🐴❤️ Atrial Fibrillation in Horses: What’s Happening Inside the Heart ❤️🐴

Atrial fibrillation (AF) is the most common heart rhythm disturbance seen in horses. It occurs when the normal, coordinated electrical activity of the atria (the heart’s upper chambers) becomes disorganized. Instead of contracting rhythmically, the atria “quiver,” leading to an irregular and often rapid heartbeat.

Because the atria are no longer pumping efficiently, the heart’s ability to fill the ventricles properly is reduced. This can decrease overall cardiac output — especially during exercise — which is why affected horses often show signs such as reduced stamina, poor recovery, or a sudden drop in performance.

Interestingly, AF can occur in otherwise healthy horses, often those with large athletic hearts and high vagal tone (such as fit racehorses or sport horses). It may also develop secondary to underlying heart disease or electrolyte imbalances.

While some horses tolerate AF at rest, it can significantly impact performance and should always be evaluated by a veterinarian. Treatment and prognosis depend on the underlying cause, duration, and the individual horse.

💡 Fun Fact:

A horse’s heart is massive — typically weighing 3.6 to 4.5 kg! During intense exercise, it can pump over 250 liters of blood per minute, that’s enough to fill a bathtub in under 30 seconds!

If you have questions about your horse’s heart health or performance, our team at Central Lakes Equine is here to help with assessment, advice, and management options.

🌬️💨 Follow-Up: Eye Issues After Windy Weather 👁️🐴

Last week, we promised to share more about problems we often see in horses after windy or stormy days — and here it is!

When the wind picks up, it’s not just leaves and dust blowing around: debris, pollen, and sand can easily irritate your horse’s eyes. After a blustery day, it’s a good idea to give your horse’s eyes a quick check.

Here are common eye issues we see following storms or high winds:

🔹 Conjunctivitis – redness, tearing, or mild swelling.

🔹 Corneal ulcers – often caused by dust or debris scratches; you might notice squinting, excessive tearing, or cloudiness.

🔹 Foreign bodies – small particles like hay seeds or grit can get trapped under the third eyelid, causing irritation or rubbing.

🔹 Uveitis (inflammation inside the eye) – light sensitivity, tearing, and a partially closed or painful eye.

👉 What to watch for:

Squinting or holding the eye closed

Excessive tearing or discharge

Swelling around the eye

Cloudiness, redness, or visible debris

If you notice any of these signs, don’t wait! Eye conditions can worsen quickly and become serious. Call us as soon as possible so we can assess and treat the issue before it progresses.

👁️ Why Eye Injuries in Horses Are So Serious

Horses’ eyes are large and exposed, making them prone to injury, but the real risk comes from melting ulcers. These are rapidly progressive corneal infections where bacteria release enzymes that “melt” the cornea and are difficult to treat.

Unlike other species, a horse’s cornea heals much more slowly, meaning even small ulcers can quickly become emergencies.

💙 Your horse’s eyes are delicate but vital, a quick look after a windy day can prevent long-term problems!

Wild Weather

🌧️ Hope everyone’s staying safe after the wild weather! 🌪️🐴

We know it’s been a rough few days with all the wind and rain, we hope you and your horses are doing okay. 💚

A few quick tips to help keep your horses safe and comfortable during and after storms:

🐎 Check paddocks and fences: high winds can bring down trees or wires, so make sure there’s no debris or damage.

💧 Fresh water: heavy rain and runoff can muddy troughs or contaminate water sources, so give them a clean refill.

🏠 Shelter and rugs: make sure rugs are dry and fitting well, and check that shelters are stable and secure.

👁️ Watch for injuries or colic: sudden weather changes can stress horses, so keep an eye out for any signs of discomfort.

If you’re worried about your horse after the storm don’t hesitate to give us a call. We’re here to help! 📞💙

Here’s a photo of us braving the wind in the Lindis Valley yesterday!

