Tag Archives: dogs

The Effect of Smoking on Dogs and Cats

We all know that smoking tobacco products is harmful to the smoker as well as their family who are exposed through second and thirdhand smoke. But what about the pets? Unfortunately, the pets are effected as well when they breathe in the toxic fumes or ingest the residue left behind in the environment. When burned, cigarettes release an amazing 7,000 chemicals including ammonia, arsenic, benzene, carbon monoxide, formaldehyde, hydrogen cyanide, lead, mercury, nicotine, toluene and uranium-236. Beside the smoker, other family members suffer secondhand exposure when they breathe the fumes. Eventually, the chemicals settle out of the air onto surfaces creating a residue. Thirdhand exposure occurs when chemicals are ingested, absorbed through the skin or inhaled through dust. Pets may also come into contact with these chemicals when they lick a smoker. These chemicals persist in the environment for months even with cleaning.

Dogs and cats who live with a smoker have an increased risk of cancer. The length of the dog’s nose will determine what kind of cancer they may develop. Dogs with long noses like Greyhounds and Dobermans have higher risks of cancer developing in their nasal passages because the cancer causing chemicals settle out there. The chemicals make it to the lungs in dogs with short and medium length noses.  This predisposes them to lung cancer. Cats have increased risk of lymphoma and squamous cell carcinoma of the mouth when they live with a smoker. The risk of a cat developing lymphoma increases by three times when they live with a 3 pack a day smoker. The squamous cell carcinoma occurs when cats groom the toxic chemicals from their fur. The risk for this aggressive cancer increases two to four times.

To prevent secondhand smoke, many people will smoke outside. Unfortunately, this does not prevent thirdhand exposure to pets and children because the toxic chemicals from tobacco contaminate the smoker’s hands and clothing. The chemicals are transferred to the children and pets through thirdhand contact. As mentioned above, pets are at the greatest risk if they lick the smoker.

For more information of the effect of smoking on pets, please check out the FDA website. Here’s the link: http://www.fda.gov/AnimalVeterinary/ResourcesforYou/AnimalHealthLiteracy/ucm520415.htm


-Bertone, E.R., et. al. ‘Environmental Tobacco Smoke and Risk of Malignant Lymphoma in Pet Cats’ J. Am. Epidemiology 2002; 156:268-273.

-Matt, G.E., et al. ‘When smokers move out and non-smokers move in: residential thirdhand smoke pollution and exposure.’ Tobacco Control 2011: 20(e1) 1-8.

-Reif, JJ. et al. ‘Cancer of the oral cavity and para-nasal sinuses and exposure to harmful tobacco smoke in pet dogs’ Am. J. Epidemiology 1988:  147(5):488-492.

-Schick, S. ‘Thirdhand smoke: here to stay’ Tobacco Control 2011:  20(1):  1-3.

-‘Be smoke-free and help you pets live longer, healthier lives.’ U.S. Food and Drug Administration Animal Health Literacy, last updated 9/22/16. www.fda.gov/AnimalVeterinary/ResourcesforYou/AnimalHealthLiteracy/ucm520415.htm

Histiocytic Sarcoma in Bernese Mountain Dogs, Retrievers and Rottweilers

Hstiocytic sarcoma (HS) is a malignant disease found most often in Bernese Mountain dogs, retrievers and rottweilers. Males are more commonly affected than females and it can occur at any age. It is also called Histiocytic sarcoma complex, malignant histiocytosis and disseminated histocytic sarcoma. There are two forms of the disease, localized or disseminated. The localized disease occurs when a lump or lumps are found in one specific area, usually on the legs and these have not spread to the lymph nodes. Localized HS tends to invade skin, subcutaneous tissue and joints. The disseminated disease occurs when tumor cells spread beyond the local lymph nodes to the lung, liver, spleen, gastrointestinal system, eyes, central nervous system, skin, muscles, bone and/or the bone marrow. The tumor is thought is arise from interstitial dendritic cells that become malignant.

