Magnetic Resonance Imaging (MRI) is an advanced imaging tool that is widely used in the veterinary and human healthcare fields. MRI has been developed for use on our equine patients and has been found to be invaluable in helping us to attain specific, accurate diagnoses for our patients. Did you know? Using MRI early on in a lameness case can actually reduce your overall spend by achieving a prompt diagnosis and treatment plan without trying numerous other approaches which are unlikely to help in the absence of a specific diagnosis. 

At Oakhill, we have a standing low-field MRI scanner which means that horses are sedated and stood up for the whole procedure, no general anaesthetic is required, YIPPEEE! The use of the standing MRI scanner is now considered the optimum tool for diagnosing orthopaedic conditions in the horse. The MRI machine is a low field scanner and the strength of the magnet is 0.27Tesla, to put this in comparison to a high field scanner used in hospitals which is 1.5Tesla in strength. This is reflected in the size of the magnet, and the ‘U’ shaped standing magnet is much smaller than those in human hospitals. It’s U-shaped and not a cylindrical shape so that the horse can escape easily from the magnet without harm if they suddenly become anxious during the procedure. 

Usually a horse has been through a lameness investigation including nerve blocks prior to MRI. This may then be followed by radiography (X-rays) and an ultrasound scan, depending on the area to be imaged. If there is still no definitive diagnosis after these imaging modalities, then MRI is often advised. Nerve blocks are essential in determining exactly which site we need to scan. 

So, what will happen if your horse requires and MRI scan? Horses are often admitted as a day case. They will have their shoes removed and a catheter placed to allow small increments of sedation at short intervals to be given easily during the scan. A scan of both front feet typically takes 2-4 hours, but this hugely depends on how well the horse stands within the magnet. 

Our MRI machine is positioned within a specially insulated cabin (called a module!). These modules are made specifically for the MRI machine, to ensure control of temperature and signal interference. Occasionally a French radio wave of a certain frequency has been known to disrupt our scanning! The magnet works within a finely monitored temperature-controlled space and is quite sensitive to change. 

The foot is the most common site that we scan with the MRI machine due to the tough hoof capsule making imaging of the soft tissues difficult. We can assess the bones through radiography, however, MRI has a further advantage of being able to assess for fluid (inflammation) within a bone which no other imaging modality can visualise. Since MRI has been being used, ‘Navicular disease’ has become an outdated term, and we now know there are many different soft tissue and bone pathologies encompassing navicular syndrome, which can be individually assessed and a more accurate guidance on prognosis of the horse’s career given through the use of MRI. 

The magnet can also scan other aspects of the lower limb, up to and including the lower carpus (knee) and hock. This can be particularly useful in areas that can be difficult to fully assess with other imaging modalities such as the proximal suspensory ligament. MRI has revolutionised our ability to achieve a fast, accurate diagnosis and has dramatically enhanced our treatment capabilities of the lame horse. 

The liver has multiple responsibilities including nutrient and toxin absorption. It has a large ability to cope with insults however, clinical signs will become apparent when 60% of the liver is damaged. 

Signs can include jaundice (a yellowing of the gums or white of eyes), weight loss and in severe cases neurological signs such as head pressing and blindness. 

This pony was presented to vet Stuart after developing excessive sunburn. Unfortunately, a large proportion of his body was white haired so this sun burn covered his face, muzzle, his legs and around his eyes as seen in the pictures below. Blood evaluation showed an increase in liver enzymes (indicating liver damage) as well as bile acids, indicating impaired liver function.

A liver biopsy was performed with the pony under sedation and local anaesthetic. This ultrasound scan shows the appearance of the liver.

The results of the biopsy showed the pony to have severe fibrosis (scarring) of the liver, due to ragwort toxicity. However, the changes observed were deemed manageable. 

The pony was placed on steroids, to reduce liver inflammation, and antibiotics for the secondary skin infections. He has had regular antibacterial baths and creams applied to sooth his skin whilst avoiding sun contact. 

