Laurie Anne Walden, DVM Photo by Zoë Gayah Jonker on Unsplash Asthma is one of the most common respiratory diseases in cats. It isn’t curable but can be managed with medication. Many cats are treated with inhalers attached to a face mask delivery system developed specifically for cats.
Causes Asthma is caused by an allergic response to something a cat has inhaled, like smoke, vapors, dust, pollens, or other substances. The resulting inflammation inside the airways causes swelling, mucus production, and airway constriction (muscle spasm), all of which reduce airflow. Cats of any age can have asthma, but it’s most often diagnosed in young adults. Asthma episodes can be triggered by stress and exertion as well as by substances in the environment. Signs Some cats with asthma cough every day; others have only occasional episodes. Cats with asthma can suddenly develop life-threatening respiratory distress at any time if something triggers airway constriction, even if their condition is usually mild. These are the typical signs of asthma in cats:
In cats, coughing can easily be mistaken for hacking up a hairball or vomiting. If you’re not sure whether your cat is coughing or vomiting, take a video if possible and schedule a veterinary examination without delay. Diagnosis Making a diagnosis of asthma can be complicated because the signs are very similar to those of other heart and lung disorders, like heart disease, chronic bronchitis, infections (bacterial, viral, fungal, or parasitic), cancer, and heartworm disease. Physical examination sometimes but not always reveals changes in breathing pattern and lung sounds. In many cats with asthma, chest radiographs show evidence of airway thickening. However, radiographs can look completely normal in cats with asthma. Additional tests are used to rule out other disorders. Some cats need advanced procedures like bronchoscopy. Response to treatment can support a diagnosis of asthma. Airway constriction is partly reversible with medication. For cats with respiratory distress caused by asthma, emergency injection of a bronchodilating drug typically improves breathing within a few minutes. Treatment Cats with severe asthma and respiratory distress need emergency care including oxygen, bronchodilators, and other medications. They must be handled carefully to minimize stress. The goals of asthma management are to reduce airway inflammation and treat airway constriction. Owners of cats with asthma need to remove as many environmental triggers as possible:
Cats with asthma need corticosteroids for life to reduce airway inflammation. Some cats also need long-term bronchodilator therapy to reduce airway constriction. However, many cats do well with steroid therapy alone, and their owners keep a bronchodilator on hand to give as rescue therapy during asthma events. Metered dose inhalers (the same ones used by people) are a good option for many cats. Inhaled corticosteroids are delivered directly to the airways and are less likely to cause the adverse effects that long-term oral or injectable steroid therapy can cause in cats. It takes time for inhaled corticosteroids to reach full effect, so cats need to start with an oral or injectable form and transition to inhaled medication over a couple of weeks. Bronchodilators are also available as inhalants. Just like small children with asthma, cats can’t time their breathing to inhale exactly when someone puffs an inhaler at them. Spacers were invented to solve this problem for children, and they’re available for cats too. Spacers are chambers with an inhaler attached to one end and a face mask attached to the other. The medication puffed from the inhaler stays inside the chamber until the child (or cat) inhales it by taking several normal breaths through the mask. Cats can be trained to accept the face mask and spacer. The training process takes time; you do not want to slap a device straight onto the face of an unprepared cat who needs to avoid stress. More Information
Image source: https://unsplash.com/photos/shallow-focus-photo-of-orange-cat-uhnbTZC7N9k Laurie Anne Walden, DVM Photo by Grant Durr on Unsplash Injury of the cranial cruciate ligament in the knee is a common cause of hind limb lameness in dogs. Surgery is often the best treatment option.