Stay tuned for next week’s post to see some of the common injuries that we see post storms.

🐴 Is Your Horse Feeling Itchy? Let’s Talk Skin Allergies! 🌿

We’ve been seeing quite a few horses with skin allergies lately. These can show up as:

✨ Itching, rubbing, or biting

✨ Hair loss or scabbing

✨ Hives or swelling

✨ Dull or patchy coats

Skin allergies can be triggered by pollen, dust, feed ingredients, or even certain grooming or cleaning products. Sometimes the cause is straightforward, other times it takes a bit of detective work!

💡 Tips to help your horse:

✅Keep bedding and feed areas clean and dust-free

✅Choose gentle, hypoallergenic shampoos and grooming products

✅Monitor any changes after introducing new feeds or supplements

✅Keep a note of flare-ups to help identify possible triggers

Here is a photo of Becci removing foreign material from a horse’s neck after he had been rubbing it!

If your horse is itchy or uncomfortable, we can help find the cause and create a tailored management or treatment plan to get them feeling great again!

Reflux, what is this?

Sadly we have seen a number of colics in the last few weeks. Nasogastric tubing is an important diagnostic tool when treating a colic. A tube is passed along the nasal cavity, into the oesophagus and down to the stomach. It is testing to see if there is gas or fluid accumulation in the stomach or upper small intestine.

A normal horse will have less than 2L of reflux

A positive reflux finding is highly suggestive of a surgical lesion, and is often caused by gas buildup, intestinal blockage, large bowel displacement, or twisting of the intestines. 

The removal of the reflux is vital, as the horses stomach is not able to stretch like our stomachs can, and as a result, they can rupture which would be fatal.

The photo attached shows our lovely patient who was very poorly, and he had 20L of spontaneous reflux.

Lameness Consults

2025 signifies my 16th year practising as an equine veterinarian. As part of this wonderful job, I perform multiple lameness assessments on a daily basis which would include nerve blocks, diagnostics including radiographs and ultrasound, and joint injections to treat painful and therefore performance limiting problems.

Whilst these are all very visible tasks to those on the day , what I have recently come to realise is, most of you do not know what im trying to best understand during an assessment. I also realise whilst I do try to ensure my clients are well informed, I may not get every detail across.

So here goes, a wider summary of all the stars I am trying to align whilst assessing your horse.

First analysis:

Horses temperament, muscle activity and muscular cover, and overall condition for their lifestyle.

Then immediately I shift my priority to my client and consider the question:

What does the client and horse need from me today?

How do I get them to that point the fastest with the least financial pressure.

Next:

I assess the horse and look for;

Symmetry, movement compared to the horses breed, each leg for quality smooth strides: Note sometimes a horse does not show ‘lameness’ but will change the entire way they move.

Asymmetry, on the lunge at all paces, flexion tests (comparison of legs is the key here).

Atypical movement, neurological steps, painful expressions, abnormal responses to myself or my client

Finally hands on;

What is each leg telling me? Do the feet give away any clues? Are the soft tissues inflamed and are any joints angry?

Then finally…. The spine

The poll, neck, saddle area, lumbar and SI region. These are all covered by muscles. Do any indicate the underlying skeleton is painful?

THE FUN PART….

Whilst my brain travels at a million km per hour, I put together an internal spider diagram of how to answer that important question:

How do I fixed my clients concern, describe the condition easily, make a treatment plan within financial constraints, quickly (of course), and also describe all the potential side effects without scaring you all half to death.

Many of you will already have experienced such instances with me, and sadly some are likely to in the future, this season or in the up coming ones.

Have confidence that I think of everything on the inside, but try to describe the scenario, and best route to recovery in simple, cost effective steps.

Remember, the greyer I get, the more answers I have for you 😉

I take pride in continually upskilling.

Insulin

Well it wouldn’t be spring without discussing good old Insulin.