He has shown a great improvement whilst on medication and as you can see from the pictures his skin is less inflamed and has started growing hair again as seen in this picture.

His bloods will be monitored going forward. We will keep you updated on his progress.  Liver biopsies are simple to perform and gives a great deal more information on how to treat the liver disease affecting your horse or pony.

If you are concerned about anything discussed then please call us and speak to a vet on 01772 861 300 

Pinworm (Oxyuris equi) infection is manifest by affected horses itching their peri-anal and tailhead regions. Adult worms reside in the large intestine with the female worm travelling down the small colon to lay eggs on the skin surrounding the anus (often indicated by a yellow discharge as seen in photo one below). This usually causes intense irritation manifest by rubbing. Occasionally, mature worms are visible protruding from the anal sphincter which we can also see in this photo. 

Diagnosis is confirmed through microscopic examination of a sellotape impression taken from the peri-anal skin or yellow discharge (if present) which will reveal the pinworm eggs (seen in photo two below). 

Most commonly used wormers are effective for pinworm (ivermectin, avermectin or pyrantel based wormers) and should be administered to clinical cases. The peri-anal region and underside of the dock should also be washed using dilute hibiscrub to remove the eggs. We generally recommend cleaning for three to five consecutive days. The stable should also be thoroughly cleaned and disinfected to endeavour to remove environmental eggs.

Pinworm infection should always be considered in cases of tailhead itching but it is also important to consider other potential causes including sweet itch, other allergies, mites and lice. It is also important to remember that pinworm infection is generally not indicated on faecal worm egg counts as the eggs are deposited on the skin surrounding the anus. Therefore, horses with negative faecal worm egg counts may still succumb to pinworm infection.

As always, should you have any questions, please do not hesitate to contact the equine team. 

Colic is the term used to describe abdominal pain. This is usually from the gastrointestinal tract but can be from any abdominal organ (e.g. the ovaries). Colic signs include curling of the top lip, pawing the ground, flank watching, rolling, increased recumbency (lying down) and change in the amount and/or consistency of droppings. Most cases require a veterinary examination to determine the cause and instigate treatment, from pain relief through to life-saving surgery. 

Initially the vet will observe the horse to see how severe the signs are. The cardiovascular system is then assessed. The mucous membranes (gums or inner eyelids) are examined to establish how well the blood is circulating round the body. The membranes should be salmon pink, and when blanched this colour should return within two seconds (the capillary refill time or CRT). Any discoloration of these membranes, with or without increased CRT, are a sign of poor circulation. Dry mucous membranes are a sign of dehydration. 

A heart rate will then be taken. Slight increases in heart rate can often be attributed to increased stress levels in the horse, but a very high rate is generally an indication of dehydration and disrupted circulation. The digital pulses (at the level of the fetlock) may also be felt – a lack of indicating poor circulation, and an increase potentially indicating toxic laminitis (caused by gut toxin leakage into the circulation). 

Poor circulation results from the leakage of toxins from damaged gut into the circulation. The gut becomes damaged when it gets twisted or stuck, cutting off the blood supply that keeps it alive and functional. Mild dehydration can arise from reduced water intake or sweating. Severe dehydration normally occurs when the damaged gut is no longer capable of absorbing fluid into the body. 

Following cardiovascular assessment, a respiratory rate is obtained. An increased rate can be due to the horse being in pain and using more energy whilst colicking. It can also be due to chemical changes in the blood caused by toxin release. Rarely, an increased respiratory rate can be caused by something in the abdomen pressing on the lungs e.g. a stomach impaction (where food fails to leave the stomach causing expansion and discomfort). 

Next the vet will listen with a stethoscope at four points on the abdomen. A moderate amount of noise should be heard, as gas and food move through the guts (borborygmi). Increased noise is generally an indication of spasmodic movement of the guts. Decrease in, or absence of noise usually indicates that gut movement has stopped or that the portion of gut that is normally positioned in this area has been displaced, which can indicate a more serious problem. 

