Nutrition

Cats are obligate carnivores. They diverged from canids approximately 30 million years ago, evolving with unique strategies for the utilization of protein, amino acids, fats and vitamins. They are anatomically and physiologically adapted to eating 10-20 small meals throughout the day and night, allowing them to hunt and eat when their prey are active. Depending on habitat, they eat small rodents, rabbits, birds, insects, frogs and reptiles. The average mouse provides 30 kcal of energy--about 8% of an average active cat's requirements; repeated hunting throughout the 24 hour period is needed to meet this need--hence the grazing feeding behaviour of domestic cats.

Because cats can't rest their metabolic processes, they catabolize body proteins when anorectic. Protein supplementation during fasting will slow hepatic lipid accumulation.. Adult cats have a much higher requirement for protein than dogs or humans: expressed as a percentage of diet, adult cats need 29% vs. the adult canine requirement (12%) or the human need (8%).

Hepatic Lipidosis

Two medical conditions that require particularly intensive nursing care in cats are hepatic lipidosis (HL) and diabetes mellitus (DM). The most important strategy in preventing and treating HL is to feed first, diagnose later. Cats require 50 kcal/kg of ideal body weight. Vomiting must be controlled quickly (Table 1)

Table 1. Selected anti-emetics for use in the cat.

Treat with Vitamin K1 (1.0 mg/kg SC q12h for three doses) while awaiting blood results.. Add water-soluble vitamins and KCl to crystalloid fluid therapy. If a cat has been inappetant/anorectic for 5-7 days, is urinating and not bradycardic, it is safe to administer KCl at 30 mEq/litre fluids before knowing the serum K value. By stabilizing the lipidotic patient quickly, an esophagostomy or other large-bore feeding device can be placed within about 48 hours of admission. Placement can be performed with less than 10 minutes' anaesthesia; feeding can be started within 2 hours after recovery. Using a syringable food is ideal. If necessary, dilute with liquid feline diet rather than water to avoid losing caloric density. Gradually increase the volume and reduce the number of feeds, meeting the daily caloric requirements. The goal is 4 feedings/day; this is reasonable for clients to cope with at home. Tubes are easily maintained and can be removed as soon as the patient is eating enough on his/her own to prevent weight loss without nutritional support over a one week period. Other essentials for successful treatment of lipidosis are L-carnitine and taurine. Ursodeoxycholic acid and S-adenosyl methionine are valuable for their choleretic and hepatoprotective properties respectively.

Diabetes Mellitus

Diabetes mellitus is another condition which requires a committed healthcare team. Confirming the diagnosis using serum fructosamine, the client is counseled and taught to handle insulin and syringes, how to use the diary, and nutrition is discussed. The first 12 hour blood glucose curve is done two weeks later; at this time, the insulin dose is adjusted and the client taught how to perform glucose measurements (ear pricks) before insulin administration. Thereafter, curves are performed every 2 weeks until the condition is stable. After one month's insulin, fructosamine is re-evaluated and the client is ready to do the curves at home and report to the doctor for recommendations.

Hospitalisation

As cats age, they tolerate less time in the clinic; Siamese are especially prone to depression. Three days is about as long as a cat can stand the indignities of hospitalization, even with daily visits from his/her person. Cats 'see' the world in overlapping clouds of smells; we must provide familiar smells and aim to reduce foreign, medicinal smells. Client worn shirts are helpful in their cages/beds. Cats' hearing is finely tuned; keep the environment as quiet and reassuring as possible without exposure to the sounds of predators (barking dogs). Certain induction agents enhance their sense of hearing, e.g., ketamine. Changing diet while hospitalized is likely to result in inappetence and the development of an aversion, thus if a therapeutic diet is required, try to make the change at home, in a gradual fashion.

Analgesia

Analgesia has come of age in veterinary medicine. We now have numerous agents that we can use safely in cats. Whether we chose opioids, NSAIDs, antidepressants, antiseizure medications or acupuncture, we must be proactive. If clients believe their cat is suffering, they are more inclined to consider euthanasia. If recovery is delayed, hospitalization costs increase, which may also influence the client's frame of mind. Conditions commonly seen in feline patients for which we may not routinely provide analgesics include lower urinary tract disease (LUTD), pancreatitis, and arthritis. In LUTD, antispasmodics may be beneficial along with an anti-inflammatory agent. Arthritis requires the use of agents that can be given long-term, such as judiciously dosed NSAIDS, glucosamine and chondroitin sulphate and acupuncture. A wonderful resource about the recognition and alleviation of pain is: Pain H.U.R.T.S. (http://www.jonkar.ca/RPain/).

Behaviour

Cats are able to function efficiently as solitary creatures. Cats do have complex and changing social interactions, much more intricate than that of a herd or pack species. Cats are also small predators. This has affected their anatomic and physiologic development, which has remained unchanged over several million years. While being predators, their size also makes them prey to other species. This aspect affects how they respond to us in a clinic setting.

Relying on the 'fight or flight' response, they escape situations viewed as dangerous. From the perspective of a cat, we are dangerous. Accordingly, one of the great challenges we see every day is the frightened and assertive cat. It is essential to remember that this small creature feels more threatened than we do, so that we do not become frightened ourselves. Because cats are small, they try to avoid physical confrontation and attempt to intimidate using sounds and posture.

