My Senior Horse Podcast: Weight Loss Part 1

Underweight or overweight horses can be an issue for many owners, especially those who have senior equids. Join us with Drs. Pat Harris and Nicky Jarvis for a three-part podcast series on managing the weight of horses.

Harris is a past president of the British Equine Veterinary Association and is a European specialist in veterinary and comparative nutrition. She is the former Director of Science for Mars Horsecare and Head of the WALTHAM™ Equine Studies Group. Harris has spent much of the last 30 years working to help improve the care and nutrition of older horses. She also is passionate about seniors because of her dedication to her own older horses. She has advised on the care of many other seniors and has authored numerous articles on their care. Harris’ involvement in several global senior research teams gives her special insight into some of these studies. Dr.Harris is also on the Executive Advisory Council for My Senior Horse.

Jarvis is head of Veterinary and Care at Redwings Horse Sanctuary in Norfolk, England. She qualified from the Royal Veterinary College, London, in 1990 and worked in mixed practice for two years before moving to Newmarket, where she completed a two-year internship at Rossdales Equine Hospital. Jarvis then joined Redwings Horse Sanctuary in Norfolk in 1996. She is now head of Veterinary and Care there, working with what she calls an “incredible” team of veterinary surgeons and nurses to care for more than 1,500 resident horses, donkeys, and mules. Jarvis attained her RCVS Certificate of Advanced Veterinary Practice in Equine Medicine in 2012 and her CertAVP in Equine Surgery Soft Tissue in 2013. Her specialist interests include equine nutrition, geriatric medicine, internal medicine, and colic.

(Editor’s note: The content of this podcast is the expert’s approach to the topic. Please consult with your practitioner if you have questions.)

Causes of Underweight Equids

“A lot of the issues that can cause an older horse to be underweight will apply to any age of horse,” said Jarvis.
“So, hopefully, this information can be quite useful for all ages of horses. And I know Pat would definitely agree with the following: One of the commonest causes of weight loss is in actual fact the diet itself.”

She discussed some of the common causes in the podcast, but here are summaries.

Dentition and Weight

No matter how lovely the diet is for the horse, the teeth must be able to process the feed, said Jarvis.

“We need our horse to have the correct dentition in order to successfully process the forage,” said Jarvis. “If the right dentition isn’t there, then we need to provide that fiber in a form they can cope with. So, it isn’t just about providing food in the right quantity, but it’s making sure that food is appropriate for that horse’s age, it’s
health, concurrent medical conditions, and its dentition.

“It can be harder than you think to formulate diets when these horses age because you’re taking into account extra factors,” she added. “The good news is, if you’ve got a healthy older horse with great dentition, you can feed them like you would a younger horse.”

Concurrent Conditions

Jarvis said owners of older horses must take into consideration physical and environmental conditions when determining the diet. She reminded that in the ‘depths of winter’ for horses that are having forages soaked due to physical conditions such as laminitis or insulin dysregulation, that “sometimes we can be missing out on some of their vitamins, minerals and proteins that they need.”

She and Harris agreed that the correct diet for the individual animal is key to proper weight management.

Jarvis said in one study looked at older and younger horses of the same body condition score in winter. The older horses required more energy to keep warm than the younger horses.

Other issues of older horses that can cause weight loss include liver and kidney disease, chronic inflammatory disease, and osteoarthritis, she noted.

“Horses have to ambulate around the field to get their food, so they need to be able to walk well,” stated Jarvis. “And if the ground’s really poached and muddy, they’re not going to get to the better grazing higher up on the hill. And they may struggle to lower their heads to eat.”

Endoparasites and Weight

The horse’s immunity can begin to weaken and change as it gets older, Jarvis noted. This means its ability to fight off internal parasites can diminish. “This is especially true of those with PPID (pituitary pars intermedia dysfunction or Cushing’s disease).

“Remember, those old guys need just as much of a good worm management program as the young ones,” she added.

Jarvis said as horses age they become more vulnerable in the social factors. Younger horses can push older ones off the feed.

She said maybe the older horse lost a companion and isn’t eating as well. “Horses really can mourn,” Jarvis said.

“Maybe there’s a new ‘kid’ on the block and that has caused stress for the [older] horse,” she added.

Body Condition and Muscle Atrophy Scoring

Harris said if you’re going to develop a diet for your horse, you need to know whether you’re you’re feeding for weight gain, weight loss, or even weight maintenance.

“But perhaps even more important than that, you’ve got to regularly monitor their body condition because they can change quickly,” Harris added. “And Nicky and I both know they suddenly can change from being that very good doer to the animal that starts losing weight. And if you’re not keeping an eye on them it can be a problem to try and pick that up quickly enough that you can put things in place and try and work it out before it becomes too much of an issue.”

We use the Muscle Atrophy Scoring System to help monitor whenwhen the horse begins to lose muscle mass. “People tend to think that it’s normal when you get older that you lose muscle,” said Harris. “Well, it isn’t necessarily normal. And it could be indicating there’s one of those problems that Nicky mentioned, which we might be able to address.”

Scoring Systems

Next, Harris said you need to decide the ‘system’ you are using for scoring and do it regularly. She added that regardless of which one you are talking about, it’s important to take rugs (blankets) off the horse and use your eyes and hands.

“I think probably we’re talking about every three to four weeks to do a body condition scoring, probably similar on your muscle atrophy, maybe a little bit longer,” said Harris. “But, if you start to think things are changing or are worried because of the season, you need to increase the frequency.”

Harris referred to articles on My Senior Horse to help owners understand the scoring systems. These are listed below in the Further Reading section.

The body condition scoring system is looking at external fat, Harris said. “That’s really important because it is not able to pick up what’s on the inside,” she explained. “In general, the amount you can see on the outside is similar to the amount that’s in the inside. But once horses or ponies become obese, that changes. There may be even more on the inside than we can pick up on the outside.”

She said it’s also important to note that horses with the same body condition score can have different muscle atrophy scores. “That’s especially true in PPID horses,” Harris added.

She said it is important to keep a record of the body condition and muscle mass scores.

Harris also pointed out that My Senior Horse has an article about body condition scoring for donkeys, as they are different.