Emergency care for kittens

Introduction

Kittens and young cats are often presented to veterinarians with life-threatening conditions. Due to their small size and unique physiology they can represent a significant challenge, and it is therefore crucial that veterinarians understand the specificities of this patient population and develop an adequate skillset to care for these animals in the acute care setting. This clinical review will present general concepts for the emergency management of kittens and young cats, and emphasize specific points relating to these animals. Note that it can be helpful to divide this patient population into neonates (from birth to two weeks of age) and pediatric patients (from two weeks to six months of age).

General emergency approach

Triage examination 

Every patient presented on an emergency basis should undergo a triage examination. The word "triage" is of French derivation and refers to the action of attending to the patient while determining priorities for action. The goal of this process is (i) to decide if the patient requires immediate life-saving measures and (ii) to prioritize resources toward specific individuals when multiple patients require medical attention simultaneously. It is important that each clinic develops specific triage protocols tailored to their own situation, but it is also essential to remember that the triage examination is the first contact with a pet’s owners, who can often be very distressed, and communicate with them accordingly. 

Traditionally, the “ABC” algorithm has been used to initiate the triage, as it evaluates airway patency, breathing (is the patient breathing spontaneously? Are there signs of respiratory distress?), and circulation (are there signs of circulation or shock?) (Figure 1). The presence of shock can be assessed on physical examination by evaluating perfusion parameters: mentation, heart rate, pulse quality, mucous membrane color, capillary refill time, and extremity-to-core gradient temperature. 

Oxygen administration 

The mainstay of therapy for patients in respiratory distress is oxygen administration and it should be instituted as soon as distress has been identified on triage examination. Multiple options are available, each with advantage and limitations (Table 1). Once oxygen administration has been initiated, the underlying condition should be investigated and treated whenever possible.

Vascular access

Vascular access is a key intervention in acute care patients as they often need intravenous (IV) fluids or medications (Figure 2). Vascular access can be challenging, in particular for patients in shock or with profound dehydration. In smaller animals, a narrow gauge catheter (e.g., 22G or 27G) might be required to access a peripheral vein such as the cephalic or medial saphenous. Vascular access can also be established by placing a 18G or 20G catheter in a jugular vein. Finally, in patients with very difficult venous access (e.g., if there is profound dehydration or hypovolemic shock, or for animals presented in cardiopulmonary arrest), an intraosseous (IO) catheter can be placed in the proximal femur or humerus ( Figure 3 and Figure 4 ). While this is a rapid and safe procedure, conventional venous access should be secured as soon as possible thereafter.

Whether the catheter is IO or IV, the skin should first be cleaned and aseptically prepared. Catheter placement should always follow aseptic technique and the catheter should be secured to the patient and protected from environmental contamination with a bandage. The catheter insertion site should be inspected and cleaned at least once a day and replaced as soon as concerns for contamination or loss of function arise. Similarly, any swelling, heat or pain of the leg distal to the catheter should mandate evaluation.

Treatment of shock

Shock can be defined as a systemic decreased cellular production of ATP, the energy-rich compound used for most cellular metabolism. In order to produce ATP, cells need to be provided with, and process, oxygen. Adequate cell function and tissue oxygen delivery (DO₂) are thus critical for ATP production. DO₂ is dependent on several physiologic factors including cardiac output and oxygen arterial content.

The different shock etiologies can be classified as hypovolemic (or vasoconstricted), distributive (or vasodilatory), cardiogenic, metabolic, or hypoxic (Table 2).

Hypovolemic and vasodilatory are the most frequently encountered types of shock in the emergency room, and their treatment will be the focus of the remainder of this discussion. The goal is to restore blood volume and maximize DO₂ using resuscitation fluids; these are preferentially administered via the IV route, although IO access can sometimes be used.

Fluids commonly employed in veterinary medicine for the treatment of hypovolemic or vasodilatory shock can be classified as either crystalloids (iso- or hypertonic) or synthetic colloids.

Crystalloids are a family of solutions that contain electrolytes. They are considered isotonic if they have the same osmolarity as the patient, or hypertonic if their osmolarity is higher. While the effects of isotonic crystalloids rely on their volume expansion properties, hypertonic saline exerts its effect through poorly understood mechanisms (increased cardiac contractility, microperfusion improvement, and immunomodulation). The various isotonic crystalloid products differ in their electrolyte and buffer composition. 

Colloids are a suspension of macromolecules in a crystalloid solution and include Hetastarch solutions. These are macromolecules characterized by numerous hydroxyethyl substitutions on a glucose backbone, and are classified by the degree of substitution and their molecular weight. Their use for the treatment of shock has been proposed as they exert a significant colloid osmotic pressure and therefore a volume expansion greater than the volume infused. In addition, their chemical complexity allows them to be degraded slowly, so they remain longer in the bloodstream. However there are downsides; they are expensive, and have been associated with the development of kidney injury in several human trials. They can also lead to a dose-dependent coagulopathy (mainly decreased platelet function) in both human and veterinary patients. Synthetic colloids should therefore be used with caution in patients at risk for kidney injury, those that are coagulopathic, or may be in need of surgical intervention.