The cranial cruciate ligament is one of the main structures that stabilizes the knee joint. This ligament is called the anterior cruciate ligament in humans. In humans, injury to this ligament is usually caused by trauma, especially while playing sports. In dogs, cranial cruciate ligament injury is more often caused by long-term, gradual degeneration that results in a partial or full ligament tear. Some of the factors involved in cranial cruciate ligament degeneration in dogs are age, knee conformation, genetics, and body weight. Because these factors affect both knees, many dogs with a ligament tear in one knee develop the same problem in the other knee within a year or two. Many dogs with cranial cruciate ligament injury also have a torn meniscus in the knee. The meniscus is a cartilage pad that provides cushioning between the femur (upper leg bone) and tibia (lower leg bone). A torn meniscus is painful. A meniscal tear can happen at the same time as the injury to the cranial cruciate ligament or much later as a result of knee instability. Cranial cruciate ligament injury causes knee arthritis. The rate of progression of the arthritis partly depends on how the cruciate ligament injury is treated (with surgery or with medical management alone), meaning how soon the knee joint is stabilized. Signs A sudden full tear of the cranial cruciate ligament causes significant lameness; dogs are often unable to bear any weight on the affected leg. The signs of partial ligament tears and chronic ligament degeneration are less obvious. In these cases the lameness might improve with rest but doesn’t entirely disappear. Meniscal tears can cause a clicking sound in the knee joint. Arthritis resulting from chronic cruciate ligament injury eventually causes thickening of the knee joint. Diagnosis Full cranial cruciate ligament tears can often be diagnosed during a physical examination with tests that reveal instability in the knee joint. However, dogs are sometimes too tense (because of knee pain) for these tests. X-ray images sometimes show evidence of cruciate ligament rupture and can also help rule out other possible causes of the lameness. Partial tears and meniscal tears are harder to diagnose and are typically found with advanced imaging techniques or seen during knee surgery. Treatment Cranial cruciate ligament injury is treated either surgically or with medical management alone. The choice of treatment for an individual dog depends on the type of injury; the dog’s size, age, activity level, and state of health; and the owner’s preferences and financial resources. For dogs with a complete ligament tear, surgical treatment followed by physical rehabilitation usually yields the best functional result. A number of surgical options are available and are typically performed by a veterinary surgery specialist. The torn ligament can’t actually be repaired, so the goals of surgery are to stabilize the joint and remove damaged (painful) parts of the meniscus. Some surgical techniques change the biomechanics of the knee joint by cutting into the tibia to adjust the way the large leg muscles attach to the front of the knee. Other techniques use suture material to mimic the function of the cranial cruciate ligament. All surgical options require strict exercise restriction for several weeks to a few months after the procedure. Medical management involves exercise restriction and anti-inflammatory medication. Physical rehabilitation and custom orthotics, or knee braces, might help some dogs. Weight management is crucial for overweight dogs with knee ligament injuries. For more information about treatment options, see the American College of Veterinary Surgeons website: https://www.acvs.org/small-animal/cranial-cruciate-ligament-disease/ Image source: https://unsplash.com/photos/yellow-labrador-retriever-puppy-lying-on-white-textile-biW4WcdmZyA Laurie Anne Walden, DVM Photo by Borna Bevanda on Unsplash Feline infectious peritonitis (FIP) is a viral disease that until recently was untreatable and almost always fatal in cats. An effective antiviral drug emerged a few years ago but was legally unavailable in the United States. Some cat owners bought the drug at high cost on the international black market, but this product was unregulated, untested, and possibly unsafe.
A compounded version of this antiviral drug, GS-441524, is now available in the United States by veterinary prescription. This means that FIP has become a treatable disease instead of a near-certain death warrant for cats. The US Food and Drug Administration (FDA) hasn’t officially approved the compounded product for use in cats. However, the FDA announced that because no approved drug is available, it won’t enforce drug approval requirements when a veterinarian prescribes this product for an individual cat.