Thursday, October 10, 2013

Linear foreign bodies can wreak havoc on pet health

Never leave cats unsupervised with string. They have a way of swallowing it and that can spell disaster.
Gastrointestinal foreign bodies - i.e. objects that animals eat that they really shouldn't - are commonly seen in small animal practice. Clinical signs vary from subtle malaise to intermittent vomiting to the severely affected, moribund patient. It all depends on exactly what the foreign body is, where it is and how long it has been there.

Gastrointestinal tract (GIT) foreign bodies (FBs) can cause complete obstruction of the gut - i.e. the intestine is totally blocked, usually resulting in severe pain and more obvious clinical signs; or partial obstruction (often associated with more subtle, more chronic signs).

Linear foreign bodies (LFBs) - string, tinsel, fishing line, rope - often lead to partial obstruction and can be challenging to diagnose. In a recent study, LFBs were associated with a lower survival rate (80% in dogs and 63% in cats) compared with discrete FBs (94% in dogs and 100% in cats) (Hayes 2009).

In other words, LFBs are a recipe for gastrointestinal chaos. Sometimes they pass without causing obvious clinical signs - but that isn't great either. Some pet owners will say "oh, my cat eats string all the time and gets away with it". This is dangerous as they will present much later for veterinary attention if the LFB DOES cause problems. (Its also the reason why a lot of veterinarians were up in arms about this ad for ladies products - some owners might conclude that these are fantastic cat toys when the combination of an expandable object and string makes them doubly dangerous).

There is a big risk that LFBs anchor somewhere in the GIT - most commonly the base of the tongue or the pylorus. As the GIT moves everything through via peristaltic waves the anchored linear foreign body becomes taut - the intestines become plicated (as seen in the photo below). 

Gastrointestinal foreign body in a canine patient. (c) Anne Fawcett 2013
Nope, the intestines are NOT meant to be bunched up like this and yes, they are red and angry with inflammation. This is a very sick dog. He made a full recovery thanks to emergency surgical intervention. Then went home and ate a remote control. [Lesson: dogs don't always associate eating dumb things with feeling sick. They WILL be repeat offenders].
The LFB becomes increasingly taut and then acts as a saw through the intestinal wall, usually at the less surgically accessible site (the mesenteric border). This leads to peritonitis. Because signs may be subtle or intermittent, animals may not present until later in the clinical course. In the study by Hayes, a longer duration of clinical signs, the presence of an LFB and multiple intestinal incisions (often required to remove LFBs) were associated with an increased risk of mortality.

But timely surgical intervention is life saving. My colleague May and I wrote up a case we treated together in the Centre for Veterinary Education's Control and Therapy series - and this one had a happy ending. To view (it does contain multiple surgical images so not for the non-surgically minded) please click here.

Hayes G (2009) Gastrointestinal foreign bodies in dogs and cats: a retrospective study of 208 cases. Journal of Small Animal Practice 50:576-583.