A rider is urging others not to dismiss signs their horses might be having problems urinating after discovering her gelding’s penis was covered in “huge masses” of melanomas.

Lowri Caswell, 22, has known her 17-year-old Irish draught Dennis for four or five years but in 2020 he became hers when she was given him by a close friend.

“I began riding him for his old owner, Elaine Owen, and competing him across the country in one-day events, showing, dressage, side-saddle, clinics, you name it — he’s a once in a lifetime horse who has done it all and he’s my best friend,” Lowri told H&H.

“We won many events and even just out hacking, galloping through fields, he is everybody’s dream horse. He’s a bit of a legend in Gower, where we live.”

In January this year Lowri’s mum noticed Dennis was urinating slightly oddly and then realised they had never seen him drop his penis.

They kept an eye on him and one day when he did drop it, Lowri’s mum “caught a glimpse of what looked like a mass”.

“We’re experienced horse owners, horses have been in our family for decades and we spoil our horses as they are our pets, they have a five-star life, but it was something we’d never noticed with him,” Lowri said.

“We casually thought it was a bean which needed removing, as most geldings need, but my mum wanted to be absolutely sure, so we booked in with the vets to have it all checked out.”

When Dennis, who is a grey, was sedated and examined, huge masses of melanomas were discovered.

“t was only a matter of time before those huge growths would have ulcerated and he would have had to be put down. We were distraught, as he truly is the most special horse I think I will ever own in my lifetime,” Lowri said.

“We blamed ourselves for not checking sooner, but we weren’t to know as they were not visible and only by absolute luck did my mum spot them on the one occasion he dropped his penis in five-plus years.”

Vet Richard Coomer, a director at Cotts Equine, advised that the only option was radical, three-hour surgery to remove Dennis’s sheath and penis and redirect his urethra to just below his anus, so he would urinate backwards like a mare.

“We cried for days beforehand and due to Covid, we couldn’t even go in to the vets and check he was all ok. We just had to have complete trust and faith in the professionals,” Lowri said.

The surgery was a success and Dennis spent a month on box rest, being walked for 10-15 minutes four or five times a day, with daily turnout to reduce the swelling.

“We had two emergency vet callouts, where we thought we were going to lose him, as he was displaying colic symptoms, we think was due to the amount of medication he was on,” Lowri said. “It was a very stressful two months.”

Dennis was given the all-clear to resume walking under saddle in May and he is learning to adapt to his new way of urinating.

“He still wees on his tail and legs as he hasn’t quite mastered it but we are hoping this will come with time,” Lowri added.

“He is now back to full health, we have spent all summer cantering on the common and he has had the best summer pain-free and is happier and cheekier than ever!

“Richard the vet advised that it can take around 12 months to completely heal internally, so we are going to wait until next spring before we take him over his first jump, just to give him enough time to fully regain his health.

“But he’s been to the beach as that’s the sea is his favourite place in the world, where he spent hours splashing around and galloping through the waves in true unicorn style. Our happiness sums up how worth it this operation has been. Having a slightly stained tail is a small price to pay for adding years onto our baby’s life so we owe the staff at Cotts everything.”

Lowri said she had been surprised when the vets told her that the operation was not uncommon, as she had struggled to find information when she tried to research the procedure.

“If we had known about the severity of melanomas in greys, perhaps we would have pushed for the vets to check him sooner when he first came to us and displayed signs of discomfort, rather than passing it off as his personality,” Lowri said. “Most experienced horse owners are aware that greys are more susceptible to melanomas, but owners of greys should consider checking in places that are less visible.

“I feel it is a bit of a taboo subject, which should be spoken about more freely and would’ve given us more confidence and knowledge in making this decision.”

Richard, who operated on Dennis, told H&H that while it is still a “comparatively rare surgery”, he had performed the procedure several times.

“In the textbooks, it’s most commonly indicated for squamous cell carcinomas, which tend to occur in older horses. Because that is relatively rare, in my experience its usually melanomas that cause us to operate,” he said. “It tends to affect relatively younger, fitter horses who have plenty of life left, which makes it a much simpler decision.”

Richard said that complications are rare and horses are usually able to urinate straight after surgery.

“If it were a human being, they’d know what to expect but for a gelding, they wake up from anaesthesia and they’re suddenly weeing out of the back. Dennis was one of those who looked terribly surprised when it happened,” he said.

He noted that while other colours of horse did suffer from melanomas, most of his surgeries have been on greys.