The signs of HS vary widely due to the many different organs that can be involved. In the early stages of localized disease, most dogs have no clinical signs of disease. Usually, they come in for an examination after a lump is found. As the disease progresses, lethargy, anorexia, lameness and coughing are the most common clinic signs. Unless a mass is found and biopsied, diagnosis can be difficult due to the nonspecific clinical signs. Anemia is the most common abnormality on general lab work. Dogs may also have decreased numbers of white blood cells, increases in liver enzymes and an increased number of histiocytes in the blood and bone marrow. X-rays may show masses in the lung or mediastinum. These masses leak fluid causing pleural effusion affecting the dog’s breathing. X-rays may also show destruction of bone or joints.

Surgical removal of solitary nodules is the treatment of choice at this time. Dogs without evidence of cancer spread who underwent amputation of the affected limb lived 6 months. Dog who had chemotherapy with amputation lived an average of 19 months. Dogs with disseminated disease fare far worse. In one study, half of the dogs with HS responded to chemotherapy and lived an average of 6 months. Dogs who responded poorly to chemotherapy only survived for about 2 months.

To clarify, HS is not the same as cutaneous histiocytoma. Histiocytomas are benign tumors of young dogs. These pink raspberry looking masses occur in thinly haired areas on the legs, head and neck. They grow quickly and can resolve on their own. I see them most often in Boxers and Dachshunds although Cocker Spaniels, Great Danes, Shetland Sheepdogs and Bull Terriers are also reported in the literature.


-Shell, Linda. ‘Malignant Histocytosis/Histiocytic Sarcoma’ Associate Database, VIN, last updated 12/11/2003.

-Skorupski, Katherine. ‘The Histiocytic Diseases: A Clinical Perspective’ Canine Medicine Symposium 2009, UCDCM2009, VIN


Macadamia Nuts are Toxic to Dogs

As a veterinarian, I caution people about giving human food to dogs. That’s because dogs and people metabolize food differently. Macadamia nuts, raisins, grapes and sugar-free gums are some of the human foods that are toxic dogs. Although the exact mechanism for the toxicity is not known, it is thought to be from a serotonin like compound that may come from the nut, processing the nut or a contaminate associated with the nut. More information on serotonin syndrome may be found by visiting Dr. Nelson’s prior post or clicking here. Clinical signs start with weakness of the rear legs, vomiting and lethargy. As the toxin builds, the dogs often experience muscle tremors and weakness. The hind leg weakness progresses until the dog cannot stand.

Like most toxicities, treatment focuses on removing the toxin and treating the symptoms. If the dog isn’t vomiting already, this is one of those toxins in which it is recommended to remove the nuts from the stomach. If too much time has passed since ingestion, then activated charcoal is given to absorb toxins from the gastrointestinal system. To avoid aspiration into the lungs, charcoal is only given to conscious animals that can swallow. Enemas may also be needed to evacuate the nuts. Symptomatic treatment is tailored to the individual patient but often includes intravenous fluids and cooling with tepid baths, fans and  ice packs wrapped in towels on abdomen, neck and paws.

Unlike other compounds, the toxic effects of macadamia nut poisoning are relatively short-lived. With prompt medical attention, most dogs will make a full recovery within two days.

IMG_1905 (1)


-Shell, Linda. ‘Macadamia Nut Toxicosis’ Associate Database, VIN, 01/02/2006.


Serotonin Syndrome in Dogs and Cats

Serotonin is a neurotransmitter found in the central nervous system (CNS) which includes the brain and spinal cord.  It is also in the peripheral nervous system which is basically, the rest of the body. It is synthetized from an amino acid called tryptophan. According to Dr. Sharon Gwaitney-Brant, this important neurotransmitter is involved “. . . in the regulation of many CNS functions including personality/behavior, sleep, appetite, aggression, temperature regulation, sexual function, motor control, and pain perception. Peripherally, serotonin is involved in platelet aggregation, and stimulation of smooth muscle contraction regulating vasoconstriction, bronchoconstriction, intestinal peristalsis and uterine contraction.”

