Vet diary: treating a horse with explosive diarrhoea

I was called out to see Lilly, a 13-year-old Thoroughbred mare with explosive diarrhoea* — it was firing out as water all up the walls, which presents a major concern for horse health.

I checked her heart rate, breathing rate and temperature, which awere all within the normal range. However, when I checked the colour of her gums, I noticed they were a darker pink than the usual salmon pink.

This is an indication of toxins building up in the horse’s system.

Blood test results also showed that the mare was losing protein and so it was decided that she should come into the clinic for further treatment.

A trip to the vets

When Lily arrived at the clinic she had a catheter fitted and was put on intravenous fluids to help with her dehydration.

At this stage, she was already becoming more toxic and her gums had a purple rim around her teeth.

We put Lilly in isolation as we didn’t know if her explosive diarrhoea was infectious to other horses — or perhaps even to us and other animals.

All of the staff caring for her, including myself, had to wear full suits, including boot covers, gloves and hats.

Everything we needed was passed over from the safe zone before we went into the isolation ward.

Treatment

Lilly was given Flunixin, which is an anti-inflammatory, at frequent small doses to counteract the toxins.

Her faeces were sent to the laboratory for analysis. Two days later they came back to show a negative result for two types of clostridial bacteria.

Thankfully, a test for salmonella also came back negative and Lilly was allowed out of isolation.

Slow Lilly’s appetite and clinical signs started to improve. As her condition improved, the method of administering her fluids was changed from going in her vein through the catheter, to going directly into her stomach via a tube.

A tube was passed into her stomach and stitched in place at her nose so that we didn’t need to repeatedly insert the tube and she could have a steady flow of fluids.

This meant the cost of her treatment was more manageable for Lilly’s owner, because the fluids going into her stomach didn’t need to be sterile, unlike those going into her veins.

Further investigation

We also did a faecal worm egg count for Lilly and this came back with a count of zero eggs per gram.

This reduced the likelihood of worms being the cause of the horse’s explosive diarrhoea.

At this stage, Lilly was brighter and eating more, but we still hadn’t found a cause.

We performed an ultrasound scan of Lilly’s abdomen through her skin. This revealed a thickened wall in part of her large intestine, which called the right dorsal colon.

Now we finally had a diagnosis of right dorsal colitis (inflammation of the right dorsal colon).

Diagnosis

With this diagnosis, we could treat the horse accordingly.

The job of the right dorsal colon is to digest the long fibres of a horse’s diet, for example hay or haylage.

For the next four to six months, Lilly would not be allowed any of these long fibre sources in her diet (or minimal amounts at most).

This was due to it being too much work for the inflamed part of her gut to digest.

We requested that the mare was turned out on grass, with lots of small feeds of chaff and conditioning cubes.

Profound weight loss

The next day, Lilly’s stomach tube was removed, as her bloods showed she was no longer dehydrated.

Her faeces were firming up to resemble cow pats, and she was maintaining her hydration levels through her diet.

Her weight loss was profound by this stage. She still looked weak on her legs as she walked across the equine unit.

We hoped that, with time and continuing on the correct diet, Lilly would gain weight and muscle tone once her gut healed and stopped leaking protein.

She went home on the above diet, with GastroGard and sucralfate to help heal any gastric ulcers.

The future

The mare’s bloods were re-tested two weeks after she went home.

Results showed that her protein (albumin) levels were normal, indicating that her colon had healed.

As you can see from the photo above she is doing fabulously.

The horse has put on a good amount of weight since recovering from her bout of explosive diarrhoea, and her owner reports that she’s full of energy and back in light work.

Lily’s body is coping well with having small amounts of forage and she hasn’t had any more diarrhoea episodes.