Rattlesnake Bites in Dogs

Rattlesnakes are highly adaptable venomous snakes that live thoughout the continental United States. They are members of the Crotalidae family of venomous snakes which is a subfamily of vipers. Beside rattlesnakes, this group includes water moccasins and copperheads. This group does not include coral, mamba or sea snakes which are part of the Elapidae family.

Vipers inject venom into prey through two large fangs that protrude from the upper jaw. The venom is a mix of toxins and enzymes that will immobilize the prey and destroy the tissue in the area of the bite which allows the venom to spread more quickly. It includes myotoxins, cytotoxins, neurotoxins, cardiotoxins and hemorrhagic toxins. The venom from rattlesnakes is the most toxic followed by venom from water moccasins and copperheads in that order. The snake controls how much venom is injected per strike. Young snakes tend to deliver their entire load of venom whereas mature snakes may not inject any venom at all. This is referred to as a ‘dry bite’.

Swelling, bruising and pain are the most common clinical signs of a snake bite. Dogs are often bit on the head or legs which is a good thing because the venom spreads more slowly from these areas when compared to the torso. Swelling develops quickly and may cause airway obstruction. Snake bites are very painful! Dogs will yelp, moan and cry if the affected area is touched. The venom also interferes with the victim’s ability to clot their blood. Bleeding from the nose, mouth and eyes as well as bloody urine or feces are common. If this isn’t bad enough, some rattlesnake venom contains neurotoxins. Dogs may suffer a variety of neurologic signs from difficulty walking to paralysis, seizures to coma.

The goal of treatment is to neutralize the venom with antivenom as soon as possible. Best outcomes occur when the antivenom is given within 4 hours of the bite. The antivenom is made of antibodies, either the entire IgG or fragments of IgG, given through an intravenous catheter.  Again, time is of the essence.  In addition, patients need fluid therapy to treat shock and strong pain management. Some patients may need blood transfusions if bleeding is severe. Unfortunately, even with aggressive therapy, some dogs will not make it. Pictured below is a dog who was bitten on the left side of the lip by a Western Diamondback Rattlesnake. Severe swelling was noted on the lip and neck. This dog was treated with ‘Rattler’ Antivenom. This is the only antivenon that has antibodies against the Mohave rattlesnake venom. The swelling started to recede within ten minutes of starting treatment and she made a complete recovery!

Prevention of snake bites:

  1. Snake Avoidance Training – In areas with a lot of indigenous venomous snakes, many dog training centers offer snake avoidance training. The dog is fitted with an electric (shock) collar then exposed to the snake that is either in a cage or wearing a hood to prevent a strike. When the dog smells the snake, they receive a small shock and are taken away from the snake. A few minutes later, the dog is exposed to the snake again. Most dogs, will freeze instantly and then leave the area. If they continue toward the snake, a stronger shock is administered until the dog gives up. This type of training works well for confident dogs but I do not recommend it for timid dogs.
  2. Crotalus Atrox Vaccine (Rattlesnake Vaccine) – Red Rock Biologics produces a vaccine for rattlesnake bites. Unfortunately, there is a lot of confusion surrounding this product. It is not a true vaccine that protects the pet from disease like the rabies vaccine. Instead, the crotalus atrox vaccine gives the dog more time to get treatment. The dog pictured above had the crotalus atrox vaccine a month and a half before the bite occurred. Most of the dogs I vaccinate live on ranches or go hiking and camping in remote areas where it may take hours to get treatment. Unfortunately, I have seen some bad reactions in my patients from this vaccine. Also, this vaccine stimulates antibodies against the Western Diamondback rattlesnake. Although the antibodies cross react with some other rattlesnakes but does not stimulate antibodies against the neurotoxin in Mohave rattlesnakes. Please discuss the pros and cons with a veterinarian before use.
  3. Prevent Snake Exposure – Snakes follow their noses to prey. Keep rats, mice and other rodents away from homes by making the environment less inviting. Keep citrus picked up and pet food indoors. Install snake fencing to keep reptiles out. Pictured below are some ideas to help you snake proof your yard. The first one if a gate showing the gate resting on pavers without a gap. The gate actually rubs the pavers when opened. The screen extends on both sides to cover the gaps that occur. The second image shows screen wired to a combination block and iron fence. The screen extends to the block without any gaps. The brush has been removed from both sides of the fence to make the area less hospitable for rodents and snakes. It also provides a defensible space in case of fire. Drains in the wall need to be covered with screen as well.


