Ask the vet: What happens when a dog gets overheated?

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Q: My sister, who lives in the South, turns her air conditioning up from 75 to 90 degrees when she leaves for work. She reasons that she’s saving money while still cooling her home enough for her 10-year-old pug, Fiona.

Please explain what happens to overheated dogs so I can convince my sister that 90 degrees is too warm for Fiona.

A: Any dog can develop heatstroke, but the risk is particularly high for pugs and other flat-faced breeds, dogs with heavy coats, puppies and seniors, overweight dogs, and those with health problems such as breathing troubles or heart conditions.

While the risk is higher in warm, humid environments or while exercising, many dogs develop heatstroke when left in cars parked in the shade, even with partially open windows and temperatures under 75 degrees.

Heatstroke occurs when the dog’s body temperature, normally 100.5 to 102.5 degrees, increases to 105 degrees or more.

Clinical signs may include panting, restlessness, rapid breathing, racing heart, poor coordination, gum color that’s not the normal pink, vomiting, diarrhea, seizures or collapse.

Heatstroke damages every organ, including the brain, and every body system, including the pathways that control blood clotting.

The blood and organs are composed of protein. As an example, let’s consider albumin, an important protein in the blood and also the goo surrounding an egg yolk. Think about what happens when you heat an egg: The clear, runny albumin turns into a white solid.

Something similar occurs with heatstroke as the dog’s body bakes. It’s no wonder that half of dogs with heatstroke die.

Advise your sister to ask Fiona’s veterinarian about the ideal indoor temperature for her during the summer. Until there’s an answer, your sister should keep the air conditioner at her usual 75 degrees.

Q: Our indoor cat Milo often accompanies us while we relax on the porch on cool evenings. Sometimes, he goes into the yard and eats grass. Why do cats eat grass?

A: As carnivores, cats eat herbivores like mice and voles. Since these herbivores eat grass, the free-roaming cat ingests any grass inside its prey’s stomach and intestines.

Grass provides the cat with roughage, which helps move hair ingested during grooming along the gastrointestinal tract.

Besides, some cats seem to like the taste and texture of grass, much as some of us humans enjoy a salad with our meat.

Eating yard grass, though, is a problem for two reasons: toxins and parasites.

If you treat your grass for weeds or insects, the herbicides and pesticides may sicken Milo.

Furthermore, any stray cats that defecated on your lawn may have deposited parasites that Milo will ingest with the grass. Among the most common are roundworm eggs, which survive for years in your yard. Once ingested, the eggs hatch and mature into spaghettilike roundworms that can cause vomiting and diarrhea in cats.

Even worse, when Milo then excretes roundworm eggs, they may inadvertently be ingested by humans, especially toddlers, who often put things in their mouths without washing their hands. In humans, animal roundworms can cause blindness, seizures and organ damage.

So, I suggest you treat Milo to an indoor grass mat. “Cat grass,” the tender young shoots of wheat, barley, oats, rye and wheat berry, is available at pet supply stores. Or buy the seeds and grow the grass yourself.

That way, Milo can enjoy grass whenever he likes, without waiting for you to take him outside on cool summer evenings.

Lee Pickett, VMD, practices companion animal medicine in North Carolina. Contact her at

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