Fever Pitch

What is a fever?

Fever is a term that refers to an elevated body temperature. The normal body temperature range for dogs is between 100o F and 102o F (38o C and 39o C). It is normal for a dog’s body temperature to fluctuate during the day. It may be somewhat higher in the evenings than the mornings, and it is likely to rise naturally on hotter days or after exercise. A bitch’s temperature may rise and fall during different stages of estrus. All these fluctuations are temporary.

A fever is initiated by the presence of a pyrogen, which is a substance that causes a rise in temperature. The pyrogen can be endogenous, which means it is produced from within the body, or exogenous, meaning it comes from the outside.

Pyrogens stimulate the release of substances from the white blood cells, which are called leukocytes. The substances that are released are interleukin-1, interleukin-6 and tumor necrosis factor. Following their release, these reset the body’s “thermostat,” which is the temperature-regulating region located in the hypothalamus area of the brain. This activates physiologic responses within the body to elevate the temperature.

Fever implies an internal resetting of the temperature center in the brain. An elevated body temperature from hyperthermia results from outside causes. Some of these causes include anxiety, environmental conditions, exercise, drugs and excessive clothing. The presence of a fever can be confirmed by taking the temperature when the dog is relaxed.

A fever can be beneficial to the body because it hinders the ability of viruses and bacteria to reproduce. It also improves the immune-system response.

Prolonged fevers, however, are not usually helpful. If the body temperature remains above 105o F (40.5o C) for more than a day or two, the patient becomes lethargic, loses appetite, and can rapidly dehydrate. If the temperature persists above 106o F (41.1o C), swelling of the brain, bone-marrow suppression and clotting disorders may develop.

Fevers that continue for more than a day are hard for the body to manage. There will be increased metabolic demands to maintain the higher temperature. This means an increase in fluid and caloric requirements. Remember the old saying, “Starve a cold, feed a fever”? There will also be increased breakdown of muscle tissues. A persistent high fever that lasts for more than 48 hours is considered serious and potentially life-threatening.

What are the signs of a fever?

A change in your dog’s behavior might be the first sign that your dog is not well. Any combination of the following symptoms is an indication that you should check your dog’s temperature. The most common signs of a fever are red or glassy eyes, shivering, panting, runny nose, decreased energy, loss of appetite, coughing and/or vomiting.

How do I take my dog’s temperature?

The best and most accurate way to check your dog’s temperature is to use a digital thermometer rectally. Some pet stores sell thermometers made just for pets, but any digital thermometer can be used rectally. Just keep it separate and clearly marked for that use.

Start by lubricating the tip with petroleum jelly (Vaseline) or a water-soluble lubricant (K-Y jelly). Lift your dog’s tail up and to the side and gently insert the thermometer about one inch into your dog’s rectum.

If possible, have a second person assist you by holding under the dog’s legs to prevent your dog from sitting. Once the thermometer registers a body temperature and beeps, you can carefully remove the thermometer and read the number.

Can I use an infrared thermometer to take my dog’s temperature?

During the pandemic, we have all become familiar with the non-contact infrared thermometers (NCIT) used to take our temperature. These devices provide a quick, hands-off method of monitoring body temperature. They beep with a reading within a few seconds.

NCITs are designed to be used on skin and will not read through fur. Place the thermometer on the inside of your dog’s ear or in the groin or armpit, where the fur is thin. You can also lift the lip and take a reading on the gums. The beep or buzz can be silenced if it disturbs your dog. Some NCITs are designed to be placed in the ear canal. Most dogs do not sit still long enough for this method to work.

While convenient and easy to read, NCITs are not calibrated to effectively measure body temperature in dogs. You can get a general idea, but a digital thermometer will give you a more accurate temperature.

What kinds of things will cause a fever?

A fever is often the result of a response from the body’s immune system. Most causes of fever are from infections, cancer or immune-system reactions. Infections may be bacterial, viral or fungal. Dogs suffering from skin wounds, dental infecti ons, ear infections or urinary-tract infections may run a fever.

Ingestion of poisonous materials, such as toxic plants, human medications or human foods can give your dog pancreatitis. This is an inflammation of the pancreas that can make your dog seriously ill. Along with vomiting, dogs with pancreatitis tend to run a high fever.

In some cases, the reason for the fever cannot be readily determined. This is often referred to as a fever of unknown origin, or FUO. These cases may have an immune-system disease, bone-marrow disorder or cancer as the reason for the fever.

How can I tell if my dog has a fever without using a thermometer?

If you think your dog has a fever, but you don’t have a thermometer handy, there are a few other ways to check. First, you should see if your dog has any of the symptoms of a fever that are listed above, such as lethargy, loss of appetite, coughing or vomiting. These are signs of a fever or another serious health problem.

You can feel your dog’s ears. A dog’s ear is usually warm at the base and cool at the tip. If your dog’s ears are abnormally hot, even at the tips, this is an indication that your dog’s body temperature is above the normal range and in the fever zone.

You can also check your dog’s nose. A dry nose doesn’t always mean a fever, but if the nose is cold and wet, it is unlikely that the body temperature is elevated. Green or yellow discharge from the nose is the sign of a nasal infection that may be accompanied by a fever. This condition should be examined by your veterinarian as soon as possible.

Your dog’s gums should be moist and pink. If they are dry, warm and red, your dog could have a fever. Lastly, you can check your dog’s groin and armpits. It they are hot or swollen, your dog probably has a fever and should be seen by your veterinarian.

How should I care for my dog with a fever?

If your dog has a fever of 106o F (41.1o C) or higher, you need to seek immediate emergency veterinary care. If the fever is lower, you can try to lower your dog’s body temperature by applying cool water with a soaked towel or cloth to your dog’s ears and paws. Placing a fan in front of the dog will also help. Monitor the temperature and stop applying water when the temperature drops below 103o F (39.4o C). Continue to monitor your dog closely to ensure the fever doesn’t spike again.

Try to coax your dog to drink small amounts of water or lick ice cubes to stay hydrated, but don’t force your dog to drink. It is important not to give your dog human medications, such as acetaminophen (Tylenol) or ibuprofen (Advil, Motrin). These medications can be toxic at certain doses and cause serious illness or death.

Any elevation of body temperature that lasts for more than a few hours is cause for a visit to your veterinarian. Once the cause of the fever is diagnosed, an appropriate treatment plan can be made.