Prognosis and outcome of critically ill neonatal crias (Proceedings)

South American Camelids (SAC) have gained significant popularity as pets, show, pack (llamas) and fiber animals in the United States, which has resulted in an increasing demand for intensive care management of critically ill neonatal crias over the past 10 years. Systemic infection (sepsis) or inflammatory responses, gastrointestinal disease, metabolic dysfunction (e.g. lipemia, glucose dysregulation), toxic injury, severe anemia, hyperthermia, immaturity and respiratory failure of neonatal crias are among the most common indications for critical-care management and are associated with significant morbidity and mortality.

Experiences and advances in equine neonatal medicine have emphasized the importance of various clinical and diagnostic parameters as prognostic outcome variables.(Hoffman, Staempfli et al. 1992; Furr, Tinker et al. 1997; Bedenice, Heuwieser et al. 2003) For example, previous studies have suggested that specific cardiovascular indices, hematological and serum biochemical variables (leukocyte and neutrophil count, venous and arterial blood gas analysis, lactate, anion gap etc.) as well as selected physical examination parameters upon presentation (such as hypothermia, tachypnea, and ability to stand) are significantly associated with outcome of critical illness.(Gayle, Cohen et al. 1998) Unfortunately, comparable information on the assessment of these variables in SAC is currently unavailable.

A recent, retrospective cohort analysis evaluated historical, clinical and laboratory variables, as prognostic indicators for survival of critically ill neonatal alpaca and llama crias that presented to the Tufts Cummings School of Veterinary Medicine (TCSVM) between 5/1999 and 12/2008.  All clinical data were obtained from an institutional software database (Microsoft Access 2000) (Bedenice 2003), which is based on the medical records of neonatal crias < 4 weeks of age.

This database records initial laboratory results and clinical findings documented within 24 hours of admission. Critically ill crias were defined as those diagnosed with one or more causes of illness requiring hospitalization and intensive care management (level III care). Final outcome was characterized by survival (discharged alive) or non-survival (not discharged alive), with a sub-categorization into crias that died and those that were euthanized. Animals euthanized for financial reasons were eliminated from the study. 

Abstract

The objective of this study was to identify historical, clinical and laboratory variables, as potential predictors of outcome in critically ill neonatal crias. 

Methods: A retrospective cohort analysis was performed on 201 critically ill neonatal crias (181 alpacas, 20 llamas ≤ 4 weeks old), which presented to the TCSVM Neonatal-Intensive-Care-Unit (5/1999–12/2008). Neonates presenting for failure of passive transfer (FPT) or trauma without systemic disease were excluded. Statistical outcome analyses included descriptive, univariate and multivariate models, based on the normality of data distribution. 

Results: 112 female and 89 male neonatal crias were hospitalized for 5.15 (+/-4.6) days at a median admission age of 2 days. The most common diagnoses included FPT (61.2%), systemic-inflammatory-response-syndrome (40.3%), lower airway disease (33.8%), diarrhea (23.9%), congenital defects (22.4%), neonatal encephalopathy (20.4%), clinical signs of prematurity (16.9%) and confirmed sepsis (13.4%). Overall survival was 71.1% (143/201), whereas 26 crias died and 30 were euthanized due to terminal illness (death unspecified in 2/58).

Tachypnea, elevated blood urea nitrogen (BUN), low serum albumin and dyspnea (open mouth breathing) upon presentation were significantly associated with mortality in the multivariate statistical outcome analysis. Furthermore, a diagnosis of lower airway disease was associated with a 3.6 fold mortality increase in the multivariate model, while treatment of FPT increased survival 3.2 fold. Acidemia was strongly related to non-survival in a subset of crias with arterial blood gas results (n=93).

Conclusions: Presenting clinical and selected laboratory results may impact survival chances of critically ill neonatal crias. Congenital defects are prevalent in camelids.

Pre-weaning morbidity and mortality

The overall pre-weaning morbidity and mortality of llamas and alpacas (Sharpe 2009) was recently evaluated using a cross-sectional observational study of 287 crias born on four farms in Ohio. The reported morbidity was 37% during the pre-weaning period, with a mortality rate of 2.1%. Of these, 47 (16%) experienced morbidity during the neonatal period. The three most common diagnoses included undifferentiated diarrhea (23%), umbilical hernia (16%) and unspecified infectious disease (15%). Difficult birth was an important risk factor for pre-weaning morbidity in this population. In comparison, a pre-weaning mortality rate of 12% was reported among alpacas born over a 3-year period at a camelid research farm in Peru (Bustinza 1988). An epidemiologic investigation of neonatal camelid mortality in the United Kingdom further determined that the highest fatality occurred in animals less than 6 months of age (Davis 1998, Wright 1998).  Many of these deaths resulted from perinatal problems.

The potential effect of the dam's age on body weight and cria survival during the first week of life was furthermore investigated using 424 pregnant alpacas (Bravo 2009). In summary, the weight and largest width of placenta, as well as birth weight of crias significantly increased with age of the dam (P<0.05). These parameters peaked at 9 years, with as subsequent progressive decline. Placental efficiency also improved with the dam's age and showed a bimodal shape, peaking in 6-year and 11-year-old alpacas. Altogether, 398 crias survived and 26 died. The cause of death was specified as emaciation in six crias, hypothermia (n=5) and stillbirth in four alpacas. It was noted that dead crias had lower body weights (6.4kg) than those that survived (7.8kg, P<0.05). Overall, more crias died from 2-year-old dams than from dams of any other age.