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  • Writer's pictureSarah L Rhoades, DVM

Cushing's, IR, Navicular - Oh My!

A lifetime of some diseases, such as obesity and lameness, can precipitate the development of comorbidities and multimorbidities that can shortern a horse's life in addition to reducing that horse's quality of life.
Little old Jewel enjoying her retirement at 20 years of age.

I stumbled across this article from TheHorse on my new feed the other day, and I was inspired to write a quick blog post about. I think it does a great job of emphasizing two points that I come across frequently, and points that I have difficulty articulating.

It is not uncommon for me to come across situations where the reason elected not to test, or not to treat, is ‘it’s just xyz’… It’s just ‘old horse’ changes… he’s just a little arthritic, look he’s getting around okay… he’s just fat… it’s a pony, they’re all fat, he doesn’t do anything athletic, he’s retired anyways, what does it matter? It’s not hurting him.

The problem is, it is hurting him. Sometimes it’s really difficult, and complicated, to explain, or probably more importantly, show why it’s hurting him. As a general practitioner, most of my job and mission is focused on preventative medicine, so you can imagine, these situations do weigh on me heavily.

These disease processes discussed in the article are what we refer to as ‘comorbidities,’ meaning there are multiple damaging disease processes occurring all at once. And what’s worse, is one often leads to or causes the other.

So, for example, if you have a horse that’s spent the last decade of his life at a 6-7/9 body condition score, fat, or perhaps a bit obese, to be clear, we’re not discussing extreme – those horses are typically living in a low level, inflammatory state throughout their entire body. That inflammation doesn’t stop at the joint capsule of his pastern or ignore the navicular bone. It’s not benign on that horse’s endocrine system, including the pituitary gland.

And I’m not saying that by keeping your horse at a healthy weight those problems would never happen – some of them are part of the process of aging and wear and tear – I am saying that obesity could contribute to the acceleration of those processes. So maybe that horse would have started having a problem at 25, but instead after years of living in a systemwide inflammatory state being overweight, it started at 18.

Lets take another example – maybe we have a horse that suffered a career ending injury, a slab fracture of the carpus in an off track thoroughbred, a bad bow or suspensory tear in a jumper, a collateral ligament tear in a western performance horse.

I pick this subject, because it wears on me pretty heavily, in particular. I think people get the idea in their head that ‘I wouldn’t want to be tossed away just because I have bad knees or a bad back and can’t work anymore, so I’m not going to do it to my horse,’ they think the injured draft horse from Animal Farm. But what often happens, is that emotional tie morphs into a mental wall – and the problem gets ignored.

Please hear my out: horses aren’t people – they are a prey species and have been subject to the evolutionary pressures of a species that must run and flea for its survival for 55,000,000 years.

5,000-10,000 years of domestication is not enough to remove those instincts - those instincts are hardwired into every neuron of their psyche – the fact that feral horse populations, like mustangs and brumbies, exist, and that a typical domestic horse can integrate into that lifestyle so easily is evidence enough that they do still retain those drives and instincts.

Addressing problems in middle age and older horses early is important for reducing comorbidities and multimorbidities later in life.
Mike sure loves little Jewel.

What I'm getting at: it’s very hard, for us as humans, as the top of the food chain, to truly understand and empathize the significance of orthopedic pain and neurologic deficits on the mental welfare of a horse’s state of being. We keep thinking Animal Farm, but that horse’s thoughts are not necessarily on the serenity of hoping for a happy retirement, but resigned to a state of stress, perhaps even terror, that ‘I can’t escape’ from a predator. No, that may not actually exist, but instinct to run from 'it' is still hardwired into our companions brain. An instinct to hide that pain from ‘the predator,’ which also hides that pain from us. Worse even still, if he has reached a state of ‘learned helplessness’ that gets interpreted as serenity.

So what exactly am I getting at? We’re talking about comorbidities – what can that chronic orthopedic stress cause or accelerate? Chronic gastric ulcers, laminitis, arthritis, PPID, chronic non-healing cornea ulcers. Even orthopedic problems on the less painful limb.

I am not saying discard our loyal companions when they can no longer perform their former job.

I am saying: don’t ignore it.

I am saying it’s not limited or benign - it is accelerating other problems.

I am saying, it is hurting him, and in ways we can’t fully appreciate or comprehend as a humans living at the top of the food chain.

I am saying, address it, wherever possible - whether that problem is arthritis, Cushing’s disease (aka ‘old horse changes’), obesity, laminitis, etc. – because often, there is something we can do to improve the situation and advances in medicine, diagnostics, and technology allow us to do so much more than we could ten or twenty years ago, and will allow us to do so much more in another ten or twenty years.

Interested in more information on some of these common disease morbidities? Check out TheHorse article that inspired this post: : A Closer Look at Comorbidities in Horses – The Horse

And, for those interested in the science, here’s a good journal article summarizing the subject matter: Prevalence, survival analysis and multimorbidity of chronic diseases in the general veterinarian-attended horse population of the UK - ScienceDirect

Sarah L Rhoades, DVM

Dr Rhoades running barrels on her older mare (now retired).
Hang tight! Little old lady rocking those barrels at 18yo.


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