CROW Case of the Week: Red-shouldered Hawk (#18-4536)

The red-shouldered hawk (Buteo lineatus) preys on mostly small mammals, amphibians, lizards and snakes or even birds such as sparrows, doves and starlings. These forest raptors hunt from perches by remaining silent until they descend swiftly, effortlessly and snatch up their target. 

At CROW, a red-shouldered hawk was admitted from Captiva Island near Blind Pass. The hawk was found down on the ground in the bushes. During its intake exam, veterinarians did not find any overt signs of trauma, but noted the hawk to have a depressed mentation and that it was severely dehydrated. A sample of its blood was tested and revealed that the bird was also very anemic. 

“This red-shouldered hawk was found down, cold and dull. The bird had severe anemia, meaning very low red blood cell levels, and this explains the patient’s condition on presentation. When a bird or any animal has a severe anemia, the causes can be broken down into a few broad categories, including blood loss, blood destruction and poor blood production,” said Dr. Kyle Abbott, CROW veterinary intern. “In this hawk’s case, the most likely causes would be reasons for blood loss. Blood destruction is unlikely as we do not often see diseases that cause that in wild animals. Poor blood production is a possibility in any animal affected by chronic or bodywide disease, but this was unlikely in this hawk’s case as he had a good body condition. Causes of blood loss that we are considering are anticoagulant rodenticides and trauma causing bleeding. For this hawk, an anticoagulant rodenticide seems like the most likely cause after it had prolonged blood clotting times after blood draws.”

Dr. Abbott further explained the pesticide is thought to be the factor in this case. “Anticoagulant rodenticides are used to kill rodents by preventing normal blood clotting. The anticoagulant affects enzymes that allow the body to recycle vitamin K, which is used to make blood clotting agents in the body, and ultimately results in inappropriate bleeding even without trauma,” he said. “This can affect raptors as they can absorb these rodenticides from prey that they would normally be eating. When we see patients like this hawk, it is a reminder that rodenticides inevitably become problems for wildlife beyond the intended rodent targets.” 

After the hawk was placed in an oxygen chamber and given fluid therapy to maintain hydration, it was given a blood transfusion with blood donated from Talon, a red-tailed hawk Animal Ambassador at CROW.

“We often perform blood transfusions on our patients who are severely anemic. When we can, we use our animal ambassadors as blood donors. However, when performing blood transfusions we try and use animals as closely related to the recipient as possible,” said Dr. Abbott. “For the past few months, many of our blood transfusions have been on sea birds, many of them affected by red tide. We do not have any sea bird animal ambassadors and, therefore, we will use other sea bird patients close to release as blood donors. When we have raptors, as in the case of this hawk, then we will use our raptor ambassadors.”

After a few days of recovery the hawk has shown signs of improvement and has been moved from the oxygen chamber to a normal ICU enclosure. “The hawk is doing very well after the therapies given to correct the anemia as well as continued therapies to treat for the suspected rodenticide toxicosis,” added Dr. Abbott. “To treat the rodenticide toxicosis, this hawk is on vitamin K supplementation. The hawk continues to have difficulties with blood clotting, and the plan is to continue with the vitamin K treatment for a few weeks until the rodenticide has been cleared from the body and the hawk can produce normal vitamin K function for itself.” 

 

CROW Case of the Week stories are written by Bob Petcher and appear weekly in the Island Sun and River Weekly Newspapers.

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