[1] Signs and Diagnosis of FIP The virus that causes FIP is a coronavirus. Feline coronavirus infection is very common in cats. The virus typically lives in the intestines without causing much trouble. In some cats, feline coronavirus mutates into a disease-causing strain that spreads through the body. This disease is FIP. The signs of FIP depend on whether a cat has the “wet” form (with fluid accumulation in the chest and abdomen) or the “dry” form (with inflammatory masses and other changes in the eyes, nervous system, kidneys, liver, or other organs). Some of the signs are swollen belly, decreased appetite, decreased energy, weight loss, fever, labored breathing, blindness, and seizures. Because the signs of FIP are nonspecific and because so many cats have been infected with feline coronavirus, diagnosis is not simple. The diagnosis is often presumptive, meaning that it’s not confirmed by definite tests but is suspected on the basis of clinical signs and the results of blood and urine tests, imaging studies, fluid analysis, and biopsy. Treatment GS-441524 is a metabolite of remdesivir. Remdesivir is used to treat COVID-19 in humans, but it’s not licensed for use in animals. Veterinarians can treat animals off label with drugs licensed for humans, so remdesivir is technically a treatment option for cats but it’s hard for veterinarians to access. Unlike remdesivir (an injectable product), compounded GS-441524 is a tuna-flavored tablet. It’s already being used to treat cats in Australia and the United Kingdom. The dose depends on the cat’s clinical signs, and the current recommendation is to continue treatment for 12 weeks. Reported survival rates for cats treated with GS-441524 range from 81% to 100%.[2] Without this treatment—or a similar antiviral drug if one becomes available—the prognosis is grim. References 1. FDA announces position on use of compounded GS-441524 to treat FIP. US Food and Drug Administration. May 10, 2024. Accessed September 3, 2024. https://www.fda.gov/animal-veterinary/cvm-updates/fda-announces-position-use-compounded-gs-441524-treat-fip 2. Tasker S, Addie DD, Egberink H, et al. Feline infectious peritonitis: European Advisory Board on Cat Diseases guidelines. Viruses. 2023;15(9):1847. doi:10.3390/v15091847 Image source: https://unsplash.com/photos/gray-tabby-kitten-leaning-on-white-wall-VwqecUsYKvs Laurie Anne Walden, DVM Image by Chris Murphy on Flickr Cleaning the litter box might not be your favorite chore, but it has a major benefit: it helps you monitor your cat’s health. Some serious illnesses that are common in cats affect their toileting behavior, urine output, and stool consistency. By scooping the litter box a couple of times a day, you can find evidence of these problems much sooner than you would if your cat toileted outdoors.
Signs to Watch For Contact your veterinarian if your cat shows any of these signs:
You don’t need to use specialty products like color-changing cat litter (marketed as a health screening tool) to detect problems. If you decide to try cat litter that changes color according to pH or other chemical factors, keep a couple of cautions in mind. First, be sure your cat is willing to use the litter. The right kind of litter is whatever kind your cat is comfortable with. For most cats, this means unscented litter that is scooped daily and replaced regularly. Second, don’t rely on the litter to rule out a medical problem. Color-changing litter can’t be used for diagnosis and might not be accurate even for screening. If your cat shows signs of a problem but the litter’s color indicator hasn’t changed, contact your veterinarian anyway. What Urine and Stool Changes Might Mean Toileting Behavior Cats tend to hide signs of illness and pain, so we need to watch for subtle behavior changes as clues to medical problems. Visiting the litter box more often might be caused by increased urinary urgency, increased urine volume, or diarrhea. Visiting the litter box less often could indicate arthritis, other mobility problems, stress, general illness, or competition from other pets. Urinating and defecating outside the litter box have lots of possible medical causes, so don’t assume your cat is just being spiteful (cats don’t feel that kind of emotion). Urine Clumps When you scoop the litter, pay attention to the size of the urine clumps. Clumps getting bigger over time could mean that your cat’s urine volume has increased. Kidney disease, diabetes, and thyroid disease are all common in cats and cause increased urine volume. A decrease in size or number of urine clumps might mean that your cat is urinating somewhere else in the house. Male cats with urinary blockage (a life-threatening emergency) produce no or very small amounts of urine. Stool Signs of urinary problems (like straining or frequent squatting in the litter box) can be mistaken for constipation. Cats with constipation produce either small hard stools or no stools. Soft stool and diarrhea are more common than constipation in cats and have many possible causes. If your cat has soft stool that lasts for more than a day, blood in the stool, or small hard stools, contact your veterinarian. Save a sample of stool that’s less than 24 hours old in case your veterinarian needs it for testing. Image source: https://www.flickr.com/photos/134294785@N06/21911087653/ Laurie Anne Walden, DVM Uffizo, a 13-week-old Maine coon, is examined by Capt. Sarah Bohac at the Fort Knox veterinary clinic. Photo by Jaden Whiteman, CST Public Affairs Office. A hands-on physical examination is a valuable part of annual wellness visits as well as sick-animal visits. Examinations during wellness visits often uncover problems that weren’t obvious at home. That is the point of a wellness exam: we want to find problems early, before they become more serious and harder to treat. Wellness exams also let us track an animal’s changes over time. For sick animals, the physical exam is a crucial part of the diagnostic workup.
