Winter 2003 PetNews Issue.
Winter PetNews Issue.
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SMALL ANIMAL NEWS
By Miguel Gavar
Hyperthyroidism (also called thyrotoxicosis) is one of the most common diseases of the middle-aged and older cat. It is a multi-system disorder caused by an increase in the amount of thyroid hormones (T3 and T4) produced by an enlarged thyroid gland. It was first documented in cats almost 30 years ago but the cause of the disease has been elusive. Although the enlargement in the thyroid gland is caused by a tumor called an adenoma, it is non-cancerous.
The most common clinical signs of hyperthyroidism in cats include weight loss, increased appetite (although some patients have decreased appetite), vomiting, increased thirst and urination, hyperactivity, and diarrhea. The high levels of thyroid hormones can cause the development of heart disease, and these patients may have a heart murmur, difficulty breathing, high heart rate and arrhythmias.
Veterinarians will order a blood chemistry panel as well as a thyroid hormone (T4) level in cats suspected of being affected by this disease. It is important to evaluate the health of the other major organs, including the kidneys and heart in these patients. Typically, hyperthyroid cats may have elevations in their liver enzymes. Chest x-rays and
cardiac ultrasound may reveal secondary hypertrophic cardiomyopathy. Generally, the cardiac changes will reverse when the hyperthyroidism is treated. In some cases, specific heart medication may be needed to stabilize cardiovascular health. In recent years, it has been recognized that many hyperthyroid cats have concurrent chronic kidney failure that is being masked by the effects of hyperthyroidism. It has also been found that treatments directed at curing hyperthyroidism in these patients could lead to a worsening of their kidney function.
Most hyperthyroid cats will have elevated levels of the thyroid hormone T4 in their bloodstream on a routine screening test. However, a small percentage of hyperthyroid cats will have normal T4 levels. If hyperthyroidism is still strongly suspected in these patients, a more sensitive test called the T3 suppression test can be performed to confirm the diagnosis. In this test, the cat is given seven oral doses of the thyroid hormone T3. Blood levels for both T3 and T4 hormones are checked before and at the end of the administration of the medication. In a normal cat, the administration of T3 hormone will cause the blood levels of T4 to drop by a negative feedback mechanism. In a hyperthyroid cat, the T4 levels will not decrease at all or will decrease very little. In this way, the veterinarian can distinguish between cats with hyperthyroidism and cats with other diseases with similar symptoms.
Once hyperthyroidism has been confirmed, there are several treatment options. They include treatment with radioactive iodine, surgical removal of the gland, and treatment with anti-thyroid medications. The initial choice of treatment is often guided by concern about the patient's kidney function status. Some cats have detectable impairment of kidney function at the time of their diagnosis with hyperthyroidism, but many do not. It is difficult to assess kidney function accurately from routine blood testing in cats. Generally about 2/3 of the kidney function must be lost before routine blood tests will show any abnormalities. This has made it very difficult in the past to detect which cats with hyperthyroidism actually have concurrent kidney failure. However, Michigan State University has introduced a very sensitive test of kidney function in cats and dogs called the iohexol clearance test. In this test, a radiographic contrast agent called iohexol is injected intravenously and the rate at which the kidneys clear the agent from the bloodstream is measured. The test is carried out in the veterinarian's office and a series of blood samples is sent to the MSU lab for analysis.
Since hyperthyroidism induces increases in blood pressure and blood supply to the kidneys, treating the disease will result in a drop in the blood supply to the kidneys. In a cat with kidney failure, this can cause a worsening of their kidney function in the few months after treatment for hyperthyroidism with either radioactive iodine or surgical removal of the gland. For this reason, patients with known kidney disease (either detected on routine blood work or with the iohexol clearance test) are often treated with anti-thyroid medications rather than surgery or radioactive iodine in an effort to preserve their remaining kidney function. Using medications allows the veterinarian better control over the concurrent kidney disease and may allow the patient to survive longer.
For hyperthyroid cats that are assessed with normal kidney function, surgery or radioactive iodine treatment are often recommended. Both these options provide a cure of the hyperthyroidism and avoid the need for life-long administration of medication. In areas where radioactive iodine treatment is available, it is usually the treatment of choice since this option avoids the risks of anesthesia and surgery. However, this is not a widely available treatment choice and veterinarians have become very skilled in surgical removal of the thyroid gland (thyroidectomy), making this an excellent option for treatment of hyperthyroidism in many cats.
In general, the treatment a cat receives for hyperthyroidism will depend on individual status, including heart and kidney function. Concern about kidney failure is a major determinant of the course of treatment and may eliminate radioactive iodine or surgery as an option. The advent of new kidney function testing makes it possible to assess each patient's risk of kidney failure following treatment for hyperthyroidism.
