Minty is a 25-year-old gelded miniature horse enjoying retirement after a successful show career. Living on a sheep and cropping farm, he had battled bouts of founder in recent years, and his owners worked hard to manage this, largely by keeping him off pasture, utilising Founderguard and phenylbutazone as required.
In February this year, another apparent flare-up occurred that failed to respond to this previously successful treatment. A veterinarian examined Minty and suggested giving the treatment a little more time to act, however after about a week it became apparent that Minty was deteriorating rather than improving. A second examination failed to find any significant response to hoof testers (a response would be expected with founder), but it did confirm lameness still present. His owners felt that he was losing muscle mass, which was put down to his limited movement. Arthritis was suspected, given his age and because Minty’s lameness appeared to worsen in his hind limbs after they were held lifted for a couple of minutes (flexion tested). His owners also reported that he was most reluctant to move first thing in the morning, but he appeared to become more mobile as the day wore on. A blood sample was taken and Minty’s pain relief was widened with some additional drugs. His bedding was deepened to lift him higher off the cold ground and to ease pressure on bones and joints when he lay down in his box.
When his blood results returned, they showed that Minty’s muscles were highly inflamed, with enzyme levels many times elevated over normal levels, and that his selenium levels were less than 20% of normal. We immediately began Minty on a weekly dose of oral selenium. Within three weeks his owner texted that Minty was “More like his old self,” but a blood test a week later showed that, although his muscle inflammation had resolved, his selenium levels were still only about 80% of the recommended minimum. Weekly doses of selenium continued for another three weeks, at which time a third blood test showed that, after six weekly doses of a product normally given monthly, we had finally got his selenium into the bottom end of the normal range Selenium deficiency is recognised in all farmed species in New Zealand. Among other things, deficiency can suppress immune function and cause muscle damage (including heart muscle) as Minty experienced. There is no sure way to assess an animal’s status without a blood or liver sample. Cattle and sheep are commonly assessed and supplemented, because farmers recognise the production benefits of ensuring mineral status is correct in these species, but horses are often forgotten about. The sheep on Minty’s home farm regularly receive injections of selenium. Minty had been doing pretty well right up until March, but his selenium levels had presumably been dropping unnoticed for quite some time for them to get as low as they had. So, just looking at the horse is no way to assess its selenium status. A selenium test for your horse is probably money well spent to establish their status. Other minerals can be tested off the same sample and then a plan made to address any deficiencies. Talk to your local Vetlife veterinarian about options. Minty is now on a monthly dose of his oral selenium and is due for another blood sample in November to assess whether that dosage is right as a long-term plan for him.
Minty’s first blood sample showing his muscle enzymes (CK and AST) very high and selenium very low compared to the normal reference range.
Thanks to Nikki and Blair Cartwright for letting us share Minty’s story.