Frankie is a one-year-old dachshund who presented to our clinic on a Sunday evening. His owners reported he was fitting, but he was actually judged to be tremoring when he presented at the clinic.
When seizuring or fitting, the patient is generally unconscious and displays extensor rigidity—their limbs are stretched out and their necks stretched back. Frankie was conscious and didn’t have that extensor rigidity. He was much more in control of his limbs apart from the fact that they were shaking—they weren’t contorted into any particular position. He also had a temperature of 42.2 degrees.
Initially he was given I/V fluid therapy and cooled. We took some blood gas readings and found his lactate was 7.5, which indicates his muscles were outstripping his heart and lungs’ ability to provide oxygen to them.
When we see tremoring the possibilities are an intoxication of some kind or a primary neurological disease.
The most common toxins we see are tremorogenic mycotoxins, human antidepressants, stimulant recreational drugs and molluscicides. The most common neurological condition is idiopathic generalised tremor syndrome, also known as ‘hairy white shakers’ (it was originally diagnosed in small white hairy dogs which is how it got its common name).
Tremorogenic mycotoxins are produced by fungi that grow in rotting food, so dogs can get them by raiding rubbish bins or compost heaps or even eating excessive amounts of blue cheeses.
Frankie certainly had no exposure to any human medications or any toxins that the owners were aware of and he was a known scavenger and had passed some foul green diarrhoea soon after presentation.
Initially we try to control the tremors pharmacologically when they come in tremoring like that. Diazepam or Valium is our first line drug, followed by methocarbamol. Neither of those had any effect in Frankie’s case, so we decided to try lipid therapy.
Lipid therapy has been around for a long time but it’s really only just gaining widespread acceptance over the last two or three years. For it to be effective, the toxin needs to be fat soluble. The fat solubility for all sorts of toxins can be looked up and if it’s got an appropriate fat solubility then lipids are likely to work. We use a product called Intralipid, which is the source of fat that we use when we’re giving patients intravenous nutrition.
The idea is it acts like a sink. The toxin will dissolve in fat, so you give the patient a big hit of fat into their bloodstream. The drug is bound up by the fat and therefore not able to get into the brain or into any of the tissues where it’s able to do harm.
The response can be quite dramatic—it certainly was in Frankie’s case. We gave an initial bolus of one to two mls over the first minute or so and then another 0.25 mls/kg/minute over the next 30 minutes. By the end of the 30 minutes Frankie had stopped tremoring.
Frankie recovered rapidly. He had presented at 6pm and was back to normal by 2am. We kept him in hospital until we were sure there was not going to be any consequences of the hyperthermia, and he was discharged the following day.
Dr Simon Lemin BVSc MANZCVS (Surgery)
This year marks 22 years for Dr Simon Lemin as a dedicated emergency and critical care veterinary professional. It is also his sixth year as president of the Veterinary Emergency and Critical Care Chapter of the Australian and New Zealand College of Veterinary scientists. In 2005 Dr Lemin and Dr Robert Webster bought the emergency hospital they were both working for. In the years since Dr Lemin has pursued his passion for emergency and trauma surgery, ventilator medicine and all the details that make him something of a pathophysiology nerd. That passion has led to five emergency hospitals (and growing) and one of the first pet intensive care units in a private practice. Dr Lemin and his wife Julanne have four kids (two girls and two boys).
Animals aren’t just part of Dr Lemin’s professional life. When he is not working he goes home to pet pigs, mini cows, horses, Shar Pei dogs and hairless cats. There are also snakes, spiders and lizards.