Not all veterinary visits involve a full physical exam. Recheck visits typically include assessment of only a single area (like the ears). And high-volume, limited-service settings like vaccine clinics generally don’t offer full physical exams. A veterinarian can often complete a physical exam within a few minutes, so you might not realize how much information your veterinarian is gathering by looking at, touching, and even smelling your pet. The following basic assessments are part of a comprehensive physical examination. Breathing effort, mental status, posture, gait, general appearance, and reaction to clinic environment: The veterinarian assesses these elements before ever touching the animal. These items are clues to the urgency of a sick animal’s condition and also tell us an animal’s overall state of health, basic neurologic status, and anxiety level. If an animal without an urgent medical problem shows signs of significant fear and anxiety in the clinic, the veterinarian might stop the examination at this point and recommend returning another day with previsit antianxiety medication. Temperature, pulse, and respirations (TPR): The TPR is part of the standard vital sign assessment, along with mucous membrane color and capillary refill time (assessed with a quick touch of the gums). Some animals object to rectal thermometers, and other types of thermometers aren’t always accurate, so the veterinarian might skip temperature measurement for a well animal. Eyes, ears, nose, and oral cavity: Dental disease is very common in dogs and cats, and external ear disease is common in dogs. These problems are often first noticed during wellness exams. The veterinarian might or might not use an ophthalmoscope and otoscope to examine the eyes and ears, depending on the animal’s clinical signs and comfort level (inserting an otoscope into an inflamed ear canal could be painful). Chest: The veterinarian listens to the heart and lungs with a stethoscope to check heart rate and rhythm, identify abnormal heart sounds like murmurs, and assess lung sounds. Abdomen: Gentle palpation of the abdomen can reveal discomfort and possibly abnormal size of individual organs. Musculoskeletal system: The veterinarian assesses muscle mass, especially in senior animals that might have arthritis, and checks the joints for common problems like patellar luxation. Animals that are limping receive a more comprehensive orthopedic examination including range-of-motion tests of multiple joints unless this would be too painful without sedation. Skin and lymph nodes: The veterinarian looks for external parasites like fleas, evidence of itching (saliva staining of the paws, for example), hair loss, signs of skin infection, skin lumps, mammary gland masses, and enlarged lymph nodes. Skin problems are very common in dogs and cats and often turn up during wellness examinations. Many skin problems need further diagnostics, such as looking at a sample of cells through a microscope. Neurologic system: For well animals with no signs of neurologic disease, the veterinarian assesses basic neurologic function and mental status. A more comprehensive neurologic examination includes tests of nerve function of the head and limbs. For animals with neck or back pain, the veterinarian carefully palpates the spine to pinpoint the location of the pain. Urogenital system: Male dogs that have not been castrated have their testicles checked. They might also have rectal palpation to evaluate the prostate. Female dogs and castrated male dogs get a quick glance at the external genitalia and receive a more thorough examination if they have signs of a problem. Image source: https://www.flickr.com/photos/armyrotc/52943246855/ Laurie Anne Walden, DVM Photo by Sophie Shankey on Unsplash Tracheal collapse causes a chronic dry cough that sounds similar to a goose honk. The disease tends to get worse with time. Tracheal collapse can’t be cured, but for most patients, medical treatment reduces the severity of the cough. In the most serious cases, tracheal collapse interferes with breathing and requires emergency care.