Serotonin syndrome is the term used to describe the clinical signs that occur when too much serotonin is found in the body. In veterinary medicine, the most common cause is an overdose of serotonergic drugs and supplements. The common history is when a veterinarian prescribes a drug that increases serotonin levels without knowing that the dog or cat is on a supplement that does the same. In my experience, this occurs most often when amitriptyline, buspirone, clomipramine or fluoxetine are combined with St. John’s wart. I have also seen it when animals are on a combination of serotonin elevating medications or when a dog or cat has been transitioned from one drug to another without allowing enough time for washout of the first drug. The worst cases occur when animals ingest large quantities of serotonergic drugs.

Signs of serotonin syndrome fall into three general categories depending upon the area of the nervous system being stimulated and can vary greatly from mild lethargy or restlessness to coma and death. The syndrome usually starts soon after ingestion with diarrhea, vomiting and a mild fever. As it progresses, dogs and cats are often ataxic which means they walk like they are drunk. By the time I usually see them, the animals are often experiencing seizures, are struggling to breathe and have dangerously high body temperatures of >105 F. If not quickly controlled, disseminated intravascular coagulation (DIC) occurs which usually results in the patient’s death.

As with all intoxications, quick medical care is the key to helping these patients. If you think your pet may be suffering from serotonin syndrome, bring them in for immediate care.


-Gwaltney-Brant, Sharon. ‘Serotonin Syndrome’. Associate Database, VIN, last updated 05/23/2011.

-Gwaltney-Brant, Sharon. ‘Serotonin Syndrome’. International Veterinary Emergency and Critical Care Symposium 2015.

Zika Virus in Dogs and Cats

Zika virus was first discovered in Africa back in the 1940’s in a monkey with a mild fever. Since then, the disease has spread all over the world. In humans, the virus causes a birth defect called microcephaly which means ‘small brain’. In animals, the virus has  been found primarily  in non-human primates. Most exposed monkeys and apes show no signs of illness. A small number will develop a mild, short-lived fever.  The virus tends to appear in monkeys and apes that live close to humans who have the virus. A recent study of Brazil’s monkeys identified the virus in a small number of monkeys. So far, no monkey or ape babies have been born with microcephaly from Zika. It is unclear at this time whether the monkeys and apes are getting the virus from humans or vice versa. The prevalence of the virus in non-human primates is also unknown.

Other than the non-human primates, there  is no evidence of Zika virus infections causing disease in other animals. One study from Indonesia performed in the 1970’s found that the virus could infect livestock and bats but there are no documented cases of any of these animals transmitting  Zika virus to humans. More research is needed to determine if Zika is a zoonotic disease meaning animals can infect people (examples are rabies, ringworm and leptospirosis) or a reverse zoonotic disease meaning people infect  (example is MRSA ).

Like dengue fever, yellow fever and West Nile virus, Zika virus is transmitted  by mosquitos of the Andes species. Female mosquitos need the protein contained in blood to lay eggs. When mosquitos bite, they inject saliva into the wound that contains an anticoagulant to keep the victim’s blood from clotting. Their saliva can contain all kinds of infectious agents including viruses, bacteria and parasites (heartworm disease, malaria, etc.) contracted from prior victims. Once infected, a single mosquito can transmit disease to many animals and/or people.  When monkeys and apes are infected with Zika, they develop antibodies against the virus in approximately 14 days. The antibodies clear the virus out of the blood stream stopping the spread of the disease. Since monkeys and apes are quarantined in screened in facilities for 31 days when entering the United States, this should prevent the disease spreading into local mosquitos. Currently, it is unknown if monkeys and apes are reservoirs for the disease.

The bottom line is that Zika virus is not a threat to dogs and cats. There are no studies that show canines or felines can be infected with the virus or spread it to humans.


-‘Questions and Answers: Zika Virus and Animals’, ARIZONA VETERINARY NEWS, Aril 2016.

-‘Zika and Animals: What we know.’ CENTERS FOR DISEASE CONTROL AND PREVENTION, Update June 8, 2016.

