There's mounting evidence that weeds are not just harming Australia's landscape, but are also killing pets. Veterinarian Chris Brown (author of The Family Guide to Pets) says that plant toxins, as well as spines, thorns and prickles, cost horse and pet owners, the livestock and poultry industry many thousands of dollars every year.
"Home gardeners need to be much more careful about what they plant in their own backyards," says Dr Brown. "They need to select plants which are not poisonous to animals, and which don't pose a risk of invading farms or native bushland."
"Probably the most toxic of common garden plants are the lilies," says Dr Brown. "It is quite a common occurrence that domestic moggies take a bite of leaves or flowers in a vase - and die of it."
Dr Brown says that young animals are more at risk from weed toxicity than older animals, and that having two dogs is more likely to cause poisoning than one.
"Two dogs will compete for a stick or a bulb which they would normally ignore. Sometimes they will eat leaves or berries simply to prevent the other dog getting a share," says Dr Brown.
"Dogs can die in dramatic and distressing circumstances with convulsions and vomiting after, for example, eating berries of the common wayside flower 'Yesterday Today and Tomorrow' (Brunsfelsia).
Another serious doggy threat is Wandering Jew (Tradescentia fluminensis), the sap of which can cause a painful skin reaction. The skin rashes can then get infected and need treatment. Often the owners have no idea that the cause is contact with broken stems of this common weed.
"Red and green cestrum regularly kills young calves as well as dogs," he says, "It can cause acute liver failure and death."
"Cotoneaster has small fruit which can cause paralysis in dogs," he says. "Oleanders are a familiar poisonous plant, but azaleas, poinsettias and even macadamia nuts can be toxic."
Invasive plants of pasture and farmland have long been implicated in the deaths of domestic and farm animals. Horse owners are warned each spring to move their animals away from paddocks infested with Paterson's Curse (known as salvationJane in SA) as the plant is toxic to horses.
St John's Wort, imported from its native Europe as an ingredient in traditional medicine because it contains a tranquillising agent, can cause abortions in stock that eat it. The plant also causes photosensitivity in the skin, and animals can become painfully sunburned.
Fireweed and rye grass are two common killers of beef and dairy cattle, and in Queensland alone, lantana is known to have killed 1500 cattle in a single year.
"Animal owners have to be vigilant, especially if they have kittens, puppies, or calves, and at times of vigorous plant growth," he says. "Areas of severe infestation should also be fenced off so that they are not available to the animals."