query.php

<?php
$data = array(
  "apikey" => "y9CJUD8A",
  "objectType" => "animals",
  "objectAction" => "publicSearch",
  "search" => array (
    "resultStart" => 0,
    "resultLimit" => 100,
    "resultSort" => "animalID",
    "resultOrder" => "asc",
    "calcFoundRows" => "Yes",    
    "filters" => array(
      array(
	    "fieldName" => "animalSpecies",
	    "operation" => "equals",
	    "criteria" => "cat",
	  ),
	),
	    "fields" => array("animalID","animalOrgID","animalName","animalBreed")
	  ),
	);

// behavior & images
$jsonData = json_encode($data);

/// create a new cURL resource
$ch = curl_init();
 
// set options, url, etc.
curl_setopt($ch, CURLOPT_HTTPHEADER, array("Content-Type: application/json"));
curl_setopt($ch, CURLOPT_URL, "https://api.rescuegroups.org/http/v2.json");
 
curl_setopt($ch, CURLOPT_POSTFIELDS, $jsonData);
curl_setopt($ch, CURLOPT_POST, 1);
 
//curl_setopt($ch, CURLOPT_VERBOSE, true);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
 
$result = curl_exec($ch);
 
if (curl_errno($ch)) {
 
  $results = curl_error($ch);
 
} else {
 
  // close cURL resource, and free up system resources
  curl_close($ch);
 
  $results = $result;
 
}

$resultsArray = json_decode($results);

print_r($results);

?>