Beware the Mouse Plague! | Gawler Animal Hospital

Beware the Mouse Plague!

Sign up to our newsletter for all the latest pet related news both locally and Australia wide.
Google Maps location for Gawler Animal Hospital

Gawler Animal Hospital
76 Adelaide Road
Gawler South
SA 5118

08 8522 3500
iStock 2


We’ve been hearing for a few weeks that farmers on the Yorke Peninsula are experiencing a huge increase in numbers of mice and, unfortunately, that mouse plague has now reached us. Over the last couple of weeks, we’ve seen several cases of mouse/rat bait toxicity and we’re expecting that the numbers of affected pets may increase dramatically over the next few weeks and months 

Local fodder stores have been telling us that they’re selling out of baits as fast as they can order them in and this is a huge concern for us.  For those of you that aren’t aware of how these things work, rodent baits act on the clotting mechanism and interfere with what we call homeostasis. That is the ability of animals (and people) to prevent bleeding from occurring. For the most part, this is the function of some of our serum proteins. When we don’t have enough of these (or if they’re not working properly), our blood vessels become ‘leaky’ and we bleed spontaneously into any body cavity. If this happens to a significant degree, we run out of red blood cells and so lose our ability to carry oxygen to the tissues.

Many of you will have heard of Warfarin, which is used in medicine as a ‘blood-thinner’. Often used in heart or stroke patients, this acts by interfering with our clotting mechanisms (and so preventing harmful clots forming in either cardiac vessels or in the brain). As it happens, Warfarin is also the active ingredient in the more basic rat baits such as ‘Ratsak’.  Given at higher dosage, Warfarin causes a major bleed and is fatal to rodents. Unfortunately, when ingested by dogs (cats are much too smart to eat baits directly), it will also kill them. Of course, the manufacturers of Ratsak (and all other baits) make these products very palatable to rodents. Guess what ? They’re equally palatable to dogs who will climb over hill and dale to get to them. 

The real problem, however, lies with the more complex rat baits. These have as their active ingredient one of the Brodifacoum agents (have a look on the label, you’ll see it mentioned somewhere). These are much longer lasting than warfarin and hang around in the blood stream for several weeks. The result of this is that they accumulate over a period of time and can be fatal if your pet ingests small amounts frequently. For example, eating the occasional baited mouse over a month or so will potentially kill a cat or a dog. This is what we term ‘secondary baiting’ and is much harder to prevent than primary baiting (there are plenty of ways you can ensure your dog can’t get to bait that you’ve laid out). Of course, baited rodents are much easier to catch when they are already slowed down by the effects of bait and so, even if your pet isn’t the best hunter in the world, they’re at much higher risk during a mouse plague like the one we’re currently experiencing.

 Ok, what are the signs of baiting in pets? Well, as I’ve already mentioned, baits cause bleeding. This can be into any body cavity and this can cause signs such as the following:

  • Blood in faeces (sometimes appears as black, tarry poo)
  • Blood in urine – can just look dark
  • Pale gums
  • Panting and reduced exercise tolerance
  • Lack of energy
  • Loss of appetite
  • Collapse (in advanced stages) 

What should you do if you see any of these signs? If in any doubt, the simple answer is to come in to see us. I don’t mean to sound alarmist but it’s a potential emergency so don’t hang around. The sooner we can get to it, the better our chance of successful treatment.

 How do we treat baiting cases? I’ll give you an example of an extreme case we saw 2 weeks ago.

‘Red’ is a kelpie cross who lives on a rural property near Mallalla. Red arrived at our hospital first thing in the morning in a very weakened state. He hadn’t been quite himself the night before but was much worse that morning so his owners brought him straight in to see us. Dr Lys was in attendance and immediately ran some blood tests. These showed that Red was slightly anaemic (not enough red blood cells) but also that his clotting factors were way off the scale (vvv slow clotting ability). Our monitors showed that he also had a low oxygen condentration in his bloodstream and a low blood pressure. We immediately started him on oxygen to help with his breathing and also on fluids to maintain his blood pressure. Despite this, he continued to deteriorate. At that point, we gave him a transfusion of plasma which is is rich in clotting proteins. Although this helped to stabilize Red, he took a turn for the worse again. At this point, x-rays of his chest showed that he was bleeding into the lung space to the point where it was very difficult for him to breathe properly. Red was now in a pretty critical condition and so we took him straight into surgery and placed a chest drain. This allowed us to draw off almost half a litre of blood and this made a significant improvement in his breathing and his oxygen levels. We used the blood we’d drawn off to give him a transfusion and this, in turn, gave him a boost in red blood cells. Through the course of the afternoon, we were able to keep his chest clear of blood. Despite all of this, Red was still in critical condition and so we transferred him for overnight monitoring  at an after-hours facility. Red survived the night but took several days to recover fully before he was fit to go home. A very relieved owner now reports he is back to his old self and a very happy boy. Over the next few weeks, Red will remain on medication to help him produce new red blood cells and we’ll repeat blood tests to ensure he’s not anaemic. 

What can you do to prevent this happening? If you live in a rural setting, it’s always going to be a danger, particularly during times of mouse plague. There are a few things you can try, however: 

  • Ensure there are no baits directly accessible to your pets
  • If you must lay down bait, ensure it is in a rodent box or somewhere your dogs can’t get to it
  • Check that your neighbours aren’t leaving bait down in accessible spots
  • If you or your neighbours are using baits, consider keeping a greyhound muzzle on your dogs (won’t work on your cats, sorry!)
  • Remember that cats are at least as likely to suffer secondary baiting as dogs
  • Be aware of the signs I’ve mentioned above
  • If in any doubt, come in to see us and we can rule out the possibility of bait problems 

Remember that, as with most problems, the sooner we get to it, the better our chances of a successful outcome. If you think there’s any chance that you’re dealing with a mouse bait ingestion, come in to see us as quickly as possible. Better to have us tell you your pet is 100% healthy than for you to lose your dog or cat in such tragic circumstances! 

For an appointment, call our friendly receptionists on 8522 3500.

Post your comment


No one has commented on this page yet.

RSS feed for comments on this page | RSS feed for all comments

Recent Blogs

Fleas and the Bubonic Plague!

>> Read more

The Joy of Reunion with your Pet

>> Read more

Seven Secrets of Allergies & Itchy Pets

>> Read more