a. I work with a lot of horses that suffer from pituitary gland dysfunction (PPID, formerly known as equine Cushing’s disease), and the good news is that horses with this condition can lead very happy, active lives when well managed, so I applaud you for wanting to in being proactive. When I think of spring management for horses with endocrine disorders, I immediately think of pasture and turf, and from there, my concerns go to laminitis. Laminopathy is the main cause of laminitis, which can become a death sentence for some horses.
Recent research has shown that foals with an insulin level over 45 have a 70% chance of developing laminitis. These are usually individuals who have some type of insulin insufficiency (ID). Not all horses with PPID also have an ID, so my first recommendation is if you don’t know if your horse also falls into the ID category, talk to your vet about doing the blood work needed to make a diagnosis. This way, you will have a better understanding of how careful you need to be in regulating your intake of non-structural carbohydrates.
PPID is not managed through diet; Instead, it’s managed with medication (pergolide), but equine metabolic syndrome (ID) and equine metabolic syndrome – which some PPID horses also suffer from – are managed with diet and exercise. If you have not retested your ACTH levels since initial diagnosis, I would suggest doing so at the same time to ensure that the dose of medication being administered is correct.
Once you know if your mare has an insulin imbalance in addition to having PPID, you will be able to make informed decisions about how best to handle and feed her. If she had ID, I would strongly caution against allowing pasture access. If their insulin values are normal, you can provide accurate access to pasture. Consider using a herding muzzle that allows access but limits total intake. Closely monitor her weight, and regularly record her body condition to determine the appearance of fat deposits. Take immediate action to keep her at an ideal weight before things get out of control.
What to feed a PPID horse
While diet is not directly used to manage PPID, diet and feeding management go a long way in helping support these horses. Not all horses with PPID are overweight; In fact, some struggle to maintain a good top line and appear very lean. Providing a source of high-quality protein in the diet can be especially beneficial for these individuals. If the overall weight is fine with feed only but there is a deficiency in the top line, a high protein ration balancer is a good option.
For those horses that generally struggle to maintain weight, finding a great low carbohydrate non-structural forage and adding it to their diet is a good choice. I also highly recommend that a qualified dental professional carefully examine the teeth of these horses, as I have worked with a number of PPID horses that also had equine odontogenic resorption and hyperoxaluria (EORTH). This condition can and has been missed previously in a client’s horse, resulting in significant discomfort and weight loss.
Internal parasites are another cause of decreased body condition in this group of horses. Horses with PPID are at greater risk of developing higher internal parasite burdens than healthy horses without PPID. (Editor’s note: Another study of FECs in preclinical PPID horses had different results, although FECs were reduced with pergolide treatment.) Monitor fecal egg counts to determine if your horse may have numbers higher than normal and if your deworming protocol is effective.
How to Manage the Moving Forward PPID Horse
Continue to monitor your blood over time so you can make dietary adjustments as necessary. In particular, retest ACTH in late summer to ensure management strategies are working well before the seasonal peak in ACTH occurs in early fall.
By carefully monitoring your ACTH and insulin values, you will be able to make good management decisions for your daughter’s mare and give her the best chance of living together for many happy years.