Fever in dogs is also known as pyrexia. A high temperature is a symptom of an underlying illness, so it's important to diagnose and treat the root cause. Many dog owners rely on feeling their dog's nose to gauge whether they have a fever or not. A cool, wet nose indicates an average body temperature while a dry, warm nose may be a sign the dog has a fever. While this method can help to spot a sick dog, it's not an accurate way of telling if a fever is present.
Dogs naturally have a higher body temperature than humans - typically in the range of 99.5-102.5 degrees, Fahrenheit is normal for dogs. However, if their temperature is higher than 103.5 degrees Fahrenheit, this qualifies as a fever and indicates that the dog has an infection or health condition causing their high temperature.
Ears or a nose that feel hotter than normal are a sign that a dog has a fever. Dogs with fevers often have other symptoms of illness. They may shiver, cough, or vomit, and their eyes may have a red appearance. Dogs with a high temperature often appear unwell and lethargic. They may lose interest in eating and drinking.
The only accurate way to check whether a dog has a fever is to take its temperature using a rectal or ear thermometer designed for dogs. Before using a rectal thermometer, lubricate it with petroleum jelly to make the process more comfortable for the dog. Ear thermometers are less invasive and less likely to cause discomfort. However, they are usually more expensive. Never use a glass thermometer rectally or in a dog's ear, as it could cause injury.
An infection or inflammation is often the cause of a raised temperature in dogs. Common infection locations in dogs are the urinary tract and ears. Alternatively, the dog may have been bitten or sustained another injury which has become infected. Infections or abscesses of the gums or teeth can also cause fevers. Less commonly, a high temperature can indicate an infection of one of the dog's vital organs. Occasionally, a high fever may be a sign of a more serious condition such as a tumor.
A dog may develop a raised temperature if they have ingested certain poisons. Some plants are toxic to dogs and cause fevers. Some foods are safe for humans but can cause illness and fever in dogs, especially those containing a type of artificial sweetener called xylitol. Swallowing medicines intended for humans can cause a high temperature in dogs. Ingesting antifreeze is also known to cause fever in canines.
Diagnosing the cause of a dog's fever is often difficult. The veterinarian will examine the dog to check for signs of illness and ask for their full health history, including vaccinations. They are also likely to carry out various laboratory tests. These include urine analysis and blood counts. They may also carry out medical imaging tests such as CT or ultrasound scans to check for tumors, obstructions, or internal infections.
Fever of Unknown Origin (FUO) is a diagnosis given when no reason can be found to explain the dog's raised temperature. This diagnosis is often given too quickly if initial tests come back negative. The definition of FUO in humans is a fever which persists for more than three weeks. Although there is no such period specified when diagnosing FUO in dogs, it should only be diagnosed after thorough testing as a cause can usually be found.
If a dog has a raised temperature, applying a cool, wet cloth to its paws or ears can help to reduce it. Continue to take their temperature and stop applying the treatment once it drops below 103 degrees Fahrenheit. Encouraging the dog to drink water can also help it to recover. If they develop accompanying symptoms or their fever returns, they should be assessed by a veterinarian. Although there are medications designed to reduce fever in humans, they should never be given to dogs as they could poison them.
Similarly to humans, vaccinations can cause a fever in dogs. Vaccinations usually only cause the dog's temperature to be mildly raised. This tends to happen a few hours after the injection and shouldn't last more than two days. It may be accompanied by swelling of the vaccination site and lethargy. If the dog's temperature doesn't return to normal after a couple of days, they should be assessed by a veterinarian.
Hyperthermia is an abnormally raised temperature in dogs due to an external cause. It is distinct from a fever because fever has an internal cause such as illness. Hyperthermia is caused by overheating, either due to an inability to pant effectively or to heatstroke. This is more likely if the dog is obese, has issues with the airway, is brachycephalic (squashed face) or has very thick or dark fur. Occasionally, anesthetics can cause hyperthermia in dogs. For this reason, it's important that a dog's temperature is monitored after surgery. Greyhounds and Labradors are particularly susceptible to anesthetic-induced hyperthermia.
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