Most of his patients have also seemed more comfortable once the masses had been removed.

“Judging that sort of low-grade pain in horses quite subjective but a lot of them seem happier and brighter, which suggests that while in theory melanomas are benign, they are a bit painful,” he added.

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The owner of a horse who underwent surgery to remove his sheath, part of his penis and two growths the size of grapefruit wants to raise awareness of melanomas, and the importance of sheath-cleaning.

East Sussex-based Annabel Dry thought she was going to lose her 11-year-old Highland gelding Angus when vets discovered the extent of his issues, late last year.

Annabel told H&H it was thanks to a friend’s diversifying her business that the melanomas were discovered, last spring.

“My friend Allie MacLeod, who runs the Horsebox Spa, started doing sheath-cleaning, which saved her business as she could do it during lockdown,” Annabel said.

“In May, she gave Angus a little spa day, including a sheath-clean, and when she felt up there, she said there were some lumps and she thought I should get the vet.”

The next day, the vet confirmed melanomas, explaining that their removal would be a simple procedure.

Angus was taken to Bell Equine for the surgery, but when he was on the table, vet Tim Mair called Annabel to say the situation was worse than previously thought.

“Tim said they’d found extensive melanomas; they couldn’t do what they’d intended as there were two huge growths in his groin, and melanomas all the way up his penis,” she said.

“Tim said he would either have to go to heaven, or have this huge operation, to remove his sheath and penis, and try to remove the lumps. That night was so horrible.”

Annabel was told the vets would not know exactly how many melanomas there were until they performed the operation, so she and they agreed that Angus would go in for the surgery.

“We left it as, if they found lots more, they’d send him to heaven, which was what I thought would happen,” she said. “But amazingly, Tim was able to remove them and he came through.”

Angus had had hundreds of coalescing melanoma masses, from a few millimetres to centimetres across, in his sheath. Vets removed the entire sheath and part of his penis, as well as the two huge melanoma masses deep in his groin, and created a new opening to allow him to urinate.

“It’s been a massive road to recovery, and they found melanoma cells in his lymph nodes so we are on borrowed time, but he’s doing so well now,” Annabel said. “The surgery means he can wee forward rather than out of the back like a mare; when he had his first wee afterwards, I was so proud!”

Continues below…

‘I’ve got my boy back’: sheath bean removal transforms horse’s life

The thoroughbred had been out of work for four years before the bean was removed

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Annabel, who thanked her aunt Lucy Verity for taking Angus to Bell, Mr Mair and her yard owner Nina Coppard for their support, as well as Allie for her discovery, wanted to raise awareness of the issue, and the importance of sheath cleaning.

“If we hadn’t found them, they could have ulcerated or burst, and been much more serious,” she said.

“He’s my first horse, and so much more than just a horse; he’s everything I work towards and my best friend. I love him to bits.

“Thank you to Tim for being amazing and giving him a chance. And for anyone else in the same position, I thought my only option was to put him to sleep but it’s not. I don’t know how long I’ll have with him, whether it’ll be a year or 10, but I’ve got that time.”

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Tim Mair FRCVS looks at the most prevalent 
types of cancer in horses and how they are treated…

1. Cancer in horses: Sarcoids

What is it? Sarcoids in horses, although a benign cancer, can be aggressive and spread locally. There are various different forms of sarcoid, each having a characteristic appearance, and individual sarcoids can change from one form to another. Bovine papillomavirus is believed to be involved with the development of sarcoids, although its precise role is unknown. The number and type of sarcoids that individual horses develop varies considerably, but in the majority of cases they tend to get larger and more numerous with time.

How is it treated? There are many different treatments available for sarcoids. The choice of treatment will vary depending on the type of sarcoid, its size and location.

Sarcoids in certain locations, such as around the eyes, can be more difficult to treat. Treatment may include chemotherapy drugs (often applied topically), radiotherapy and surgery (including laser surgery and cryotherapy). A recently trialled treatment that can be useful in some cases is electrochemotherapy, which involves injecting a chemotherapy drug into the sarcoid and then applying an electric current that drives the drug into the sarcoid cells. This type of treatment must be done under general anaesthesia and often needs to be repeated at a later date.

Laser surgery can also be an effective form of treatment, and can sometimes be undertaken in standing, sedated horses using local anaesthesia. Its advantages over conventional sharp surgery include less bleeding, less swelling and less pain.

