Common farm items can poison dogs, and to a lesser extent, cats. Cats tend to be more discriminant in their eating habits than dogs so are less often exposed.
Antifreeze is one such farm item that can be particularly lethal to dogs that ingest it. The toxic ingredient in most types of antifreeze is ethylene glycol.
Unfortunately, ethylene glycol makes the antifreeze taste sweet, which can be appetizing to dogs and other animals.
Once absorbed through the intestines, this molecule is transported by blood to the liver where it is metabolized into an even-more toxic molecule. Again, via blood, it enters the kidneys where crystals form. These crystals cause severe damage to the kidneys and can eventually cause them to fail.
Dogs that have ingested ethylene glycol look drunk. They may lose co-ordination and experience vomiting and diarrhea. They may drink and urinate more frequently in the early stages. Diagnosis of antifreeze toxicity is based on history of exposure (or possible exposure) and clinical signs, which can be non-specific.
Additional supportive testing, such as blood work and urine analysis, can help establish the diagnosis. Treatment of antifreeze toxicity is intensive and involves intravenous fluids to support the kidneys.
Medication is administered that uses the same liver enzyme as the one that metabolizes the ethylene glycol, so it reduces the production of the highly toxic molecule and allows the less potent form to be excreted.
If the specialty medication isn’t available, ethanol can be administered by intravenous drip in one of the more bizarre treatments in veterinary medicine.
Dogs are at highest risk in the fall, winter and spring when antifreeze is added and flushed from equipment for the cold seasons.
Prevention is really important for this toxin. Antifreeze should be properly stored in leak-proof containers. Clean up all antifreeze spills and consider using only products that are free of ethylene glycol.
Another type of toxin present on farms is rodent poisons, also known as rodenticides. Dogs that get into rodent poison may suffer severe consequences. There are several types of rodent poisons available, so if you suspect your dog has ingested a rodenticide, make sure to keep the packaging because the type will affect the treatment necessary.
Anticoagulant rodenticides kill animals by affecting the blood clotting factors that need vitamin K to work properly. Animals bleed internally, resulting in their death.
Dogs usually eat this poison either directly from the storage container or from the rodent’s stash. It is less common that dogs will ingest and have severe outcomes from eating rodents that die of poisoning, although this can occur.
The clinical signs in these cases follow a gradual progression. Dogs appear normal for the first three to five days following ingestion because it takes several days for the vitamin K to be used up. Once these clotting factors are used, bleeding can occur any place in the body, most commonly from the nose, and into the gastrointestinal tract, chest, abdomen and joints.
Signs of rodenticide intoxication range from non-specific lack of energy and weakness from internal blood loss to nose bleeds and coughing up blood. Monitoring blood-clotting times and treatment with a specific type of vitamin K supplement for several weeks is common. In severe cases, dogs may require blood or plasma transfusions to replace the blood that is lost.
Another type of rodenticide available in Canada is bromethalin. This molecule is toxic to cells of the nervous system. Signs of high-dose intoxication occur four to 16 hours following consumption and can include tremors, circling, excitability, seizures, coma and death. At smaller doses, bromethalin causes progressive paralysis, eventually leading to paralysis of the diaphragm and death by asphyxiation.
Treatment for bromethalin intoxication is supportive and most cases with neurological signs have a poor prognosis. In dogs that recover, permanent damage to the brain may occur.
Rodenticides should be used cautiously and deliberately to manage rodents. The use of bait stations is important to reduce the chance of non-target species including dogs and wildlife from accidentally ingesting these poisons. It is also worth considering non-poison approaches to rodent control.
With knowledge of toxins on your property, you can take some simple steps to reduce the risk of exposure to farm dogs.
Dr. Jamie Rothenburger, DVM, MVetSc,PhD, DACVP, is a veterinarian who practices pathology and is an assistant professor at the University of Calgary’s Faculty of Veterinary Medicine. Twitter: @JRothenburger