Tracheal collapse can affect dogs of any breed but is most common in small-breed dogs like Yorkshire terriers and Pomeranians. It’s rare in cats. Cause The trachea (windpipe) is a tube held open by rings of cartilage. In animals with tracheal collapse, the cartilage rings soften and become weakened over time. The cartilage rings lose their ability to hold the trachea open and the trachea flattens during breathing or coughing, blocking the flow of air. The severity of the signs depends on the percentage of airway that’s blocked. The signs also partly depend on the location of the affected section of trachea: outside the rib cage (in the neck) versus within the rib cage. In dogs with tracheal collapse, coughing is made worse by pressure on the neck, excess weight, stress, excitement, exercise, respiratory irritants like smoke, and respiratory infections. Some dogs with tracheal collapse also have abnormalities of the larynx and the bronchi (airways inside the lungs). Chronic coughing causes airway inflammation, which in turn leads to more coughing. Tracheal collapse and heart disease are both common in middle-aged and older small-breed dogs, so many dogs have both diseases at the same time. Both diseases cause coughing and exercise intolerance. Figuring out which disease is most responsible for the cough can be a bit of a diagnostic challenge. Signs
Diagnosis Tracheal collapse is suspected on the basis of the patient’s history, the sound of the cough, and physical examination findings. A definite diagnosis is made with imaging studies. Radiographs (x-ray images) sometimes show a collapsed trachea and are also used to evaluate heart size and the appearance of the lungs. In many dogs the trachea collapses only on inhalation or only on exhalation, so fluoroscopy—an x-ray “movie”—can reveal collapse that doesn’t appear on radiographs. Tracheoscopy is examination of the inside of the trachea and bronchi with a fiber optic camera in an endoscopy tube. An advantage of tracheoscopy is that it allows samples from inside the trachea to be collected for laboratory analysis; a disadvantage is that it requires general anesthesia. Dogs with tracheal collapse might have bloodwork to assess their overall condition, especially if they are older or have concerning clinical signs. Because the signs of tracheal collapse and heart disease overlap, dogs with suspected or known heart disease also benefit from echocardiography to evaluate heart function. Treatment Tracheal collapse isn’t curable, so medical treatment needs to continue for life. Medications chosen for an individual patient might include cough suppressants to break the cough cycle, corticosteroids to reduce airway inflammation, bronchodilators, and antianxiety medications or sedatives to reduce stress. The choice of medication can change over time as the dog’s disease progresses. Nonmedical management is crucial for dogs with tracheal collapse and includes the following:
Surgical procedures like tracheal stent placement are available for dogs with severe signs. However, surgical options don’t cure the underlying tracheal problem and might not eliminate the cough. Image source: https://unsplash.com/photos/a-small-dog-standing-under-a-wooden-bench-HSs4t4TWPFg Laurie Anne Walden, DVM Photo by Saru Robert on Unsplash If your cat vomits, don’t assume it’s because of hairballs (or just because he’s sitting on an expensive rug). Vomiting has lots of possible causes, and some are serious. A mistaken belief that vomiting is normal for cats can delay diagnosis and treatment.
When to Seek Veterinary Care Many cats vomit occasionally, just like dogs and people. Some cats vomit frequently, and these cats need an examination and diagnostic tests. “Frequently” means different things for different cats, but in general, cats that vomit more than about once a month should see a veterinarian. These are some other signs that a vomiting cat needs veterinary care:
Vomiting or Coughing? Respiratory problems in cats can be mistaken for vomiting. Coughing can look a lot like hacking up a hairball. Asthma is common in cats, and the hunched posture and raspy breathing of an asthma attack can look and sound very similar to retching. True vomiting means forcefully expelling stomach contents from the mouth. Hacking up food or a hairball is vomiting. Hacking up a little bit of foam is harder to interpret. Signs that the problem is with the lungs or heart instead of the stomach include open-mouth breathing, wheezing, and increased sleeping respiratory rate (more than 30 breaths per minute while asleep). It’s OK if you can’t tell if your cat is vomiting or coughing. Take a video to show your veterinarian and make an appointment as soon as you can; lung and heart problems shouldn’t wait. Causes of Vomiting Vomiting has too many possible causes to list here. These are some of the most common in cats:
Diagnostic Tests The tests chosen depend on the cat’s history, signs, and physical examination findings. Cats with chronic vomiting typically undergo a series of tests until the cause is found. Baseline laboratory tests include bloodwork, urinalysis, and stool tests for parasites. Radiography (x-ray imaging) can show some of the problems that cause vomiting; ultrasonography is more useful for others. Inflammatory bowel disease and some other intestinal disorders are diagnosed with biopsy of the intestine, which requires general anesthesia. Treatment The type and duration of treatment depend on the cause. Foreign objects and hairballs that are blocking the intestine are removed surgically. Some problems can be treated with a single course of medication; others require lifelong treatment. If your cat resists oral medication (pills or liquids), tell your veterinarian so you can explore alternatives. Image source: https://unsplash.com/photos/a-gray-cat-sitting-on-top-of-a-rug-ybibgcEcv2w Laurie Anne Walden, DVM Photo by Manja Vitolic on Unsplash Urinary tract disorders are common in cats. Feline lower urinary tract disease (FLUTD) is a general term that describes disorders of the bladder and urethra. A number of disorders cause FLUTD, so cats with any changes in urination or litter box behavior need to see a veterinarian.
