Pathology in Practice.

In collaboration with the American College of Veterinary Pathologists.

Acquired left-to-right shunting through a valve-incompetent foramen ovale in a cat with hypertrophic cardiomyopathy and congestive heart failure.

CASE SUMMARY: An 8-year-old spayed female domestic shorthair cat was presented for a recheck evaluation of hypertrophic cardiomyopathy and chronic kidney disease. Three years prior to presentation, the patient was diagnosed with obstructive hypertrophic cardiomyopathy and started on atenolol. The left ventricular outflow tract obstruction subsequently resolved. Biochemical analysis a week prior to presentation demonstrated severe azotemia. Transthoracic echocardiograph revealed pericardial effusion, pleural effusion, severe left ventricular concentric hypertrophy, severe left atrial enlargement and continuous left-to-right flow through the interatrial septum near the fossa ovalis. The patient was euthanized owing to poor prognosis, and gross examination at necropsy revealed a valve-incompetent patent foramen ovale secondary to severe left atrial dilation. RELEVANCE AND NOVEL INFORMATION: To our knowledge, this is the first report of an acquired left-to-right shunt through a valve-incompetent foramen ovale in a cat with hypertrophic cardiomyopathy. Severe left atrial dilation was suspected to cause interatrial shunting through the valve-incompetent foramen ovale, and this finding may be relevant to echocardiographic evaluations in other cats.

Why is living fast dangerous? Disentangling the roles of resistance and tolerance of disease.

Primary axes of host developmental tempo (HDT; e.g., slow-quick return continuum) represent latent biological processes and are increasingly used to a priori identify hosts that contribute disproportionately more to pathogen transmission. The influence of HDT on host contributions to transmission depends on how HDT influences both resistance and tolerance of disease. Here, we use structural equation modeling to address known limitations of conventional measures of resistance and tolerance. We first provide a general resistance-tolerance metamodel from which system-specific models can be derived. We then develop a model specific to a group of vector-transmitted viruses that infect hundreds of grass species worldwide. We tested the model using experimental inoculations of six phylogenetically paired grass species. We found that (1) host traits covaried according to a prominent HDT axis, the slow-quick continuum; (2) infection caused a greater reduction in the performance of quick returns, with >80% of that greater impact explained by lesser resistance; (3) resistance-tolerance trade-off did not occur; and (4) phylogenetic control was necessary to measure the slow-quick continuum, resistance, and tolerance. These results support the conclusion that HDT's main influence on host contributions to transmission is via resistance. More broadly, this study provides a framework for quantifying HDT's influence on host contributions to transmission.