October 2006 Newsletter

In this issue:

2006 Fall Reminders

Another beautiful New England autumn is in full swing. The air is crisp, the foliage is in full bloom and there is no better time of year to enjoy your horse(s). But winter is coming and it’s time to:

  • Protect your horses against infectious respiratory disease:
    • Booster with Influenza/Rhinopneumonitis vaccination
    • Booster with Intranasal Strangles (Strep equi) vaccination
  • Any horse heading “south” for the winter months should receive booster shots for the following vaccinations:
    • Rabies
    • Eastern/Western Encephalitis
    • West Nile Virus
  • As the cooler months approach, make sure your horse has had a recent dental exam and treatment (floating). All horses should be seen every 6 to 12 months for dental procedures. Improve their ability to chew! Improve their performance under saddle! Improve their quality of life!

Cushings Disease in Horses: Myths & Clinical Signs

As an educated and proactive horse owner concerned about the health and welfare of your horses, I’m sure you’ve heard of Cushings Disease. Unfortunately, a lot of misinformation about Cushings Disease exists in the “horse world.” What you’ve heard from friends, trainers, farriers and veterinarians may simply be untrue or only part of the picture. Cushings Disease is often misunderstood, mistreated, and flat out missed by horse owners and professionals alike. Misinformation and myths abound about Cushings.

Cushings Disease is one of various “metabolic syndromes” that affect horses. Known technically as Pituitary Pars Intermedia Dysfunction (PPID), Cushings is a dysfunction of the pituitary gland, specifically the intermediate lobe of the pituitary gland. This dysfunction is usually caused by a pituitary adenoma (an otherwise benign tumor); sometimes it is due to excessive use of steroids (maybe given to a horse in the treatment of another disease). The pituitary gland dysfunction leads to an excess of glucocorticoids, like cortisol, and other hormones in a horse’s system.

Normally cortisol helps a horse’s body respond to stress and change. It maintains a horse’s blood pressure and heart function; it suppresses the immune system’s response to infection and inflammation. Cortisol regulates the breakdown of nutrients and helps to balance the effects of insulin in the body. It regulates nerve tissue function and connective tissue repair. When a horse’s body has too much cortisol, significant changes occur in numerous tissue and organs systems in the body.

The exact clinical signs and adverse effects of Cushings Disease are wide and varied. Some of the clinical signs of Cushings are well known–like coat changes. Others clinical signs are less well known. Maybe because the clinical signs and adverse effects are so varied, myths and misinformation about Cushing Disease spreads. But whatever the case, a poor understanding of the signs of Cushing Disease potentially harms the quality of life of unrecognized Cushings positive horses. Let’s look at common myths and misunderstandings surrounding Cushings as well as some of its less well known clinical signs:

  1. Myth: “My horse isn’t old enough.” Recent research has found that as many as HALF of horses 13-14 years of age and older are affected. Cushings Disease is not just a disease of “really old” horses in their 20s and 30s.
  2. Myth: “All horses with Cushings are really hairy and curly–like a Woolly Mammoth!” Yes, hirsutism, as this is called, is a classic sign of Cushings Disease. Horses with these “woolly” coats are more than likely dealing with PPID. However, horses may not have extreme coat changes and may still be affected. The changes in a horse’s coat may be subtle. The hair coat may be slightly heavier than normal, shed just a little later, or re-grow earlier in the fall than other horses in the same environment/barn. Patchy, slow shedding or even patchy hair loss may be all that is seen. Even subtler, it is possible that all one notices is a prevalence of “guard” or secondary hairs along the chin, the neck, or other areas of the body.
  3. Myth: “All horses with Cushings Disease founder.” Yes, chronic recurrent laminitis or “founder” is commonly seen in Cushings positive horses. If your horse suffers from chronic laminitis and/or chronic foot problems Cushings Disease may be a prime suspect. However, chronic solar abscesses may often be seen in Cushings positive horses with or without laminitis. Especially in the early stages of Cushings, chronic laminitis and foot problems may not be noticed at all–or may be subtle.
  4. Look For: Cushings Disease may cause increased drinking and increased urination in your horse. It may also produce a “ravenous” appetite in your horse. Monitor your horse’s eating, drinking and urination closely.
  5. Look For: Excessive or inappropriate sweating, or “hyperhidrosis,” is sometime seen in horses with Cushings Disease.
  6. Look For: Complaints that “my horse won’t muscle up” may actually be due to excessive glucocorticoids. Excess levels of these hormones may cause muscle breakdown, especially along the topline and hindquarters.
  7. Look For: The common thought/complaint that “my horse has a hay belly” may actually be sign of a deeper problem. Horses with PPID often have abnormal fat depositions. Fat may settle in the abdomen area, sheath area, mammary gland area, or crest of the neck. Some mares even will lactate when they build up enough fat in the mammary gland. Some geldings look so “swollen” in their sheath/prepuce areas that owners may become concerned that the horse cannot urinate.
  8. Look For: The complaints that “my horse always seems sick” or that “he just can’t shake this infection” may be a sign of Cushings Disease. Excess levels of glucocorticoids depress the immune system. Infections of tooth roots, sinus infections, non-healing wounds or cuts, resistant bacterial and fungal infections like rain rot, chronic Lyme infection, EPM, and/or COPD or other respiratory ailments may all have an underlying root cause of Cushings Disease.

Cushings Disease is widespread in the equine population. Clinical signs may be overt and obvious or they may be subtle. Your horse may have one or many of the above signs. The effects of pituitary dysfunction are serious and may require substantial management changes–changes in daily routine, diet and hoof care–and medical treatment. Early diagnosis and early treatment of Cushings Disease is critical if the more serious medical effects are to be avoided or mitigated. Call or email today if you have additional questions about Cushings Disease or if you have questions about how the above picture relates to your horse.

Aimee M. Eggleston, DVM

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