Signs Cats with FLUTD have similar signs regardless of the underlying cause:
Causes Idiopathic Cystitis The most common cause of FLUTD is idiopathic cystitis. Idiopathic means “of unknown cause,” so this condition is diagnosed when tests don’t reveal another cause. Chronic stress appears to be a major risk factor. An abnormality of the bladder lining could also be involved. Idiopathic cystitis is managed rather than cured. The signs tend to come and go over time. Flare-ups often improve on their own regardless of treatment, which makes it hard to tell if a particular treatment has actually had any effect. Cats with idiopathic cystitis are treated with stress-reducing measures like environmental enrichment and antianxiety medication. Some cats benefit from other medications or special diets. Urinary Tract Infection Urinary tract infections are uncommon in young and middle-aged cats. Cat urine is normally so concentrated that bacteria can’t easily survive in it. However, diseases that affect urine concentration and chemical composition (like kidney disease and diabetes) are very common in older cats, so cats in this age group are much more likely to have urinary tract infections. A diagnosis of urinary tract infection requires urinalysis and ideally a urine culture to identify the specific bacteria. Older cats with urinary tract infections should also have bloodwork and radiography or ultrasonography of the abdomen to find the underlying cause. Bacterial urinary tract infections are treated with antibiotics, ideally chosen according to culture results. Uroliths (Bladder Stones) Uroliths are rocklike mineral collections that form in the bladder or any other part of the urinary tract. Uroliths are found with radiography or ultrasonography. Some types of uroliths can be dissolved with a prescription diet; others require surgical removal. Even the dissolvable types often need to be removed surgically because they can be painful, cause infection, and block the urethra of male cats. Uroliths that form in a kidney or ureter (the tube connecting the kidney to the bladder) usually warrant referral to a veterinary surgery specialist. Urethral Obstruction Urethral obstruction is a life-threatening condition in which a urolith or mucus plug blocks the urethra. Male cats are at much higher risk than female cats because male cats’ urethras are narrower and longer. Cats with urethral obstruction initially have the same signs as cats with FLUTD from any other cause. If the obstruction isn’t removed, the bladder becomes large and painful and can rupture. The kidneys can no longer function normally, and the cat can die of toxin buildup and electrolyte imbalance. Cats with urethral obstruction need emergency care and usually at least a few days of hospitalization. Other Causes Cancer, injury of the spinal cord or urinary tract, and anatomical problems with the urinary tract can also cause FLUTD. Image source: https://unsplash.com/photos/black-and-white-cat-lying-on-brown-bamboo-chair-inside-room-gKXKBY-C-Dk Laurie Anne Walden, DVM Photo by Kari Shea on Unsplash Arterial thromboembolism (ATE) in cats has a guarded to poor prognosis and a high mortality/euthanasia rate. In ATE, a blood clot forms in the heart, travels through the circulation, and lodges in an artery. The clot blocks blood flow through that artery, causing significant pain and tissue damage. When the clot blocks an artery supplying a limb, as is usually the case, the limb becomes weak or paralyzed.
The most common site for ATE in cats is the aorta at the point where it divides into smaller arteries that supply the rear legs. A clot stuck here takes on the shape of a saddle, so ATE in this location is called a saddle thrombus. Cats with a saddle thrombus have sudden extreme pain and paralysis of the rear legs (usually both rear legs but sometimes just 1). Witnessing their pain and distress can be quite upsetting to their caretakers. Cause ATE is usually caused by heart disease. Unfortunately, a saddle thrombus can be the very first sign that a cat has heart trouble. The most common type of heart disease in cats—and thus the most common cause of ATE—is hypertrophic cardiomyopathy, an abnormal thickening of the heart muscle. Hypertrophic cardiomyopathy is most common in senior cats but can also affect younger cats. An estimated 15% of all cats and up to 29% of senior cats have hypertrophic cardiomyopathy.[1] Of these cats, a reported 11.3% develop ATE within 10 years after diagnosis.