Monday 19 August 2019

Black dogs are prone to overheating in the sun

Dark coloured animals absorb heat in sunny weather
Dark coloured animals absorb heat in sunny weather

Pete Wedderburn - Animal Doctor

As a vet, the cornerstone of making a diagnosis in a sick animal is the physical examination. This is sacrosanct in the veterinary world: there's a specific way of doing this, starting at the tip of the animal's nose, and working backwards, checking every small physical aspect of the creature. Instruments are used as needed, such as an ophthalmoscope to check the eyes, an otoscope to examine the ears, a stethocope to listen to the chest and a thermometer to check the animal's temperature. Without a physical examination, it isn't possible to make a proper diagnosis about what's wrong with an animal.

However, of course, there are exceptions to every rule.

The other week, I was away in Edinburgh for the weekend when I received a phone call from a friend on my mobile phone. He had a problem that he needed help with, at once.

It was a scorching hot sunny day in Ireland, and he had taken his Black Labrador dog, Henry, for a hike into the local countryside for the day. The walk had been going well, with the young adult dog charging along beside him, running up hills and down banks. Henry was used to this type of exercise, and he was fit enough to enjoy heavy exercise like this for four or five hours.

Then, for no obvious reason, Henry seemed to have had enough. He flopped down on the path, panting, and refusing to get up. However much my friend pleaded and cajoled him, Henry would not move. He lay there, panting continuously, and staring slightly desperately at my friend. He realised that there must be something seriously amiss, which is why he had phoned me on my mobile.

In most circumstances, if my friends phone me about a sick pet when I am overseas, while I may give some simple advice, I normally suggest that they take their pet to the local vet. But this was different: Henry had collapsed in the middle of nowhere, many miles from the nearest vet. He needed some sort of help on the spot, as soon as possible. Was there anything I could do?

When I listened to my friend's saga, an obvious likely diagnosis came to mind: heatstroke. There were three reasons.

First, it was a hot, sunny day in Ireland: this always leads to a higher risk of heatstroke.

Second, Henry was a black dog: dark coloured dogs are especially vulnerable to overheating on sunny days: their dark coat absorbs sunlight, in contrast with white dogs whose coats reflect the sun's rays. The dark coat means that black dogs are far more likely to suffer from heat stroke than light coloured dogs.

Third, Henry had been exercising heavily in the full sunshine. When a dog is running, the muscles are fully engaged, and their activity generates serious amounts of heat. Normally, this heat is carried away from the muscles by the blood stream, and then lost from the body in the form of water vapour evaporating from the dog's tongue during panting. However, on a hot day, a dog cannot lose enough heat by panting, so the dog's body temperature goes up and up and up.

Heatstroke describes the condition when a dog's temperature goes up so high that they cannot carry on normally any more: they collapse, panting. When this happens, their owner needs to take urgent action to save the animal's life.

The first thing is that owners should be aware of the risk factors (e.g. sunny day, black dog, exercising heavily) and secondly, the signs of heatstroke (weakness, collapse, continual panting, unwillingness to do anything other than just lie there). Of course there are many other reasons why a dog could show these signs, but the circumstantial evidence of the risk factors meant that heatstroke was high enough on the list of possibilities to tell me that first aid action was indicated.

One recent study demonstrated the value of first aid in dogs with heatstroke: only 38% of dogs died when cooled by the owner before going to the vet, compared to 61% dying after being taken to the vet without being cooled by their owner first.

What does first aid involve? Essentially, taking the dog out of the heat and soaking them with water. Ideally this should be lukewarm water rather than ice-cold water. The dog should be cooled until the panting eases.After an affected dog has cooled down enough to walk normally, they should still be taken at once to the vet.

Vets use other treatments (such as intravenous fluids) that limit the damage done to the internal organs by the excessive heat. Dogs affected by heatstroke often seem to recover initially but then die the following day because of the damage to their liver, kidneys and gastrointestinal tract, as well as the disruption to their blood clotting system. Extra treatments like intravenous fluids reduce the risk of this happening.

My friend had to pick up his overheated, collapsed dog and put him over his shoulders, carrying him half a mile to a running stream. He stood Henry in the water, splashing more water over his back, and after ten minutes, the panting stopped, and Henry was able to stand up and walk. The immediate overheating crisis was over.

Henry went to the vet and was kept on intravenous fluids overnight. He was lucky enough to make a full recovery. The first aid had been enough to save his life.

Gorey Guardian