In order to provide compassionate and effective care, try to think like a cat. Imagine what their experience might be like. When we reach into a carrier or kennel, we are huge creatures, blocking the light. We smell wrong and don't sound familiar. Shushing sounds like hissing. Remember that 'less is more' when restraint is required. Always leave as much contact with the floor as possible; if collecting from a jugular in sternal position, have the forefeet touch the table; procedures requiring lateral recumbency are less frightening when the front end is sternal. Allow the client to be with the kitty whenever possible. And don't forget that hissing, spitting, growling and posturing are all attempts to not have to strike or bite you.

Diagnostics

Being largely self-dependent, cats mask illness and pain extremely well. Listening carefully to clients is extremely important; often they detect changes intuitively that represent real problems. This is more common, in the author's experience, than the client who is blissfully unaware of significant health problems. By asking open-ended questions, one elicits a more detailed history than using only specific (yes/no) questions. For example, asking 'What does his stool look like?' rather than 'Have you noticed any change' provides a more useful answer.

Subtle changes can be detected by measuring body weight at every visit and calculating percentage change(% = previous weight--current weight/ previous weight). By 12-15 months of age, adult weight should be reached. By noting slight increases or decreases, one can follow trends and hopefully avert problems such as lipidosis or obesity and detect malabsorption or catabolism in the early stages.

Bladder agitation just before cystocentesis provides a better urine sediment yield. Because sediment is heavier than urine and is gravity dependent, resuspension within the bladder is diagnostically beneficial. A low number of white blood cells, trace protein or the absence of bacteria should be interpreted with suspicion in dilute urine. A culture and sensitivity may be warranted when the specific gravity is <1.025 in this situation. Conversely, when high numbers of bacteria are seen in a highly concentrated urine (e.g., usg >1.050), collection induced contamination should be expected, especially when a mixture of rods and cocci are reported.

Blood pressure evaluation should be performed in every cat over the age of eight years and in any ill or anaesthetized patient. Hypertension is common in cats with renal insufficiency or hyperthyroidism. Hypotension in an ill cat may signal hypovolemia or sepsis. During anaesthesia, hypotension precedes alterations in pulse oximetry and, if remedied promptly, can prevent hypoxemia from developing.

Hematocrit tubes provide vital information. Not only should the PCV and total solid (TS) be noted, but also the percentage buffy coat, (an estimate of white cell numbers) and the character/colour of the serum. Icterus may be noted in the serum (or in the urine) before serum bilirubin rises or before it becomes evident in the tissues. Calculation of fluid rates for patients requires knowing the TS along with the PCV. These measurements should be taken minimally once a day; more frequently in more anemic and volume fragile patients. Blood for hematocrits may be collected by ear pricking with minimal annoyance for the patient. Assessment of dehydration should take all of the following parameters into consideration: skin turgor, eye position, mucous membrane moisture, TS and stool hardness. Replacement of volume deficit + maintenance requirements of 60 ml/kg/day should be calculated using the normal, hydrated weight, not the ill weight. When prescribing subcutaneous fluid therapy as part of home care for a patient (for constipation, renal insufficiency, etc.), assuming the patient has been rehydrated, the volume to be given at home should be 60 ml/kg/day.

Bronchopulmonary disease requires cytologic and microbiologic evaluation of airway secretions for differentiation of the various causes of coughing and/or wheezing. Tracheal wash is readily available to all practitioners for sampling the contents of larger airways. Using a sterile endotracheal tube is less stressful than the traditional trans-tracheal technique. Pass a 3-5 Fr. red rubber feeding tube through an opening made in the end of its packaging, through the endotracheal tube until slight resistance is met. Flush two 6 ml aliquots of physiologic saline and aspirate back into a sterile collection syringe. Repeat this until 6-12 mls of saline have flushed the airways. Submit some of the sample on air-dried slides, in an EDTA tube as well as in a sterile red top tube for culture if cytology shows significant organisms. The presence of Simonsiella bacteria or squamous cells indicates oropharyngeal contamination.

Bone marrow taps may intimidate some practitioners. The author uses 16G needles rather than a Jamshidi needle to harvest bone core and marrow samples from femur (medial to the greater trochanter), wing of the ilium or humerus. After surgical preparation the samples are placed into EDTA tubes; at least 6 slides should be made and air-dried and the bone core placed into formalin in a red top tube. Be sure to collect a blood sample for a CBC at the same time to evaluate how the cells are being released into the periphery.

Inhalers

Recently aerosol inhalers (for both steroids and bronchodilators) have been recommended and used with success in small animal medicine. Fluticasone is a steroid, which comes in 3 dose strengths (44, 110, 220 mcg/dose). Beta₂-adrenergic agonists include albuterol, salmeterol or terbutaline. These may be delivered with the use of an Aerokat (http://www.aerokat.com/) held over the cat's muzzle for 30 seconds. Drug delivery remains a significant question, both getting effective drug concentrations into the affected airways as well as avoiding overdosing these small animals.

Tips on aerosol use:

 Acclimate kitty to device over several days, letting him/her investigate it.

 Reward fearless approaches to device and start placing it near kitty's face (praise, food, catnip, stroking?).

 Practice with the mask over the cat's face without anything in the chamber.

 Pre-load the chamber with a puff of albuterol (in addition to the dose required).

 Make sure the mask is over the muzzle for 4-6 breaths.

 Administer bronchodilator (albuterol) first, to allow better delivery of corticosteroid.