Insulin is an important hormone produced by the pancreas that allows the sugar in the food we eat, to be stored for energy when it is required.

When horses graze grass, the hormone is released, increasing blood levels of Insulin.

Horses that are overweight or have metabolic conditions such as Equine Metabolic Syndrome, get an exaggerated Insulin Spike from normal grazing. In more severe cases this spike stays high and the horse has a condition called Insulin Resistance.

Insulin resistance is diagnosed with a road side test that confirms elevated Insulin Levels.

These horses are extremely high risk for developing laminitis, and the Spring is a very risky time. In addition our winter weather conditions have been perfect for fast grass growth this Spring, increasing the risk further.

Do not wait until its too late. Have a plan ready. Bring your horses off the lush growing grass and feed them hay during the rapid grass growth period.

If your horse has put on weight over the winter, has developed a cresty neck, or has had previous laminitis, check their Insulin level.

Be proactive as laminitis has the potential for very serious long term foot damage.

Worming Wonders

Exciting news. Whilst most of new Zealand suffers with the impending doom of Drench Resistance, thanks to all of my clients that follow my individual and tailored worming plans, we must currently be the leading region for warding off that dreaded resistance.

80% of my clients are only worming once a year. And Another 10% haven’t wormed for over 2 years!! Trust in the process!! It works.

The worm that most adult horses are struggling with is the small Red Worm aka Cyathostome/Small Strongyle. The biggest issue in my opinion that has lead to drench resistance is over drenching due to perceived health concerns, alongside the development of drenches that have prolonged activity and are therefore being used too regularly.

Many times I hear the following comments;

My horses faeces became loose so I drenched them

My horse is bloated it must have worms

I haven’t drenched my horse in a while, they must be due, Ill just worm them now.

PLEASE PLEASE do not be tempted by the above inaccuracies. There is no scientific evidence for a consistent relationship between external signs and the worm burden of an adult horse.

99.9% of horses in Central Otago have loose faeces due to hind gut disturbance.

FACT:

Did you know that worming a horse with a high worm burden without educated advice and/or additional veterinary medication, can actually cause diarrhoea, colic, or a sick horse to become sicker.

For any of you that do not know, we provide a free worming plan and have done for 7 years. There is a charge for the egg count procedure but not the reporting or the scheduled follow ups.

Simply Label the bag with:

‘Horses name’

‘Clients Surname’

And leave the rest to me.

Competition Fitness

Bringing your horse back in work after the winter?

I have put some tips together to ensure your spring exercise programme is free from hiccups.

Loss of Fitness:

If your horse has had 8 weeks off work, then scientific evidence suggests there will be loss of fitness. The loss of fitness happens in the cardiovascular system (heart, lungs and blood flow to muscles), but also in the musculoskeletal system (muscles and skeleton).

Understanding how to resolve this fitness loss is key in preventing sport horse injuries.

Training your muscles:

Returning your horse to work safely, involves training the heart and lungs to establish blood flow to the muscle more efficiently, and also increase the blood flow to the muscles being worked. The more you train, the more efficient this system becomes, meaning oxygen can be used during your muscular work out to prevent lactic acid build up.

Lactic acid build up causes muscle fatigue. Muscle fatigue is one of the key contributors to injury.

Training the brain:

Another area that become more efficient during training is the proprioceptive system: This is the brain and nerve system that is responsible for awareness of foot, leg and body placement. The better this system works, the less likely soft tissue injuries will occur.

Warm up:

In addition to training, warm up is very important: A good warm up turns on the heart and brain systems for exercise, ensuring the systems work efficiently to prevent lactic acid build up and injury.

Donkeys vs Horses

Not all of our equine patients are horses and ponies. We look after donkeys and mules as well!

At first glance, donkeys may seem similar to horses, but they’re different species with unique needs. 

Donkeys are incredibly intelligent, cautious animals. They have different responses to stress and often get labelled as “stubborn,” but really, they’re just more thoughtful and less flighty than horses. Different approaches are needed to handle them successfully. 