-Rothrock, Kari. ‘Snake Evenomation, Crotalid’. VIN Associate Database, last updated 10/26/2017.



Holiday Dangers for Pets

Winter holidays are fun but can present dangers for pets. Here are some of the common hazards for dogs and cats:

  1. Chocolate – 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.
  2. Lilies – Lilies cause severe kidney problems (renal tubular necrosis) within two to three days of ingestion.   All parts of the plant are poisonous including the pollen.  In my experience, cats are more attracted to these plants than dogs. If your pet is exposed, bring them in for veterinary care immediately!  This is not something you can treat at home.
  3. Poinsettias – These plants irritate the mouth and stomach leading to vomiting and gastrointestinal upset. Despite the hype, I have never seen any serious toxicity from poinsettias ingestion.
  4. Mistletoe – At high doses, this plant can cause cardiovascular disease.
  5. Christmas Tree Water – Bacterial overgrowth often develops in the stagnant Christmas tree water. The water may also contain fertilizers. To be safe, use water free of additives and change it out at regular intervals.
  6. Batteries – batteries are extremely toxic to animals. Most batteries contain a strong acid or alkaline material that will burn any tissue it contacts. Some batteries emit an electrical current that causes severe electrical burns. Batteries may also contain heavy metals such as zinc, mercury and lead which are poisonous.
  7. Escape – During parties, open doors and gate provide opportunity for escape. In my practice, we see the most lost pets during holiday parties.
  8. Antifreeze – Antifreeze causes serious kidney damage and often death. If there is even a remote chance that your pet has ingested antifreeze, seek immediate medical care. Treatment will only help if given early to prevent kidney destruction.
  9. Electric cords – Electrocution is a big problem when the decorations go up. Keep pets away from electrical cords at all times.
  10. Tinsel and Ribbon – Tinsel and ribbon can cause serious damage to the intestines when eaten.
  11. Potpourris –  Dry potpourris may contain toxic plants or cause obstruction when eaten. The simmer pots can also be dangerous if the pet drinks it or gets it on their fur.
  12. Candles – Thermal burns are common during the holidays. I see a lot of cats with singed whiskers.
  13. Xylitol – Xylitol is an artificial sweetener used in many products including gum, mints, candy and even baked goods.  When dogs ingest this compound, it causes insulin release from the islet cells of the pancreas.  The insulin causes a drop in blood sugar.  The drop is dose dependent which means the bigger the dose the more severe the drop in blood sugar.  Dogs who ingest toxic doses of xylitol may be depressed, shaky on their feet, tremor and even seizure if blood sugar drops low enough.  This effect lasts about twelve hours.
    In addition to causing excessive insulin release, xylitol also harms the liver by causing necrosis. In my experience, the liver enzymes begin to rise about 12 hours after ingestion and peak about two days later.  The full extent of liver damage may not be known for several days.  Unfortunately, there are no antidotes for this poison in dogs.  Victims of xylitol toxicity are treated symptomatically.
  14. Ornament Dough – Ornament dough contains high levels of salt that is dangerous to dogs and cats. Ingestion of a large amount can cause severe neurological disease including seizures.


-Lee, Justine A. ‘Holiday Dangers Poisonous to Dogs and Cats’ Midwestvet.net/resources/articles. Dec. 2016, pp 11-12.                           -Wisner, Tina, ‘Winter Holiday Hazards for Pets’ VIN Veterinary Partner, Published Dec. 11, 2001 and revised June 7, 2010.

You Make The Diagnosis: Name This Fecal Parasite Found in Dogs

Pictured below is a worm that was found crawling on the fur around the anus of a dog. The owner also found more of the worms on the dog’s stool. Study the picture of this flat, off-white colored worm and then answer the following questions: 1) What is the name of this parasite? 2) How is it differentiated from maggots? 3) How are animals infected?


Diagnosis: Tapeworm Taenia pisiformis and Dipylidium caninum are the most common types in dogs.

The worm or parasite in the picture is a tapeworm segment.  Unfortunately, no eggs were found during fecal analysis to determine the exact species. The segments of tapeworms are flat whereas maggots are round. Dried segments look like grains of rice. Tapeworms are made up of a head and neck followed by segments that make up the rest of the body. Each segment absorbs nutrients from the small intestine of the host. Segments at the end of the worm, break off and are discarded in the feces. Fleas eat the segments releasing the eggs inside. Dogs and cats are infected when they eat fleas.


