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Cats are NOT Small Dogs | VETgirl Veterinary Continuing Education Podcasts

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In this VETgirl online veterinary continuing education podcast, we review the difference between dogs and cats in the veterinary setting. As the old saying goes… ”cats are not small dogs!” The question remains, what does that really mean? They can both be small. They can both be fluffy. Catch them at the wrong time and they can both bite! But what does it mean when we say, “cats are not small dogs”? What we are referring to is the medical response to disease as we compare our feline and canine patients. Our feline patients have unique physiologic responses to shock, medications, fluid therapy, and even neoplasia as compared to the canine patient. As a result, it is crucial that the veterinary team understands these unique feline characteristics!

SHOCK AND THE CARDIAC RESPONSE
If you have ever attempted to resuscitate a feline patient in shock, you appreciate that this is a challenge. In shock (or sepsis), as compared to the tachycardic canine patient, the feline patient is often bradycardic. When evaluating these feline patients, it was noted that their compensatory response to shock is blunted. Moreover, they tend to not have the hyperdynamic signs of shock seen in other (canine) species. As compared to the canine patient, shock in our feline patients is commonly decompensatory. These characteristics include normal to bradycardic heart rates, hypothermia (< 98 F), poor peripheral pulses, pale mucous membranes, and mental depression.

FLUID THERAPY
The blood volume in the dog is approximately 90ml/kg. In comparison, the blood volume in the cat is 60ml/kg. This is an important difference as fluid rates and volumes, notably shock fluid volumes, vary significantly between species. Feline shock doses of crystalloid fluid therapy (10-20ml/kg) are lower than canine shock crystalloid fluid volumes (10-30ml/kg). Our feline patients also appear to be much more sensitive to fluid therapy with the concern for fluid overload, pulmonary edema, and pleural effusion developing.

STRESS RESPONSE – BIOCHEMISTRY PANEL
While both canine and feline patients can be stressed, the stress response in the cat common leads to (transient) hyperglycemia. This should be recognized and differentiated from diabetes mellitus (historical polyuria, polydipsia, polyphagia, weight loss, glucosuria). If there is a concern for pathologic hyperglycemia, repeat blood glucose levels at a later, less stressful time can be considered. A fructosamine level can also be considered.

CARDIAC DISEASE
As compared to the common valvular disease seen in canine patients, feline cardiomyopathy is more commonly hypertrophic, dilated, or restrictive in nature. Although careful auscultation of the heart is required to detect murmurs and gallop rhythms, subclinical heart disease may be missed on auscultation as a murmur is not a hallmark early characteristic of these cardiac conditions. Chest x-rays can be considered in any feline patient, especially older feline patients to look for evidence of cardiac disease including cardiomegaly prior to an echocardiogram.

BLOOD TYPES
Our canine patients are assessed for the DEA 1.1 antigen prior to transfusion with a universal donor considered to be the DEA 1.1- patient. Cats do not have a universal donor, and more specifically have 3 major blood types: A, B, and AB. Just like B students hate A students in school (humor), cats with type B erythrocytes hate receiving A blood. In fact, in can be fatal! Cats with type B blood have strong, naturally occurring anti-A antibody. Because of the strong possibility of a potentially fatal transfusion reaction, a blood type and cross-match is recommended prior to a feline blood transfusion.

DRUG DOSES AND METABOLISM
Our feline patients metabolize and generally tolerate certain medications differently as compared to their canine counterparts. Cats lack many of the hepatic glucuronyl transferases that are important for drug metabolism, conjugation and excretion. As a result, toxic levels of these drugs or metabolites can accumulate. Medications which we must recognize as unique include (but are not limited to) morphine, chloramphenicol, aspirin, primidone, acetaminophen, phenols, barbiturates, and benzodiazepines.

NUTRITION
Cats need to eat! Inappetance and anorexia in our feline patients should be taken seriously. Lack of nutrition for as little as 2-3 days may result in hepatic lipidosis. Lack of nutrition results in catabolism and development hepatic lipidosis. While less concerning with modern nutritional preparations, our feline patients also require taurine and arginine.

ANALGESIA AND PAIN ASSESSMENT
Pain assessment in both cats and dogs can be a challenge based on their stoic nature. Cats, if possible, are even more challenging in the author’s experience to assess pain. Cats may be lethargic and reluctant to interact or they may be aggressive. Potential signs of discomfort to consider may include dilated pupils, hyperthermia, inappetance, lethargy, and hiding.

ONCOLOGY
Cats have a few unique oncology related differences as compared to their canine counterparts. A lame feline patient should have their digits checked. Swollen, painful digits may be the presenting complaint for cats with primary lung cancer. Commonly known as feline ‘lung-digit syndrome,’ this describes an unusual pattern of metastasis that is seen with various types of primary lung tumors, notably bronchial and bronchioalveolar adenocarcinoma. Cats may also be more likely to have neoplasia manifest as dermatological disease including thymoma, lymphoma, pancreatic, and liver cancer. This may be primarily neoplastic or dermatologic disease that is paraneoplastic. Finally, malignancy-associated hypercalcemia in cats is common, seen with squamous cell carcinoma or, to a lesser degree, lymphoma. This differs from the etiology in dogs, in which lymphoma predominates as the underlying cause of paraneoplastic hypercalcemia.

ORTHOPEDICS
Anyone who has ever attempted to do an orthopedic examination on a cat understands the challenge of this examination. They are flat-out uncooperative! Rather than a great hands-on examination, the veterinary team member may need to observe and analyze their gait from a distance, such as through the examination door or window. Another option would be to have the owners provide a video of the abnormal behavior for evaluation and analysis.

SEIZURES
As compared to canine patients, in which idiopathic epilepsy seems to be quite common in dogs ranging from 1-6 years of age, true idiopathic epilepsy in cats is less common. Whether infectious, inflammatory, metabolic, or neoplastic, the veterinary team member should be more concerned when a feline patient presents with a history of seizure behavior. For this case, following initial bloodwork and radiograph evaluation, advanced imaging and CSF analysis should be considered in all seizing cats. Treatment options are similar to dogs, our feline patients should not receive bromide as this may result in a fatal pulmonary disease.

REFERENCES
1) Armstrong PJ, Gross KL, et al. Introduction to feeding normal cats. In: Hand MS, Thatcher CD, Remillard RL, Roudebush P, Novotny BJ, eds. Small Animal Clinical Nutrition. 5th ed. Topeka, KS: Mark Morris Institute; 2010.
2) Gaynor J, Muir W. The Handbook of Veterinary Pain Management. 2nd ed. St. Louis, MO: Mosby; 2009.
3) Hamper B, Bartges J, Kirk C, et al. The unique nutritional requirements of the cat: a strict carnivore. In: Little S, ed. The Cat: Clinical Medicine and Management. St. Louis, MO: Elsevier Saunders; 2012.
4) Kirby, R: Septic shock. In: Bonagura J, ed: Kirk’s Current Veterinary Therapy XII. Philadelphia, WB Saunders, 1995, p 139.
5) Kohn CW, DiBartola SP: Composition and distribution of body fluids in dogs and cats, In: DiBartola SP, ed: Fluid Therapy In Small Animal Practice. Philadelphia: WB Saunders, 1989, p 1.
6) Kirby R, Rudloff E. Wilson W: Cats Are Not Dogs in Critical Care, In Bonagura J, ed: Kirk’s Current Veterinary Therapy XIII. Philadelphia, WB Saunders, 2000, p 99.
7) Robertson S. Managing pain in feline patients. Vet Clin North Am Small Anim Pract. 2008;38(6):1267-90.

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