Anatomically, there are lots of differences including hoof, mouth and body shape. They also metabolise feed differently and are prone to weight gain and laminitis. 

Vet care differs too—donkeys often hide signs of illness, so early signs can be subtle. They also respond differently to some medications.

Understanding these differences helps us provide better care for donkeys and mules. 

Infundibular Caries

Infundibular caries is a common dental issue in horses, affecting the infundibulum—the central, cup-like enamel structure in the upper cheek teeth. This area is naturally filled with cementum, but if it doesn’t form properly, food and bacteria can get trapped, leading to decay. Over time, this can cause painful infections, tooth fractures, or even sinus disease.

Regular dental exams help us catch these issues early and keep your horse’s mouth healthy and pain-free.

📞 If it’s been a while since their last check-up, get in touch today! Prevention starts with a closer look.

The Squamous Cell Carcinoma (SCC)

Last week we showed you the surgical resection of a growth on a penis. The reason for full resection was to achieve a diagnosis to ensure it was not a Squamous Cell Carcinoma. This week follows on from last weeks post, giving you more information on SCC disease.

SCC are frequently diagnosed in horses. They are the most common cancer of the eye. They are also the most common malignant skin tumour of horses: Malignant means they are rapidly changing and highly invasive. Over time they become high risk of spreading around the body. This is why we need to identify them and remove them ASAP.

What do they look like:

Solitary raised masses often with an irregular surface.

Most commonly affected areas:

Eye lids and third eyelid

Genitals- Penis or vulva

Face- lips and nose

Ears

Anal region

Horses most at risk:

Palamino, Grey and Coloured horses

Predisposing factors:

Sunlight exposure

Skin pigmentation

Smegma

Chronic skin irritation

Genetic predisposition is currently being investigated

Treatment:

There are a wide range of treatment options available depending on the location of the lesion. Surgical resection, cryotherapy and chemotherapy would be the most common.

Early treatment is key before local invasion occurs.

A new therapy is being investigated called Photodynamic Therapy: This is a medical treatment that combines light energy with photosensitising agent to target and destroy abnormal cells. And that team…. Is all I know about this treatment as it is new 😉

Prognosis:

Poor without early veterinary intervention

Willies need inspecting!

Penile growths are very common and when treated early are of low risk for future health concerns.

The first change that happens on a penis is usually small abrasions underneath the smegma (skin cells with oils). Checking the penis and removing all the smegma allows us to ensure no nasty lesions are developing.

Squamous Cell Carcinomas are tumours of the cells of the penis skin. They can be removed when they are small and solitary.

A great reason we sedate for our dentals is to provide a full penis WOF.

One of our patients this week had a growth that was very large (see photo).

I surgically removed this lesion under topical local anaesthetic and send it away to the laboratory.

Great news, this one was fully resected with good margins (no naughty cells were left behind) and it was only a large wart!!

Being proactive saves a lot of heart ache later on! Look after those willies!

Naso-Lacrimal Ducts

Tearing or Gunky Eyes…

Central Otago windy weather predisposes to blocked tear ducts.

The tear duct is the drainage portal from the eye to the nose. In many situations, but especially windy and dusty ones, the ducts can narrow or get fully blocked.

If your horse has tearing or gunky eyes, it is possible this duct could need flushing. The photo demonstrates how the tears drain into the nose (the green is a special dye used in eyes).

Get in touch if you have concerns about your horse.

Proud Cut

In 99.9% of cases, cutting a horse proud is near impossible.

When a client says my gelding was ‘cut proud’ what they mean is there was testicular tissue left in the horse when it was gelded.

My photo this week was simply to show you the anatomy of a castrated testicle within its sac, to help you understand how unlikely it is that a vet has made a mistake.

It is more likely that there is a different explanation such as only 1 testicle descended and only 1 testicle was castrated (Note: This is not a practice that I would recommend).