Don’t wait and watch. The bigger the sarcoids become the more difficult they are to treat. Some chronic and extensive sarcoids may be impossible to treat. Unfortunately, there is always a risk of recurrence of sarcoids following treatment; once a horse has developed a sarcoid it will be prone to getting more in the future, and repeated treatments may be necessary.

2. Squamous cell carcinoma

What is it? This cancer usually affects the eyes and eyelids, and the penis and prepuce of males. It is an invasive form of cancer in horses that is often slow-growing but later can become more malignant and spread internally.

How is it treated? Effective management relies 
on early diagnosis and treatment, which 
may include surgery, chemotherapy or radiation therapy.

The penile form of this cancer is most common in older geldings. Regular sheath inspection, if necessary using sedation, is important to identify and treat early lesions before they become extensive.

3. Melanomas

What are they? Melanomas are skin tumours which are more prominent in grey and cremello horses. They become more common with age and it is estimated that at least 80% of grey horses over the age of 12 years will have melanomas. They most commonly involve the tail and perineum (around the anus and vulva in mares), the sheath of males, the eyelids and the mouth.

How are they treated? In young horses, most melanomas behave as benign cancers but with age they are more likely to become malignant and can then spread internally. For this reason, removal (with laser surgery) is advised when the melanomas are small. There is a vaccine that has recently been launched to treat horses with melanomas, but currently there is limited information available about its effectiveness.

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• This article has been edited and approved by Karen Coumbe MRCVS, H&H’s veterinary advisor since 1991.

Melanomas in horses are a type of tumour made up of the cells that produce black pigment. They are most commonly found in grey horses over five years old, although they can occur in horses of any colour. They are typically a black circular growth that forms part of the skin, or is located just below the skin, but can be found elsewhere.

Equine malignant melanomas: Signs | Are they serious? | Diagnosis | Treatment | Prognosis

While melanomas used to be considered not a major cause for concern, in more recent years it has been recognised that the commonly benign tumours have potential to transform into a malignant form, which can spread rapidly around the body with fatal consequences, hence the current veterinary advice is to remove them early, while they are small and not problematic.

Typical signs of melanomas in horses

Melanomas are fairly easy to recognise due to their typical raised, smooth, black, knobbly appearance when on areas of the horse’s skin that is without hair. In other areas they will be covered with hair. They can occur singularly or in groups.

They are most commonly found:

• On the underside of the tail
• Around the anus
• On the vulva of mares
• Around the sheath of male horses

Other possible locations include:

• On the ears
• On the iris of the eye
• On the lips
• Behind the large rounded cheek bone (parotid salivary gland area)
• On the neck
• On the limbs
• In lymphatic tissue, internal organs and the guttural pouch

Are they serious?

Many horses with melanomas have long and successful careers with the tumours having little effect on their quality of life beyond their unsightly appearance. But as horses age, the likelihood of a growth developing increases (studies have suggested approximately 80% of greys older than 15 years will have at least one melanoma) and most tumours will also increase in size over time.

As they grow in size or expand in number, they can become increasingly problematic depending on their location. Those in the area under the tail have the potential to interfere with the horse’s ability to pass droppings and there is always a concern that they may lead to impactions occurring. In reality the constant pressure for droppings to pass means such impactions are rare, however that can cause significant discomfort, especially as the tumour masses enlarge and ulcerate. Growths around the horse’s throat can prevent the horse from flexing its neck normally and may affect the ability to swallow comfortably.

When a cluster of melanomas occurs, or a single melanoma becomes very large, they can ulcerate and release thick black fluid. In these cases the potential for secondary infection is high, which can cause complications.

There is also the risk that the benign tumours can switch to a malignant form spreading to the horse’s internal organs, including the heart, lungs, spleen, kidneys, bone, brain and guttural pouch with fatal consequences, particularly in elderly horses.

Diagnosis of melanomas in horses

Horse owners commonly notice melanomas as a small nodule under the skin while grooming their horse or undertaking regular healthcare tasks. Any lumps should be brought to your vet’s attention. A vet will often diagnose based on the location and appearance of the lump, although a biopsy can be performed if the nature of the lump is unclear.

Treatment of melanomas in horses

While most vets used to advise leaving melanomas alone, it is now widely recommended that small growths should be surgically removed as early as possible when their location allows and before they enlarge sufficiently to cause problems. This prevents the problems associated with larger tumours and removes the risk of the tumours becoming malignant at a later date.

