Is horse manure dangerous to dogs?

Many dogs have a tendency to eat things they shouldn’t when out and about, including horse and livestock manure. Although it’s unpleasant, most breeds of dog that eat a small amount of manure will not become ill.

But there is a risk of toxicity due to chemicals in horse worming medications which will be passed in the horse's poo. Some dog breeds are at a higher risk of ivermectin poisoning. For this reason, dog owners – particularly those with breeds at risk – should try to prevent their dog from eating it as much as possible.

Why can horse manure be dangerous to dogs?

Some horse worming treatments contain a chemical called ivermectin which is effective against many different parasites across a range of species.

There is a high concentration of ivermectin in horse and livestock worming treatments and this can be passed in manure for days after the animal has taken the medication. This can be toxic to dogs that eat it, but the risk depends on the breed of dog, when the animals were treated and the amount consumed.

What breeds are most at risk from ivermectin poisoning?

Any dog that consumes a large amount of horse manure containing ivermectin could become very ill. But some dogs of certain breeds have a gene mutation which puts them at risk of poisoning from ivermectin, even if they ingest a small amount.

Breeds at risk include:

• collies
• Shetland sheepdogs
• Australian shepherds
• old English sheepdogs
• long haired whippets
• merle Pomeranians

Other herding breeds are possibly at risk as well. A test for the gene mutation can be done so you can check whether your pet is at risk. Poisoning in breeds without the genetic predisposition is very rare.

What are the symptoms of ivermectin poisoning?

• Dilated pupils 
• A lack of balance or disorientation 
• Lethargy 
• Vomiting
• Drooling
• Seizures
• Difficulty breathing

What should I do if I suspect ivermectin poisoning in my dog?

If your dog has eaten horse manure and begins to show symptoms of ivermectin poisoning, they should be seen by a vet immediately. Without fast veterinary attention, ivermectin poisoning can be fatal.

What treatment can be given for ivermectin poisoning?

There is no antidote to ivermectin toxicity. With supportive veterinary care, most dogs will have a good chance of recovery. But this will depend on the amount consumed and whether or not the dog is sensitive to ivermectin.

How do I stop my dog from eating horse poo?

Early training to teach your dog to ‘leave’ while out and about should help you to stop them eating manure. But keep a watchful eye over them, particularly if the dog is from an at-risk breed. If your dog is determined to scavenge, you may want to consider muzzle training. 

All dog owners should be extra vigilant around stable yards and farms.