Testicle descent 101:

When a colt is young, the testicle migrates from the abdomen, through a hole in the abdominal wall, until it reaches the scrotal skin.

As it migrates, it gets enveloped in a fibrous sac call the ‘Tunic’. This tunic surrounds the testicle and the elements that allow sperm maturation before it enters the duct to the penis.

How I castrate my horses, is to cut through the skin, pop out this sac, and then use a special instrument called ‘Emasculators’ which clamp the cord and sac together above the testicle, before it is cut off.

Chorioptic Mange

Does your horse back up to objects and itch its legs?

Does your horse stomp their feet?

Your horse could be suffering from feather mites.

Feather mites are caused by a Chorioptic mite that likes to feed on skin debris from the legs of horses. They hide in the feathers and there are reports of them surviving for up to 70 days on or off the horse.

Mite size: 0.3mm

Mite life cycle: 3 weeks

Mite sprint speed: Very fast 😊

Where are they found?

Any horse can have feather mites, however the feathers on horses legs help to keep the mites warm through the winter months, hence feathered legs horses harbour the highest population of the mites.

Do not forget, the mites can also survive in the environment on objects such as fence posts, stables and bedding

Symptoms:

Itching is caused by crawling mites, however, not all horses respond as dramatically. Some horses can have mites without any symptoms.

Another very obvious symptom is dandruff like flakes at the skin surface and through the feathers: Mites feed on this scurf and it can be quite dramatic in chronic cases.

If a horse is very itchy, they can self mutilate and scabs and bleeding can be seen.

Treatment:

Treatment options are varied, but sadly none are licensed in NZ. Studies have been performed, so we have several good options including drugs which act systemically, and also drugs which are applied topically.

In addition there are topical products that can act alongside drugs to help in reducing re-infection.

Due to the life cycle of the mites, it is very important that treatments are repeated to ensure the mites from the hatched eggs are treated which can happen 7-10 days after initial treatment.

Do not forget the environment; treatment options are available for this also.

Will my normal wormer kill mites?

It has been shown that wormers, despite having the correct ingredient to kill the mites, do not reach a high enough concentration at the skin to be effective to reduce mite numbers to zero.

Helpful tips

1: Some horses are hypersensitive/allergic to the mites: This means even a very small number of them can cause severe itching/irritation.

2: Clipping away the feathers with not cure the issues; it can however make some topical treatments easier to apply and increase the kill rate during winter months.

3: In chronic cases of feather mites, thick crusts of skin flakes can form at the back of the knee; this is called Mallanders.

4: Given the ability of the mite to survive in the environment, re-infection poses a significant risk and full eradication is near impossible in many instances.

5: Non-clinical carriers are a likely source of re-infection.

Degloving Injuries

A degloving injury is one that involves the tearing away of a complete area of skin, with or without underlying soft tissue damage.

This week I wanted to share a case example with you: I think you will all agree, he is doing very very well! The photos are from day 0, and show his journey of 3 weeks.

This lovely boy was found in the morning after a sad and eventful evening: How did this happen…. Well who would know….

He had sustained a moderately severe degloving injury of the dorsal aspect of his LH canon bone.

The skin was torn away from the leg and was hanging down, very swollen, over the pastern region. There was some tearing of the extensor tendon, and marked contamination from the mud. In addition there was exposed bone which had been stripped from its protective cover called periosteum: This leaves the bone sensitive, and at risk of infection.

Treatment:

The area was cleaned, and a pressure bandage applied for a short period to the degloved skin when it was held back its normal position. The aim was to remove all the swelling in the skin tissue.

Next it was bandaged over a 24 hour period with a wet to dry bandage technique, to remove the last bits of dirt from the wound.

The following day, under general anaesthesia, the wound was stitched: I stitched this wound to give immediate protection to the bone and give the skin the best change to be viable, limiting the amount of second intention healing that needed to occur.

