Fever in dogs

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Knowing a dog’s temperature is essential when performing a general clinical examination, especially on a sick animal, in order to establish diagnostic hypotheses. A rectal temperature above 39.1 ° C is considered elevated and abnormal in an unstressed dog .

About temperature and fever, many misconceptions circulate

  • When a dog has a high temperature, he necessarily has an infection: it is not true . Many non-infectious diseases can raise the temperature.
  • A dog with a normal temperature (around 38-38.5 ° C) does not have an infection: it is wrong . In some cases of infectious diseases, the temperature peaks can be cyclical. Likewise, some very localized infections (such as urinary tract infections) are not always associated with fever.
  • A dog with a high temperature is bound to be sick: this is not true . For example, exertion or stress can cause an animal’s temperature to rise.
  • A dog that has a normal temperature is not sick or does not have a very serious illness: it is not true .
  • A dog with a wet nose does not have a high body temperature: it is wrong .
  • ….

But how is the dog’s temperature regulated?

A dog’s body temperature is regulated and kept relatively constant by a kind of thermostat, called a thermoregulation center, located in an area of ​​the brain: the hypothalamus.

This thermostat receives information from sensors, called thermoreceptors, located all over the body (mainly in the skin and the nervous system), which detect changes in temperature.

When the hypothalamus receives information that the temperature in an area of ​​the body is too high, it stimulates effectors to dissipate the temperature and lower it by various means (panting, sweating, decreased motor activity, thirst, etc. search for freshness,…).

During fever, the hypothalamic thermostat is out of adjustment, and therefore the temperature control is no longer effective. This deregulation is due to the presence of elements in the organism called “pyrogens” which: either come from external agents (microbes: bacteria, viruses, fungi; drugs, etc.), or are produced “internally” in the body. organism (by the immune system, by a tumor, etc.).

Note: This fever should be distinguished from hyperthermia: in the latter case, the increase in body temperature is not linked to a dysfunction of the hypothalamic thermostat but is secondary to an excess of heat production by the body ( exertion, convulsions, tetany) or a lack of heat elimination (heat stroke in a car, brachycephalic dog – nose crushed – who have difficulty breathing…). There are then no pyrogens .

It is important to note that fever in dogs is not always deleterious: indeed, during infection, the increase in temperature represents a real help for the body because it stimulates the immune system to fight the infection. and it slows down the multiplication of the microbe. It is therefore not always necessary to want to fight against it.

However, if the temperature (rectal) exceeds 41 ° C or remains high for too long, the immune system is impaired and a vicious cycle of degradation of the organism sets in: severe dysfunction (concerning the cardiovascular system, the respiratory system, the nervous system, the liver, the kidneys, etc.) are set up and may lead to the death of the animal.

How to take your dog’s temperature?

The temperature is taken with an electronic thermometer, identical to those used in human medicine, which you can buy at a pharmacy. The temperature is taken rectally by inserting the thermometer about 2-3cm into the anus, and trying to attach the end of the thermometer to the wall of the rectum. Indeed, if you insert the thermometer in the middle of a saddle, the temperature displayed may not be representative.

Human medicine thermometers for taking temperature under the arm, in the ear or on the forehead should be avoided in dogs: they do not work.

The sensation of heat when touching your animal on the skin, the appearance of the nose (wet / dry, hot / cold, etc.) are not reliable for correctly assessing your dog’s temperature.

Symptoms

With fever in dogs, the symptoms observed are often nonspecific and may include the following:

  • rapid breathing, panting
  • increased water intake
  • depression, prostration, loss of appetite

Sometimes they can be more specific to the disease causing the fever (see next paragraph):

  • lameness, difficulty moving, head down, difficulty turning your head
  • dermatological lesions: redness, ulcers, etc.
  • vomiting, diarrhea, stomach pain, swollen stomach
  • cough, …

Causes of fever

Several conditions can cause fever in dogs.

  • Infectious diseases
    • Localized to an organ, most often linked to one or more bacteria (uterus, prostate, kidney, liver, peritoneum, pancreas, etc.)
    • Generalized: leptospirosis, borreliosis, piroplasmosis, ehrlichiosis, leishmaniasis, toxoplasmosis, parvovirus, distemper, …
  • Tumor (cancerous) diseases
  • Immunological diseases *: hemolytic anemia, polyarthritis, immunological thrombocytopenia, systemic lupus erythematosus, …
  • Other causes:
    • Medicines: some treatments can raise the temperature
    • Certain bone diseases: panosteitis in young large dogs for example
    • Trauma: pain can be a cause of fever

* these diseases result from a disruption of the immune system of the dog’s organism which suddenly begins to no longer recognize an element of its body (its red blood cells, its platelets, its joints, its meninges, its skin, etc.) and which begins to degrade it.

Diagnostic

It is essential to give your veterinarian as much information as possible about your animal: its vaccinations, current treatments, medical history, trips, etc.

In some dogs who are very stressed in consultation, the temperature can sometimes reach 39.5 ° C or more. The veterinarian may possibly ask you to carry out a temperature curve at home (rectal temperature measurement) over one or more days in order to have a precise idea of ​​the variations in body temperature.

Your veterinarian will perform a comprehensive physical examination to try to look for abnormalities. Depending on the anomalies obtained, he will offer you additional examinations which can be very varied:

  • blood test and urinalysis (essential)
  • x-ray, ultrasound
  • joint puncture, cerebrospinal fluid puncture,
  • scanner
  • biopsy, …

Finding a cause of fever can be very difficult and may require several days or even weeks of investigation.

In some cases, we speak of Fever of Undetermined Origin (Fever) when additional examinations do not allow a cause to be isolated.

Treatment and prognosis

The management and prognosis will depend on the cause of the fever in the dog.

The proud, when it becomes deleterious, can be treated symptomatically by antipyretics: the most effective drugs remain non-steroidal anti-inflammatory drugs. All are not equal and do not have the same effectiveness. Your veterinarian will prescribe the most suitable for your dog.

In some difficult cases, this symptomatic treatment will be insufficient and treatment of the cause of the fever will be essential.

When the cause is determined, a specific treatment can be prescribed: antibiotic, corticosteroids, anti-parasitic, surgical intervention, chemotherapy, etc.

Conclusion

Fever is a frequent reason for consultation. It is not always, and even far from it, synonymous with infection. It is therefore not systematically treated with antibiotic treatment.

Your veterinarian can offer you a diagnostic procedure to determine the cause of this fever. Anti-pyretics may be administered as a first-line treatment.

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