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Transfusion practices for treatment of critically ill or emergent dogs | VETgirl Veterinary CE Podcasts

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In today’s VETgirl online veterinary continuing education podcast, we review two studies that describe the transfusion practices used for the treatment of dogs hospitalized after trauma and for dogs undergoing splenectomy for splenic masses. These are both large retrospective studies out of Tufts University, a busy veterinary teaching hospital in Massachusetts.

Dogs with trauma and dogs undergoing splenectomy for splenic masses are frequently administered blood transfusions. However, little is known about the clinical signs that trigger the administration of blood products to these dogs or the outcome of these dogs that receive transfusions. In human medicine, it is widely known that transfusion administration is associated with decreased survival and poorer outcomes, as well as increased complications and longer hospitalization times. These associations have been minimally investigated in dogs. Therefore, the objective of both of these studies was to determine reasons for the administration of blood products to dogs after trauma or to dogs undergoing splenectomy for splenic masses, as well as to determine associations between the transfusion and patient admission characteristics, injuries in trauma dogs, histopathology in splenectomy dogs, and outcome.

In the first of two studies, Lynch et al wanted to describe transfusion practices in dogs after trauma. They retrospectively evaluated dogs (from 2008-2013) that were hospitalized for at least 24 hours. Data collected included signalment, cause of injury, characteristics of injuries sustained, admission physical examination findings, clinicopathologic data at the time of admission, and results of A-FAST and T-FAST exams. Transfusion-specific data included the primary reason for transfusion, blood products given, and any reported evidence of transfusion reactions. Massive transfusion was defined as administration of a volume of blood or blood products more than 90 mL/kg in a 24-hour period or more than 45 mL/kg in a 3-hour period. In addition, survival data including cause of death or reason for euthanasia was recorded. The Animal Trauma Triage (ATT) score was also calculated using information from the medical record to indicate severity of injuries.

Overall, 165 dogs were included in this study, with a 50:50 split between males and females. The average age was 4.5 years with a 22 kg average body weight. Mixed breed dogs were the most common breed represented in this study. 90% of dogs suffered from blunt trauma with a total of 86% from motor vehicle accidents, whereas 10% of dogs had penetrating trauma (secondary to bite wounds). 36% of the dogs were given a blood transfusion; of those transfused dogs, 93% receiving packed RBCs, 33% receiving fresh frozen plasma, and 11% receiving fresh whole blood. Reasons for blood product administration included perioperative hemodynamic optimization (for 40% of dogs), worsening shock during resuscitation (in 31%), worsening anemia (in 20%), and coagulopathy (based on prolonged clotting times) in 6%.

Overall, dogs that received transfusions were more likely to have penetrating bite wounds, higher heart rates, lower rectal temperatures, increased respiratory effort, increased gum pallor, lower PCV and total solids, higher blood lactate concentrations, and higher ATT scores. Interestingly, the mean PCV at which dogs were transfused was 38%, which is generally considered the low end of the reference interval for healthy dogs. However, keep in mind that acute blood loss commonly has a “normal” PCV due to fluid shifts and splenic contraction; classically, these dogs with acute blood loss have a very low total protein (That’s your little clue to look for acute blood loss, folks). In this study, 87% of the dogs survived, including 7 of 10 dogs undergoing massive transfusions. However, dogs that received transfusions had an overall lower survival rate of 78% compared to a 93% survival rate in dogs that did not receive transfusions. The authors attributed this difference to increased severity of injuries in the dogs that required transfusions, rather than the transfusions themselves.

It is interesting to note that fractures were not associated with transfusion administration; however, 9 of 10 dogs that had long bone fractures and required transfusions had femoral fractures. This confirms the risk of blood loss requiring transfusions that can occur with femoral fractures, given their close proximity to large vessels within the hind limbs. Remember, there are only a few spaces or places where the body can catastrophically bleed, and long bones is one of them (along with pleural space, abdominal cavity, arterial source, pericardial space, etc.).

Ultimately, this first study showed that 1/3 of dogs admitted to this veterinary teaching hospital for > 24 hours of care were given a blood transfusion and usually for perioperative stabilization. Unfortunately, because dogs hospitalization for < 24 hours were excluded, many dogs that had injuries that did not require ongoing hospitalization, dogs with owners that declined hospitalization for financial reasons, or dogs with substantial injuries that did not survive 24 hours might have required transfusions but were not included in this study.

Does this study change the way we practice transfusion medicine when it comes to our trauma patients? Probably not…but it reminds us that if you are resuscitating a dog after trauma and you notice that its PCV is trending down or its total solids is low, especially if the dog is not responding to your shock resuscitation as nicely as you would like, your first thought should be that it might need a transfusion! Remember, we don’t jump to blood right away – we want to try appropriate resuscitation first (including crystalloids and colloids), but if your patient fails to respond to resuscitation, a blood transfusion may be in its near future. This study also confirms that depending on your trauma caseload and whether you’re in a position to take these trauma cases to surgery for repair, it might be worth having blood products on hand!

