Lumps and bumps
Lumps and bumps are all too common in our equine friends and grooming tends to be the time that you will notice them most easily. Some lumps just need a ‘watch and wait’ approach, whilst others need urgent veterinary attention. The difficulty is differentiating between the two courses of action. Here we run through several of the common causes of lumps and bumps, and what you need to do about them.
If you notice a new lump or bump on your horse, there are five questions you need to ask before you call your vet. This will help your vet to assess what they need to do and how urgently they need to respond.
- Where is the lump? You need to try and be as specific as possible as to the lump’s location on your horse’s body.
- How long has it been there?
- What does it feel like? Is it hard and bony or soft and squishy?
- Is it a painful lump? Or does it seem to be itchy?
- Is your horse showing any other symptoms? For example lameness, fever, shortness of breath or general malaise.
True skin lumps
These are skin lumps that originate in the skin itself.
Seromas
What they are
Seromas are fluid-filled sacs that occur secondary to direct trauma, such as being kicked by another horse. They usually start out as haematomas (bruises) that become seromas over the course of a few days. These lesions can appear anywhere on your horse’s body but the most common locations are on his chest or upper hind legs. A seroma will feel like a fluid-filled lump to the touch, and it usually won’t concern your horse too much. However, if you find the lump in the early haematoma phase, the lump is likely to be painful, hot and hard to palpation.
Treatment
Most seromas resolve on their own. However, in some persistent cases, your vet may drain large seromas. This is a last resort, as any draining of a seroma risks infection.
Abscesses
What they are
Abscesses are an accumulation of pus under the skin or in the deeper tissues. Abscesses can occur anywhere on a horse’s body and are caused when a foreign body or infection stimulates white blood cells to congregate in one place. The white blood cells form pus and then the body starts to seal off the site of the infection by walling off the infected area. Initially an abscess is just a hard swelling that is painful when touched, but it will quickly grow bigger and typically within about a week a centre, head or tip of the swelling can be identified. When this occurs on the skin of the horse, it is likely that the abscess will burst through the skin.
Treatment
Initially some vets may try and treat a small abscess with antibiotics. However, if the abscess is large or contains a foreign body, they will commonly proceed straight to drainage and removal of any foreign body if necessary. Once an abscess has formed a centre, head or tip to its swelling, it is ready to drain. The abscess cavity will be drained and then flushed out for the next few days to prevent it closing and trapping more pus inside. Draining an abscess is much better than simply waiting for it to burst, as upon bursting the abscess can damage surrounding tissues and the infection can more easily spread. Draining is a much more controlled procedure.
Scars
What they are
Scars can form lumps and bumps anywhere on your horse’s body. A scar forms when an injury heals but some disorganised tissue remains. Scars that occur across bones are especially noticeable. Scars typically feel somewhat hard, and perhaps stringy. In most cases, they are not sensitive to touch or pressure.
Treatment
It is important that you know your horse’s scars. Old scars rarely cause problems, but if you see anything that concerns you and you didn’t see an original injury to explain it, call your vet.
Sarcoids
What they are
Sarcoids are unfortunately very common, being the most common skin tumour in horses. Sarcoids can have a varied appearance and will appear as anything ranging from a hairless area of skin to a big multi-lobed ulcerated mass. It is often difficult to identify sarcoids as they have such a variety of common appearances.
Sarcoids can show up anywhere on the body, but are most commonly found on the abdomen, on the inside of the back legs, around the sheath, on the chest and around the face. It is also common for them to occur in old scars. Sarcoids are difficult to classify. While they can have an innocent enough appearance and don’t spread to other parts of the body, they usually ultimately destroy the tissue that surrounds them. This is why some vets consider them to be a form of skin cancer and others do not.
Treatment
Some vets prefer to use a ‘wait and see’ approach with sarcoids, as often they recur after removal, so putting the horse through a procedure is not worthwhile. However, if the sarcoid is large or causing trouble to the horse it may be removed by cryotherapy (freezing of the sarcoid) or surgically. Some vets will try injections into the sarcoids of immune-stimulating substances or chemotherapeutic drugs before they resort to a surgical approach. It is in fact likely that your horse will receive a number of different treatment modalities, and often the treatments will be combined. Unfortunately, however, sarcoids have a bad habit of recurring and can come back even bigger than before, so no treatment is a 100% guarantee that the sarcoid is gone.
Squamous cell carcinomas
What they are
Squamous cell carcinomas typically occur in warm, sunny climates (like ours!) and often show up on non-pigmented skin like white eyelids or sheaths. They are the most common malignant skin tumours in horses, and 18% of them will spread throughout the body. These lumps often appear innocuous at first and it is easy to mistake them for bites or minor scratches. With time they will become an ulcerated area that will spread.
Treatment
‘Wait and see’ is not a valid option with squamous cell carcinomas. They must be treated or removed as soon as possible. If the lesion cannot be excised in surgery with a clear margin of 1cm all around it, then other treatments will definitely be needed. Many vets, regardless of the margin, will opt for combination therapy such as surgical removal and injection with chemotherapeutic agents to help prevent the recurrence of these troublesome lesions.
Melanomas
What they are
These are big, commonly dark-coloured masses that occur around the tail, genitals, mouth and throat-latch of mature grey horses. These tumours are usually benign and grow slowly, although in a small number of animals they will continue to be a problem and may even prove fatal. Owners typically notice a small nodule beneath the skin but, over time, often only over years, other nodules appear and the growths can join up to form a large mass that may ulcerate through the skin. Melanomas around the tail and anus commonly become ulcerated, and keeping these areas clean is important.
The difficult thing with melanomas is that while most will remain benign, some will become malignant over time, and some start out malignant. The ones that become malignant will spread via the blood and lymph nodes to other sites in the body like the lungs, liver and spleen. If a melanoma starts out malignant it often spreads very rapidly.
