What is rain rot
Rain rot otherwise known as rain scald is a relatively common, bacterial skin condition in horses. Rain rot is caused by the bacteria Dermatophilus congolensis. This bacterium is present on the skin of many horses but becomes problematic when the skin is compromised due to prolonged exposure to wet conditions.
Symptoms of rain rot:
Rain rot is characterised by the appearance of scabs across the body, these can appear on any part of the body but are most common on the neck, back and hind quarters and these scabs are sometimes accompanied by further swellings. The hair attached to these scabs is often matted and falls out in tufts which will normally resemble small paint brushes. In some cases these scabs may ooze with pus. Lesions of rain rot can often be found on the lower legs, this condition is known as mud fever.
Causes of rain scald
Rain scald can happen at any time of year however cases are more commonly reported during the Autumn and Winter months as this is when rainfall is at its highest. Horses who spend prolonged periods of time out in the rain with little to no protection or shelter are at higher risk of developing rain rot. Leaving wet rugs on the skin or applying a rug over a wet coat can also increase the likelihood of developing rain rot.
It is a common misconception that horses can only develop rain scald when it is raining. The skin can also become compromised during periods of high humidity and warm conditions that result in excessive sweating.
Factors Affecting Susceptibility
Weakened Immune System
Whilst rain rot can affect any horse, horses with a weakened immune system such as older horses and those with Cushings disease are more susceptible to developing the condition. These horses can benefit from extra preventative measures being put in place and closer monitoring as a compromised immune system can also affect healing times.
Temperatures and Humidity
During summer when the temperatures and humidity levels are higher horses with metabolic conditions such as Cushings, who struggle to maintain their body temperature and regulate coat growth, can be more prone to developing rain rot as a result of overheating. These horses may benefit from being clipped year round as this will help them to regulate their body temperature more effectively.
Light Coloured Skin
It is believed that areas on the body with light coloured skin are also more prone to being affected by rain scald and mud fever, however there is no real scientific evidence to support this. The condition may appear more noticeable on these areas due to the lack of pigmentation on the skin.
A diagnosis of rain rot is usually made upon clinical signs and presentation. In some cases a vet may wish to collect skin scrapings in order to rule out other diagnoses as the lesions can sometimes be mistaken for other common skin conditions such as ring worm.
In suspected cases of rain rot, it is always a good idea to consult with a vet as the condition can lead to further complications and secondary infections if not treated promptly and appropriately. Vets will normally prescribe topical treatments either in the form of ointments, lotions or washes. These topical treatments for rain scald can be highly effective in mild cases for optimum efficacy. The top layer of scabs should be removed as this allows treatments to penetrate the skin underneath. Care should be taken when removing scabs as this can be very painful. Always seek veterinary guidance before using your own topical treatments for rain rot as certain ingredients may irritate the skin and exacerbate the condition further.
For more severe cases a course of oral antibiotics may be required, if this is the case, it is important that the complete course of antibiotics is given.
If rain rot lesions appear on an area of this skin where tack would normally sit, ridden work should be avoided until these have fully healed.
Rain scald rarely leads to further complications. Due to the location on the body however, mud fever can be more problematic and may result in lameness or progress to a condition known as lymphangitis in more severe cases. If you suspect your horse has mud fever contact your vet immediately.
How To Manage Rain Rot?
Preventing and managing rain scald in the winter months can be difficult as we cannot control the weather, however there are several measures owners can take to minimise their horse’s risk of developing the condition.
Practical Measures to Minimise Rain Rot Risk
Proper Rug Management
Minimising your horse’s exposure to rain and muddy conditions can greatly reduce the risk of developing rain scald. Owners can make use of turn out rugs to keep their horses protected from the rain. All turn out rugs should be waterproof, it is important to keep your rugs in good condition with regular washing and reproofing to ensure they remain effective. Rugs should also be checked for damage regularly and repaired if necessary. Turn out shelters that provide protection from the elements are also a good option if your horse lives outside or is turned out for long periods of time.
Your horse’s rug should be changed if it becomes saturated as leaving wet rugs on the skin for too long can also increase the likelihood of rain rot. Stable rugs and turn out rugs should also not be applied to wet skin as this will trap moisture underneath again increasing the risk of developing rain rot
Whilst rugs can be useful for preventing rain rot, it is important not to over rug your horse. Over-rugging can cause your horse to overheat and sweat as a result. When sweat sits on the skin and coat, unable to evaporate, this will also increase your horse’s likelihood of developing rain scald. Horses have a much broader therm-neutral zone than humans - just because we feel the cold, doesn’t mean our horses do!
Selecting the Right Rug for Your Horse
There are a number of factors that will determine the type of rug your horse requires. Things to consider when rugging include your horse’s age, current workload, body condition, health issues and whether or not they are clipped.
Field and Paddock Maintenance
Horses who spend longer periods of time on wet or muddy ground become more susceptible to conditions such as rain rot and mud fever. Proper field and paddock maintenance can minimise the risk of ground becoming poached and waterlogged in the first place. Avoid overstocking and overgrazing paddocks and where necessary rotate grazing to minimise the risk of damage to the ground.
Grooming in Detecting and Preventing Rain Rot
Daily grooming and inspecting of your horse’s coat is important as this will allow you to pick up on any symptoms or changes that may be an indication of rain rot - the sooner the condition is spotted, the easier it tends to be to treat. All horses should have their own grooming kits and the sharing of equipment should be limited wherever possible to minimise the risk of bacteria being transferred from horse to horse. It is also recommended that grooming kits are washed and disinfected on a regular basis. All grooming utensils, rugs and tack should be thoroughly disinfected following treatment of rain rot to minimise the risk of re-infection.
Navigating the Challenges of Rain Rot
Whilst the condition can be an inconvenience, it is thankfully rarely a huge concern, in fact most horse owners will deal with a case of rain rot at some point in their life. Recognising the symptoms, understanding the causes, and identifying factors affecting susceptibility are crucial for effective management of rain rot.