Tuesday, September 16, 2008

hot town...summer in the city...back of my neck gettin' dirt and gritty...isn't it a pity - doesn't seem to be a shadow in the city!

when the dog came to the back, i listened to her history while the tech recited it, and then asked for a temperature. rectal temperature was 104.5. not horrendous - certainly compatible with a fever. unfortunately - the overweight, female hunting dog had been out hunting that morning. she had hunted for about 3 hours in 90+ degree heat and >60% humidity. she was not in good conditioning. the owner - a nice man in his 30s - had taken her home and left her in the air conditioned house. several hours later, she refused to rise. concerned, he brought her to us.

i suspected that she'd had a heat stroke in the early afternoon, despite having a body temperature of less than 106. this often happens because owners don't recognize a heat stroke. they think the animal is tired, take it home, allow it to rest in the air conditioning, and then - often very belatedly - realize something is amiss. when the animal comes to us - the temperature has usually dropped to a "less than heat stroke" level.

so why did i think this dog was a heat stroke? history - first and foremost. a fat, out of condition hunting dog working for 3 hours in late august heat. secondly, she was passing mucoid, foul-smelling feces that looked suspiciously like the lining of her GI tract. her mentation was also obtunded. she wasn't very responsive to us or our ministrations.

while the techs placed an IV catheter and bolused her IV fluids, i went to talk with her distraught owner.

heat stroke is a terrible condition and one we see fairly commonly here due to our very hot summers. many people keep breeds that are poorly suited to our area - huskies, saint bernards, malamutes, chows...the list of heavy coated, winter breeds is endless, and we see them all. when these animals go outside to play, they can over-exert themselves easily and have a heatstroke as a result. it always comes as a shock to owners - generally because the dog has never had a problem before.

when the body temperature rises past a certain point - there are terrible consequences. body temperature is a closely regulated homeostasis. cells can only survive and function within a narrow range. the body keeps this range constant - or close to constant - at all times. when the temperature goes up past the body's ability to cool (dogs cannot sweat - except a small bit through their footpads, but they can pant) - cells start to die. the increased temperature causes cells to swell, eventually rupture and die. this leads to cerebral edema (one of the many consequences). cerebral edema = swelling of the cells in the brain = very very bad. this causes changes such as increased blood pressure, slowed heart rate, unequal pupil size, and stupor or coma due to brain damage.

this is only one of the unfortunate problems. when heat stroke occurs - blood sugar will often drop precipitiously (the mechanism is poorly understood). further, the delicate balance of blood will be upset. as i've said before - the body is always in homeostasis. small platelet clots are made at all times to plug tears in the vasculature - these are then broken down by the body. when heat stroke occurs, this balance is upset. the bloood begins to make inappropriate clots everywhere - millions of them. all of the clotting factors are consumed - and then the body has nothing left to make clots with - and the animal will bleed to death. this syndrome is called disseminated intravascular coagluation (DIC) - also known as consumptive coagulopathy. DIC is a very common consequence of heat stroke (and snakebites, and sepsis...etc).

it just gets worse. in the dog - the "shock" organ is the GI tract and by proxy - the liver. the cells lining the GI tract die and are sloughed into the gut so that the dog essentially defecates out the lining of its guts. this leads to extraordinarily bloody diarrhea and bloody vomiting.

heat stroke is a horrible thing to see.

my patient - while having a blood glucose 0f 35 (normal 80-120) and mucoid diarrhea - didn't look too bad. i told the owner we could try.

"trying" involves giving plasma transfusions (of questionable efficacy - the idea is to provide clotting factors that are found in plasma to slow/stop DIC), heavy duty fluid therapy, antibiotics (when the gut sloughs - bacteria in the GI system can cross straight into the bloodstream = VERY VERY bad --> sepsis), pain medications, supplementation with dextrose to keep the blood sugar up, and intensive nursing care. the prognosis is not great.

the owner elected for treatment, so we started. my patient received 2 liters of fluids, then was started on heavy duty fluids (at about three times her maintenance rate) as well as dextrose to maintain her blood sugar. i started a plasma transfusion immediately, and i selected my antibiotics (broad-spectrum!). i gave her an anti-emetic injection, as well as a constant infusion of another drug called Reglan to prevent her from throwing up. she received pain medication (i can't imagine that losing the lining of your guts is terribly comfortable). she was also treated for cerebral edema with mannitol (to draw fluid out of the brain cells). i sat with her for several hours - but she never became terribly responsive. when i left - she looked okay. not great, not horrible.

when i returned the next morning, she was still hanging in there. despite aggressive fluid therapy, she was not rehydrated - and so i increased her fluids even more - despite fear that i might overhydrate her. she began to look worse. her mentation was incredibly dull - she would only respond if her name was shouted accompanied with a brisk clap. at around noon, she suddenly sat up and spewed out a liter of blood (the lining of her stomach). she also began to pass incredibly hemorrhagic diarrhea. during all of this - she made a low, pitiful moaning sound.

i looked at her and knew that i couldn't fix the damage done to her. she had all of the factors that have been associated with a negative outcome for heat strokes (>90 minutes between stroke and presentation to a clinic, DIC, and hypoglycemia). she wasn't getting better...she was getting worse.

and that's where the question always arises. when do you stop? when do you know that your patient isn't going to get better? the truest answer is that you don't. there is no way to know. you have to make the best decision you can based on the information you have. it's unfortunate - because i'm sure that sometimes i euthanize animals that might have pulled through eventually. i'll never know i suppose.

the owner came in to talk to me, and i explained the dog's dire condition. he was visibly distraught - but insisted that he didn't want to be present when we euthanized her. in the end, alll i could do was assure him that someone would be petting her and telling her she was a good dog...and that she wouldn't hurt anymore.

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