Dosing guidelines are presented in Table 3 . The treatment of shock should be rapid — within 20 minutes of diagnosis if possible.

History

A full history should be gathered from the owner to understand the motive for presentation. It is important to note the age of the animal and identify the diet offered. Kittens fed inappropriately (insufficient diet caloric content or infrequent feeding) can suffer from dehydration, hypothermia, and hypoglycemia. This is a particular concern in very young or orphan animals. The patient’s origin is also important, as some animals acquired from large catteries or poorly managed breeding programs may present with a significant internal roundworm (Toxocara), tapeworm (Dipylidium), or whipworm (Trichuris) parasite burden, as well as an external (flea) infestation. Dates of prophylactic treatments (deworming and vaccinations) should also be recorded and the presence of any coughing, sneezing, vomiting, or diarrhea noted. Potential exposure to common compounds known to be toxic to cats should also be investigated (e.g., lilies of the Lilium or Hemerocallis genus, ethylene glycol, medications, rodenticides, etc.). 

Full physical examination 

After the triage examination and implementation of necessary emergency therapy, a full physical examination should be performed. In neonates, mentation can be assessed by evaluation of vocalization, although overt noise production is abnormal. Mobility and ability to suckle milk are also good markers of mentation. Dehydration is a common comorbidity in kittens and should be estimated by evaluation of skin turgor and moisture of the oral and ocular mucous membranes. Importantly, standards for evaluation of dehydration in adults cannot be translated to the young cat population without modification; the threshold for the diagnosis of dehydration should be lower in this age group. Any decreased skin turgor or dry mucous membrane is a reflection of severe dehydration. 

The oral cavity should be carefully examined, as animals with cleft palates will present with failure to thrive, inability to swallow milk, or signs of respiratory distress. In some animals with severe diarrhea, rectal prolapse may also be found on physical examination (Figure 5). Rectal temperature should be promptly measured to rule out hypothermia, which is frequent in these patients. Rectal temperature at birth ranges from 35.2-37.0°C and reaches 38.5°C around 28 days 1 2. Thoracic auscultation not uncommonly reveals the presence of a physiologic heart murmur, although congenital cardiac disorders are also possible in this age group. The physical examination will provide crucial information to decide on additional diagnostic and therapeutic interventions. 

Emergency laboratory evaluation

Additional laboratory analysis may prove valuable information to complement the history and physical examination. It is vital to bear in mind that kittens may become anemic if too much blood is removed at sampling; a small sample volume should therefore be acquired, and only required tests should be prescribed. For kittens, packed cell volume (PCV), total protein and blood glucose measurements often prove helpful in managing common conditions encountered in this patient population. Such tests are typically inexpensive and offer a rapid method to gather a broad spectrum of information; for example, anemia and hypoglycemia are frequent conditions in young cats. Clinicians should remember that while in adults a refractometer specific gravity (SG) measurement on a urine sample provides key information for renal concentrating abilities, kittens have an inability to concentrate urine, which makes SG a poor surrogate to assess renal function. 

If sufficient blood can be acquired and clinical indications are present, a complete blood count will provide valuable information about erythrocytes, leukocytes, and platelets. A biochemistry panel will give insight into renal function and liver function. Age-, and ideally machine-, specific normal values should be used, as shown in Table 4 1 2. 

Common conditions 

Anemia

Anemia is a frequent problem in kittens and often the result of overt parasitism, especially flea infestation. Animals with flea-induced anemia may initially have a regenerative anemia that progresses to normocytic, normochromic, non-regenerative anemia in the later stages. Anemia in kittens can be further compounded by nutritional imbalances; iron and vitamin B₁₂ deficiency are often encountered. Anemia not explained by flea infestation should be approached similarly as in the adult population and is classified as regenerative or non-regenerative; normocytic or microcytic; and normochromic or hypochromic. It can be due to decreased erythrocyte production (e.g., aplastic anemia, retroviral infection), blood loss (e.g., from hemorrhage, flea infestation) or erythrocyte destruction (e.g., immune mediated, zinc toxicity). Testing for feline leukemia virus (FeLV) infection is an important step in the work-up of anemia in kittens 3.

Hypoglycemia

Young cats, and neonate patients in particular, are prone to hypoglycemia due to their high metabolic requirement for glucose and limited gluconeogenesis ability, as well as renal losses. Adequate nutrition is key to prevent hypoglycemia and hypothermia in kittens and young cats. Neonates should be weighed daily to ensure weight gain (Figure 6). Voluntary intake should be confirmed — both the patient and the food can be weighed before and after each meal to confirm and quantify intake. Animals should be fed frequently with a caloric-dense diet tailored to their needs; neonates should be fed every 2-4 hours, whilst older kittens can be fed 3-4 times a day. Animals unwilling or unable to ingest food voluntarily may be fed via tube feeding (although this can be associated with catastrophic consequences should the feeding tube be inadvertently placed in the trachea). Pregnant and lactating queens should also have a diet tailored to their metabolic demand to ensure quality milk.