Heat Exhaustion in Dogs and Cats

Heat exhaustion is a life-threatening condition that occurs in animals of all kinds. It is also called heat stress, heat stroke and hyperpyrexia. In the clinic, I see it most often in dogs. When dogs and cats are not able to dissipate heat, their body temperature soars well above the normal range of 100 to 102.5 degrees Fahrenheit. If the body temperature rises over 105.5, the internal organs are injured.  Kidney failure, liver disease, clotting problems, bloody diarrhea, vomiting, gastric ulceration, seizures and coma are a few of the conditions that may occur. Even with aggressive treatment, the prognosis is poor.

In my experience, heat stroke occurs most often when animals with problems cooling themselves are exposed to excessive heat and/or humidity. Here is a list of the health factors associated with heat exhaustion:

  1. Obesity
  2. Brachiocephalic breeds (The short and broad head is often associated with narrowed nostrils, elongated soft pallets and narrowed windpipes making it difficult to breathe.)  – In dogs this includes bulldogs of all varieties, Shih Tzu, Lhasa apsos, Boxers, Pugs and Pekinese. In cats, Persians and Himalayans are brachiocephalic. Some of these breeds like boxers and mastiffs are also heavily muscled which compounds the problem.
  3. Laryngeal paralysis
  4. Heavy coated breeds – Long hair cats especially Maine coon cats, Siberian huskies, Samoyeds,  Malamutes, etc

Environmental factors also play a huge role in causing heat exhaustion. Every summer, I am saddened to hear of children and pets who died after being left in a car. In climates with extreme temperatures including Las Vegas and Phoenix, leaving a pet outside can kill them. Recently, the evening news reported the death of a Labrador retriever who was left on an apartment balcony. I have seen animals develop heat stroke from the blowers used after grooming. High humidity is also lethal because panting isn’t as effective.

If you live with a pet prone to heat stroke, please keep them out of the heat.  I have seen heat stroke develop in as little as five minutes in geriatric pets who went outside and then couldn’t get back in the doggy door.  Watch for rapid respirations, a depressed attitude and dark red gums.  They may also experience vomiting and diarrhea.  If the dog is not cooled off quickly, their condition rapidly deteriorates into bloody vomiting, collapse, bloody diarrhea, seizures and problems breathing.  When the gum color changes into a sick, pale gray I know death is coming.

To prevent heat stroke, keep your pet at a healthy weight.  Take walks and play ball early in the morning when temperatures are mild.  Limit their time outdoors during the heat of the day to a quick trip to urinate and/or defecate in the shade.  Then, return to air conditioning.  Last, watch their tongues closely for a change in color.  If their normal pink color deepens to purple or lilac, it is time to get indoors.  I know we all like to have our pets with us to soccer and baseball games, but sometimes the safest and most loving thing to do is leave them home.  They can help you celebrate after the event!



Shell, L. “Heat Prostration”, Associate Database – VIN, last updated 8/11/2007.

You Make The Diagnosis: Dental Fracture In Dogs

Pictured below is the right side of a dog’s mouth. During her annual exam, I noticed an abnormality on her upper fourth premolar called a slab fracture. Part of the enamel had fractured away from the rest of the tooth exposing the pulp cavity. The gingival tissue is still attached which holds it in place. With the  nerves exposed, the tooth was painful. It was also infected. The tooth was removed and now this dog is pain free. Please study the picture then answer the following questions: What is this fracture called?  What causes this type of injury to occur?

slab fracture

Diagnosis: Slab Fracture

Chewing on hard objects is the cause of these fractures. Here is a list of the most common objects that I have seen cause slab fractures in my canine patients:

  1. Cow hooves
  2. Ice cubes
  3. Bones
  4. Hard toys such as Nylabones. The gumabones from the same company are softer.
  5. Deer antlers

When deciding what to let your dog chew on, remember the advice given by the veterinary dentist, Dr. Steve Holmstrom. He discourages people from giving their dogs anything that doesn’t bend or break easily, anything that makes you grimace at the thought of chewing it yourself and anything that would hurt if it hit your kneecap.