Treatment
Many animals affected by melanomas will have long and successful careers with the tumours impacting little on their quality of life. However, some melanomas will need treatment because of malignancy or more commonly because they are in an inconvenient place. The treatment options for these melanomas have varying levels of success. Small, solitary nodules can often be removed surgically, but this depends on the area and the surrounding structures. Some melanomas can also be removed by freezing (cryosurgery) but this has had very variable results, with treatments often needing to be repeated. Other methods of treatment include radiotherapy, chemotherapy and immune-mediated treatments – all of these modalities have variable degrees of success.
Warts
What they are
Warts are a type of tumour and are the most common growths found in horses. They are raised grey or pinkish cauliflower-like growths that are usually fairly small (usually not much bigger than the size of a pea). They can appear alone or in groups, and the most common location in which to find them is on the muzzle or around the eyes. However, they have occasionally been seen to occur on the ears, lower legs and genitals. The growths appear to be symptomless in that they do not appear to cause any pain or discomfort.
Warts are caused by a virus, the equine papillomavirus, which can survive outside the body for weeks. Young horses under 18 months of age are the most vulnerable to infection, although warts can be found in adult horses.
Treatment
Warts are usually harmless and do not need treating. However, if their location is problematic, they may need removal. If, for example, they are preventing a horse from eating or moving comfortably or they are being rubbed by tack, they probably warrant removal. Left alone, warts will typically shrink and ultimately disappear altogether, leaving no scars. This process usually takes around four months in a younger horse, as the immune system develops to tackle the virus, but in an older horse it can take more than a year for the horse’s immune system to clear the warts.
Warts that warrant removal can be cut out using a laser or cryosurgery (freezing the wart), but these processes are likely to leave scars. Drugs that stimulate immunity may also be helpful. However, if the warts do not clear or they grow to a larger size, get your vet to come and examine them, as some conditions, like sarcoids for example, can have an appearance very similar to that of a wart.
It is important to isolate affected horses from unaffected horses, especially younger horses. Any tack or shared equipment used on a horse with warts must be disinfected thoroughly before being used on another horse.
Nodules
What they are
Nodules are referred to as simply nodules or as pressure bumps or sweat bumps. In medical terms they are referred to as eosinophilic granulomas with collagen degeneration, nodular collagenolytic granulomas or nodular necrobiosis. They are distinct, firm nodules about the size of a R2 coin, usually found on the neck, withers or back. Several small nodules can cluster together to form what appears to be a larger lump. The skin above the nodule or nodules appears normal with no hair loss, and the nodules do not contain any infectious material. These bumps can occur in horses of any age, breed or gender. They are usually not painful or itchy unless they are in an area where they get rubbed. Over time these nodules can calcify, which makes them feel harder.
The nodules are caused by the breakdown of collagen, a protein found in the middle layer of the skin. The mechanism by which these nodules form has not been fully understood, but the precipitating event is believed to be hypersensitivity when the immune system overreacts to the presence of an allergen and creates a mass to contain it. Allergic reactions to insect bites are therefore thought to be the most common cause of these nodules, but injections and minor scratches from trauma can be the cause in some cases.
Treatment
Nodules are harmless unless they cause the horse discomfort because they are in an area that gets rubbed, or because they continue to grow in size. If treatment is felt to be necessary, your vet can inject steroids into the nodule to shrink it. Sometimes a course of these injections is required and in other cases, if the nodule has become calcified, it may require surgical removal.
Urticaria
What is it
Urticaria (also known as hives) is the result of a hypersensitivity response in the body. Urticaria has a dramatic appearance with bumps all over the horse’s skin, but often urticaria causes little discomfort to the horse as it is rare for it to be itchy or painful. An urticarial reaction follows exposure to a whole range of possible allergens, including medicines, foodstuffs or pollens. Exposure is normally through ingestion, inhalation or injection of a substance that spreads through the body via the blood. Urticaria can be caused by direct skin contact, but this is rare. It can be several hours, or longer, between exposure and the skin signs – known as wheals or plaques of tissue swelling – appearing.
Treatment
The first step in treatment is obviously to remove the suspected cause of the allergen from the horse’s environment. Often vets will then give steroids to help the acute reaction, especially if it is severe. Antihistamines do not produce good results in horses. Antigen desensitisation and neutralisation can be tried, where the antigen is introduced to the horse in small amounts to ‘get them used to it’, but there is very little evidence suggesting that this is in any way effective.
When to call the vet
Don’t take any risks! While it is unlikely that a skin problem is an emergency, skin problems can be a sign of something more sinister. For example, the urticaria seen in allergies may not be particularly alarming in itself, but when you consider that the airways will also respond to the allergen by narrowing and restricting breathing, it suddenly becomes important to get the vet NOW. If you are in any doubt, the best advice is to call your vet.
‘Red flags’ are signs and symptoms that will alert you to the fact that something is seriously wrong and in need of veterinary attention. If you notice any of them, do not hesitate to contact your vet. The ‘red flags’ are not skin-specific, but all owners need to be aware of them:
- Pain
- Raised or lowered temperature
- Laboured or difficulty breathing
- Inability to get up
- Staggering
- Unexplained sweating
- Sensitivity to light
- Swelling of the eye region
- Red or purple spots on the mucous membranes (these are called petechiae)
- Unpleasant discharge from the nose, the vulva or a wound
- Loss of blood
- Diarrhoea
- Absence of droppings
- Extreme thirst
- Dehydration
- Abnormally flat mood
You need to know what is ‘normal’ for your horse. As owners we must do a top-to-tail scan of our horses at least once a week to ensure that any changes are picked up. Invariably, the earlier something is found, the better the outcome.