Summer in New Zealand often brings intense weather – not all of it very summery!
However, there will still be stretches of hot, sunny weather to enjoy (while taking care you are protected from the well-known damaging effects of the sun). Our horses need protection from the sun’s ultraviolet radiation too, and some are more obviously affected than others. The warm weather also brings with it an increase in other horse skin problems such as photosensitisation, insect bites and allergies. These can be tricky to manage, and it is often a case of trial and error until the right management strategy is found. In this article we will look at some of the common summer skin issues and what can be done to manage them. A more serious skin condition related to the sun will also be discussed, as prevention and early detection are key to a better outcome.
Sunburn
Horses and ponies with white/pink noses are obviously at the risk of a sunburnt nose. With sunburn, the pale pink area becomes red, inflamed and sore, and can blister and ooze. This area is hard to miss, but you will also need to watch out for sunburn on other white areas, such as on white socks or even white ears.
Ideally, sunburn needs to be prevented rather than treated, and if your horse or pony does become burned you may need to seek veterinary advice. While the most likely cause is the direct effect of sun exposure, but there is another cause – photosensitisation, which we will discuss below.
Your vet can advise you on how to make sure it is straightforward sunburn you are dealing with, and how to treat it.
Sunburn can be prevented by using one of several options, or a combination:
- Provide shade. This is the most important – shade should always be provided, whether it is the natural shade of trees or supplying a shelter. Some horses will opt to stay in the shade themselves, but others might need to be physically kept out of the sun, for example by taping them off an area under trees on sunny days, letting them have the rest of the paddock overnight.
- UV nose shade or face mask. Some are designed to be used alone, and some need to be attached to a halter. There is always a concern about turning a horse out with anything attached to the head, as some horrific accidents can happen, so use a breakaway halter to reduce the risk, and inspect your paddocks carefully for hazards. Masks and nose shades do work well if you can get them to stay in place safely.
- Sunblock. A range of products are available, from lotions and creams to powders, and different ones suit different horses. Ideally, you want a long-lasting one to ensure you have good protection throughout the day. Applying it twice a day would be optimal. Some horses don’t like sunblock being applied and you may need to experiment to find one he or she will tolerate. Getting into the routine of applying sunblock as part of your horse’s daily routine is key.
Photosensitisation
Photosensitisation is when the white or pink areas of the skin become extremely sensitive to the damaging effects of the sun. It looks very similar to sunburn, but one way to tell the difference is to assess how much of the white area is affected. In photosensitisation, all the white area is inflamed, where as with sunburn, the areas most directly exposed to the sun will be more obviously affected – so the top surface of the nose will be more clearly burned than the underside.
Why is this important? It is important to know whether there is photosensitisation or not for two reasons
- The cause of the photosensitisation needs to be removed to allow the skin to recover, or it will continue to be oversensitive.
- One cause of photosensitisation is liver damage, and this is a lot more serious issue than sore skin and will need investigating, treating (if possible) and ongoing management.
Photosensitisation can be caused by horses eating certain plants which directly make the skin more sensitive to the sun. St John’s Wort is one such plant, and there are others too. Sometimes, you may not be able to identify the plant involved, especially in a large paddock. It may be that only one horse out of a herd has eaten the offending plant and becomes affected, and the others are all fine.
It can also be a side effect of liver damage. A horse with a damaged liver can no longer detoxify the normal products of digestion, and these toxins cause photosensitisation. The most common cause of liver damage in horses and ponies is eating poisonous plants such as ragwort.
Some medications can cause photosensitisation too.
In all cases, the underlying cause needs to be investigated and removed where possible. Then, the damaged skin is treated as for sunburn (and any secondary infection treated) and the horse needs to be kept in shade until the skin becomes less sensitive.
Skin complications
Any damage to the skin, including sunburn, can allow bacterial infection to take hold if it is not treated properly. One of the bacteria involved in mud fever and rain scald (Dermatophilus congolensis) can take the opportunity to grow and multiply in sun-damaged skin. This causes more damage, pain, and the typical crusty scabs. Other bacteria can also take hold, so do talk to your veterinarian about treatment if you are at all concerned.
Another complication to be aware of is that some topical sprays we use on horses may irritate the skin – and this irritated skin is more likely to become affected by the sun.
Insect repellents such as fly and tick sprays may do their job in keeping bugs at bay, but some horses with sensitive skin (again, particularly on white socks) may react to them. Take a note of all sprays and treatments you have used in case your horse has a skin reaction.
Biting flies and insects
Ticks are an issue for horse owners during much of the year in the northern parts of the country, but are particularly rife in the warmer months. Other areas of the country are well known for having biting flies.
You will see small, raised lumps with a small dot or scab in the middle. Some horses and ponies react a lot more than others (they are hypersensitive or allergic to the bites).