Leptospirosis in Dogs

Leptospirosis is a serious disease that affects dogs, cats, horses, swine, sheep, goats, deer, marine mammals and humans. The disease starts when leptospires, the immature form of the bacteria, enter the body and make their way into the bloodstream. They stick to the endothelial cells within the blood vessels causing severe vasculitis (inflammation). As the organism replicates it causes more and more damage to the blood vessels. Eventually, the blood vessel walls begin to hemorrhage. The liver and kidneys are the two organs that are affected most often, but the bacteria can also attack the spleen, eyes, nervous system and reproductive organs. Once an animal is infected, they may shed the organism for years and thus infect others.

There are two species of Leptospira that are further divided into over 250 smaller groups called serovars. The most common serovars and the animals that are asymptomatic hosts in the United States are: grippotyphosa carried by raccoons, bratislava carried by rats and horses, autumnalis carried by mice and pomona carried by cows and pigs. Dogs infected with canicola, bratislava and grippotyphosa usually have severe kidney disease with mild liver disease. Dogs with icterohaemorrhagiae and pomona have more liver disease. Pomona is associated with the most severe kidney disease and has the worst prognosis.

Leptospira bacteria like to live in warm moist environments with alkaline soil. Under these conditions, the bacteria can survive for months. Infections occur through direct exposure to the urine, saliva (bite wounds) or tissues of animals infected with the disease.  It can also be contracted indirectly by contact with water, soil, food or bedding that is contaminated with the organism. The leptospires can penetrate mucous membranes and damaged skin.  In the February 2016, nine dogs tested positive for this disease in Scottsdale, Arizona. It is thought that heavy storms left standing water that was contaminated by pack rats. Unfortunately, two died.

Signs of leptospirosis vary greatly from mild malaise to death. The incubation period is usually 7 days. The most common signs in dogs in the early phase are fever, shivering, lethargy, decreased appetite and muscle tenderness. As the disease progresses, increased thirst and urination, abdominal pain, vomiting, eye disease, diarrhea, joint stiffness, bruising of the skin, coughing and a runny nose are just a few of the symptoms that can occur.  The exact symptoms depend upon which organ is affected. Animals with liver involvement become jaundiced (yellow color of the skin). If the nervous system is involved, animals may seizure, have problems walking or suffer neurologic deficits.

Diagnosis of leptospirosis requires special testing to identify the organism. Routine blood work, urinalysis and clotting tests will make it a rule-out but not make the diagnosis. 87-100% of dogs present with elevated creatinine and BUN. The specific tests for this bacteria are listed as follows: 1) Microscopic Agglutination Test – This is the most common test in veterinary medicine. Blood is collected for measurement of the titer. Since this test is a measurement of the antibodies generated against the bacteria, it will be negative early in the disease. It usually takes about 7-10 days for antibodies to be found. 2) ELISA Testing – This test is another antibody test that is sometimes used to distinguish vaccination titers from naturally occurring infections. 3) Polymerase Chain Reaction Assays – This test identifies the nucleic acid of leptospires which means it does not require production of antibodies. Early in the disease, the test is performed on blood. After 10 days, urine is used instead because higher numbers of the leptospires are found there. Unfortunately, the test may give a false negative result if the patient is receiving antibiotics. This is the test used to detect dogs who are carriers of leptospirosis. 4) Culture – Growing this bacteria is difficult because it requires specific conditions and grows slowly.

Antibiotics are used to treat leptospirosis. Due to the severity of this disease, treatment with doxycycline is started while waiting for test results. Most dogs will also require hospitalization with fluid therapy and careful monitoring of their kidney function. Since leptospirosis is a zoonotic disease, the dog must be kept in strict isolation. Caregivers should take precautions to prevent contracting or spreading the disease including waterproof gowns, gloves and face shields. All waste must be carefully collected and disposed of properly.

Prevention is the key to dealing with leptospirosis. Thankfully, there are two vaccines available for dogs in the United Sates. One is a bivalent which means it only contains two serovars, icterohaemorrhagiae and canicola. I recommend the other vaccine which contains 4 serovars – canicola, icterohaemorrhagiae, grippotyphosa and pomona. This vaccine is licensed for pups 6 weeks and older. The manufacturer recommends 2 doses of the vaccine given 2-3 weeks apart and then boosted annually.


