzle. The dog did not react as she approached him, from the side, but suddenly bit the middle finger on her left hand - leaving her with a painful, open communiuted fracture. She was given oral antibiotics but two days ago developed a draining sinus. Tomorrow she is scheduled for a general anaesthetic so the wound can be debrided. She will require weeks and weeks off work, and now her partner has to take time off work to change their baby because she can't do anything with this hideously infected and very sore finger. I went in to visit her today.

Aside from being bored (do animals get bored in hospital? few show signs if they do) and frustrated she is learning some interesting things you can only learn through experience: IV catheters are uncomfortable for the duration that they are in and the fluids feel very cold (its amazing that most animal patients tolerate them relatively well). The nursing staff initially covered the entire wound in plastic for fear of contamination - but this effectively placed a seal around the draining sinus, causing an increase in temperature and humidity and consequently pus - and pain. She since did what a lot of animals do and just removed the bandage (mind you she didn't eat it). People don't realise how dangerous, destructive and nasty dog bites can be. The owners in this case were frightened of their own dog but felt it was acceptable to bring to a vet without a muzzle on. This attitude is fairly common - people seem to assume that as vets we are somehow immune to the havoc animal bites can wreak, or we have some magical forcefield that protects us against being bitten. Others just think we're being a bit weak if we're worried about being by "an old dog with hardly any teeth" or "a little cat". As professionals we take care but that can't protect you against a bite for which there are no warning signs. Nothing can.

Working cattle

This weekend I got out of the city and stayed with a friend to help out on his cattle farm. There was no mobile phone access, no internet, not even a landline close by and although it was a short time it was so nice to get out in the paddock (as a small animal vet this rarely happens). The nice thing is that my friend, a senior small animal colleague, uses anaesthesia when castrating cattle (not everyone does). The cattle pictured are very heavily sedated and not unwell.

Almost missed it...

A nasty traffic jam caused me to run late for a media call with Taronga Zoo's first baby Pygmy hippo in 23 years. I almost turned back - except for the mention in the media release that this little gal is only 6kg. ie the size of a biggish cat. Her name is Monifa. She's being hand-reared by keepers. Throughout the press call she seemed fixated on nuzzling their shirts. I can reveal that most members of the media pack were besotted. Its a terrible shame such a birth is a rarity and world news. Anyway, check out Monifa for yourself...

Post mortems: It's worth looking

Yesterday I attended an excellent seminar on conducting post mortems. These are extremely rare when it comes to animals, although they are a valuable source of information and can answer questions. I had some clients bring the body of their six-year-old cat in a few weeks ago. The cat had been perfectly normal, with no clinical signs or symptoms suggesting any illness, and was found deceased that day. Understandably they were incredibly distressed. I offered a post mortem (as a vet we can conduct a PM ourselves, looking for any gross or obvious signs of pathology, or we can send the body to a pathologist. We also take tissue samples for histopathology), but they declined on the grounds that it would not make a difference to the outcome of the cat. I appreciate that. But it is also good to have answers - if it happens to be something infectious or something that another animal household might be exposed to, a post mortem can be lifesaving. The seminar I attended yesterday gave a protocol for performing a full post mortem. This is critical in cases of suspect abuse or deliberate harm, which can end up in court, as well as deaths of unknown cause. I won't beat around the bush - to perform a full PM you need to be extremely thorough and open up all body cavities, but this can be done gently and respectfully. I've not yet performed a "full" post mortem -often the answer is very obvious when I open the abdominal or thoracic cavity. For example, I have discovered large tumours attached to abdominal organs. I performed a post mortem on my obese mouse after he passed away suddenly, and discovered a mass on the liver. I sent this off to a pathologist (which costs a few hundred dollars) and they diagnosed a hepatic lymphosarcoma). I'm glad I did it because it gave me closure.

Of course not every cause of death is obvious even on post mortem. I performed a post mortem on one of my guinea pigs who died with respiratory signs and there were no lesions on the lungs, nor could the pathologists identify anything out of the ordinary.

One of the useful things I learned about sample collecting is that the samples must be stored in formalin in a volume of 1:10 to achieve adequate fixation. While it is important to try to keep samples under 1cm thick, it doesn't matter as much if you follow the 1:10 rule.

Foreign bodies

The last few weeks at work has been madness. We've done quite a few enterotomies which are always a challenge. This is a radiograph of a medium sized dog which had ingested a rubber bone (see arrows). She began vomiting. To cut a long story short we took her to surgery (you can see the enterotomy site) and removed the offending object (pictured). Another lesson in why choosing indestructible, dog-size appropriate toys is critical.