Removing a small single growth is typically far less complicated and results in better healing than when dealing with a larger cluster of melanomas. Modern surgical techniques mean many melanomas can be removed using laser technology, with standing sedation and local anaesthetic techniques, such as epidurals. Once removed, the growth can be sent to the lab for further analysis to confirm the diagnosis. There is a risk of recurrence after removal.

When removal is not an option, treatment becomes more complicated. There are a range of drugs being used to try to reduce the size of the tumours, including cimetidine and chemotherapy drugs, cisplatin and 5-fluorouracil, but treatment is expensive and the results are inconsistent.

A trial of a melanoma vaccine that is licensed for use in dogs in the United States has seen some promising results¹. The vaccine prompts an immune response against the melanoma cells throughout the body, enabling treatment of growths that cannot be seen externally as well as those immediately under the skin. Currently the vaccine is only available to vets in the UK with specialist qualifications (diploma holders). As the vaccine is currently not licensed for use in Europe, vets must obtain authorisation from the Veterinary Medicines Directorate — the organisation that regulates drug use in the UK — to import it.

If melanomas ulcerate, they need to be kept clean and the area protected from flies. If a secondary infection occurs, then antibiotics may be needed, but sadly are not going to solve the problem long term and is far better to consider local treatment in the early stages and be prepared to repeat it if the masses recur.

Prognosis for cases of melanomas in horses

Melanomas are relatively common² and some horses will function well despite their melanomas, but the tumours are a risk that needs to be considered. While some horses will carry on without suffering any obvious ill effects throughout their lives, the growths can lead to euthanasia on welfare grounds in others.

If you are buying a horse that has any lumps on the skin, mention this to the vet ahead of the pre-purchase examination so he can assess their nature. If you buy a horse that has melanomas at the time of purchase then any treatment they require will not be covered under your insurance as they are a pre-existing condition.

Useful references

• Dog vaccine on trial as cure for melanoma in horses
• A database survey of equine tumours in the United Kingdom

Also: Melanoma in horses: Current perspectives

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A horse who faced being put down after a tumour was found in his eye has a won championship title after the affected eye was removed.

Kate O’Shea from Cork and her 16.2hh part-bred Connemara Send Me On (Hudson) won the advanced intermediate championship at the national hunter trials championships at Annaharvey Farm in Co. Offaly, Republic of Ireland on 31 March.

Kate beat 30 other riders to take the title, with three seconds separating the top three combinations.

“Cross-country is his favourite,” Kate told H&H. “We mostly event during the summer but our season hasn’t started yet so we’ve been doing hunter trials.”

Kate, who has owned Hudson for five years, said his eye became cloudy at the beginning of 2016.

“We got the vet who originally thought he’d been pricked by a thorn or something out hunting so he diagnosed an infection of the cornea and we were treating that for two weeks,” she said.

“The vet came back again and gave us strong drops to try but when he didn’t improve he wanted a second opinion.”

Hudson was seen by a specialist who diagnosed a melanoma tumour in his left eye.

“They ultrasounded his eye and found a tumour growing rapidly against his cornea and said his eye would have to be removed.

“We were obviously very upset and had to decide what to do. People had different opinions about whether we should go ahead with surgery and take his eye out, or put him to sleep.

“My family are very into horses and my aunt used to work in a racing yard and knew two horses with one eye – one didn’t cope. He became very nervous and anxious and lost weight rapidly, it just stressed him out so much. No one wanted to put Hudson down but we had to consider what was best for him and whether he would cope with one eye.”

Kate went ahead with the surgery on 23 January 2016.

“Hudson is a kind horse and our vet said he had the right temperament and there shouldn’t be problems in him having one eye. He knew plenty of horses who were very successful with one missing, so we went ahead with the operation and hoped for the best.

“We collected him from the vets two days later and he travelled home perfectly.”

Kate said Hudson adapted well to having one eye and soon returned to hunting.

“He was on box rest for two weeks and had his stitches out on 5 February. I got on him the following day and walked around the arena – my mum was more nervous than me, I just couldn’t wait to get back on and he was absolutely perfect,” she said.

“We went out hunting a week later and he was leading the other horses over ditches.”

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Kate said she does not mind what Hudson looks like and that people do not notice he only has one eye.

“I had seen horses with one eye like Adventure De Kannan the Hickstead derby winner, and there’s an event horse in Ireland called Wysteria Lane, so you see them out competing. The vet did a really good job, a lot of people don’t even notice until you point it out to them.

“His behaviour is exceptional. He’ll be eager pulling me round cross-country, but then my mum can also get on him and he’ll walk up the road slowly for her – he’s so safe. He’s just brilliant.”