Winter Pet Safety
Although we only get a mild to moderate winter here in the island, winter can still be a challenge for most of our pets. Here are some common dangers to watch for and what to do to avoid these problems.
If your pet is housed outside, make sure that adequate shelter is provided -- to shield from wind, moisture, and cold. Take extra care to ensure that your pet is comfortable and can get into and out of their housing easily.
Pets need to have fresh water at all times - make sure the water is not frozen during this time of year. Contrary to what some people think, animals do not know how to break the ice. (OK, some may have learned this trick, but they are in the minority). Heated pet bowls are a solution for frigid temperatures.
Several pet and feed stores carry safe heated floor mats or non-electric warm bedding. Deeply bedded straw is another good insulator. Do not use a heat lamp or other type of home heater - this is dangerous, and is the cause of many fires.
Cold, damp weather aggravates arthritis. Arthritis can appear in young pets, but is most common in the middle age and geriatric pets. A fracture can also make the bone susceptible to arthritis after the injury is healed. Overweight pets suffer from arthritis more than their normal-weight counterparts.
If your pet is having trouble getting up or laying down, navigating the stairs, or has started to snap or cry when picked up, a visit to the veterinarian is in order. Many new arthritis treatments are available, both natural and traditional.
NEVER medicate your dog with human prescription or over-the-counter medications without consulting your veterinarian first! One Tylenol™ tablet can be fatal to a cat.
This is actually a winter and summer potential problem. Cats and dogs are attracted to the sweet smell and taste of antifreeze, and will often sample some if left out in a container or spilled on the garage floor.
Antifreeze is highly toxic - it is rapidly absorbed (initial signs appear approximately one hour post-ingestion), and there is a high mortality rate. Other sources of this deadly chemical are: heat exchange fluids (sometimes used in solar collectors), some brake and transmissions fluids as well as diethylene glycol used in color film processing.
Acute cases (within 12 hours of ingestion) often present as if the animal was intoxicated with alcohol: stumbling, vomiting and depression are common signs. The kidneys are most severely affected, and even if the animal seems to improve initially with treatment, they may succumb shortly after to kidney failure. The kidneys shut down, and the animal is unable to produce urine. This type of kidney failure usually happens 12-24 hours after ingestion in cats, and 36-72 hours post ingestion in dogs. Success of treatment is dependent upon quick treatment. If you suspect that your animal has come into contact with antifreeze, contact your veterinarian immediately.
A safe alternative to Ethylene Glycol antifreeze is available, it is called propylene glycol, and while it does cost a small amount more than 'regular' antifreeze, it is worth the piece of mind.
Pardon the “Anal Expression”
By Miguel Gavar
Most cats and dogs owners asked why their normally sweet-smelling pets stink some times. Chances are the animal is also noticed scooting, rubbing the hind end in their living room carpets and constantly licking and biting at the anal area, perineum and base of tail. Chewing and licking may result in areas of self-inflicted skin problems. Anal sac disorders are the most common problem of the anal area in small animals, especially in dogs and cats. The specific cause of anal sac disease is poorly understood. It is believed to be associated with conditions that promote inadequate emptying of the sacs, which should normally occur during defecation when feces of normal consistency are forced through a normally functioning anal sphincter. All breeds of dogs can be affected. Anal sac disease is uncommon in cats and usually involves only impaction.
What are anal glands and what do they do?
Technically, what we see and describe as "glands" are actually anal sacs, which contain the glands that secrete an oily, strong-smelling substance. Both male and female cats have anal glands, as do dogs and some other animals. You can see the anal sacs beneath the anus at roughly the 5 o'clock and 7 o'clock position. They are described as "pea-sized" in small dogs, and are smaller in cats.
In the wild, cats "express" this substance along with their feces, for marking purposes, a practice akin to leaving a calling card for subsequent visitors to read. As the anal canal opens for the feces to pass, the hard contents press against the anal glands, causing secretion of some of the substance. Cats will also spontaneously express their anal glands when alarmed, much as skunks do. Some veterinarians believe the anal gland is vestigial because it requires hard feces to properly express. They argue that the commercial cat food we give our kitties produces softer "poop," which doesn't exert the necessary pressure to make the gland work right. On the other hand, cats still "express" their anal glands when alarmed or upset, and this would certainly serve as a territorial marking, judging from the strong odor. Commonly-cited spontaneous expressions occur when a rectal thermometer is used on a cat, or when a groomer is working near the rectal area.
Some cats need to have their anal glands manually expressed from time-to-time, usually by a veterinarian or groomer, although a cat owner can learn the procedure, which is fairly straightforward.