The horse’s temperature is then taken. A low temperature can indicate poor circulation, and a high temperature generally indicates infection. 

If the vet is now satisfied that the horse merely has some spasmodic gut pain, the colic examination is complete and appropriate medication can be administered. However, if a more serious cause of colic is suspected, a rectal examination will occur. A lubricated, gloved arm is inserted into the horse’s rectum so the vet can feel deeper into the abdomen. The size, position and content of different portions of the gut (and other structures e.g ovaries, tumours) can be assessed allowing an accurate diagnosis of which part of the gut (or otherwise) is affected. Rectal examination has huge benefits but also carries a small risk of tearing the lining, hence it will not be carried out if deemed unnecessary. 

Horses are unable to vomit, so if your vet is suspicious that the passage of food and liquid through the stomach is obstructed, they will pass a tube via the nostril to aspirate excessive fluid build-up. Without the ability to vomit or the act of stomach tubing, a horse’s stomach can eventually rupture. Once your vet is confident that no excess ingesta is present in the stomach, they may use it as a route of treatment for dehydration, administering fluid and electrolytes. 

This is routinely the end of an ‘on-yard’ colic examination. If your horse needs to be admitted to a clinic, further examinations may take place. These include abdominal ultrasound, blood sampling and peritoneal fluid (the fluid lubricating the abdominal organs) sampling. These samples can be looked at with the naked eye or machine analysed to provide information about how the rest of the body is coping with the problem causing the colic signs. 

Ultimately, the vet will be able to make an accurate diagnosis and appreciate how sick the horse is. Appropriate treatment can be advised with the vet able to predict the horse is well enough to recover after treatment, or if (on some sad occasions) euthanasia needs to be considered. 

Approximately 90% of colic are diagnosed as medical. Of these, only a very small proportion will require more than one treatment. The sooner the horse arrives at a surgical facility, the better the prognosis. In all cases, this detailed examination will limit any period of discomfort and distress for both you and your horse. 

There are many different causes of skin disease in horses and ponies, with the most common being associated with parasites and insects. However, occasionally immune mediated skin conditions can occur spontaneously or as a reaction to a drug or stressful situation. Below is a picture of a horse presented to us for excess scabs which had originally started on the lower leg but had progressed rapidly and was now affecting the belly and flanks (see picture on the left).

Skin biopsies are required to diagnose immune mediated conditions and the process is well tolerated by horses. Local anaesthetic and a punch biopsy tool (like a small apple core) are used in several areas to obtain samples which are then sent to the lab. The lab can then determine based on the cells present which condition is causing the skins appearance. 

In this case pemphigus foliaceous was diagnosed. In this disease the body directs antibodies against the cells on the skin surface and in doing so causes blister and excessive crust formation. The mainstay of treatment for autoimmune conditions is immunosuppression using corticosteroids. Autoimmune conditions carry a good to guarded prognosis depending upon how well the immunosuppressive therapy works. However, we are pleased to report that in this case the corticosteroids have worked wonders. The pony is back in full work and as you can see the skin appears completely normal (like in the picture at the top). The pony will be closely monitored to detect any future recurrence. If you have any queries about your horse/ ponies’ skin then please call us to speak to one of our vets on 01772 861 300.

Summer time is hopefully a period that we are blessed with good weather and sunshine and while this is inevitably good for the soul, the sunshine and resulting UV, sadly can have negative implications for our equine patients namely in the form of sunburn and photosensitization. 

The first, simple sunburn, occurs when light- coloured skin, including flesh marks, becomes red and scaly following excessive exposure to UV light. Similar to humans, the severity of the damage depends on the strength of the radiation and the individual’s skin sensitivity. Light-coloured skin is predisposed due to a lack of melanin pigment which absorbs UV light and scatters the radiation. Hairless skin is also more severely affected. The most common affected area is arguably the muzzle.