The horse was given pain relief and antibiotics, and was not lame.

Over the next 3 weeks, the stitched skin and bandage allowed a good environment for granulation tissue to form, and gave the skin the best opportunity to stay viable and knit back together.

The last picture shows you what we achieved in 3 weeks.

We wish this boy all the best for his recovery, and thank him for sharing his story.

Fibrosarcoma: aka the dreaded SARCOID

Sarcoids are a type of skin tumour.  We see them very commonly in Central Otago.

The areas most likely affected are the face and thin skinned areas; chest, groin, sheath.

Sarcoids can be locally aggressive and even if they look small on the surface, they can be widespread underneath: A bit like the tip of an iceburg.

There are 6 main presentations:

• Flat, scaley and hairless (Sparky)

• Round nodules (Luna)

• Wart like (Cabella)

• Granulation tissue like: Raised and ulcerated (Rachel McDougal)

• Mixed - two or more forms in one lesion. (cocoa)

• Very occasionally they can be deeply aggressive

Treatment options:

Treatment depends on the type and the location; each sarcoid needs a tailored treatment plan. It is important that this is understood.

The question of Marmite….does it work? In my experience I have healed 98% of my cases with a veterinary treatment plan. I have never used Marmite and have never been presented with a horse that has received marmite topically. I have seen no scientific reports of its efficacy.

What to do if you suspect one?

Do not put anything topical on a suspected sarcoid without advice from a vet. Get your diagnosis confirmed before starting treatment.

Why won't this Mud Fever go?

Have you been treating Mud Fever for months now and feel like it won’t go away? There is a possibility that the ‘Mud Fever’ you are treating is not Mud Fever at all and could be Vasculitis. 

What is the difference?

Mud fever (Dermatophilosis) is a bacterial or fungal infection of the skin. This infection often accumulates in areas of moisture and can commonly be seen around the lower limbs in periods of wet weather. Therefore we treat Mud Fever by keeping the areas clean and dry, and by using anti-bacterial/anti-fungal washes and topical creams. 

Vasculitis on the other hand is caused by an underlying immune-mediated condition whereby the immune system attacks the small blood vessels in the skin when the pink skin is exposed to sunlight causing large scabs on the skin. Although these two conditions may look similar, there are also clear differences. Treatment options are also very different for each condition: Mud Fever can be treated with antibacterial treatments and antibiotics whereas Vasculitis requires steroids. 

If you've been treating mud fever for months with little or no improvement, it is possible that vasculitis could be the underlying issue. Don’t hesitate to get in touch—we’re here to help.

A Bang to the Head

This lovely boy was purchased as an exciting new ride. Unfortunately, during the float ride home, he sustained an injury to the eye. The injury caused a rupture to the eyeball itself and can be seen around the edge of the eye near the junction of the brown colour (iris) and white colour (scleral-limbal border). When the eye ruptures in such a location, the brown iris is seen prolapsing through the hole. This luckily plugged the eyeball (globe) from losing too much internal fluid and therefore stopping the eye from becoming deflated.

A low-pressure eye (deflated eye) is at risk of retinal detachment and long-term blindness.

The client was able to treat the eye with pain relief and preventative antibiotics whilst the eye healed. However, the prolapsed iris was preventing the healing of the cornea.

So…. What was next…

Becci had to suture the eyeball closed.

With sedation and topical pain relief, the surgery was performed in our hospital crush. The prolapsed iris was trimmed, and special sutures were used in a tension relieving pattern to bring the edges of the cornea together.

An ocular treatment system was sutured into the eye to allow easy administration of antibiotics and anti-spasm drugs for the iris.

This horse is now 4 weeks post-surgery and the surgical site is free of infection and has fully healed. The sutures used will dissolve over the next 2-4 weeks.

Luckily due to the early detection by the owner, dedicated treatments by the owner, and a successful surgery, there are no long-term complications for this lovely horse.