One well-known skin allergy you hear of in horses is sweet itch; this is a hypersensitivity to a particular type of midge (Cullicoides) which fortunately don’t have in New Zealand. We do, however, see very similar insect hypersensitivity signs caused by other types of insects. The reaction can cause really intense itchiness; horses can injure themselves trying to get some relief.
For insect hypersensitivity, the use of good repellents is important. Ones containing permethrin are often effective. They come in different forms, and you may even use permethrin-impregnated ear tags plaited in a section of mane or tail.
The important thing is to keep up regular insect control. Looking at the environment may help, for example moving the horse away from near a stream where midges are in large numbers at certain times of the year.
Stabling your horse before the biting flies come out at dusk may help if things are really bad, especially with a fan at the entrance to the stall (the midges are often deterred by moving air) and using fly repellent as well.
For rapid relief from itching, your vet may use steroids and/or antihistamine treatment. This is a short-term fix. It is then important to try and identify the most likely cause of the problem so preventative measures can be started.
Your vet may recommend washing your horse with a special shampoo which will have ingredients to soothe the skin, remove any potential allergens (in this case, the insect saliva) treat any bacterial infection and help rebuilding a healthy skin barrier.
Other skin allergies
It’s not just insects that can cause skin allergies in horses. Allergies to something in the environment, which is known as atopy, can be very frustrating to manage. The allergy can be to pollen, mould spores, tiny mites or something in the diet.
It can be a case of trial and error, working out what seems to be causing it and what measures can be taken to reduce exposure.
There are a couple of specialised tests available, the intradermal skin test and the serum Ige test. These have not been used as much in horses yet, so may still need further validation, but may be worth discussing with your vet if you are struggling to keep your horse comfortable.
Once a cause for the allergic reaction (often several causes show up) have been identified then a desensitisation treatment protocol may be put in place which can help, but this will need to be fully discussed with your vet.
It may be worth supplementing your horse’s diet to ensure their skin is in optimal health – you need to make sure your horse is receiving the correct amounts of vitamins and minerals remembering that New Zealand has lots of areas where the soil is deficient in selenium.
For allergies, in particular, there are lots of different supplements on the shelves. Increased essential fatty acid supplementation with Omega 3 does seem to help reduce the inflammation in both respiratory and skin allergies, so it is recommended to try a supplement containing high levels of Omega 3 – for example, flaxseed is a good option.
Pin worms
Just as an aside, is worth remembering that not all skin itching is due to allergies. Pin worm problems may be becoming more common. These worms lay their eggs in a sticky substance under the horse’s tail, which cases irritation and rubbing of the tail seen in some horses. Vets can check for signs of eggs in the area if the rubbing seems to be localised to the tailhead. Some horses react more than others and some are quite severely irritated by pin worms. Once treated, a post-worming check will be carried out to check it has been effective.
Eye cancer
A more serious problem for horses that is linked to UV radiation is a type of eye cancer called squamous cell carcinoma (SCC for short). It is the most common eye cancer in horses, and there are several risk factors involved.
One of these is lack of pigment (colour) around the eye. Pigment in the skin around the eye protects the DNA in the cells being changed (mutated) by the UV radiation, so horses with with pink around the eye are more at risk, and it also appears that chestnut horses have a greater risk too.
Certain breeds are more at risk of developing SCC – there are genetic tests on several breeds including Haflingers being researched.
If your horse has pink around the eye (commonly seen in pinto and cremello horses), and/or is chestnut, increased exposure to UV radiation will increase the chance of SCC developing. The tumour starts as a small red or pink, raised area and can be on the eyelids, the eye itself, the third eyelid or any of the structures to do with the eye. It is important that if you notice any changes in your horse’s eye (whether they are high risk or not) that you have a veterinarian to examine them. Early treatment of any eye problem (cancer or not) is much more likely to be successful.
The best way to reduce the risk is to reduce the amount of UV exposure using fly masks, keeping the horse indoors during peak sunlight hours and of course, always providing shade.
Summary
Routine care of your horse’s coat and skin is important all year round. Winter may bring with it muddy paddocks, longer thicker coats, and lots of rain, which is challenging for the skin, but summer has its own challenges. Heat and sweat can lead to rubs, saddle sores and girth galls, so making sure your gear fits well and your horse is hosed down and skin checked after every ride will prevent problems developing. For horses prone to sunburn, extra care must be taken to protect the sensitive skin. Summer skin allergies can be particularly frustrating to deal with, it is hard seeing your horse itchy and covered with lumps and bumps. Talk to your vet and get started on a plan to manage the problem while at the same time ensuring you are giving optimal nutrition and skin care. Finally, keep cool with plenty of shade and water – for horses and humans too!
