With a string of top-level showing titles to his name, Patros HB (known as Paddy) has conquered all in the world of ridden Arabians. Yet last year the 10-year-old stallion faced a challenge of a very different nature when a sizeable stone, or calculus, was discovered in his bladder.

Paddy’s story starts when he is in his winter routine of light work and gentle hacking, with daily turnout…

December 2014

When Paddy urinates on returning from a hack, his producer Clare Fitch notices that his urine looks darker than normal.

“It wasn’t anything that set alarm bells ringing, but I recall thinking that I would keep an eye on it,” she says. “On the next few occasions that I saw him urinate I couldn’t really decide whether it was darker or not, so I decided to ‘catch’ some for closer examination.”

Clare collects Paddy’s urine over a couple of days, comparing samples in glass jars.

“The samples appeared roughly the same, so I carried on working him,” she says. “On the first day that I increased his workload and included some canter, he urinated as usual afterwards. He appeared to strain slightly and the urine was most certainly red in colour, so I immediately called the vet.”

January 2015

An ultrasound scan at the clinic reveals that Paddy has a large bladder stone, measuring approximately 7cm (pictured top).

“We discussed whether Paddy would require abdominal surgery,” says Clare. “Unfortunately, he experienced a seizure of some sort while in the examination stocks — thought to be an adverse reaction to the sedative administered.

This obviously caused us further concerns, so we took Paddy home to decide whether he should undergo such invasive surgery.

“A previous horse belonging to Paddy’s owners, Rick and Edwina Warner, had been referred to Rossdales Equine Hospital with great success,” adds Clare. “We agreed that it would be useful to get their advice.”

Clare discusses the case by telephone with Rossdales surgeon Lewis Smith, who advises her Paddy should have the surgery to remove the bladder stone.

After consultation with her vet, Clare drives Paddy to Rossdales for further investigation. A date is set for the operation.

Patros HB in action

Patros HB in action

March 2015

Paddy is taken to the Rossdales operating theatre.

“Surgery is the best option for a stone of this size,” says Lewis. “However, it’s not a simple operation. Access to the bladder can be difficult, as there are so many delicate structures in the way.

“We placed Paddy on his back, under general anaesthetic, before locating the bladder using keyhole surgery,” Lewis explains. “We then guided the bladder up to the side of his abdomen wall.

“The anatomy of the male horse means that the penis is directly in the path of where you would ideally make an incision, so we made a small opening to one side of the sheath, into the abdomen, and then cut into the bladder. It’s important that urine doesn’t spill back into the abdomen.

“We then removed the stone and suctioned any urine out of the bladder, before suturing it and making sure it was watertight. Finally, we sutured the abdomen wall and the keyhole portals.”

A relieved Clare receives the message that the operation has gone well. Although this surgery is minimally invasive, it is still a major abdominal procedure and the next few days are critical. Paddy needs intensive nursing care before he is given the go-ahead to return home.

“Paddy is incredibly special to us,” says Clare, who has produced the stallion since he was three. “We honestly would not have minded at that point if he never saw a show ring again, as long as he pulled through.

“We picked him up 11 days after surgery, which felt like an eternity. I can’t speak highly enough of the level of care he received.”

Small stones passed by Patros HB in his urine after his operation

Small stones passed by Patros HB in his urine after his operation

April 2015

Box rest is advised, but Clare is worried about the lack of turnout.

“Lewis agreed that he could spend some time in a stable-sized paddock,” she says. “We built five small pens that we could rotate daily.

“Paddy was fantastic — just glad to be home, I believe. He walked daily into his ‘corral’ and would spend an hour or so grazing there and gazing across at his friends.”

May 2015

Paddy makes good progress. After six weeks he is allowed out into a larger area, so Clare doubles the size of the corrals before moving him into a small paddock.

Summer 2015

At around 10 weeks post-op, Paddy starts light work.

A former national, European and UK international ridden champion, he had not returned to the Horse of the Year Show (HOYS) since taking the title there in 2012.

“After he survived his surgery, we decided to try for HOYS again,” says Clare. “He qualified first time.”

October 2015

Paddy takes the ridden purebred Arab championship at HOYS; a win made “more special than ever”, says Clare, because of his ordeal.

‘Stones can act like a ballcock’

Removal of the bladder stone is not a simple procedure, with delicate structures around the bladder, and requires general anaesthesia

Removal of the bladder stone is not a simple procedure, with delicate structures around the bladder, and requires general anaesthesia

A bladder stone is a formation of lots of tiny calcium carbonate crystals, writes Lewis Smith MRCVS. Calcium carbonate is usually present in the urine, and small crystals are washed out as the horse empties his bladder.

Larger rocklike masses can measure from 1-2cm in diameter and can reach up 10cm. They are relatively rare, but occasionally cause a medical emergency.

In mares they’re not too much of a problem. The urethra (the tube that connects the bladder to the outside world) is able to expand sufficiently to allow the stone to pass in the urine. It’s even possible that the vet can reach a hand into the urethra to retrieve a larger mass.

In male horses, however, stones can be a nightmare. There’s no easy exit for smaller particles, so masses increase in size and act like a ballcock. If urine flow is stopped and the horse can’t empty his bladder fully, this will lead to pooling of the urine and growth in the size of the stone.

Smaller stones can also be dangerous, sometimes becoming stuck in the urethra on the way out and causing a urinary obstruction. In these cases, rupture of the bladder is a real possibility.

Treatment and cause

The biggest challenge with stones in the male horse is getting at them, as the bladder is situated right in the middle of the body.

One option with a smaller stone is to pass a flexible endoscope up the penis to look into the bladder, before using an instrument called a lithotriptor to break up the stone using shockwaves. The particles are then flushed out or removed through the urethra using a grasper.

Slightly larger stones can be pulled out via a perineal urethrostomy — a temporary hole made under the tail. In Paddy’s case, the sheer size of the stone meant that keyhole abdmominal surgery was the preferred option.

In most horses, the body regulates the amount of calcium carbonate produced. Formation of a stone is usually down to no more than bad luck — a piece of debris in the bladder, perhaps, that acts as a “nidus” (centre) for crystals to collect around. Stones can also develop in the kidney and fall into the bladder.

There are few practical preventative measures, but what’s important is to be vigilant about changes in urinary habits, especially in male horses. If you spot blood in the urine or a flow that comes in short bursts, sometimes accompanied by straining or grunting, don’t ignore it.

Ref: Horse & Hound; 24 March 2016