I recently wrote about the seasonal dangers of hidden adders and oak processionary moths, but the Veterinary Poisons Information Service highlights a recently published paper reporting that there is a canine hazard hiding in plain sight – the common stinging nettle (Urtica dioica).
Two gun dogs developed signs of neurological toxicity after working in the same area on the same day. One was a seven-year-old castrated male springer spaniel weighing 18kg and the other a two-year-old spayed female Labrador retriever weighing 21 kg. The dogs presented with slightly different signs that included a skin reaction (urticaria), rapid, abnormal breathing (tachypnoea), hypersalivation, constricted pupils in both eyes, reduced ability to walk showing in all four legs, twitching muscles and decreases in normal reflex actions. One dog suffered three episodes over a three week period and the other just one. Both dogs made a complete recovery after veterinary treatment. Some dogs have been reported as circling and showing signs of gastrointestinal problems and collapse after exposure to stinging nettles.
Pretty much everyone will have been stung by nettles – was it just my dog who chose to defecate amidst nettles or brambles? They are also often a hazard when wearing short sleeved clothing when it is easy to brush against them on overgrown paths. Nettles grow hairs known as trichomes that contain, amongst other chemicals, histamine, acetylcholine and 5-hydroxytryptamine (serotonin), all of which can cause toxicity in humans and other animals. Different species of nettle contain different concentrations of toxins and individuals vary in their susceptibility.
I am particularly interested in this report because I suspect that I might be particularly susceptible to at least one toxin. If I am stung, symptoms often persist over several days and flare up when I think that they have died down. I don’t know of anyone else that reacts in the same way.
So, it seems that we need to be cautious when our dogs are rooting around, seemingly unperturbed by nettles and perhaps consider it as a possibility if any of the above signs are seen following a walk or after a dog has been working in nettles.