By Samantha Miles
Some horses don’t fare well during long trips, whether across the state or across the country. They develop a pulmonary disorder associated with transport called shipping fever. Here is how your veterinarian might go about diagnosing and treating shipping fever, along with ways you can prevent it.
Researchers have shown that these horses’ stress responses are partly to blame, causing adrenocorticotropic hormone (ACTH), glucose, and white blood cell levels to rise. Higher ACTH levels lead to increased secretion of cortisol, known as the stress hormone. The longer the horse’s transit time, the greater the stress response, potentially resulting in pneumonia and pleuropneumonia.
Other factors associated with shipping fever include the horse’s inability to lower his head during shipment, ambient conditions and air quality, diseases such as strangles, viral disease, and pre-existing airway disease.
Clinical signs of fever and increased respiratory rate usually appear within 24 to 72 hours after shipment. Horses can also exhibit depression, loss of appetite, fever, nasal discharge, and coughing.
Veterinarians can often resolve this by administering non-steroidal anti-inflammatories (NSAIDs). But it’s important to call your veterinarian immediately upon seeing signs, because shipping fever can progress to pleuropneumonia, which can escalate quickly and result in serious complications if not addressed quickly.
If clinical signs worsen despite initial veterinary treatment, diagnostic tools are key. Your veterinarian might first run bloodwork. Having a baseline white blood cell count can help him or her evaluate disease progression. Packed cell volume (PCV, the percentage of red blood cells compared to plasma) and total protein indicate hydration status and can dictate whether the horse needs intravenous (IV) fluids. Also useful is a chemistry test, or at least kidney enzyme measurements, because often these horses are dehydrated. Dehydration makes the kidneys susceptible to damage from NSAID usage; therefore, it’s important to know kidney status prior to administering NSAIDs.
Recently, serum amyloid A (SAA) has become a popular biomarker of inflammation and infection. This is an acute phase protein that rises quickly during an infection and whose trends can help veterinarians monitor treatment response.
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