Weight Gain Challenges in Horses

Q: I have a 24-year-old Quarter Horse mare that was diagnosed with navicular syndrome about 11 years ago. Since we retired her from barrel racing and cut back her exercise she had gained a lot of weight. So we always worked hard to reduce how much she ate to help with the weight on her front feet and the navicular.

Fast forward to spring 2011, when we noticed she had lost a lot of weight over the winter. While she was feeling sprier (started trotting more, had less inflammation in her fetlocks from arthritis, etc.), we were worried about getting her weight back up for winter. We increased the amount of grain and forage through the summer and fall, and while she gained some weight back, she is still rather skinny--possibly a 3 (out of 9) on the Henneke body condition scale.

We're not sure what else we can do--she is in good condition dental-wise, and she has a good appetite. We feed her an equine senior feed mixed with some sweet feed and either alfalfa pellets or cubes, along with two flakes of an alfalfa/timothy hay mix.

We're afraid she might have cancer of some sort. We're concerned about ... getting some more weight on her. What are your thoughts?

via e-mail

A: While it is not uncommon for older horses to have difficulty maintaining their weight through the winter, it does seem rather concerning for an easy keeper to suddenly have difficulty keeping weight on. At 24 years old with good teeth, she should not have trouble maintaining her weight if fed an appropriate diet. Personally, I do not feed older horses sweet feed as the energy required to digest corn and oats is about the same as what they extract from the grain. I prefer extruded grains (such as senior products) and high-fat performance horse feeds.

Even though she is not being ridden anymore due to her navicular disease, her body is expending extra energy in the winter generating heat and dealing with chronic inflammation. Energy-dense feeds with fat content between 10-14% provide older horses with more calories and require less effort to chew.

Since her appetite is good and her teeth are not likely the culprit, it is possible there is something wrong systemically. I would be concerned about disease processes that increase catabolism (break down of complex molecules to simpler compounds). Some causes of weight loss in a horse with a good appetite include infection, metabolic disease, chronic pain, liver dysfunction, parasites, and, as you mentioned, cancer.

Infection and inflammation and later-stage organ dysfunction can be detected with basic blood work. Elevated fibrinogen can indicate the presence of an internal abscess such as is common with pigeon fever (Corynebacterium pseudotuberculosis, or dryland distemper). Lymphoma, a type of cancer, can sometimes be diagnosed on blood work or by analyzing the fluid obtained via an abdominocentesis (belly tap). Other types of cancer are often diagnosed by exclusion once more common ailments have been ruled out.

My recommendation would be for you to have your veterinarian perform a thorough physical examination (including an oral exam under sedation) and basic blood work (chemistry and complete blood count). The results of those findings would determine if additional tests are needed.

About the Author

Kelleyerin Clabaugh, DVM

Kelleyerin Clabaugh, DVM, with the Columbia Equine Hospital in Portlan, Ore.

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