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Rosie Naylor MRCVS is a consultant in equine medicine at Newmarket Equine Hospital, where she sees a broad range of referred internal medicine cases in horses of all disciplines. She holds the ACVIM Diploma in Large Animal Medicine and recently completed a PhD at the Royal Veterinary College. She reports on a promising new therapy for melanoma, shown to increase survival rates in dogs, that could work for horses, too.

Melanomas are one of the most common tumours that affect horses. They are usually found in the skin, particularly (but not exclusively) of grey horses. Affected horses typically develop firm, darkly pigmented nodules in characteristic locations — underneath the tail, around the anus, adjacent to the lips, on the sheath or in the throatlash region.

While many melanomas are benign and slow-growing, seeming to cause few problems, they can become locally invasive and also spread to other parts of the body.

In severe cases they can interfere with vital bodily functions such as passing droppings, head flexing or swallowing, leading to problems ranging from constipation or colic to neurological deficits.

Melanoma can also affect the internal organs such as the intestinal tract, salivary glands, guttural pouches, liver and spleen.

Local treatment of melanomas in the skin is often performed, using a variety of chemotherapeutic agents such as cisplatin or 5-fluorouracil. These can be injected directly into the tumour, with some success, however, even if a reduction in tumour size is observed, tumour cells may still metastasise.

A medicine called Cimetidine is sometimes prescribed, with often disappointing results. Surgical management is occasionally attempted but can be problematic if the tumour is close to vital structures.

Target practice

A new melanoma treatment vaccine with the trade name Oncept could provide the answer.

This DNA-based vaccine stimulates the horse’s own immune system to mount a response to tyrosinase, a protein found in high concentrations in melanoma cells.

This is an attractive approach as it will target all melanoma cells — internal and external — including those not accessible with other treatments.

The vaccine was originally developed for the treatment of malignant melanoma in dogs, where it has been shown to increase survival rates significantly. It is now licensed for use in dogs in the US.

Pioneering work has subsequently been performed in the USA, at the University of Tennessee, to evaluate the possibility of extending this therapy for the treatment of melanoma in horses. Research has shown that equine melanoma express similarly high levels of tyrosinase, the target protein, to those in canine melanoma, and that the vaccine is safe to administer to horses.

After a course of four vaccinations at fortnightly intervals, the horses developed a detectable immune response. A significant reduction in tumour size was observed in four out of five horses within six months.

The vaccine is currently being trialled in a larger group of horses with melanoma, in North America.

Although the final results have not been released, the clinical impression suggests a positive response in a proportion of horses.

A shot of hope

Due to these promising reports, the vaccine is now available to vets in the UK with specialist qualifications (diploma holders). As the vaccine is currently not licensed for use in Europe, vets must obtain authorisation from the Veterinary Medicines Directorate — the organisation that regulates drug use in the UK — to import it.

The vaccine is administered into the chest area using a specialised high-pressure device. With time, it is hoped that it will become a realistic and readily available option to control melanoma growth.

Tumours can occur in all parts of the eye and its associated structures.

Typical sites include the eyelid, the inner “third eyelid” or the mucous membrane known as the conjunctiva that covers the eye. The surface of the eye (cornea), the central structure known as the iris and the optic nerve can also be affected.

Signs of tumours include lumps or bumps, discharge or cloudiness and pain — indicated by excessive blinking or the horse holding the eye closed.

You may also notice a change in the horse’s behaviour.

A detailed ophthalmic examination is required for a diagnosis to be made. Such an examination will probably include the use of specialist equipment, such as ultrasound, and may need to be carried out by the specialist.

Treatment is often challenging due to the complicated anatomy of the area and the sensitivity

of the eye. Methods are evolving, however, and prognosis can be good.

Types of tumour

Squamous cell carcinoma

This tumour can affect various structures — most notably the third eyelid, towards the inner eye. The conjunctiva and cornea can also be affected. Squamous cell carcinoma (SCC) should be suspected with any erosive, cobblestone or cauliflower-like raised ocular mass. Lesions are typically white-pink and rough or fleshy in appearance but may occasionally be firm with a smooth surface. Draught horses, appaloosas and paint horses are more at risk. Irritation from ultraviolet (UV) light is thought to promote the development of SCC.

Sarcoid

These skin tumours are of fibrous tissue origin. Sarcoids around the eye and eyelid are common and may result in significant damage by disrupting normal eyelid function or rubbing directly on the eye. Due to the proximity of vital structures, some treatments for sarcoids elsewhere on the body are deemed too hazardous to use near the eyelid.