Animals with hypoglycemia may present with obtundation, stupor, coma, or seizure. Acquiring blood may be difficult in small patients, and for kittens with severe obtundation, coma, or seizures it is acceptable to assume and treat for hypoglycemia without testing. If clinical signs do not improve or recur despite adequate dietary and heat support, the underlying etiology should be investigated. Emergency hypoglycemia treatment can be achieved with an IV or IO injection of dextrose (0.25-0.5 mg/kg). Dextrose solutions often come in 50% (500 mg/mL) concentration and are therefore hypertonic; they should be diluted with sterile water (in at least a 1:1 ratio) to reduce irritation. In animals unable to sustain oral diet intake, supplementation of maintenance fluids with dextrose to achieve a final concentration of 2.5-5% (25-50 mg/mL) may be required. In patients with compromised vascular access, rubbing the gums with corn syrup might be a reasonable bridging therapy for transmucosal absorption until vascular access can be established. 

Hypothermia

Kittens have a large body surface area and a small body weight, and since thermoregulation matures at around 4 weeks of age, kittens under one month are therefore prone to hypothermia. Neonatal animals should receive species-specific milk and provided with a heat source (heat lamp, warm water circulating blanket, heating pad, warm water bottles, etc.) while making sure to avoid superficial burns. Appropriate food intake should be confirmed and adjusted to the animal’s age. 

Patients presenting with hypothermia (< 34.4° C) should receive active warming with one of the devices mentioned above. Warm water enemas can also help in increasing body temperature. If IV fluids are administered, especially for the treatment of shock, it is important to use warmed fluids. As the patient’s body temperature increases, perfusion parameters should be monitored, since clinical signs of shock may arise as cold-induced peripheral vasoconstriction is reversed. 

Dehydration

Dehydration is a common problem in neonate and pediatric patients because of several physiologic characteristics, including high surface-to-volume ratio, immature renal concentrating abilities, higher metabolic rate, and lower body fat content. Overall, dehydration is a result of excess losses in the face of inadequate intake, and medical interventions should aim at correcting this disequilibrium. Excess losses of salt and water are often the result of vomiting and diarrhea in this patient population (Figure 7). Common infectious causes for enteritis in young cats include parasites such as Giardia spp., Cystoisospora spp., Tritrichomonas foetus, and Cryptosporidium felis infestation. Helminths [roundworm (Toxocara), tapeworm (Dipylidium), and whipworm (Trichuris)] can also be a source of enteritis and failure to thrive, whilst a wide array of bacteria such as Salmonella, Clostridium, or Campylobacter may also cause enteritis in this population. Feline panleukopenia due to parvoviral infection can also occur, especially in unvaccinated animals; the syndrome is very similar to the one encountered in dogs and is characterized by severe gastroenteritis and leukopenia 4.

Specificity compared to the adult patient

Daily fluid therapy

As with adults, the treatment of shock should precede building a daily fluid plan in kittens. Shock should be treated with infusion boluses as described above. In stable patients, the daily fluid plan should consider three crucial elements, as follows;

(i) maintenance, which encompasses insensible losses such as those through respiration, and normal urine and feces production.

(ii) the deficit in salt and water or dehydration; this is based on physical examination and expressed as a percentage of body weight.

(iii) abnormal ongoing losses, or sensible losses, such as vomiting or diarrhea. 

Due to their higher metabolic rate and higher total body water content compared to adults, kittens, in particular neonates, have a higher maintenance fluid requirement than adults. The maintenance fluid rate for kittens is 3-6 mL/kg/hour, with neonates being on the higher end of the spectrum.

Dehydrated animals should be promptly rehydrated, ideally within 2-4 hours of presentation. For instance, a 100 g kitten with an estimated 8% dehydration may be given 8 mL of isotonic crystalloids over 2 hours. Lactated Ringer solution can be a good choice since the lactate can be a good source of energy for young animals 5.

Abnormal ongoing losses can be hard to quantify. Vomitus or diarrhea can be weighed, whilst urine production beyond the normal 1-2 mL/kg/hour may be measured by weighing diapers or incontinence pads used for bedding. Accurate urine production measurement can also be achieved in patients with an indwelling urinary catheter, but this is frequently not feasible in very small animals. 

Regardless of calculations, patients should be reassessed at least three times a day for clinical signs of shock, dehydration, or overhydration, and prompt appropriate adjustments to the fluid therapy plans should then be made. 

Kittens and young cats can present with unique specificities, and emergency and critical care clinicians should be aware of these in order to care appropriately for their patients. Specific attention and reference values should be used when evaluating laboratory data in these animals. Hypothermia and hypoglycemia are common conditions in this patient population, particularly in neonates. Proper husbandry and prophylactic interventions (vaccination and deworming), along with appropriate dietary intake, are key.