-Adams, Laura. Canine Leptospirosis in Arizona, Arizona Veterinary News, Arizona Veterinary Medical Association, March 2016.

-Morgan, Rhea. Leptospirosis (Zoonotic), Associate Database, Veterinary Information Network, 1/29/2014, Last updated by Kari Rothrock 1/20/2012.

You Make The Diagnosis: Thickened Black Skin in Dogs

The pictures below are of the abdominal skin of a dog. The skin is black in color and thickened like an elephant’s skin. Although this dog developed it on the abdomen, it can also commonly occur around the anus, underarms and muzzle. Look closely at the pictures and then answer the following questions: What is the term used to describe this kind of skin?  What causes this condition to occur?

photo 1 (8)

photo 2 (7)

Diagnosis: Lichenification

Lichenification is the term used to describe skin that looks like elephant skin. Here are the most common causes of this condition ranked in the order I see them:

  1. Food Allergy
  2. Pyoderma – Bacterial infection of the skin
  3. Malassezia Dermatitis – Fungal infection of the skin by an organism called Malassezia
  4. Atopic Dermatitis – This is often simply called allergies or environmental allergies
  5. Demodectic Mange – I have seen dogs with lichenification of all their skin from demodex mites
  6. Cutaneous Diroflilariasis
  7. Primary and Secondary Acanthosis Nigrans

Chocolate Toxicity In Pets

Chocolate is one of the most common toxicities I see, especially around Christmas and Valentine’s Day. Pets climb counters to get to candy dishes and desserts. They also rip open boxes of chocolates wrapped as gifts. One of my patients, a cocker spaniel, ate a 5 pound box of dark chocolate that was left under the tree.  They found him unconscious on his doggy bed.

Chocolate contains caffeine and theobromine which are toxic to animals.  This fact surprises a lot of people because humans are fairly resistant to this class of drugs. We can drink a lot of coffee and eat chocolate without too many problems. But dogs are much more sensitive to the effects of these chemicals. The half life of caffeine in dogs is 4.5 hours while the half life of theobromine is 17.5 hours!

The amount of these two chemicals varies with the type of chocolate. Milk chocolate contains the least amount of caffeine and theobromine while the bitter chocolate used in cooking contains the most. Dark chocolate falls in between. The general rule that I was taught in veterinary college is the more bitter the chocolate, the more of these chemicals and the greater the danger of poisoning.

Clinical signs of chocolate toxicity depend upon the amount of theobromine and caffeine ingested i.e., the type and amount of chocolate and the size of the pet. A golden retriever who steals a dark chocolate candy bar may show no signs of toxicity whereas a Chihuahua may develop seizures. In general, signs of mild toxicity include an increased heart rate and hyperactivity which many people wrongly attribute to the sugar high.  After the initial rush, some dogs will develop gastrointestinal signs including vomiting and diarrhea. Others drink and urinate excessively. Dogs who ingest large amounts of chocolate often seizure and may die.

Treatment of chocolate toxicity usually starts with ‘decontamination’ which means removing the toxin. If the dog is conscious, vomiting is induced to get rid of as much of it as possible. After the stomach is empty, the dog is given charcoal to absorb the remaining chocolate once they have stopped vomiting. The rest of therapy is tailored to the patient. Seizures are treated with anticonvulsant medications, life threatening ventricular tachycardia is slowed with heart drugs such as lidocaine or propranolol and stomach ulcers are given gastrointestinal protectants. The cocker spaniel mentioned above spent 3 days in the hospital on IV fluids and anticonvulsant therapy. For the first day, diarrhea poured out of his anus.  It looked and smelled like chocolate. He was one of the lucky ones. Unfortunately, he still liked chocolate. His family said he managed to grab a brownie about a week after his ordeal.

If your pet ingests chocolate, contact your veterinarian or the Pet Poison Helpline right away. Have the type of chocolate, quantity of chocolate and weight of the pet ready when you call. The number for Pet Poison Helpline is: 800.213.6680. More helpful information on poison of all kinds can be found at www.petpoisonhelpline.com.


-Shell, Linda. “Xanthine Toxicosis” VIN Associate, Lasted updated 1/17/2006.