Lymphosarcoma

Lymphosarcoma are tumours of cells in the blood and can occur throughout the bod y. One study found 27% of horses with lymphosarcoma elsewhere also had lesions in or around the eye. Infiltration of the eyelids and conjunctiva are the most common manifestation of lymphosarcoma but all structures of the eye can be affected.

Melanoma

This tumour is usually pigmented (black), and can affect any part of the horse’s eye. It can also be non-pigmented or variable pigmented. Melanoma are typically seen in grey horses where there is a genetic predisposition, but can be found in horses of other colour. Older horses are predisposed.

Mast cell tumour

A tumour of the immune cells, in other species mast cell tumours (MCT) can be aggressive and spread readily (metastasize) to other parts of the body. In the horse, they are usually slow-growing, non-metastic and superficial, although in rare cases may have spread. The conjunctiva, white of the eye (sclera), third eyelid and globe are all areas where MCT has occurred.

Treatment options

Amniotic membrane transplantation is one of the more promising treatments. Amnion is a constituent part of the placenta. It is anti-inflammatory and also anti-angiogenic, meaning it decreases the chance of the blood vessel formation that is generally detrimental to corneal healing.

It can also decrease scar tissue formation and produces chemicals promoting cell growth and subsequent healing. Amniotic membrane transplants are used in human medicine to treat corneal perforations and deep or infected corneal ulcers.

The University of Florida, USA, has pioneered the use of equine amnion in equine eye surgery.

The membrane acts as a graft and support for the cornea when a substantial part has had to be removed because an SCC has been cut away.

Radiation therapy

There are also different types of radiation therapy. Radiation from radioactive sources, such as strontium and iridium, can either be held in place or placed within the tissue — a method called called brachytherapy.

Radiation can also be delivered from an external machine and aimed at the area requiring treatment; this method is known as teletherapy.

Historically, the sheer size of the animal prevented the use of teletherapy on horses, but it is now offered by a few UK centres.

Iridium wires are used in difficult sarcoids cases around the eye with success rates of more than 90%. Strontium is used for a number of corneal tumours, most commonly SCC.

Strontium can be applied during surgery to the remaining corneal tissue (stroma). This type of therapy is carried out alongside surgery and decreases the chance of reoccurrence of the tumour.

The cost and availability of brachytherapy limits its use to a few specialist centres, but for challenging cases it is an important treatment.

Teletherapy is expensive and availability is scarce, but it is a potentially useful treatment for deeper structures of the eye where brachytherapy materials cannot be placed.

Antibiotic hope

Colleagues at Liverpool University have pioneered an antibiotic with anti-tumour properties in the treatment of ocular SCC.

The treatment, known as Mitomycin-C, is applied via ocular drops. Good results have been reported when the antibiotic is used alone or, for bigger tumours, with surgery.

Photodynamic therapy (PDT) is an evolving treatment for various conditions.

In humans, PDT involves injecting a photosensitiser into the bloodstream. This concentrates selectively in certain cells, which are then exposed to a special light — such as laser or ultraviolet — to destroy the abnormal tissue.

This method is not yet possible in the horse, but there have been trials of injecting a photoactive agent locally into the wound-bed immediately after surgical resection of the tumour. This is then followed by light irradiation.

Early results have been positive but more research is needed to evaluate this treatment.

This article was first published in Horse & Hound magazine (28 August 2014)

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A mare given just a 25% chance of survival a year ago, following the discovery of a massive tumour in her neck, has made an extraordinary recovery. She was placed in a showjumping class at Hickstead last week.

Wealden Silvanite endured 2 operations and 8 weeks of chemotherapy last summer to get rid of the malignant melanoma, which weighed more than 2kg.

The 6-year-old Irish sport horse delighted her owner, Michaela Francis, by jumping a double clear in the 1.05m at the Royal International on 4 August.

“It feels like a miracle,” said Michaela, from West Sussex.

“I was devastated when the vet gave her a 25% chance of just making it out of surgery and lots of people said we should have her put to sleep. But we thought as she was only 5 and it was worth giving her a chance,” she added.

“Silvia” went lame and developed a lump on her neck in June 2012. The removal of the aggressive tumour left the mare with a gaping hole in her neck. She had to spend 8 months on box-rest, due to the risk of infection, with her dressings changed daily.

Since coming back into work, Silvia has jumped double clears every time out and Michaela hopes to qualify for the 1.20m amateur final at Horse of the Year Show next year.