-Rothrock, Kari. ‘Tapeworm Infestation’ Associate Database, VIN last updated 10/31/2012.

You Make The Diagnosis: Abnormal Bowel Function In Cavalier King Charles Spaniel

Pictured below is an X-ray of a Cavalier King Charles Spaniel. The dog’s belly was distended and painful. This patient was also having problems walking.  The dog had been normal up until a few days ago. Study the film and then answer the following questions: 1) What is the gastrointestinal condition seen in this X-ray? 2) Does the dog have any orthopedic or neurological conditions? 3) What sex is this dog? 4) Does this dog suffer from anorexia?

Whidby ConstipationIVD Xray before

Whidby ConstipationIVD Xray before annotated


  1. Constipation – The colon is distended with feces. It is so full that gas is accumulating in the small bowel causing bloating. (Marked with yellow lines that extend from side to side.)
  2. Intervertebral Disc Disease – Look closely at the vertebra between the ribs and pelvis. The disc spaces between lumbar vertebra 2-3, 3-4 and 4-5 are narrowed which indicates a disc problem. (The disc space marked with a red circle is L3-4.  L2-3 is to the left of the circle and L4-5 is the the right.)
  3. Bridging Spondylosis – On the bottom of the 3rd and 4th lumbar vertebra, an abnormal outgrowth of bone is forming. The bone is trying to bridge the gap between the two vertebrae to stabilize the joint. (Marked with the red circle.)
  4. Male – Dogs have a bone in their penis that shows up on X-rays. Look at the right side of the X-ray just in front of the femur to see a long narrow bone lying under the abdominal wall. (Marked with a blue box.)
  5. This dog has a great appetite. His stomach is full of food with a little gas. (Marked with white star.)

Treatment of this dog started with an injection of an opioid to relieve pain and an enema to evacuate the colon. After two enemas, the bloating and feces were gone. Although there was still gas in the intestines, the little guy felt so much better. I think his constipation occurred because his disc disease was either making it too painful to defecate and/or it was interfering with nerve function in the colon. He was discharged with medication to soften his stools as well as medication for his back.

Here is the X-ray taken after the enema. Now his intestines are filled with gas which looks black on X-rays.

Whidby Constipation IVD Xray After


This Is Why Your Dog Needs A Dental With Anesthesia

Dental disease is the most common problem I see in dogs and cats. During physical examination, I look for large accumulations of tartar, inflammation of the gums, masses, fractured teeth and other problems. Pictured below is the mouth of a dog before having a complete oral examination including dental X-rays and treatment.


See the severe accumulation of tartar on the upper premolar and molar?  The tip of the large canine tooth as well as the back surface is worn creating a large defect in the enamel.  Now look on the inside of the teeth on the other side of the jaw. The premolars and molars located on the right side of the picture are stained and covered with tartar.

After dental X-rays were taken to look for problems below the gum line, the treatment could finally begin. The first step was to remove the large chunks of tartar or calculus from the surface of the teeth. (Calculus is pictured below.)

Tartar Snip

Then an ultrasonic scaler was used to remove smaller pieces of tarter. The tip must be kept moving at all times to prevent damage to the enamel surface of each tooth. After the crowns (exposed surface of each tooth) is cleaned, the area below the gums are scaled by hand to remove calculus and infection. In my opinion, if this step is not performed, the dental is worthless. The last step in the dental  is polishing all the surfaces and treating all problems that were found. This dog has periodontal pockets of infection that were cleaned, polished and packed with an antibiotic gel.


In this ‘after’ picture, note the bleeding along the gum line of the premolar and molar. The tartar extended under the gums causing severe inflammation and infection. The damage gums bleeds after treatment but will heal if kept clean. If the area under the gums had not been cleaned, the infection would have spread up the root. The dog would have been in extreme pain until the tooth was removed. That is why I consider anesthesia-free dentals malpractice. Cleaning the crowns make the teeth look good but does nothing for the areas under the gums – the roots. Also, without anesthesia it is very difficult to clean the inside surfaces of the crowns and polish. I have seen an image of a cat who had their tongue almost ripped-off during an anesthesia-free dental. The damage was so severe that the cat couldn’t eat and was euthanized.