In the second study, Lynch et al also published a study describing transfusion practices in dogs undergoing splenectomy for splenic masses. This was a retrospective study conducted between 2001-2012, and looked at dogs admitted to Tufts University and the affiliated specialty hospital Tufts VETS. Data collected from the medical records included signalment, physical examination findings; systolic arterial blood pressure at hospital admission; clinicopathologic information at the time of initial evaluation at the hospital; presence or absence of abdominal effusion and a subjective assessment of volume; as well as final histopathologic diagnosis for the splenic mass. The major reason for transfusion, the specific blood product or products administered, and evidence of transfusion reactions were also determined from the medical record. Massive transfusions were defined the same as in the previous trauma paper. APPLE-fast scores were also calculated as a measure of illness severity. Survival was recorded at discharge from the hospital, as well as 30 and 180 days after discharge and death was recorded as euthanasia or natural death when applicable.

A total of 542 dogs were included in this study with 56% male and 44% female dogs. The most common breeds were Goldens, Labs, and German shepherds, followed by mixed breed dogs. BOO, hemangiosarcoma in our favorite breeds of dogs. In this study, 44% of the dogs received a blood transfusion during hospitalization. Of those dogs transfused, 91% of dogs received packed RBCs, 25% received fresh frozen plasma, and 5% received fresh whole blood. Reasons for blood transfusions included 38% dogs for perioperative management of shock, 37% for perioperative management of anemia, 12% for intraoperative hemodynamic optimization, 8% for coagulopathy, and 4% for postoperative hemodynamic optimization.
As far as laboratory assessments, dogs that required transfusions were more likely to have a lower PCV, total solids, albumin, base excess, and platelets, as well as higher blood lactate, total white blood cell count, BUN, creatinine, and prothrombin time. As far as clinical signs and other assessments, dogs that required transfusions were also more likely to have a lower rectal temperature, as well as a higher heart and respiratory rate, increased respiratory effort, increased gum pallor, and higher APPLE-fast score.
Not surprisingly, hemoabdomen was diagnosed in 63% of dogs. The presence of hemoabdomen, especially a subjectively “large volume” hemoabdomen was associated with transfusion administration, although the PCV of the peritoneal effusion was not associated with transfusion administration. Hemangiosarcoma was diagnosed in 55% of dogs receiving a transfusion, which was a higher incidence compared to a 33% incidence of hemangiosarcoma in dogs that did not receive a transfusion. These numbers are comparable with previous studies.

92% of dogs survived to hospital discharge, although all 3 dogs receiving massive transfusions died before discharge from the hospital. Of the transfused dogs, non-survival was associated with larger total blood product administration described as 26 mL/kg in non-surviving dogs compared to 16 mL/kg in surviving dogs. Likewise, spontaneous death or euthanasia was more likely in dogs receiving transfusions and 30 and 180 day survival were lower in dogs receiving transfusions.

Overall, what do the results of this study show that might change our clinical practice? Well, given that more than half of dogs with a splenic mass undergoing splenectomy will be diagnosed with hemangiosarcoma, if they require a transfusion and because these dogs have a lower survival at 1 and 6 months after hospital discharge, this might affect an owner’s decision to pursue treatment. Thus, this study provides us with more information to help improve owner expectations in these situations and possibly help guide client decisions. Also, if you are at a practice that sees these dogs, this study provides more reason to have blood products on hand, especially if you are comfortable cutting these cases yourself rather than referring them!

The limitations of both of these studies should be noted including their retrospective nature, which means that different treatment plans, owner financial abilities, and clinician discretion would have dictated transfusion administration. Interestingly, the rate of transfusion reactions in both studies was very low, suggesting that if you do decide to transfuse dogs after trauma or perioperatively for splenectomy, transfusion reactions are considered unlikely.

So, what can we take from this VETgirl podcast? When in doubt, if you see a lot of trauma or hemoabdomen cases, having blood products on hand is a must. Know that the rate of transfusion reaction is very low, but keep in mind that we want to give blood products when appropriate.

References:
Lynch AM. O’Toole TE, Respess M. Transfusion practices for treatment of dogs hospitalized following trauma: 125 cases (2008–2013). J Am Vet Med Assoc 2015;247(6):643-649.

Lynch AM, O’Toole TE, Hamilton J. Transfusion practices for treatment of dogs undergoing splenectomy for splenic masses: 542 cases (2001–2012). J Am Vet Med Assoc 2015;

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