Vet Suzanne Duncan of Arundel Equine Hospital, who treated Silvia, said the outcome was “very gratifying”.

She added: “With melanomas, there is always the caveat that it might come back — but the further we get down the line, the less likely that is to happen.”

This news story was first published in Horse & Hound magazine (15 August 2013)

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The Animal Health Trust (AHT) has begun building a new cancer centre at its Lanwades Park base in Suffolk — but needs to raise £1.5 million to complete the project.

Due to open next summer, it will treat horses, dogs and cats as well as conduct research into treatments for animals and humans.

The AHT hopes to treat more than 100 equine cases a year at the new centre.

Sue Murphy, head of clinical cancer treatment, said: “Having all three treatment options [surgery, chemotherapy and radiotherapy] on one site means that whatever the diagnosis, we will be able to offer patients the very best option for their case.”

An extra £250,000 is needed to buy a linear accelerator — a radiotherapy machine that irradiates cancerous cells without destroying the surrounding tissue.

Stamford-based Ian Scott, whose showjumper Lackaview Cruise (known as “Fern”) has been diagnosed with cancer, said the centre was much needed.

“Fern has inoperable and untreatable tumours — hopefully research could lead to treatment being an option for owners in the future living with this diagnosis,” he said.

And Dr Tim Mair of the Bell Equine Veterinary Clinic in Kent, who has studied cancerous tumours in the horse, said: “Equine cancer is an area that needs a lot more work to improve treatment as it lags far behind other small animals and humans.

“All types of cancer are problematic and generally have a high reoccurrence rate — by the time of diagnosis we often can’t do anything.”

For more information, including how to donate, visit: www.aht.org.uk or tel: 01638 555648.

This news story was first published in the current issue of Horse & Hound (28 July, 2011)

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Find an equine vet

Learn more about tumours and melanomas

In equines cancerous tumours are not particularly rare. In fact, tumours of the external genitalia are second in number only to the skin.

The most common form of penile cancer is the squamous cell carcinoma (SCC). This is a malignant tumour capable of spreading and having devastating consequences.

SCCs account for more than half of all penile tumours, while melanomas and sarcoids are the other common cancers found in this region.

Most penile tumours occur in older horses — over 17 years old — but any middle-aged horse is at risk.

A typical clinical sign is a blood-stained or pus-like discharge from the sheath, which often alerts owners to a problem.

A biopsy is useful to prove that the lesion is a tumour.

Occasionally, lameness can be a sign of a penile tumour and horses may be tender in the sheath area.

Contact your vet straight away if you suspect something is amiss.

To find out more about the dangers of penile cancer and how it can be treated, see the vet clinic in the current issue of Horse & Hound, 23 December

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Read more articles on tumours and melanomas

Find an equine vet

Need to know more about melanomas?

A melanoma vaccine has been developed for humans and is currently undergoing clinical trials.

It is early, but the tests have seen a range of results from making no difference to the size of melanoma to significant shrinking, and in some cases the disappearance of the disease.

Cancer vaccines are a type of biological therapy, which use natural body substances, or drugs that block them, to treat cancer.

Doctors need to understand why the vaccine works in some people and not others.

They are beginning to see who will benefit and who won’t by looking at the immune response in the first few weeks of treatment. If you have a good immune response, the vaccine is more likely to work.

These developments in the management of human malignant melanoma suggest that there may be some hope of developing a vaccine for treating horses in the future.

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Read more about melanomas

More articles on tumours and cancer in horses

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A keratoma is a rare, benign tumour that is found within the foot. It consists of abnormal masses of keratin (the main substance of hoof), which is deposited between the hoof wall and the underlying pedal bone.

What causes them?

We don’t know for sure, but they are thought to result from trauma or inflammation of the cells that produce horn.

Keratomas are most commonly found immediately below the coronary band, but they can develop anywhere within the foot.

They prevent the normal attachment of hoof to the pedal bone.

As the horn grows down from the coronary band, it can be pushed away from its attachment to the underlying pedal bone by the keratoma, resulting in an area of weakness at the toe.

This can allow infection to track up the white line and may cause abscessation within the foot.

The pressure created by the keratoma causes bulging of the hoof wall and resorption of the pedal bone, but in most cases the signs are subtle.

What are the treatment options?

Surgical removal of keratomas has been found to be more successful than conservative management.

Surgery is more easily achieved with the horse anaesthetised, but in some co-operative patients surgery can be performed under sedation with a nerve block to anaesthetise the foot and a tourniquet applied to control haemorrhage.

