Equine Hirsutism

The horses pictured below are both suffering from a condition known as equine hirsutism. The condition can be described as an irregular or excessive hair coat throughout the year. Normally, a horse will develop a winter coat for the cooler months and then shed the coat throughout the spring months. Horses suffering from  hirsutism will develop a thick coat throughout the year and will require regular, full body clips to keep cool during the hot summer months. 

By far, the most likely cause of equine hirsutism is equine cushing's disease. This is an endocrine disorder that is centered in the brain of the horse and results in excessive cortisone production. Much more serious than a persistent shaggy hair coat, horses with cushing's disease are highly susceptible to founder (laminitis) and a compromised immune system. Testing for equine cushing's disease is a tricky process and may involve measuring serum levels of cortisol and ACTH. In addition, horses can be tested via a Dexamethasone suppression test which may be risky procedure if the horse has a history of founder. As such, it is commonly recommended that if the horse is suffering from hirsutism, it should be assumed that the horse is likely to be also suffering from equine cushing's disease and should be treated for the latter. Recently, the preferred drug of treatment knows as Pergolide became available to equine owners in the form of a FDA approved drug called Prascend. Horses as young as 10 years of age can develop these symptoms and should be treated sooner than later!

Read more about equine cushing's disease @

http://www.aaep.org/health_articles_view.php?id=340

When Is A "Wind Puff" Abnormal?

Figure 1

 The "wind puff" noted in the right hind leg is not necessarily an immediate cause for alarm (Figure 1) . However, when you compare it to the left hind leg, there is a significant difference in the size of the wind puff between legs (Figure 2). This is a reason for concern!

A "wind puff" refers to the accumulation of synovial fluid with the distal flexor tendon sheath of the lower leg. All 4 limbs have a distal flexor tendon sheath and they extend from just above the fetlock down to the coffin bone area. Most people notice the swelling once it is above the fetlock joint however there is often significant fluid within the pastern area that goes unnoticed. For many horses that are in regular work a mild amount of fluid accumulation within the flexor tendon sheath is normal and should be symmetrical. When there is more fluid in one leg or a sudden increase in fluid then there is reason to be concerned.

Figure 2

Within the flexor tendon sheath there are a various tendons and ligaments. Any inflammation within these tendons and ligaments may result in a sudden increase in fluid within the sheath and eventually a reduction in performance. To thoroughly assess these soft tissues, an ultrasound exam should be performed and the soft tissue structures above AND below the fetlock should be evaluated. The image below is that of a abnormal deep digital flexor tendon. The area of concern is at the level of the fetlock joint and within the flexor tendon sheath.  The tendinitis has been chronic and there is evidence of tendon mineralization!. This horse was lame on presentation and there was significant fluid within the distal flexor tendon sheath.

Figure 3

Clostridial Myositis and Banamine Injections

Intra-muscular Banamine is not recommended by this veterinarian!

The picture above is that of a horse that was treated by its owner with 10cc of Banamine (Flunixin Meglumine) in the muscle (IM) of the left hind leg for colic symptoms. The good news was that the horse's symptoms of colic resolved however 2 days later the injection site was swollen and painful to the touch. The following day, the horse was febrile and lame at the walk. The wound was examined via ultra-sound and a large, fluid filled pocket was noted deep to the swelling. The pocket was drained of purulent (pus) fluid and the horse was started on antibiotics. Fortunately, the horse recovered fully with only a minor scar.

This type of reaction may occur secondary to any intra-muscular injection. However, the big concern with injection site abscesses caused by IM Banamine is the association with the bacteria Clostridium and the resulting Clostridial myositis.  These bacteria are anaerobic and thrive in low oxygen environment, hence treatment involves aggressive surgical exposure and drainage of the contaminated tissue. Severe Clostridial myositis can readily result in death of the horse!!

The preferred route of administration for Banamine is either intra-venous or by mouth.

Core Biopsy Please!!

The only way to know for sure would require a core biopsy. This procedure is quite simple to perform in the field and will save significant time with regards to treatment and resolution of clinical signs. The first image was treated unsuccessfully as a "summer sore" with medication that actually worsened the clinical signs. The biopsy results were consistent with Pythiosis and aggressive medial/surgical treatment was instituted. The prognosis for full recovery is not good once there has been significant disruption of the soft tissue structures and in a case that involves the lower pastern/coronary band area. Early diagnosis is key!

The case below was treated as a suspect "summer sore" with minimal improvement. Biopsy results indicated that it in fact it was a case of Habronemiasis that was not responsive to the treatment provided (systemic and topical ivermectin). Habronemiasis or "Summer Sores" is a condition that results from flies depositing larvae within the skin causing a significant allergic reaction. Treatment involves medication to kill any living fly larvae and most importantly medication to suppress the local allergic reaction. Treating with ivermectin systemically and topically is often not enough!! Yet that is how many try to treat this condition! For small lesions, topical treatment with concentrated cortisone can be effective, however, for more aggressive lesions, systemic administration with corticosteroids is necessary. Importantly, systemic treatment with corticosteroids is the treatment you definitely want to avoid if you are dealing with Pythiosis! Hence the importance of a core biopsy.