Other Potential Problems with Anal Glands
How can I help prevent these problems?
Heightened awareness of your cat's usual physical condition and routines is as critical with his anal sac as with other body functions. Some experts believe a diet high in fat can contribute to thick, viscous anal sac secretions, which can harden and cause impaction. Others hypothesize that a diet higher in fiber will create firmer stools, thus facilitating the expression of anal sac substance. Your experience will vary, but diet is something you can discuss with your veterinarian. If you are interested in diet modification, your veterinarian can advise you with the type of food you can feed your pets. If your cat has had anal sac impaction in the past, or regularly needs to be manually expressed, you probably already are paying close attention to potential symptoms of problems.
If your cat has had no previous problems, just remain aware and be observant of changes. Being aware of your cat's normal body condition is probably the best thing you can do for your cat's overall health, in the long run.
Let’s Talk About WORMS:
Preventing Human Transmission of Worms From Animals
Ascarids (Toxocara canis, T. cati) and hookworms (Ancylostoma spp.) are common intestinal parasites of dogs and cats. Not only can ascarids and hookworms cause disease in their respective hosts, they are also well-known causes of larva migrans syndromes in humans, especially children. While ascarids and hookworms are most commonly diagnosed in puppies and kittens, infections can occur in dogs and cats of all ages. Dogs can also become infected with Baylisascaris procyonis, the common raccoon ascarid, which can cause serious disease in other animals and humans.1
Ascarids Because of the occurrence of both transplacental and transmammary transmission of T. canis, puppies are usually born with or acquire ascarid infections early in life. Kittens do not become infected in utero, but like puppies, can acquire ascarids (T. cati) through the queen’s milk.3 The tissue-migrating and early intestinal stages of these worms may cause severe, sometimes life-threatening, disease in the first few weeks of life. Left untreated, this can lead to widespread contamination of the environment with infective eggs.
Hookworms Both puppies and kittens acquire hookworm infections (A. caninum, A. braziliense, and A. tubaeforme) through ingestion of or skin penetration by infective larvae, or from infective larvae passed in their dam’s milk (A. caninum).2 Hookworms suck large amounts of blood from their hosts and while infected animals may look healthy in the first week of life, they can develop a rapidly severe, often fatal, anemia.
Zoonotic Transmission and Human Disease
The growing popularity of dogs and cats in the Canada, together with high rates of ascarid and hookworm infections, has resulted in widespread contamination of the soil with infective eggs and larvae. Epidemiologic studies have implicated the presence of dogs, particularly puppies, in a household, and pica (dirt eating) as the principal risk factors for human disease. Children’s play habits and their attraction to pets put them at higher risk for infection than adults.
Humans become infected with ascarids (Toxocara spp., Baylisascaris spp.) through ingestion of infective eggs in the environment. When a human ingests infective eggs, the eggs hatch and release larvae that can migrate anywhere in the body, a condition known as visceral larva migrans. The signs and symptoms seen in humans are determined by the tissues or organs damaged during larval migration. Organs commonly affected are the eye, brain, liver, and lung, where infections can cause permanent visual, neurologic, or other tissue damage. The common dog ascarid, T. canis, has long been recognized as a cause of larva migrans syndromes in children. The cat ascarid, T. cati, can also cause disease in humans, although for reasons partly related to the defecation habits of cats, it does so less frequently. The raccoon ascarid, B. procyonis, is increasingly being recognized as a cause of human disease.10
Humans can become infected with hookworms through ingestion of infective larvae or through direct penetration of the skin.7 When infective larvae penetrate the skin, they undergo a prolonged migration that causes a condition known as cutaneous larva migrans. These larval migrations are characterized by the appearance of progressive, intensely pruritic, linear eruptive lesions, which are usually more extensive with A. braziliense infections. A. caninum larvae may also penetrate into deeper tissues and induce symptoms of visceral larva migrans, or migrate to the intestine and induce an eosinophilic enteritis.11,12
Veterinarians Can Help Prevent Human Disease
Most cases of human ascarid and hookworm infections can be prevented by practicing good personal hygiene, eliminating intestinal parasites from pets through regular deworming, and making potentially contaminated environments, such as unprotected sand boxes, off limits to children. It is also important to clean up pet feces on a regular basis to remove potentially infective eggs before they become disseminated in the environment via rain, insects, or the active migration of the larvae. Once the eggs become infective, they can remain infective in the environment for years.
Most pet owners do not know that their pets may carry worms capable of infecting people. Therefore, practicing veterinarians can provide an important public service by recommending regular fecal examinations, providing well-timed anthelmintic treatments, counseling clients on potential public health hazards, and advising them on any precautionary measures that may be undertaken. Veterinarians are in an ideal position to provide pet owners with this service because of their access to the pet-owning public, their knowledge and training, and their role in the human-animal bond.
