Dealing with oppressive heat

The last few days have not only seen very high temperatures for Iowa, but when combined with the humidity, the heat has been oppressive. Worse yet, the night-time lows have remained around eighty, meaning that our sheep can’t even cool off at night – the very worst of hot weather in the Midwest.

Our lambs grazing the Timber early one morning this week

Our lambs grazing the Timber early one morning this week

This type of weather should send warning signals to any shepherd who cares about their flock. High temperatures can cause a variety of issues in a flock of sheep, and a good shepherd will watch the flock members carefully to look for signs of temperature-based illness.

The signs can be quite well hidden since sheep are prey animals and know that showing weakness around a predator can mean the difference between life and death. Yet, if you know what to look for, the hints are typically there. As I approach the flock, I first look across the entire group – is there one sheep that seems removed from the rest? This is often a sign of illness or fly strike and encourages a more up-close-and-personal look. I also listen for coughing, since summer pneumonia has more to do with weather and activity than anything else. When the days are hot and humid, the sheep move around less, creating less airflow deep in the lungs where these bugs lie. Couple that with the damp and/or humid conditions – the perfect environment for these bugs to replicate – and you could easily find one or more of the flock down with pneumonia.

The rams require special care in this type of heat since anything over 90 degrees can cause temporary infertility that can last up to six weeks or more. We make sure that all of our sheep have access to shade in very hot weather, and if there is no breeze, we provide a fan for our rams to keep them more comfortable. The closer we get to breeding season, the more we need to worry about this issue.

Although our sheep are all sporting some length of wool at this point (many of our Romney ewes now wear four inches of fleece!), sheep don’t normally cool off through perspiration through the skin as we do – at least, not in the same way. Sheep lose heat through the blood vessels in their ears, and through sweat between their toes and in their flanks (the area in front or behind their legs where wool seldom grows). If they can find a cool place to lie down or can walk in cool water, it helps to keep their whole body cool. The coats that we use to protect their fleeces also help; they are silvery and a bit reflective of the sun’s heat, cooling the colored sheep much better than if they were uncoated.

In this type of hot weather, fly strike is a risk. For those who know what that is and want to avoid thinking of it (and I don’t blame you!), skip to the next paragraph, but for the rest of you, here goes! Flies love to bite in hot, humid weather, and if they find the right conditions (damp and soiled wool – often around the anus or penis of sheep), they will lay eggs that soon hatch out into larvae that can literally eat the sheep alive. Fly strike is fairly easy to identify even from a distance: the sheep usually separates itself from the flock, will exhibit one or more wet spots on the wool,  and will be surrounded by a terrible odor. Upon further inspection, the wet area is usually riddled with maggots at the skin – the source of the odor. The only solution once fly strike is present is to remove as many maggots as possible, and there are a variety of ways to do this. Our method uses a credit card to scrape against the skin where the maggots have burrowed. The pressure of the card forces the maggots to the surface of the skin and they are scraped off onto the ground. Once nearly all maggots are removed from their burrows and the wool is clipped from the damaged areas of skin, we gently wash the injured area and treat the sheep with an injectible dewormer (which will kill any remaining maggots). We also treat with a topical salve daily to protect the skin and encourage healing. An antibiotic may also be used if the skin begins to show signs of infection from the death and decomposition of the maggots that remain. All in all, this is one illness I seriously never want to see again – I still squirm at the thought!

Finally, our sheep do fairly well in hot weather if we make sure they have both shade and cool water to drink. As a result, we often go out both morning and evening to add ice to their water tanks to keep their water cool. If we think far enough ahead, we freeze gallon milk jugs full of water and float them in the tanks – but if things are last minute, I’ve been known to dump all of the ice from our freezer’s ice-maker into a bucket and haul it out to dump into the water tank(s). If they can get to cool water and shade, they seem to do just fine.

I think we are all already looking forward to cooler weather!

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