Starting the clinical evaluation by weighing the animals, the mean and standard deviation for the 12 specimens of C. thous was 6.2 ± 0.96 kg, which is within the reference values for body mass described in the literature (4.5 to 8.5kg) (Jorge & Jorge 2014). The HR was also with the reference standards described in the literature (Camacho & Mucha 2014) for small domestic dogs, which correlate with the weight of the wild canids. On the other hand, SAP presented mean values within the reference range proposed for dogs with the Doppler method (Acierno et al. 2018) and were close to the systolic arterial pressure values measured in a population of 150 domestic dogs with the petmap® method (Tebaldi et al. 2012). However, after adding the standard deviation to the mean, the upper values exceed the acceptable threshold. These values may be correlated to increased systolic arterial pressure values in three animals included in the study, which increased the mean for the 12 animals. Therefore, we need to consider a possible discordance between systolic arterial pressure values exceeding 140 mmHg in comparison with values obtained through invasive methods (Garofalo et al. 2012).
The wild canids evaluated in this study presented VHS values within the reference standards, presenting a mean and standard deviation of 8.22 ± 0.55 vertebrae, a result that is close to the VHS values of 8.27 ± 0.48 observed in maned wolves (Chrysocyon brachyurus) (Estrada et al. 2009). The VHS evaluation in this study was performed by a single observer in the right latero-lateral projection, but it is important to highlight a possible interobserver difference reported in both healthy and sick dogs (1.05 ± 0.32 vertebrae) (Hansson et al. 2005).
Other innovative quantitative radiographic methods such as VLAS and RLAD are based on the specific evaluation of the left atrium, taking as reference the physiopathology of cardiac remodeling in myxomatous mitral valve disease, which is the most recurrent cardiopathy in domestic dogs. Therefore, considering reference values described in the literature of ≤ 2.3v and ≤ 1.8v respectively for VLAS and RLAD, the sample group of C. thous were within normality, presenting values of 1.77v ± 0.20v for VLAS, and 1.25v ± 0.18v for RLAD.
Starting the echocardiographic examination by positioning the transducer in the thorax of the animals, we noticed a higher degree of cardiac horizontality in Cerdocyon thous than in imaging examinations performed in domestic dogs, which is correlated to the different thoracic conformations in the species. However, the formation of echocardiographic images through different windows, axes and views in C. thous was similar to that of domestic felines. Progressing to the subjective analysis in bidimensional and colored Doppler modes, we did not observe engorged chambers, regurgitations, communications or stenoses in the 12 specimens of C. thous evaluated.
In the echocardiographic evaluation in M-Mode and B-Mode, the analyses were compared to the weight of the animals. When comparing only the echocardiographic findings to the values observed in the literature for mean weight, LVd, IVSs, and the diameter of the root of the aorta obtained in bidimensional mode and M-Mode where lower in comparison to domestic dogs.
However, when we exclude weight as a variable through the allometric equation (Cornell et al. 2004), the values for left ventricular diameter in systole and diastole were lower (Table 3).
In the evaluation of the transmitral, aortic and pulmonary flows (Table 2), it is possible to note a reduction in EDT and the fusion of the E and A waves in three animals, both possibly happening due to the increased heart rate observed. Therefore, the statistical analysis of the velocity of the A wave and of the E/A ratio was calculated for nine animals, excluding those that presented the aforementioned fusion of the waves referring to the transmitral flow.
The subjective analysis of segmental contractions did not note any complications related to the action of the anesthetic agents applied and noticed that the values for left ventricular fractional shortening (LVFS) by the Teicholz method and for the ejection fraction (EF) were maintained. The evaluation of a maned wolf (Chrysocyon brachyurus) under the same protocol (Mantovani et al. 2012) presented similarities in the assessment of the systolic function in M-Mode, arterial flow, pulmonary flow and transmitral flow. The animal in question was described to weight 29 kg and, after adjusting the weight and the measurements obtained in the allometric scale (Cornell et al. 2004), the values were similar to those observed in this study.
Therefore, due to the absence of acquired or congenital cardiopathies in the sample group after the aforementioned complementary examinations, we understand the reason for the lack of alterations in the serum troponin dosage during the analysis, presenting values compatible with those found in healthy dogs (< 0.01 ng/ml) (O’Brien et al. 2006), which means these values could be used as a reference for C. thous. It is important to note the higher specificity of this test in mammals with heart disorders in comparison with birds and reptiles (Feltrer et al. 2016; Zafalon-Silva et al. 2018).
Given these results, the study may still be limited by the small sample group used. However, considering this study in a descriptive light, these results may be used as parameters for future studies dealing with exotic and wild animals, as well as in the evaluation of Cerdocyon thous and other wild canids in the field or in captivity, however, it is important to underline that utility of the allometric equation and the comparison of the values with wild animals of distinct body weights that belong to the same taxonomic class due to the scarcity of literature regarding cardiac evaluation in wild canids.