Mild cases generally self-resolve provided further exposure to UV light is prevented and the skin is given a chance to heal. More severely affected patients require veterinary attention and topical medications are frequently indicated (usually steroid-based creams).

Prevention is based on avoiding exposure to intense sunlight by stabling at periods of intensity, use of water-repellent sunblock and if the muzzle is an ‘at risk’ area, use of a face shade mask (which includes a shade to cover the muzzle area).

Ragwort 

· Whilst intact, ragwort is generally quite unpalatable and horses don’t tend to eat it unless no alternate forage is available. Ragwort becomes much more palatable for horses when it is treated using a herbicide but hasn’t yet fully decomposed or when it is cut down and subsequently dries out. Therefore, one of the main sources of exposure to our horses is when it is inadvertently incorporated into hay or haylage. 

· The toxin in ragwort, pyrrolizidine alkaloid, is generally a cumulative toxin. While a toxic dose may be consumed on one occasion, it is much more common for a patient to consume the toxic dose over a longer period of time i.e. years. 

· The toxin causes irreparable damage to the patient’s liver which can lead to liver failure which is fatal. Clinical signs of liver failure are often only apparent when greater than 75% of a patient’s liver is affected. Clinical signs include depression/abnormal demeanor, reduced appetite, weight loss, jaundice, diarrhoea and photosensitisation to name but a few. 

· Diagnosis is based on the presence of compatible clinical signs, with/without a history of grazing ragwort-infested pasture, blood work and ideally, a liver biopsy. 

· Treatment is generally of a palliative nature.

Did you know taking a blood sample from your horse can not only aid in the diagnosis of disease but can be performed for many other reasons? Once collected, samples are analysed either in our clinic or sent to a veterinary laboratory externally. Some tests are quick to run, while others can take several days or longer to complete before the results are available. 

Apart from helping the vet diagnose a disease, blood sampling can also be used to: 

1. Monitor the response to treatment after diagnosing an illness – this may be to ensure tissues are healing, an infection is resolving or assessing response to treatment. For example checking the dosage of ‘Prascend’ is suitable in Cushing’s disease cases. 

2. Screen normal animals – Although animals may not show any signs of being unwell, there may be early indicators of disease that can be blood on routine haematology and biochemistry blood analysis. This is particularly relevant with older animals or those recently exposed to a contagious disease. 

3. Pre-purchase examinations – blood is routinely collected prior to purchase by the attending vet to allow for future testing of medicines that may mask signs of illness or injury. These are collected and stored frozen for six months. For example, if a lameness issue arises shortly after purchase then the sample can be tested for anti-inflammatory and pain relief medicines. 

4. Confirm exposure to infectious diseases – during an outbreak exposure to diseases such as equine influenza and strangles can be confirmed or ruled out. In some cases a second sample may need to be taken two weeks later if results are considered borderline or inconclusive. 

5. Confirm the health status of an animal before export/import – horses may need to be free from certain disease before entry into another country. Blood tests are used to rule out several serious diseases and maintain the disease-free status of a country. Diseases may include equine infectious anaemia, equine viral arteritis, African horse sickness or equine influenza etc but each country has its own specification for which tests must be taken. 

6. Confirm the health status of a mare or stallion prior to breeding – some diseases can be spread during the breeding process, affecting both mare and stallion with fertility or illness. These include equine infectious anaemia, equine viral arteritis and strangles in some cases. 

7. Monitor a patient prior to and during a general anaesthetic (GA) – Bloods are often checked before surgery to identify any additional risks of performing a GA. These can be repeated during surgery to allow the anaesthetist to respond to any deterioration during the procedure. 

8. Identify banned substances during competition – Professional equestrian competitions (e.g. BHA, FEI etc) monitor for the presence of prohibited performance enhancing drugs. The blood (and urine) of competitors may be tested to prevent any unfair advantage. For example, administration of anti-inflammatory and pain relief medication such as phenylbutazone (bute).