Preventive Anthelmintic Treatment
Because puppies, kittens, and pregnant and nursing animals are at highest risk for these infections, and therefore responsible for most of the environmental contamination and human disease, anthelmintic treatments are most effective when they are initiated early and targeted at these populations.
Avian Pet Feature:
Budgerigars (Melopsittacus undulatus), or "betcherrygah" as the Aborigines of Australia call them, are small parrots sporting a long tapered tail. Originally from Australia, the wild budgerigar is a green bird, with a yellow face, and black spots on the mask, black wavy bands on the wings, back and head. Once taken out of their native land and bred, color mutations occurred so that now there are so many color strains from which to chose.
Many people wonder if a parakeet and a budgerigar, also called budgie, are the same thing. A budgie is always a parakeet but a parakeet isn't always a budgie. To clarify, parakeet means small parrot. There are a number of birds in the psittacine family that have parakeet in their names such as Bourke's parakeets, green cheeked parakeets, orange chinned parakeets, etc. A budgie is a type of parakeet.
Budgies are readily available at inexpensive prices. But don't let their inexpensive price fool you. Their small bodies are packed with a huge personality. Budgies are very playful and mischievous and in most cases, easily tamed. Plenty of toys and playtime should be provided. Balls and bells seem to be big favorites, as well as objects to climb. Be aware that you will need to carefully follow rules of safety when your budgie is enjoying out of cage time. They are very curious and can get into trouble very fast. Accidents are the leading cause of death in budgies.
Most young budgies have stripes, or a wavy pattern, across their forehead which they lose after the first molt (molting is the shedding and regrowth of feathers). You may not be able to determine the sex of your budgie until after the first molt; the cere is beige or light pink color in young budgies. After the first molt (4-6 months of age) a male's cere will turn blue, and a female's will stay beige/tan. Of course there are exceptions to the rule depending on the color mutation of your budgie. One way to tell a young male from a female is their way of communicating. A young male will sit and sing away in a very sweet voice. A female sounds more like she is lecturing the world on everything it is doing wrong. Males tend to be much more vocal than females too.
Diet is very important. In the wild, budgies eat ripened green seeds and greens, not the dried seeds everyone thinks they eat. While we keep them in cages, we are responsible for providing a balanced diet. Pellets, vegetables, sprouts and some seed gives a varied, well balanced diet. Pellets should be available all the time, a veggie mix during the day, and a token amount of seed offered in the evening seems to work very well. If your budgie was fed a seed only diet, converting to pellets requires much patience, but will be well worth the wait.
Also important to a healthy happy bird is bathing. Budgies seem to think they are in the duck family and love nothing more than to splash around daily. But, like people, some budgies are bath birds and some are shower birds.
Housing is also important. Your budgie shouldn't be in too small a cage. An 18" cube is a decent size for a single budgie, although the larger the better. Cages that are longer than higher are more preferred. This gives them room to get some exercise because, contrary to popular belief, birds are closer to airplanes, than helicopters. Bar spacing should be no greater than 1/2 inch. If the bird's head can fit through the space between bars, the cage is not safe for a budgie.
On the Lighter Side:
A woman brought a very limp duck into a veterinary surgeon. As she lasy her pet on the table, the vet pulled out his stethoscope and listened to the bird’s chest. After a moment or two, the vet shook his head and said, “ I’m so sorry, your pet has passed away.”
The distressed owner wailed, “ Are you sure?”
“Yes, I’m sure. The duck is dead,” he replied.
“ How can you be so sure” she protested. “ I mean, you haven’t done any testing on him or anything. He might just be in a coma or something.”
The vet rolled his eye, turned around and left the room.
He returned a few moments later with a black Labrador retriever. As the duck’s owner looked on in amazement, the dog stood on his hind legs, put his front paws on the examination table and sniffed the duck from top to bottom. He then looked at the vet with sad eyes and shook his head.
The vet patted the dog and took it out and returned a few moments later with a beautiful cat. The cat jumped on the table and also sniffed the bird from its peak to its tail and back again.
The cat sat back on its haunches, shook its head, meowed softly, jumped down and strolled out of the room.
The vet looked at the woman and said, “ I’m sorry, but as I said, this is most definitely, 100% certifiably, a dead duck.” Then the vet turned to his computer terminal, hit a few keys and produced a bill, which he handed to the woman.
The duck’s owner, still in shock, took the bill. “$150 just to tell me my duck is dead?!!”
The vet shrugged. “I’m sorry. If you’d taken my word for it, the bill would have been $20. But with the Lab report and the Cat scan, it all adds up.”