It is important to remove all abnormal tissue.

Can keratomas recur?

Keratomas can recur, but a recent study by the University of Liverpool vet school found that 25 out of 26 horses undergoing surgery returned to their intended use between six and 36 months after surgery (three of those horses required further surgery before returning to work).

For the full article on keratomas, see the current issue of Horse & Hound (21 January, ’10)

Watch video of keratoma surgery provided by World Horse Welfare

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More veterinary advice for horse owners

Fortunately, melanomas in horses are not quite as nasty a form of cancer as their human counterparts and they often grow slowly.

They are more common in grey horses and can develop in multiple sites. Common locations for melanomas include under the tail and around the head area.

They can metastasise to other organs in the body, but it can take years before they start to become problematic.

While those under the tail are slow-growing, they can develop to a size where it becomes difficult for horses to pass faeces normally.

Treatment options:

• There is no evidence to suggest that metastasis is more likely to occur if small melanomas are removed surgically and so it may be sensible for your vet to remove these at an early stage while they are still small.

• Melanomas that grow on the margin of the eyelids can become particularly problematic if they start to rub in the surface of the eye itself and so, again, these should be removed at an early stage.

For the full article on equine cancer, see the current issue of Horse & Hound (16 April, ’09)

Looking for more veterinary advice for horse owners?

A keratoma is a rare, benign tumour of the keratin or horn-producing cells. These cells usually form the hard, water-resistant hoof capsule that encloses and protects the sensitive structures in the foot.

The cells that produce the wall are located at the top of the hoof wall at the coronary band. The entire wall continuously grows down from this point alone, in a similar way that the cells that produce a human’s fingernail are located under the cuticle.

The cells that produce the sole are located at the bottom of the pedal bone. Therefore, the only dividing and living cells that produce the hoof capsule are found at the coronary band and along the bottom surface of the pedal bone. The hard external hoof consists of dead cells.

If anything alters the normal pathways controlling the activity of the dividing cells, it may result in a constantly increasing mass of abnormal tissue, with a keratin core, between the outer hoof capsule and the pedal bone.

Although it is thought that chronic irritation may make the horse prone to the condition, many horses diagnosed with keratomas have no history of either infection nor injury at the site. Any size, breed or gender of horse may succumb to the problem — it may simply be bad luck.

Signs of keratoma

Some horses may remain sound, but they generally show a mild, intermittent lameness that gets gradually worse. The only indication may be an abnormality of the contour of the sole or wall noticed during routine farriery.

Keratomas of the wall tend to originate from the coronary band and can cause bulging and distortion of the wall, which is visible externally. Keratomas of the sole are generally circular and their size can vary from 0.5-2cm in diameter. In either case, widening of the white line with dense rubbery white tissue is frequently apparent.

The first signs to look for are the characteristic changes in contour of the wall and sole, and an abnormal area of the white line. X-rays can then be used to examine the mass and any damage to the underlying pedal bone. This happens if the mass has exerted sufficient pressure to cause absorption of the bone. The result is a smooth bordered semicircular defect in the bone.

Magnetic resonance imaging (MRI) has also been used to define accurately the margins of the abnormal tissue and the extent of the damage, making it easier to decide how to treat it.

Treatment

“If in doubt, get it out” is the best approach. Treatment of a keratoma is based on removal of the abnormal tissue, but is often easier said than done. The appropriate section of the outer hoof wall must be removed to allow access to the underlying keratoma.

Depending on the position and extent of the tumour, this may be achieved with the horse standing under sedation, with local anaesthetic blocks to numb the foot pain. Otherwise a general anaesthetic will be required. In either case, it is essential to ensure removal of all abnormal tissue — especially if it goes as far as the coronary band — otherwise the tumour will keep growing.

A commonly used surgical technique involves making two parallel cuts either side of the keratoma, from the sole up the wall as far as is necessary, to ensure the whole of the mass is removed. The wall is then removed by pulling it up and effectively “unpeeling” the hoof wall from the bottom of the hoof to above the tumour. The tumour can then be completely removed.

The wound is covered with a sterile dressing until it dries out. Suitable support is provided for the hoof capsule, if necessary, by means of a bar shoe. Once the wound has dried out, hoof reconstructive material can be used to protect the area while the hoof wall grows down. This can take between six and 12 months. Most horses recover well from keratomas, as long as the entire tumour is removed.

H&H 18 August 2005