[2] Signs Signs of ATE usually appear suddenly. A cat with ATE will cry loudly in pain and might vomit. The cat will drag the affected limb or be unable to walk. The affected limb might feel cool to the touch. If the cat’s underlying heart disease has progressed to heart failure, the cat might also have signs like panting or rapid breathing. Diagnosis ATE can usually be diagnosed with a physical examination. The affected limb is typically cool, the nail beds are bluer or paler than those of the other paws, and the pulse in that limb is absent or weak. A heart murmur might be present. Diagnostic tests can be used to rule out other possible causes, especially if the cat has less obvious signs caused by a partial blockage. Treatment Many cats with ATE are euthanized before treatment is attempted. Factors linked to a better prognosis include involvement of only 1 limb, ability to move the affected limb, and absence of heart failure (meaning that the heart disease has not yet progressed to the level of heart failure). For cats that receive treatment, the immediate priority is pain control. They also receive anticoagulant medications (blood thinners), treatment for shock and tissue damage, and treatment for heart disease. Cats that don’t have heart failure and survive the first few days in the hospital have a chance of regaining the use of the affected limb once the clot dissolves. Prevention For cats known to have heart disease, certain findings on echocardiography (heart ultrasound) can indicate an increased risk for ATE. These cats can receive preventive anticoagulant medications. However, many cats with heart disease have no obvious signs, so their heart disease isn’t diagnosed. References 1. Luis Fuentes V, Abbott J, Chetboul V, et al. ACVIM consensus statement guidelines for the classification, diagnosis, and management of cardiomyopathies in cats. J Vet Intern Med. 2020;34(3):1062-1077. doi:10.1111/jvim.15745 2. Lo ST, Walker AL, Georges CJ, Li RH, Stern JA. Dual therapy with clopidogrel and rivaroxaban in cats with thromboembolic disease. J Feline Med Surg. 2022;24(4):277-283. doi:10.1177/1098612X211013736 Image source: https://unsplash.com/photos/gray-tabby-cat-FilM6ng7VGQ Laurie Anne Walden, DVM Photo by Anya Prygunova on Unsplash In recent years, monoclonal antibodies have been approved to treat some common medical conditions in animals:
More monoclonal antibodies are likely to become available for dogs and cats. Monoclonal antibodies are used in humans to treat infections, autoimmune disorders, cancer, and other conditions, and they’re being investigated for similar uses in dogs and cats. How Monoclonal Antibodies Work Monoclonal antibodies are in a therapy class called biologics, meaning therapies made from living sources like animal cells, plant cells, or microorganisms. Biologics are large molecules that interact with receptors on the outer surfaces of cells; they don’t enter cells. In contrast, most traditional drugs are small molecules that work inside cells. Monoclonal antibodies are similar to the natural antibodies produced by the immune system. When the immune system detects an antigen, different immune cells release lots of different antibodies that tag different sites on that antigen. (An antigen is anything that triggers an immune response.) Once the antibodies have tagged the antigen, other components of the immune system arrive to destroy it. Monoclonal antibodies are cloned in a laboratory from just one antibody made by one type of immune cell (mono means “one”). They tag only a single site on an antigen. Monoclonal antibody therapy can be very precise because it directs the immune response to a narrow target. In addition to tagging invaders like viruses, monoclonal antibodies can be engineered to tag a receptor on an animal’s own cells. The monoclonal antibodies that relieve pain in dogs and cats, for example, block production of a protein that’s partly responsible for the pain sensation. After monoclonal antibodies have activated the immune system, they’re broken down in the body the same way that natural antibodies are. Unlike small-molecule drugs that enter an animal’s cells, they aren’t cleared through the liver or kidneys. Administration Monoclonal antibodies are given by injection at a veterinary clinic. They can’t be given by mouth because they’re proteins and would be destroyed by digestion. Their effect lasts a few weeks (4-8 weeks for Cytopoint, 4 weeks for Solensia and Librela). These therapies are species specific: monoclonal antibodies for dogs work only for dogs, not for cats. Benefits The monoclonal antibodies that are available for dogs and cats generally work well for their approved uses. They are less likely than some traditional drugs to cause adverse effects because they have a narrow target of action and don’t enter cells. Because they are not cleared through the liver or kidneys, they can be safer than other drugs for animals with liver or kidney disease. Injections given every few weeks might be more convenient for pet owners than pills given multiple times a day, especially if their pets resist oral medication. Adverse Effects Monoclonal antibodies have fewer adverse effects than many traditional drugs. An antibody injection can cause an allergic reaction, although this is rare. Manufacturers might recommend precautions for individual monoclonal antibody products. Image source: https://unsplash.com/photos/a-dog-wearing-a-baseball-glove-E3K7xyAvQ8M |
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The contents of this blog are for information only and should not substitute for advice from a veterinarian who has examined the animal. All blog content is copyrighted by Mallard Creek Animal Hospital and may not be copied, reproduced, transmitted, or distributed without permission.
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