Journal of Feline Medicine and Surgery

This is the second article in a two-part series on urinalysis in the cat. The specific focus is urine microscopic examination. Part 1, which appeared in the March 2016 issue, discussed urine macroscopic examination.

Urinalysis is an essential procedure in feline medicine but often little attention is paid to optimising the data yielded or minimising factors that can affect the results.

For the best results, appropriately collected urine should be prepared promptly by specialist laboratory personnel for the relevant tests and assessed by a clinical pathologist. This is invariably impractical in clinical settings but careful attention can minimise artefacts and allow maximum useful information to be obtained from this seemingly simple process.

Clinical pathologists would be familiar with the information provided in this article, but it is rarely available to general or specialist practitioners, and both groups can potentially benefit.

Most of the required equipment is routinely available to veterinarians. However, instructions have been provided to give practical alternatives for specialist procedures in some instances.

The evidence base for feline microscopic urinalysis is quite poor and information has largely been extrapolated from the human literature. Information from feline studies has been included where available. In addition, practical clinicopathological and clinical observations are provided.

Calcium is essential for many normal physiological processes within the body. Aberrations in calcium homeostasis leading to hypercalcaemia can result in clinical signs such as polyuriav and polydipsia, lethargy and weakness due to depressed excitability of muscle and nervous tissue, and gastrointestinal (GI) signs due to effects on GI smooth muscle. Hypercalcaemia in cats is mostly idiopathic, with chronic kidney disease and neoplasia also being common causes.

Hypercalcaemia can be a diagnostic challenge and a good understanding of the regulation of calcium homeostasis can aid in interpreting results of diagnostic tests. Furthermore, the management approach may depend on the underlying cause of hypercalcaemia, and also its severity and chronicity.

This review offers a comprehensive discussion of the regulation of calcium homeostasis, with a focus on the normal response to hypercalcaemia. It also discusses the diagnostic approach to, and management of, hypercalcaemia in cats, as well as specific aetiologies. This is relevant to all clinicians working with feline patients.

The review draws evidence from peer-reviewed publications and also the author’s own clinical experience.

Since 1979 and 1980 when the first reports of clinical feline hyperthyroidism (FHT) appeared in the literature, our understanding of the disease has evolved tremendously. Initially, FHT was a disease that only referral clinicians treated. Now it is a disease that primary clinicians routinely manage. Inclusion of the measurement of total thyroxine concentration in senior wellness panels, as well as in diagnostic work-ups for sick cats, now enables diagnosis of the condition long before the cat becomes the classic scrawny, unkempt, agitated patient with a bulge in its neck. However, earlier recognition of the problem has given rise to several related questions: how to recognize the health significance of the early presentations of the disease; how early to treat the disease; whether to treat FHT when comorbid conditions are present; and how to manage comorbid conditions such as chronic kidney disease and cardiac disease with treatment of FHT. The 2016 AAFP Guidelines for the Management of Feline Hyperthyroidism (hereafter referred to as the Guidelines) will shed light on these questions for the general practitioner and suggest when referral may benefit the cat.

The Guidelines explain FHT as a primary disease process with compounding factors, and provide a concise explanation of what we know to be true about the etiology and pathogenesis of the disease.

The Guidelines also:

Distill the current research literature into simple recommendations for testing sequences that will avoid misdiagnosis and separate an FHT diagnosis into six clinical categories with associated management strategies.

To help ensure better case outcomes, the Guidelines reflect currently available, evidenced-based knowledge. If research is lacking, or if a consensus does not exist, the expert panel of authors has made recommendations based on their extensive, cumulative clinical experience.

This is Article 3 of a three-part series on clinical reasoning that encourages practitioners to explore and understand how they think and make case-based decisions. It is hoped that, in the process, they will learn to trust their intuition but, at the same time, put in place safeguards to diminish the impact of bias and misguided logic on their diagnostic decision-making.

Article 1, published in the January 2016 issue of JFMS, discussed the relative merits and shortcomings of System 1 thinking (immediate and unconscious) and System 2 thinking (effortful and analytical). In Article 2, published in the March 2016 issue, ways of managing cognitive error, particularly the negative impact of bias, in making a diagnosis were examined. This final article explores the use of heuristics (mental short cuts) and illness scripts in diagnostic reasoning.