Wither Abscess or Fistulous Withers?

Uh-oh, we’re in trouble. So that theoretical “kick”- definite blunt trauma of some variety - that Copper received on his withers about a week and a half ago has burst into a large open sore. It may be some sort of bacterial infection, a parasite, or possibly Fistulous Withers – a chronic inflammatory disease of the supraspinous bursa¹ caused by either infection, parasites, or physical factors. Swelling of the withers, drainage of pus from an open lesion resulting from inflammation, and infection that spreads from the infected bursa to surrounding tissues are common characteristics of the disease. Actinomyces bovis and Brucella abortus are the most common organisms responsible for this disease.*

The stages of this injury went like so:

Sunday, 13th of April: Discovered Copper has localized swelling around the side and top of his withers. Extremely painful to the touch, little to no heat in it, and does not appear to effect soundness. Palpitation of shoulder, and flexion tests reveal no soreness anywhere else besides the swelling. 

Wednesday, 16th of April: Swelling appears to have gone down, but I think that Copper’s rug is not helping with the healing so I remove it.

Saturday, 19th of April: There are two strange, yelllow-ish crusty patches on his wither. One on the top and one on the left side – off the side to the base of his wither and above his shoulder. The top one is about the width of my pointer finger and around an inch – inch and a half long. The other patch on the right side is smaller, about half the size.

I think that these are odd – they look like some sort of infection. The hair is not disturbed, or scraped off, like bite marks usually look. It looks more to me like the event has occurred underneath the skin and some sort of infection has broken through the skin and crusted up.

I decide that if it is an infection – perhaps it is an abscess due to the blunt trauma, something needs to draw it out. So I apply some poultice – good old Tuff Rock.

Thursday, 24th of April: I come out to find this -

I immediately call the vet, something strange is going on.

His withers are now swollen on both sides, but there still isn’t much heat in the area - although Copper is still extremely sensitive to any pressure. The vet gives him a mild sedative so that we can take a good look. After washing and inspecting the wounds, the vet suspects either a parasite or bacterial infection – but there is no mention of Fistulous Withers.  Copper is given a jab of antibiotics for systemic treatment and the vet advises me to wash the wound down daily with Betadine and the apply Savlon - which is topical anti-bacterial cream used for humans, but it works great for horses as well.

Friday, 25th of April: So that brings us to today. All the regional swelling seems to have subsided, and Copper is a bit less sensitive around the wound areas. The Salvon has scabbed over, and I didn’t wash it all off, but plan to do that tomorrow to check out the flesh underneath.

One of the girls down at the paddocks today mentioned Fistulous Withers, and of course, I wondered if that was going to be a problem. I jumped on the internet and did some research. Originally, Fistulous Withers is a very nasty condition that used be quite difficult to eradicate back in time, and quite often would render the infected horse useless or dead!

After further study, I don’t think we have to worry about the infectious Fistulous Wither condition – yet.

Causes of the disease may be the result of infectious, parasitic, or physical factors. Actinomyces bovis and Brucella abortus are the common organisms responsible for fistulous withers, blunt trauma to the withers caused by tack or sharp contact with a fence or another horse or object can lead to infection and inflammation resulting in fistulous withers. The hair-like parasite Onchocerca cervicalis has also been implicated in the early stages of the disease.*

As we know that Copper was subjected to some kind of blunt trauma, and so far hasn’t shown any symptoms of an actual bursa infection which are:

• Swollen withers – this has dissipated
• Signs of fever and pain – some localized sensitivity, but no other pain symptoms
• Open drainage fistulas – these are described as long, narrow tubes², which his wounds are not.
• Lameness – no signs
• Systemic illness – no signs
• Swelling at other areas – no signs

I am assuming that he has not yet been deeply infected in that region. However, in saying that, he obviously has had some kind of abscess in the region of his withers, and whether or not that has fully drained when it burst, or is still causing problems which may lead to a full-on case of Fistulous Withers still remains to be seen.

Unfortunately, my vet did not mention this AT ALL so I have no idea if Fistulous Withers is even on the radar, and it’s public holiday, so I can’t contact them to find out. :/ Plus, tomorrow is Saturday and I don’t know if I’ll be able to get a hold of her then either.

She did take a slid of the infection so I will ask her to test it for any nasty bugs when I contact them.

I will also wash the wound out thoroughly and keep a very close eye on it. The antibiotic jab the vet gave Copper was good for four days, so hopefully that will keep things under control internally and stem any infection until I can get a hold of her again.

So stressful, but I think we have the situation under control for now…

See ya,

bonita

^{1 The Bursa: A closed fluid-filled sac or sac-like cavity. The bursa provides a sliding surface between tissues of the body. Poll Evil and Fistulous Withers are two inflammatory conditions that are closely related and differ essentially only in their location in the respective supraspinous (withers) or supra-atlantal (poll) bursae.
The Merck Veterinary Manual}

^{2 Fistulas are narrow mouthed ulcers or abscesses that can can run a long way under the skin like pipes.
Fistulous Withers}

^{*Information from EquiMed.com}